1
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Shan T, Chen L, Guo Z, Xiao D, Wang M, Xiao X, Li G, Huang F. Designing High-Mechanical-Property Organic Polymeric Crystals: Insights from Stress Dispersion and Energy Dissipation Strategies. J Am Chem Soc 2025; 147:17477-17485. [PMID: 40343493 DOI: 10.1021/jacs.5c04397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2025]
Abstract
Despite recent significant advancements in the applications of organic polymeric crystals (OPCs), a comprehensive understanding of the design principles for high-mechanical-property crystals remains somewhat elusive. Here, we investigate the mechanical properties of OPCs from the perspectives of stress dispersion and energy dissipation by examining crystals of a macrocycle and three analogous polymers with different solvent fillings, utilizing a novel research platform constructed via dative B-N bonds. Through a thorough mechanical study and investigation into the molecular mechanisms of these model topologies, it was demonstrated that structural expansion and solvent filling are effective pathways for enhancing the mechanical performance of the OPCs by employing stress dispersion and energy dissipation strategies. Overall, our research showcases precise control over the molecular topology of the OPC materials and elucidates specific pathways for stress dispersion and energy dissipation in modulating their mechanical performance, offering a broader design perspective for efficiently enhancing the mechanical properties of other crystalline polymers, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs).
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Affiliation(s)
- Tianyu Shan
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Liya Chen
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Zhewen Guo
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ding Xiao
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Mengbin Wang
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Xuedong Xiao
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Guangfeng Li
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
| | - Feihe Huang
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
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2
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Bowser BH, Brown CL, Meisner J, Kouznetsova TB, Martinez TJ, Craig SL. Structure-property relationships for the force-triggered disrotatory ring-opening of cyclobutene. Chem Sci 2025; 16:7311-7319. [PMID: 40051651 PMCID: PMC11881290 DOI: 10.1039/d5sc00253b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2025] [Accepted: 02/10/2025] [Indexed: 03/09/2025] Open
Abstract
Symmetry forbidden reactions are notoriously difficult to study experimentally, for the simple reason that their competing symmetry allowed pathways typically dominate. Covalent polymer mechanochemistry offers an opportunity to broaden access to symmetry forbidden reactions, through the judicious placement of polymer handles on mechanophore reactants. Here, single molecule force spectroscopy and computation are used to evaluate substituent effects on the disrotatory ring opening reaction of cyclobutene to butadiene. Theory and experiment reveal that the formally forbidden reaction is more sensitive to substituents on the scissile carbon-carbon bond than on the alkene, with each of two Me substituents providing approximately 1.5-2 kcal mol-1 of stabilization and a trimethylsilyl alkyne substituent approximately 4.5-6.5 kcal mol-1.
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Affiliation(s)
| | | | - Jan Meisner
- Department of Chemistry, Stanford University Stanford CA USA
| | | | - Todd J Martinez
- Department of Chemistry, Stanford University Stanford CA USA
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3
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Xu D, Wang M, Huang R, Stoddart JF, Wang Y. A Dual-Pathway Responsive Mechanophore for Intelligent Luminescent Polymer Materials. J Am Chem Soc 2025; 147:4450-4458. [PMID: 39849299 DOI: 10.1021/jacs.4c15655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2025]
Abstract
Mechanoluminescent units, when integrated into polymer matrices, undergo structural transformations in response to mechanical force, resulting in changes in fluorescence. This phenomenon holds considerable promise for the development of stress-sensing materials. Despite the high demand for robust, tunable mechanoluminescent mechanophores for force assessment and smart force-responsive materials, strategies for their design and synthesis remain underdeveloped. In an attempt to address this challenge, we have introduced a novel dual-pathway responsive mechanophore, bis(2-(2-(tert-butyldimethylsilanyloxy)benzylidene)amino)aryl disulfides (SSTBS), which, when incorporated into polymer chains, exhibits fluorescence upon the combined application of force and chemical stimulus, irrespective of their sequence. This property is facilitated by the disulfide bond's sensitivity to mechanical force and the fluoride anion-induced desilylation and deprotonation. Notably, the force-responsive threshold of the SSTBS mechanophore can be finely tuned by TBAF treatment, as supported by both experimental and computational studies, providing a simple, yet effective means, to regulate polymer force responsiveness on demand. We believe that the strategy developed in this investigation will shed light on the design of mechanophores for the fabrication of intelligent luminescent polymer materials and advance the development of smart force-reporting systems.
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Affiliation(s)
- Dejing Xu
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
| | - Maolin Wang
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
| | - Ruozhou Huang
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
| | - J Fraser Stoddart
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, P. R. China
- Weinberg College of Arts and Science, Northwestern University, Evanston, Illinois 60208, United States
- Department of Chemistry, University of Hong Kong, Kowloon Hong Kong SAR 999077, PR China
- Center for Regenerative Nanomedieine, Northwestern University, Chicago, Illinois 60611, United States
- School of Chemistry, University of New South Wales, Sydney 2052, Australia
| | - Yuping Wang
- Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou 310058, PR China
- Zhejiang-Israel Joint Laboratory of Self-Assembling Functional Materials, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311215, PR China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311215, P. R. China
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4
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Wang C, Boulatov R. Autonomic Self-Healing of Polymers: Mechanisms, Applications, and Challenges. Molecules 2025; 30:469. [PMID: 39942572 PMCID: PMC11821010 DOI: 10.3390/molecules30030469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2024] [Revised: 01/14/2025] [Accepted: 01/14/2025] [Indexed: 02/16/2025] Open
Abstract
Mechanical loads degrade polymers by enabling mechanochemical fragmentation of macromolecular backbones. In most polymers, this fragmentation is irreversible, and its accumulation leads to the appearance and propagation of cracks and, ultimately, fracture of the material. Self-healing describes a diverse and loosely defined collection of approaches that aim at reversing this damage. Most reported synthetic self-healing polymers are non-autonomic, i.e., they require the user to input free energy (in the form of heat, irradiation, or reagents) into the damaged material to initiate its repair. Here, we critically discuss emerging chemical approaches to autonomic self-healing that rely on regenerating the density of load-bearing, dissociatively-inert backbone bonds either after the load on a partially damaged material dissipated or continuously and in competition with the mechanochemically driven loss of backbones in the loaded material. We group the reported chemistries into three broad types whose analysis yields a set of criteria against which the potential of a prospective approach to yield practically relevant self-healing polymers can be assessed quantitatively. Our analysis suggests that the direct chain-to-chain addition in mechanically loaded unsaturated polyolefins is the most promising chemical strategy reported to date to achieve autonomic synchronous self-healing of practical significance.
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Affiliation(s)
- Chenxu Wang
- College of Chemistry and Chemical Engineering, Xi’an University of Science and Technology, Xi’an 710054, China;
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK
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5
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Zhang C, Kouznetsova TB, Zhu B, Sweeney L, Lancer M, Gitsov I, Craig SL, Hu X. Advancing the Mechanosensitivity of Atropisomeric Diarylethene Mechanophores through a Lever-Arm Effect. J Am Chem Soc 2025; 147:2502-2509. [PMID: 39793028 PMCID: PMC11760174 DOI: 10.1021/jacs.4c13480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2024] [Revised: 12/11/2024] [Accepted: 12/12/2024] [Indexed: 01/12/2025]
Abstract
Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties, yet SMARs in noncovalent mechanical transformations remain relatively underexplored. In this study, we designed a subset of diarylethene mechanophores based on a lever-arm hypothesis and systematically investigated their mechanical activity toward a noncovalent-yet-chemical conversion of atropisomer stereochemistry. Results from Density functional theory (DFT) calculations, single-molecule force spectroscopy (SMFS) measurements, and ultrasonication experiments collectively support the lever-arm hypothesis and confirm the exceptional sensitivity of chemo-mechanical coupling in these atropisomers. Notably, the transition force for the diarylethene M3 featuring extended 5-phenylbenzo[b]thiophene aryl groups is determined to be 131 pN ± 4 pN by SMFS. This value is lower than those typically recorded for other mechanically induced chemical processes, highlighting its exceptional sensitivity to low-magnitude forces. This work contributes a fundamental understanding of chemo-mechanical coupling in atropisomeric configurational mechanophores and paves the way for designing highly sensitive mechanochemical processes that could facilitate the study of nanoscale mechanical behaviors across scientific disciplines.
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Affiliation(s)
- Cijun Zhang
- Department
of Chemistry, BioInspired Institute, Syracuse
University, Syracuse, New York 13244, United States
| | | | - Boyu Zhu
- Department
of Chemistry, BioInspired Institute, Syracuse
University, Syracuse, New York 13244, United States
| | - Liam Sweeney
- Department
of Chemistry, BioInspired Institute, Syracuse
University, Syracuse, New York 13244, United States
| | - Max Lancer
- Department
of Chemistry, BioInspired Institute, Syracuse
University, Syracuse, New York 13244, United States
| | - Ivan Gitsov
- Department
of Chemistry, The Michael M. Szwarc Polymer Research Institute, State University of New York - ESF, Syracuse, New York 13210, United States
- Department
of Biomedical and Chemical Engineering, BioInspired Institute, Syracuse University, Syracuse, New York 13244, United States
| | - Stephen L. Craig
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Xiaoran Hu
- Department
of Chemistry, BioInspired Institute, Syracuse
University, Syracuse, New York 13244, United States
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6
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Wang C, Sun CL, Boulatov R. Productive chemistry induced by mechanochemically generated macroradicals. Chem Commun (Camb) 2024; 60:10629-10641. [PMID: 39171460 DOI: 10.1039/d4cc03206c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Large or repeated mechanical loads degrade polymeric materials by accelerating chain fragmentation. This mechanochemical backbone fracture usually occurs by homolysis of otherwise inert C-C, C-O and C-S bonds, generating highly reactive macroradicals. Because backbone fracture is detrimental on its own and the resulting macroradicals can initiate damaging reaction cascades, a major thrust in contemporary polymer mechanochemistry is to suppress it, usually by mechanochemical release of "hidden length" that dissipates local molecular strain. Here we summarize an emerging complementary strategy of channelling mechanochemically generated macroradicals in reaction cascades to form new load-bearing chemical bonds, which enables local self-healing or self-strengthening, and/or to generate mechanofluorescence, which could yield detailed quantitative molecular understanding of how material-failure-inducing macroscopic mechanical loads distribute across the network. We aim to identify generalizable lessons derivable from the reported implementations of this strategy and outline the key challenges in adapting it to diverse polymeric materials and loading scenarios.
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Affiliation(s)
- Chenxu Wang
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an 710054, China.
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
| | - Cai-Li Sun
- College of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi'an 710054, China.
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
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7
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O'Neill RT, Boulatov R. Mechanochemical Approaches to Fundamental Studies in Soft-Matter Physics. Angew Chem Int Ed Engl 2024; 63:e202402442. [PMID: 38404161 PMCID: PMC11497353 DOI: 10.1002/anie.202402442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 02/24/2024] [Accepted: 02/25/2024] [Indexed: 02/27/2024]
Abstract
Stretching a segment of a polymer beyond its contour length makes its (primarily backbone) bonds more dissociatively labile, which enables polymer mechanochemistry. Integrating some backbone bonds into suitably designed molecular moieties yields mechanistically and kinetically diverse chemistry, which is becoming increasingly exploitable. Examples include, most prominently, attempts to improve mechanical properties of bulk polymers, as well as prospective applications in drug delivery and synthesis. This review aims to highlight an emerging effort to apply the concepts and experimental tools of mechanochemistry to fundamental physical questions in soft matter. A succinct summary of the state-of-the-knowledge of the field, with emphasis on foundational concepts and generalizable observations, is followed by analysis of 3 recent examples of mechanochemistry yielding molecular-level details of elastomer failure, macromolecular chain dynamics in elongational flows and kinetic allostery. We conclude with reasons to assume that the highlighted approaches are generalizable to a broader range of physical problems than considered to date.
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Affiliation(s)
- Robert T. O'Neill
- Department of ChemistryUniversity of LiverpoolUniversity of LiverpoolDepartment of ChemistryGrove StreetLiverpoolL69 7ZD
| | - Roman Boulatov
- Department of ChemistryUniversity of LiverpoolUniversity of LiverpoolDepartment of ChemistryGrove StreetLiverpoolL69 7ZD
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8
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Sun Y, Neary WJ, Huang X, Kouznetsova TB, Ouchi T, Kevlishvili I, Wang K, Chen Y, Kulik HJ, Craig SL, Moore JS. A Thermally Stable SO 2-Releasing Mechanophore: Facile Activation, Single-Event Spectroscopy, and Molecular Dynamic Simulations. J Am Chem Soc 2024; 146:10943-10952. [PMID: 38581383 DOI: 10.1021/jacs.4c02139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2024]
Abstract
Polymers that release small molecules in response to mechanical force are promising candidates as next-generation on-demand delivery systems. Despite advancements in the development of mechanophores for releasing diverse payloads through careful molecular design, the availability of scaffolds capable of discharging biomedically significant cargos in substantial quantities remains scarce. In this report, we detail a nonscissile mechanophore built from an 8-thiabicyclo[3.2.1]octane 8,8-dioxide (TBO) motif that releases one equivalent of sulfur dioxide (SO2) from each repeat unit. The TBO mechanophore exhibits high thermal stability but is activated mechanochemically using solution ultrasonication in either organic solvent or aqueous media with up to 63% efficiency, equating to 206 molecules of SO2 released per 143.3 kDa chain. We quantified the mechanochemical reactivity of TBO by single-molecule force spectroscopy and resolved its single-event activation. The force-coupled rate constant for TBO opening reaches ∼9.0 s-1 at ∼1520 pN, and each reaction of a single TBO domain releases a stored length of ∼0.68 nm. We investigated the mechanism of TBO activation using ab initio steered molecular dynamic simulations and rationalized the observed stereoselectivity. These comprehensive studies of the TBO mechanophore provide a mechanically coupled mechanism of multi-SO2 release from one polymer chain, facilitating the translation of polymer mechanochemistry to potential biomedical applications.
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Affiliation(s)
- Yunyan Sun
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - William J Neary
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Xiao Huang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Tetsu Ouchi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Ilia Kevlishvili
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kecheng Wang
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yingying Chen
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Material Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Heather J Kulik
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Jeffrey S Moore
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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9
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Ding S, Wang W, Germann A, Wei Y, Du T, Meisner J, Zhu R, Liu Y. Bicyclo[2.2.0]hexene: A Multicyclic Mechanophore with Reactivity Diversified by External Forces. J Am Chem Soc 2024; 146:6104-6113. [PMID: 38377579 DOI: 10.1021/jacs.3c13589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Polymer mechanochemistry has been established as an enabling tool in accessing chemical reactivity and reaction pathways that are distinctive from their thermal counterparts. However, eliciting diversified reaction pathways by activating different constituent chemical bonds from the same mechanophore structure remains challenging. Here, we report the design of a bicyclo[2.2.0]hexene (BCH) mechanophore to leverage its structural simplicity and relatively low molecular symmetry to demonstrate this idea of multimodal activation. Upon changing the attachment points of pendant polymer chains, three different C-C bonds in bicyclo[2.2.0]hexene are specifically activated via externally applied force by sonication. Experimental characterization confirms that in different scenarios of polymer attachment, the regioisomers of BCH undergo different activation reactions, entailing retro-[2+2] cycloreversion, 1,3-allylic migration, and retro-4π ring-opening reactions, respectively. Control experiments with small-molecule analogues reveal that the observed diversified reactivity of BCH regioisomers is possible only with mechanical force. Theoretical studies further elucidate that the differences in the positions of substitution between regioisomers have a minimal impact on the potential energy surface of the parent BCH scaffold. The mechanochemical selectivity between different C-C bonds in each constitutional isomer is a result of selective and effective coupling of force to the aligned C-C bond in each case.
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Affiliation(s)
- Shihao Ding
- Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Wenkai Wang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Anne Germann
- Institute for Physical Chemistry, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Yiting Wei
- Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Tianyi Du
- Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Jan Meisner
- Institute for Physical Chemistry, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Rong Zhu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
| | - Yun Liu
- Beijing National Laboratory for Molecular Sciences, Center for Soft Matter Science and Engineering, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, and College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
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10
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Yokochi H, O’Neill RT, Abe T, Aoki D, Boulatov R, Otsuka H. Sacrificial Mechanical Bond is as Effective as a Sacrificial Covalent Bond in Increasing Cross-Linked Polymer Toughness. J Am Chem Soc 2023; 145:23794-23801. [PMID: 37851530 PMCID: PMC10623562 DOI: 10.1021/jacs.3c08595] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Indexed: 10/20/2023]
Abstract
Sacrificial chemical bonds have been used effectively to increase the toughness of elastomers because such bonds dissociate at forces significantly below the fracture limit of the primary load-bearing bonds, thereby dissipating local stress. This approach owes much of its success to the ability to adjust the threshold force at which the sacrificial bonds fail at the desired rate, for example, by selecting either covalent or noncovalent sacrificial bonds. Here, we report experimental and computational evidence that a mechanical bond, responsible for the structural integrity of a rotaxane or a catenane, increases the elastomer's fracture strain, stress, and energy as much as a covalent bond of comparable mechanochemical dissociation kinetics. We synthesized and studied 6 polyacrylates cross-linked by either difluorenylsuccinonitrile (DFSN), which is an established sacrificial mechanochromic moiety; a [2]rotaxane, whose stopper allows its wheel to dethread on the same subsecond time scale as DFSN dissociates when either is under tensile force of 1.5-2 nN; a structurally homologous [2]rotaxane with a much bulkier stopper that is stable at force >5.5 nN; similarly stoppered [3]rotaxanes containing DFSN in their axles; and a control polymer with aliphatic nonsacrificial cross-links. Our data suggest that mechanochemical dethreading of a rotaxane without failure of any covalent bonds may be an important, hitherto unrecognized, contributor to the toughness of some rotaxane-cross-linked polymers and that sacrificial mechanical bonds provide a mechanism to control material fracture behavior independently of the mechanochemical response of the covalent networks, due to their distinct relationships between structure and mechanochemical reactivity.
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Affiliation(s)
- Hirogi Yokochi
- Department
of Chemical Science and Engineering, Tokyo
Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Robert T. O’Neill
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Takumi Abe
- Department
of Chemical Science and Engineering, Tokyo
Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Daisuke Aoki
- Department
of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba 263-8522, Japan
| | - Roman Boulatov
- Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.
| | - Hideyuki Otsuka
- Department
of Chemical Science and Engineering, Tokyo
Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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11
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He X, Tian Y, O’Neill RT, Xu Y, Lin Y, Weng W, Boulatov R. Coumarin Dimer Is an Effective Photomechanochemical AND Gate for Small-Molecule Release. J Am Chem Soc 2023; 145:23214-23226. [PMID: 37821455 PMCID: PMC10603814 DOI: 10.1021/jacs.3c07883] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Indexed: 10/13/2023]
Abstract
Stimulus-responsive gating of chemical reactions is of considerable practical and conceptual interest. For example, photocleavable protective groups and gating mechanophores allow the kinetics of purely thermally activated reactions to be controlled optically or by mechanical load by inducing the release of small-molecule reactants. Such release only in response to a sequential application of both stimuli (photomechanochemical gating) has not been demonstrated despite its unique expected benefits. Here, we describe computational and experimental evidence that coumarin dimers are highly promising moieties for realizing photomechanochemical control of small-molecule release. Such dimers are transparent and photochemically inert at wavelengths >300 nm but can be made to dissociate rapidly under tensile force. The resulting coumarins are mechanochemically and thermally stable, but rapidly release their payload upon irradiation. Our DFT calculations reveal that both strain-free and mechanochemical kinetics of dimer dissociation are highly tunable over an unusually broad range of rates by simple substitution. In head-to-head dimers, the phenyl groups act as molecular levers to allow systematic and predictable variation in the force sensitivity of the dissociation barriers by choice of the pulling axis. As a proof-of-concept, we synthesized and characterized the reactivity of one such dimer for photomechanochemically controlled release of aniline and its application for controlling bulk gelation.
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Affiliation(s)
- Xiaojun He
- Department
of Chemistry, College of Chemistry and Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Yancong Tian
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Robert T. O’Neill
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
| | - Yuanze Xu
- Department
of Chemistry, College of Chemistry and Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Yangju Lin
- Department
of Chemistry, College of Chemistry and Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Wengui Weng
- Department
of Chemistry, College of Chemistry and Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Roman Boulatov
- Department
of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
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12
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Jiang L, Peng Z, Liang Y, Tang ZB, Liang K, Liu J, Liu Z. Strain-Driven Formal [1,3]-Aryl Shift within Molecular Bows. Angew Chem Int Ed Engl 2023; 62:e202312238. [PMID: 37656430 DOI: 10.1002/anie.202312238] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/01/2023] [Accepted: 09/01/2023] [Indexed: 09/02/2023]
Abstract
Delving into the influence of strain on organic reactions in small molecules at the molecular level can unveil valuable insight into developing innovative synthetic strategies and structuring molecules with superior properties. Herein, we present a molecular-strain engineering approach to facilitate the consecutive [1,2]-aryl shift (formal [1,3]-aryl shift) in molecular bows (MBs) that integrate 1,4-dimethoxy-2,5-cyclohexadiene moieties. By introducing ring strain into MBs through tethering the bow limb, we can harness the intrinsic mechanical forces to drive multistep aryl shifts from the para- to the meta- to the ortho-position. Through the use of precise intramolecular strain, the seemingly impractical [1,3]-aryl shift was realized, resulting in the formation of ortho-disubstituted products. The solvent and temperature play a crucial role in the occurrence of the [1,3]-aryl shift. The free energy calculations with inclusion of solvation support a feasible mechanism, which entails multistep carbocation rearrangements, for the formal [1,3]-aryl shift. By exploring the application of molecular strain in synthetic chemistry, this research offers a promising direction for developing new tools and strategies towards precision organic synthesis.
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Affiliation(s)
- Liang Jiang
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zhen Peng
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Yimin Liang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zheng-Bin Tang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Kejiang Liang
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Jiali Liu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
| | - Zhichang Liu
- Key Laboratory of Precise Synthesis of Functional Molecules of Zhejiang Province, Department of Chemistry, School of Science and Research Center for Industries of the Future, Westlake University, Westlake Institute for Advanced Study, 600 Dunyu Road, Hangzhou, Zhejiang 310030, China
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13
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O'Neill RT, Boulatov R. Experimental quantitation of molecular conditions responsible for flow-induced polymer mechanochemistry. Nat Chem 2023; 15:1214-1223. [PMID: 37430105 DOI: 10.1038/s41557-023-01266-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 06/05/2023] [Indexed: 07/12/2023]
Abstract
Fragmentation of macromolecular solutes in rapid flows is of considerable fundamental and practical importance. The sequence of molecular events preceding chain fracture is poorly understood, because such events cannot be visualized directly but must be inferred from changes in the bulk composition of the flowing solution. Here we describe how analysis of same-chain competition between fracture of a polystyrene chain and isomerization of a chromophore embedded in its backbone yields detailed characterization of the distribution of molecular geometries of mechanochemically reacting chains in sonicated solutions. In our experiments the overstretched (mechanically loaded) chain segment grew and drifted along the backbone on the same timescale as, and in competition with, the mechanochemical reactions. Consequently, only <30% of the backbone of a fragmenting chain is overstretched, with both the maximum force and the maximum reaction probabilities located away from the chain centre. We argue that quantifying intrachain competition is likely to be mechanistically informative for any flow fast enough to fracture polymer chains.
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Affiliation(s)
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool, Liverpool, UK.
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14
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Di W, Xue K, Cai J, Zhu Z, Li Z, Fu H, Lei H, Hu W, Tang C, Wang W, Cao Y. Single-Molecule Force Spectroscopy Reveals Cation-π Interactions in Aqueous Media Are Highly Affected by Cation Dehydration. PHYSICAL REVIEW LETTERS 2023; 130:118101. [PMID: 37001074 DOI: 10.1103/physrevlett.130.118101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 01/24/2023] [Indexed: 06/19/2023]
Abstract
Cation-π interactions underlie many important processes in biology and materials science. However, experimental investigations of cation-π interactions in aqueous media remain challenging. Here, we studied the cation-π binding strength and mechanism by pulling two hydrophobic polymers with distinct cation binding properties, i.e., poly-pentafluorostyrene and polystyrene, in aqueous media using single-molecule force spectroscopy and nuclear magnetic resonance measurement. We found that the interaction strengths linearly depend on the cation concentrations, following the order of Li^{+}<NH_{4}^{+}<Na^{+}<K^{+}. The binding energies are 0.03-0.23 kJ mol^{-1} M^{-1}. This order is distinct from the strength of cation-π interactions in gas phase and may be caused by the different dehydration ability of the cations. Taken together, our method provides a unique perspective to investigate cation-π interactions under physiologically relevant conditions.
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Affiliation(s)
- Weishuai Di
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| | - Kai Xue
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
- School of Physical and Mathematical Science Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Jun Cai
- Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023 Nanjing, China
| | - Zhenshu Zhu
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zihan Li
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Hui Fu
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Hai Lei
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
| | - Wenbing Hu
- Department of Polymer Science and Engineering, State Key Laboratory of Coordination Chemistry, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, 210023 Nanjing, China
| | - Chun Tang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Wei Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
- Institute for Brain Sciences, Nanjing University, Nanjing 210093, China
- Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing 210093, China
| | - Yi Cao
- Wenzhou Key Laboratory of Biophysics, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
- Institute for Brain Sciences, Nanjing University, Nanjing 210093, China
- Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing 210093, China
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15
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Ma Z, Zhang H, Song Y, Mei Q, Shi P, Park JW, Zhang W. Increasing the Mechanical Stability of Polymer-Gold Interfacial Connection: A Parallel Covalent Strategy. ACS Macro Lett 2023; 12:421-427. [PMID: 36924462 DOI: 10.1021/acsmacrolett.3c00058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Thiol-gold (S-Au) chemistry has been widely used in coating and functionalizing gold surfaces because it is robust and highly efficient. However, recent studies have shown that the S-Au-based self-assembled monolayers can lead to significant instability under external mechanical loading (e.g., in a swelled polymer film). Such instability limits further applications of S-Au chemistry-based functional materials. Here, we report a surface-modifying procedure based on a parallel covalent strategy. By employing dendritic macromolecules as a "middle layer" between the gold surface and polymer, the interfacial connecting strength increased by at least 350% as revealed by atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS). The ultimate cleavage structure is confirmed to be an amide bond by control SMFS experiments, fluorescent microscopy, and dynamic force spectroscopy. This study/concept paves the way to prepare stable stimuli-responsive polymer brushes on solid surfaces and study mechanophores with high force stability.
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Affiliation(s)
- Ziwen Ma
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Honglin Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Yu Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Qiuping Mei
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Pengju Shi
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Joon Won Park
- Department of Chemistry, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang 37673, Korea
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
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16
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Bao Y, Cui S. Single-Chain Inherent Elasticity of Macromolecules: From Concept to Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:3527-3536. [PMID: 36848243 DOI: 10.1021/acs.langmuir.2c03234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
"The Tao begets the One. One begets all things of the world." These words of wisdom from Tao Te Ching are of great inspiration to scientists in polymer materials science and engineering: The "One" means an individual polymer chain while polymer materials consist of numerous chains. The understanding of the single-chain mechanics of polymers is crucial for the bottom-up rational design of polymer materials. With a backbone and side chains, a polymer chain is more complex than a small molecule. Moreover, an individual polymer chain is usually placed in a complicated environment (such as solvent, cosolute, and solid surface), which significantly affects the behaviors of the chain. With all these factors, it is hard to fully understand the elastic behaviors of polymers. Herein, we will first introduce the concept of the single-chain inherent elasticity of polymers, which is a fundamental property determined by the polymer backbone. Then, the applications of inherent elasticity in quantifying the effects of side chains and surrounding environment will be summarized. Finally, the challenges in related fields at present and potential research directions in the future will be discussed.
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Affiliation(s)
- Yu Bao
- School of Chemistry, Key Lab of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
| | - Shuxun Cui
- School of Chemistry, Key Lab of Advanced Technologies of Materials (Ministry of Education), Southwest Jiaotong University, Chengdu 610031, China
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17
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Lloyd EM, Vakil JR, Yao Y, Sottos NR, Craig SL. Covalent Mechanochemistry and Contemporary Polymer Network Chemistry: A Marriage in the Making. J Am Chem Soc 2023; 145:751-768. [PMID: 36599076 DOI: 10.1021/jacs.2c09623] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Over the past 20 years, the field of polymer mechanochemistry has amassed a toolbox of mechanophores that translate mechanical energy into a variety of functional responses ranging from color change to small-molecule release. These productive chemical changes typically occur at the length scale of a few covalent bonds (Å) but require large energy inputs and strains on the micro-to-macro scale in order to achieve even low levels of mechanophore activation. The minimal activation hinders the translation of the available chemical responses into materials and device applications. The mechanophore activation challenge inspires core questions at yet another length scale of chemical control, namely: What are the molecular-scale features of a polymeric material that determine the extent of mechanophore activation? Further, how do we marry advances in the chemistry of polymer networks with the chemistry of mechanophores to create stress-responsive materials that are well suited for an intended application? In this Perspective, we speculate as to the potential match between covalent polymer mechanochemistry and recent advances in polymer network chemistry, specifically, topologically controlled networks and the hierarchical material responses enabled by multi-network architectures and mechanically interlocked polymers. Both fundamental and applied opportunities unique to the union of these two fields are discussed.
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Affiliation(s)
- Evan M Lloyd
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States
| | - Jafer R Vakil
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
| | - Yunxin Yao
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
| | - Nancy R Sottos
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States.,Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois61801, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina27708, United States.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina27708, United States
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18
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Craig SL. Concluding remarks: Fundamentals, applications and future of mechanochemistry. Faraday Discuss 2023; 241:485-491. [PMID: 36472143 DOI: 10.1039/d2fd00141a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper provides a summary of the Faraday Discussions meeting on "Mechanochemistry: fundamentals, applications, and future" in the context of broad themes whose exploration might contribute to a unified framework of mechanochemical phenomena.
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Affiliation(s)
- Stephen L Craig
- Department of Chemistry, Duke University, Durham, NC 27708-0346, USA.
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19
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Liu J, Guo H, Gao Q, Li H, An Z, Zhang W. Coil–Globule Transition of a Water-Soluble Polymer. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jianyu Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Huazhang Guo
- Institute of Nanochemistry and Nanobiology, Shanghai University, Shanghai 200444, China
| | - Qingjie Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Hongbin Li
- Department of Chemistry, University of British Columbia, Vancouver V6T 1Z4, Canada
| | - Zesheng An
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
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20
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Ma Y. Construction of Biologic Microscopic Image Segmentation Model Based on Smoothing of Fourth-Order Partial Differential Equation. SCANNING 2022; 2022:1908644. [PMID: 35959152 PMCID: PMC9343209 DOI: 10.1155/2022/1908644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/03/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
In order to solve the problem of microscopic image noise, a biological microscopic image segmentation model based on the smoothing of the fourth-order partial differential equation was proposed. Based on the functional description of image smoothness by directional curvature mode value, a fourth-order PDE image denoising model is derived, which can effectively reduce noise while preserving edges. The result of this method is piecewise linear image, and the gradient at the edge of the target has a step. Using the feature of noise reduction, a new geodesic active contour model is proposed. The experiment result shows that when the variance of Gaussian white noise is 15, the enhancement and denoising effects of the proposed method are 80.35% and 69.84 higher than those of the original vibration filtering method and L. Alvarez method. In terms of time, the proposed method is 1.3075 seconds slower than the original vibration filtering method and 17.5754 seconds faster than the L. Alvarez method. When the variance of Gaussian white noise is 25, the enhancement and denoising effects of the proposed method are 97.79% and 81.16 higher than those of the original vibration filtering method and L. Alvarez method. In terms of time, the proposed method is 1.3246 seconds slower than the original vibration filtering method and 17.5796 seconds faster than the L. Alvarez method. Conclusion. The new model is not only stable but also has strong ability of contour extraction and fast convergence.
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Affiliation(s)
- Ye Ma
- Department of Biomedical Engineering, Jilin Medical University, Jilin, China 132013
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21
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Li F. Construction of Computer Microscope Image Segmentation Model Based on Fourth-Order Partial Differential Equation Smoothing. SCANNING 2022; 2022:4355184. [PMID: 35937671 PMCID: PMC9296342 DOI: 10.1155/2022/4355184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 06/26/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
In order to solve the problem of image noise, the author proposes a computer microscope image segmentation model based on the smoothing of fourth-order partial differential equations. On the basis of the functional describing the smoothness of the image by the directional curvature modulus, the author deduces a fourth-order partial differential equation (PDE) image noise reduction model, while effectively reducing noise, the edges are well preserved. The processing result of this method is a piecewise linear image, and there is a step in the gradient at the edge of the target. Taking advantage of this feature of the noise reduction results, the author proposes a new geodesic active contour model. The experimental results show that the reference method directly segments the results, iterates 10 times, and takes 160.721 seconds. Using the noise reduction model in the paper to preprocess and then using the reference method to segment the result, iterating 8 times, it takes 32.347 seconds. Conclusion. The new model is not only stable but also has strong contour extraction ability and fast convergence speed.
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Affiliation(s)
- Feng Li
- Yellow River Conservancy Technical Institute, Kaifeng Henan 475004, China
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22
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Sha Y, Zhou Z, Zhu M, Luo Z, Xu E, Li X, Yan H. The Mechanochemistry of Carboranes. Angew Chem Int Ed Engl 2022; 61:e202203169. [DOI: 10.1002/anie.202203169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Ye Sha
- Department of Chemistry and Material Science College of Science Nanjing Forestry University Nanjing 210037 China
| | - Zhou Zhou
- Department of Chemistry and Material Science College of Science Nanjing Forestry University Nanjing 210037 China
| | - Miao Zhu
- Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry College of Science Nanjing Agricultural University Nanjing 210095 China
| | - Zhenyang Luo
- Department of Chemistry and Material Science College of Science Nanjing Forestry University Nanjing 210037 China
| | - Enhua Xu
- Graduate School of System Informatics Kobe University Kobe 657-8501 Japan
| | - Xiang Li
- Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry College of Science Nanjing Agricultural University Nanjing 210095 China
| | - Hong Yan
- State Key Laboratory of Coordination Chemistry Nanjing University Nanjing 210023 China
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23
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Du M, Houck HA, Yin Q, Xu Y, Huang Y, Lan Y, Yang L, Du Prez FE, Chang G. Force-reversible chemical reaction at ambient temperature for designing toughened dynamic covalent polymer networks. Nat Commun 2022; 13:3231. [PMID: 35680925 PMCID: PMC9184613 DOI: 10.1038/s41467-022-30972-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 05/26/2022] [Indexed: 11/23/2022] Open
Abstract
Force-reversible C-N bonds, resulting from the click chemistry reaction between triazolinedione (TAD) and indole derivatives, offer exciting opportunities for molecular-level engineering to design materials that respond to mechanical loads. Here, we displayed that TAD-indole adducts, acting as crosslink points in dry-state covalently crosslinked polymers, enable materials to display reversible stress-responsiveness in real time already at ambient temperature. Whereas the exergonic TAD-indole reaction results in the formation of bench-stable adducts, they were shown to dissociate at ambient temperature when embedded in a polymer network and subjected to a stretching force to recover the original products. Moreover, the nascent TAD moiety can spontaneously and immediately be recombined after dissociation with an indole reaction partners at ambient temperature, thus allowing for the adjustment of the polymer segment conformation and the maintenance of the network integrity by force-reversible behaviors. Overall, our strategy represents a general method to create toughened covalently crosslinked polymer materials with simultaneous enhancement of mechanical strength and ductility, which is quite challenging to achieve by conventional chemical methods. Weak force-activated covalent bonds as crosslink points can increase mechanical strength and ductility in polymers but the bonds, once broken, cannot be reformed in real time under ambient conditions leading to irreversible damage. Here, the authors demonstrate that triazolinedione (TAD)-indole adducts acting as crosslink points enable materials to display already at ambient temperature reversible stress-responsiveness in real time.
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Affiliation(s)
- Mengqi Du
- State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China
| | - Hannes A Houck
- Polymer Chemistry Research Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000, Ghent, Belgium
| | - Qiang Yin
- Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900, P. R. China
| | - Yewei Xu
- State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China
| | - Ying Huang
- State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China
| | - Yang Lan
- Melville Laboratory for Polymer Synthesis, Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Li Yang
- State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China. .,Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Filip E Du Prez
- Polymer Chemistry Research Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000, Ghent, Belgium.
| | - Guanjun Chang
- State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China. .,Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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24
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Wang C, Akbulatov S, Chen Q, Tian Y, Sun CL, Couty M, Boulatov R. The molecular mechanism of constructive remodeling of a mechanically-loaded polymer. Nat Commun 2022; 13:3154. [PMID: 35672410 PMCID: PMC9174275 DOI: 10.1038/s41467-022-30947-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 05/25/2022] [Indexed: 02/03/2023] Open
Abstract
Large or repeated mechanical loads usually degrade polymers by accelerating fragmentation of their backbones but rarely, they can cause new backbone bonds to form. When these new bonds form faster than the original bonds break, mechanical degradation may be arrested or reversed in real time. Exploiting such constructive remodeling has proven challenging because we lack an understanding of the competition between bond-forming and bond-breaking reactions in mechanically-stressed polymers. Here we report the molecular mechanism and analysis of constructive remodeling driven by the macroradical products of mechanochemical fragmentation of a hydrocarbon backbone. By studying the changing compositions of a random copolymer of styrene and butadiene sheared at 10 °C in the presence of different additives we developed an approach to characterizing this growth/fracture competition, which is generalizable to other underlying chemistries. Our results demonstrate that constructive remodeling is achievable under practically relevant conditions, requires neither complex chemistries, elaborate macromolecular architectures or free monomers, and is amenable to detailed mechanistic interrogation and simulation. These findings constitute a quantitative framework for systematic studies of polymers capable of autonomously counteracting mechanical degradation at the molecular level.
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Affiliation(s)
- Chenxu Wang
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Sergey Akbulatov
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Qihan Chen
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Yancong Tian
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Cai-Li Sun
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
| | - Marc Couty
- Manufacture Française des Pneumatiques Michelin, Clermont-Ferrand, 63000, France.
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK.
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25
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Song Y, Ma Z, Zhang W. Manipulation of a Single Polymer Chain: From the Nanomechanical Properties to Dynamic Structure Evolution. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yu Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Ziwen Ma
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
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26
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Bao Y, Huang X, Xu D, Xu J, Jiang L, Lu ZY, Cui S. Bound water governs the single-chain property of Poly(vinyl alcohol) in aqueous environments. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.124996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Sha Y, Zhou Z, Zhu M, Luo Z, Xu E, Li X, Yan H. The Mechanochemistry of Carboranes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ye Sha
- Nanjing Forestry University Chemistry and Biochemistry 159 Longpan StNanjing Forestry University 210037 Nanjing CHINA
| | - Zhou Zhou
- Nanjing Forestry University Chemistry CHINA
| | - Miao Zhu
- Nanjing Agricultural University Chemistry CHINA
| | | | - Enhua Xu
- Kobe University Graduate School of System Informatics: Kobe Daigaku Daigakuin System Johogaku Kenkyuka Chemistry JAPAN
| | - Xiang Li
- Nanjing Agricultural University Chemistry CHINA
| | - Hong Yan
- Nanjing University Chemistry CHINA
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28
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Gao W, Tang R, Bai M, Yu H, Ruan Y, Zheng J, Chen Y, Weng W. Dynamic covalent polymer networks with mechanical and mechanoresponsive properties reinforced by strong hydrogen bonding. Polym Chem 2022. [DOI: 10.1039/d2py00179a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic polymer materials with superior mechanical properties and mechanochromism are of great importance to a vast variety of applications including stress sensing, damage detecting, soft robot. Herein, mechanoresponsive dynamic covalent...
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29
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O’Neill RT, Boulatov R. The Contributions of Model Studies for Fundamental Understanding of Polymer Mechanochemistry. Synlett 2021. [DOI: 10.1055/a-1710-5656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
AbstractThe exciting field of polymer mechanochemistry has made great empirical progress in discovering reactions in which a stretching force accelerates scission of strained bonds using single molecule force spectroscopy and ultrasonication experiments. Understanding why these reactions happen, i.e., the fundamental physical processes that govern coupling of macroscopic motion to chemical reactions, as well as discovering other patterns of mechanochemical reactivity require complementary techniques, which permit a much more detailed characterization of reaction mechanisms and the distribution of force in reacting molecules than are achievable in SMFS or ultrasonication. A molecular force probe allows the specific pattern of molecular strain that is responsible for localized reactions in stretched polymers to be reproduced accurately in non-polymeric substrates using molecular design rather than atomistically intractable collective motions of millions of atoms comprising macroscopic motion. In this review, we highlight the necessary features of a useful molecular force probe and describe their realization in stiff stilbene macrocycles. We describe how studying these macrocycles using classical tools of physical organic chemistry has allowed detailed characterizations of mechanochemical reactivity, explain some of the most unexpected insights enabled by these probes, and speculate how they may guide the next stage of mechanochemistry.
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Affiliation(s)
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University
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30
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Qi Q, Sekhon G, Chandradat R, Ofodum NM, Shen T, Scrimgeour J, Joy M, Wriedt M, Jayathirtha M, Darie CC, Shipp DA, Liu X, Lu X. Force-Induced Near-Infrared Chromism of Mechanophore-Linked Polymers. J Am Chem Soc 2021; 143:17337-17343. [PMID: 34586805 DOI: 10.1021/jacs.1c05923] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A near-infrared (NIR) mechanophore was developed and incorporated into a poly(methyl acrylate) chain to showcase the first force-induced NIR chromism in polymeric materials. This mechanophore, based on benzo[1,3]oxazine (OX) fused with a heptamethine cyanine moiety, exhibited NIR mechanochromism in solution, thin-film, and bulk states. The mechanochemical activity was validated using UV-vis-NIR absorption/fluorescence spectroscopies, gel permeation chromatography (GPC), NMR, and DFT simulations. Our work demonstrates that NIR mechanochromic polymers have considerable potential in mechanical force sensing, damage detection, bioimaging, and biomechanics.
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Affiliation(s)
| | | | | | | | - Tianruo Shen
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore
| | | | | | | | | | | | | | - Xiaogang Liu
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore
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31
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Wang Z, Zheng X, Ouchi T, Kouznetsova TB, Beech HK, Av-Ron S, Matsuda T, Bowser BH, Wang S, Johnson JA, Kalow JA, Olsen BD, Gong JP, Rubinstein M, Craig SL. Toughening hydrogels through force-triggered chemical reactions that lengthen polymer strands. Science 2021; 374:193-196. [PMID: 34618576 DOI: 10.1126/science.abg2689] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Zi Wang
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA
| | - Xujun Zheng
- Department of Chemistry, Duke University, Durham, NC, USA
| | - Tetsu Ouchi
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA
| | - Haley K Beech
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Department of Chemical Engineering, Massachussetts Institute of Technology (MIT), Boston, MA, USA
| | - Sarah Av-Ron
- Department of Chemical Engineering, Massachussetts Institute of Technology (MIT), Boston, MA, USA
| | - Takahiro Matsuda
- Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Brandon H Bowser
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA
| | - Shu Wang
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA
| | - Jeremiah A Johnson
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Department of Chemistry, MIT, Boston, MA, USA
| | - Julia A Kalow
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Bradley D Olsen
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Department of Chemical Engineering, Massachussetts Institute of Technology (MIT), Boston, MA, USA
| | - Jian Ping Gong
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Faculty of Advanced Life Science, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan.,Soft Matter GI-CoRE, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan.,Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
| | - Michael Rubinstein
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Soft Matter GI-CoRE, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan.,Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan.,Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA.,Department of Biomedical Engineering, Duke University, Durham, NC, USA.,Department of Physics, Duke University, Durham, NC, USA
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, NC, USA.,NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, NC, USA.,Soft Matter GI-CoRE, Hokkaido University, N21W11, Kita-ku, Sapporo 001-0021, Japan
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32
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Nie J, Tian F, Zheng B, Wang Z, Zheng P. Exploration of Metal-Ligand Coordination Bonds in Proteins by Single-molecule Force Spectroscopy. CHEM LETT 2021. [DOI: 10.1246/cl.210307] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jingyuan Nie
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Fang Tian
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Bin Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Ziyi Wang
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Peng Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
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33
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Yu Y, Wang C, Wang L, Sun CL, Boulatov R, Widenhoefer RA, Craig SL. Force-modulated reductive elimination from platinum(ii) diaryl complexes. Chem Sci 2021; 12:11130-11137. [PMID: 34522310 PMCID: PMC8386663 DOI: 10.1039/d1sc03182a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 07/19/2021] [Indexed: 11/21/2022] Open
Abstract
Coupled mechanical forces are known to drive a range of covalent chemical reactions, but the effect of mechanical force applied to a spectator ligand on transition metal reactivity is relatively unexplored. Here we quantify the rate of C(sp2)-C(sp2) reductive elimination from platinum(ii) diaryl complexes containing macrocyclic bis(phosphine) ligands as a function of mechanical force applied to these ligands. DFT computations reveal complex dependence of mechanochemical kinetics on the structure of the force-transducing ligand. We validated experimentally the computational finding for the most sensitive of the ligand designs, based on MeOBiphep, by coupling it to a macrocyclic force probe ligand. Consistent with the computations, compressive forces decreased the rate of reductive elimination whereas extension forces increased the rate relative to the strain-free MeOBiphep complex with a 3.4-fold change in rate over a ∼290 pN range of restoring forces. The calculated natural bite angle of the free macrocyclic ligand changes with force, but 31P NMR analysis and calculations strongly suggest no significant force-induced perturbation of ground state geometry within the first coordination sphere of the (P-P)PtAr2 complexes. Rather, the force/rate behavior observed across this range of forces is attributed to the coupling of force to the elongation of the O⋯O distance in the transition state for reductive elimination. The results suggest opportunities to experimentally map geometry changes associated with reactions in transition metal complexes and potential strategies for force-modulated catalysis.
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Affiliation(s)
- Yichen Yu
- Department of Chemistry, Duke University Durham North Carolina 27708 USA
| | - Chenxu Wang
- Department of Chemistry, University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Liqi Wang
- Department of Chemistry, Duke University Durham North Carolina 27708 USA
| | - Cai-Li Sun
- Department of Chemistry, University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Roman Boulatov
- Department of Chemistry, University of Liverpool Crown Street Liverpool L69 7ZD UK
| | - Ross A Widenhoefer
- Department of Chemistry, Duke University Durham North Carolina 27708 USA
| | - Stephen L Craig
- Department of Chemistry, Duke University Durham North Carolina 27708 USA
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34
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Lei H, Ma Q, Li W, Wen J, Ma H, Qin M, Wang W, Cao Y. An ester bond underlies the mechanical strength of a pathogen surface protein. Nat Commun 2021; 12:5082. [PMID: 34426584 PMCID: PMC8382745 DOI: 10.1038/s41467-021-25425-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 08/10/2021] [Indexed: 11/23/2022] Open
Abstract
Gram-positive bacteria can resist large mechanical perturbations during their invasion and colonization by secreting various surface proteins with intramolecular isopeptide or ester bonds. Compared to isopeptide bonds, ester bonds are prone to hydrolysis. It remains elusive whether ester bonds can completely block mechanical extension similarly to isopeptide bonds, or whether ester bonds dissipate mechanical energy by bond rupture. Here, we show that an ester-bond containing stalk domain of Cpe0147 is inextensible even at forces > 2 nN. The ester bond locks the structure to a partially unfolded conformation, in which the ester bond remains largely water inaccessible. This allows the ester bond to withstand considerable mechanical forces and in turn prevent complete protein unfolding. However, the protecting effect might be reduced at non-physiological basic pHs or low calcium concentrations due to destabilizing the protein structures. Inspired by this design principle, we engineer a disulfide mutant resistant to mechanical unfolding under reducing conditions. Bacterial surface adhesion proteins are characterized by unusual mechanical properties. Here, the authors use atomic force microscopy-based technique to study a surface-anchoring protein Cpe0147 from Clostridium perfringens and show that an ester bond can withstand considerable mechanical forces and prevent complete protein unfolding.
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Affiliation(s)
- Hai Lei
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China.,Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing, China
| | - Quan Ma
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China
| | - Wenfei Li
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China
| | - Jing Wen
- Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing, China
| | - Haibo Ma
- Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing, China
| | - Meng Qin
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China
| | - Wei Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China
| | - Yi Cao
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing, China. .,Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing, China.
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35
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Horst M, Yang J, Meisner J, Kouznetsova TB, Martínez TJ, Craig SL, Xia Y. Understanding the Mechanochemistry of Ladder-Type Cyclobutane Mechanophores by Single Molecule Force Spectroscopy. J Am Chem Soc 2021; 143:12328-12334. [PMID: 34310875 DOI: 10.1021/jacs.1c05857] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have recently reported a series of ladder-type cyclobutane mechanophores, polymers of which can transform from nonconjugated structures to conjugated structures and change many properties at once. These multicyclic mechanophores, namely, exo-ladderane/ene, endo-benzoladderene, and exo-bicyclohexene-peri-naphthalene, have different ring structures fused to the first cyclobutane, significantly different free energy changes for ring-opening, and different stereochemistry. To better understand their mechanochemistry, we used single molecule force spectroscopy (SMFS) to characterize their force-extension behavior and measure the threshold forces. The threshold forces correlate with the activation energy of the first bond, but not with the strain of the fused rings distal to the polymer main chain, suggesting that the activation of these ladder-type mechanophores occurs with similar early transition states, which is supported by force-modified potential energy surface calculations. We further determined the stereochemistry of the mechanically generated dienes and observed significant and variable contour length elongation for these mechanophores both experimentally and computationally. The fundamental understanding of ladder-type mechanophores will facilitate future design of multicyclic mechanophores with amplified force-response and their applications as mechanically responsive materials.
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Affiliation(s)
- Matías Horst
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jinghui Yang
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jan Meisner
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Todd J Martínez
- Department of Chemistry, Stanford University, Stanford, California 94305, United States.,SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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36
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Bao Y, Huang X, Xu J, Cui S. Effect of Intramolecular Hydrogen Bonds on the Single-Chain Elasticity of Poly(vinyl alcohol): Evidencing the Synergistic Enhancement Effect at the Single-Molecule Level. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01251] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Yu Bao
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, China
| | - Xiaobo Huang
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, China
| | - Jun Xu
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, China
| | - Shuxun Cui
- Key Lab of Advanced Technologies of Materials, Ministry of Education of China, Southwest Jiaotong University, Chengdu 610031, China
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37
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Kida J, Aoki D, Otsuka H. Self-Strengthening of Cross-Linked Elastomers via the Use of Dynamic Covalent Macrocyclic Mechanophores. ACS Macro Lett 2021; 10:558-563. [PMID: 35570767 DOI: 10.1021/acsmacrolett.1c00124] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The creation of polymeric materials that self-strengthen in response to a mechanical force is an important objective in the field of polymer chemistry. Here, the mechanochemical strengthening of cross-linked elastomers using macrocyclic mechanophores that contain a dynamic covalent disulfide bond is reported. Cross-linked poly(hexyl methacrylate) (CPHMA) polymers with macrocyclic mechanophores inserted at the cross-linking points were synthesized via free radical polymerization. Tensile and swelling tests showed that the addition of the macrocyclic mechanophores to the CPHMA polymers successfully impart them with self-strengthening functionality following compression, without the need for any additives such as monomers and modifiers, or any other stimuli.
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38
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Bowser BH, Wang S, Kouznetsova TB, Beech HK, Olsen BD, Rubinstein M, Craig SL. Single-Event Spectroscopy and Unravelling Kinetics of Covalent Domains Based on Cyclobutane Mechanophores. J Am Chem Soc 2021; 143:5269-5276. [PMID: 33783187 DOI: 10.1021/jacs.1c02149] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mechanochemical reactions that lead to an increase in polymer contour length have the potential to serve as covalent synthetic mimics of the mechanical unfolding of noncovalent "stored length" domains in structural proteins. Here we report the force-dependent kinetics of stored length release in a family of covalent domain polymers based on cis-1,2-substituted cyclobutane mechanophores. The stored length is determined by the size (n) of a fused ring in an [n.2.0] bicyclic architecture, and it can be made sufficiently large (>3 nm per event) that individual unravelling events are resolved in both constant-velocity and constant-force single-molecule force spectroscopy (SMFS) experiments. Replacing a methylene in the pulling attachment with a phenyl group drops the force necessary to achieve rate constants of 1 s-1 from ca. 1970 pN (dialkyl handles) to 630 pN (diaryl handles), and the substituent effect is attributed to a combination of electronic stabilization and mechanical leverage effects. In contrast, the kinetics are negligibly perturbed by changes in the amount of stored length. The independent control of unravelling force and extension holds promise as a probe of molecular behavior in polymer networks and for optimizing the behaviors of materials made from covalent domain polymers.
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Affiliation(s)
- Brandon H Bowser
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Shu Wang
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Tatiana B Kouznetsova
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Haley K Beech
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Bradley D Olsen
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael Rubinstein
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.,Departments of Physics, Mechanical Engineering and Materials Science, and Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States.,World Premier Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo, Japan
| | - Stephen L Craig
- NSF Center for the Chemistry of Molecularly Optimized Networks, Duke University, Durham, North Carolina 27708, United States.,Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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39
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Novel composite films based on sodium alginate and gallnut extract with enhanced antioxidant, antimicrobial, barrier and mechanical properties. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106508] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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40
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Wang S, Beech HK, Bowser BH, Kouznetsova TB, Olsen BD, Rubinstein M, Craig SL. Mechanism Dictates Mechanics: A Molecular Substituent Effect in the Macroscopic Fracture of a Covalent Polymer Network. J Am Chem Soc 2021; 143:3714-3718. [PMID: 33651599 DOI: 10.1021/jacs.1c00265] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The fracture of rubbery polymer networks involves a series of molecular events, beginning with conformational changes along the polymer backbone and culminating with a chain scission reaction. Here, we report covalent polymer gels in which the macroscopic fracture "reaction" is controlled by mechanophores embedded within mechanically active network strands. We synthesized poly(ethylene glycol) (PEG) gels through the end-linking of azide-terminated tetra-arm PEG (Mn = 5 kDa) with bis-alkyne linkers. Networks were formed under identical conditions, except that the bis-alkyne was varied to include either a cis-diaryl (1) or cis-dialkyl (2) linked cyclobutane mechanophore that acts as a mechanochemical "weak link" through a force-coupled cycloreversion. A control network featuring a bis-alkyne without cyclobutane (3) was also synthesized. The networks show the same linear elasticity (G' = 23-24 kPa, 0.1-100 Hz) and equilibrium mass swelling ratios (Q = 10-11 in tetrahydrofuran), but they exhibit tearing energies that span a factor of 8 (3.4 J, 10.6, and 27.1 J·m-2 for networks with 1, 2, and 3, respectively). The difference in fracture energy is well-aligned with the force-coupled scission kinetics of the mechanophores observed in single-molecule force spectroscopy experiments, implicating local resonance stabilization of a diradical transition state in the cycloreversion of 1 as a key determinant of the relative ease with which its network is torn. The connection between macroscopic fracture and a small-molecule reaction mechanism suggests opportunities for molecular understanding and optimization of polymer network behavior.
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Affiliation(s)
| | - Haley K Beech
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | | | | | - Bradley D Olsen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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41
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Brown CL, Bowser BH, Meisner J, Kouznetsova TB, Seritan S, Martinez TJ, Craig SL. Substituent Effects in Mechanochemical Allowed and Forbidden Cyclobutene Ring-Opening Reactions. J Am Chem Soc 2021; 143:3846-3855. [PMID: 33667078 DOI: 10.1021/jacs.0c12088] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Woodward and Hoffman once jested that a very powerful Maxwell demon could seize a molecule of cyclobutene at its methylene groups and tear it open in a disrotatory fashion to obtain butadiene (Woodward, R. B.; Hoffmann, R. The Conservation of Orbital Symmetry. Angew. Chem., Int. Ed. 1969, 8, 781-853). Nearly 40 years later, that demon was discovered, and the field of covalent polymer mechanochemistry was born. In the decade since our demon was befriended, many fundamental investigations have been undertaken to build up our understanding of force-modified pathways for electrocyclic ring-opening reactions. Here, we seek to extend that fundamental understanding by exploring substituent effects in allowed and forbidden ring-opening reactions of cyclobutene (CBE) and benzocyclobutene (BCB) using a combination of single-molecule force spectroscopy (SMFS) and computation. We show that, while the forbidden ring-opening of cis-BCB occurs at a lower force than the allowed ring-opening of trans-BCB on the time scale of the SMFS experiment, the opposite is true for cis- and trans-CBE. Such a reactivity flip is explained through computational analysis and discussion of the so-called allowed/forbidden gap.
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Affiliation(s)
- Cameron L Brown
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Brandon H Bowser
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Jan Meisner
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States.,SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Stefan Seritan
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States.,SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Todd J Martinez
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States.,SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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Kumar S, Stauch T. The activation efficiency of mechanophores can be modulated by adjacent polymer composition. RSC Adv 2021; 11:7391-7396. [PMID: 35423252 PMCID: PMC8695044 DOI: 10.1039/d0ra09834e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/05/2021] [Indexed: 11/21/2022] Open
Abstract
The activation efficiency of mechanophores in stress-responsive polymers is generally limited by the competing process of unspecific scission in other parts of the polymer chain. Here it is shown that the linker between the mechanophore and the polymer backbone determines the force required to activate the mechanophore. Using quantum chemical methods, it is demonstrated that the activation forces of three mechanophores (Dewar benzene, benzocyclobutene and gem-dichlorocyclopropane) can be adjusted over a range of almost 300% by modifying the chemical composition of the linker. The results are discussed in terms of changes in electron density, strain distribution and structural parameters during the rupture process. Using these findings it is straightforward to either significantly enhance or reduce the activation rate of mechanophores in stress-responsive materials, depending on the desired use case. The methodology is applied to switch a one-step "gating" of a mechanochemical transformation to a two-step process.
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Affiliation(s)
- Sourabh Kumar
- University of Bremen, Institute for Physical and Theoretical Chemistry Leobener Straße NW2 D-28359 Bremen Germany
| | - Tim Stauch
- University of Bremen, Institute for Physical and Theoretical Chemistry Leobener Straße NW2 D-28359 Bremen Germany
- Bremen Center for Computational Materials Science, University of Bremen Am Fallturm 1 D-28359 Bremen Germany
- MAPEX Center for Materials and Processes, University of Bremen Bibliothekstraße 1 D-28359 Bremen Germany
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O’Neill RT, Boulatov R. The many flavours of mechanochemistry and its plausible conceptual underpinnings. Nat Rev Chem 2021; 5:148-167. [PMID: 37117533 DOI: 10.1038/s41570-020-00249-y] [Citation(s) in RCA: 156] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2020] [Indexed: 12/12/2022]
Abstract
Mechanochemistry describes diverse phenomena in which mechanical load affects chemical reactivity. The fuzziness of this definition means that it includes processes as seemingly disparate as motor protein function, organic synthesis in a ball mill, reactions at a propagating crack, chemical actuation, and polymer fragmentation in fast solvent flows and in mastication. In chemistry, the rate of a reaction in a flask does not depend on how fast the flask moves in space. In mechanochemistry, the rate at which a material is deformed affects which and how many bonds break. In other words, in some manifestations of mechanochemistry, macroscopic motion powers otherwise endergonic reactions. In others, spontaneous chemical reactions drive mechanical motion. Neither requires thermal or electrostatic gradients. Distinct manifestations of mechanochemistry are conventionally treated as being conceptually independent, which slows the field in its transformation from being a collection of observations to a rigorous discipline. In this Review, we highlight observations suggesting that the unifying feature of mechanochemical phenomena may be the coupling between inertial motion at the microscale to macroscale and changes in chemical bonding enabled by transient build-up and relaxation of strains, from macroscopic to molecular. This dynamic coupling across multiple length scales and timescales also greatly complicates the conceptual understanding of mechanochemistry.
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