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Deng J, Huang Z, Sundell BJ, Harrigan DJ, Sharber SA, Zhang K, Guo R, Galizia M. State of the art and prospects of chemically and thermally aggressive membrane gas separations: Insights from polymer science. POLYMER 2021. [DOI: 10.1016/j.polymer.2021.123988] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Mullin WJ, Sharber SA, Thomas SW. Optimizing the
self‐assembly
of conjugated polymers and small molecules through structurally programmed
non‐covalent
control. Journal of Polymer Science 2021. [DOI: 10.1002/pol.20210290] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | - Seth A. Sharber
- Department of Chemistry Tufts University Medford Massachusetts USA
- Aramco Services Company, Aramco Research Center Boston Massachusetts USA
| | - Samuel W. Thomas
- Department of Chemistry Tufts University Medford Massachusetts USA
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Brega V, Kanari SN, Doherty CT, Che D, Sharber SA, Thomas SW. Spectroscopy and Reactivity of Dialkoxy Acenes. Chemistry 2019; 25:10400-10407. [DOI: 10.1002/chem.201901258] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/13/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Valentina Brega
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
| | - Sare Nur Kanari
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
| | - Connor T. Doherty
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
| | - Dante Che
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
| | - Seth A. Sharber
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
| | - Samuel W. Thomas
- Department of Chemistry Tufts University 62 Talbot Avenue Medford MA 02155 United States
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Sharber SA, Mann A, Shih KC, Mullin WJ, Nieh MP, Thomas SW. Directed Polymorphism and Mechanofluorochromism of Conjugated Materials through Weak Non-Covalent Control. J Mater Chem C Mater 2019; 7:8316-8324. [PMID: 33133604 PMCID: PMC7597496 DOI: 10.1039/c9tc01301f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding and manipulating crystal polymorphism can provide novel strategies for materials discovery in organic optoelectronics. In this paper, a series of seven ester-terminated three-ring phenylene ethynylenes (PEs) exhibit structure-dependent polymorphism wherein alkyl chain length modulates the propensity to form violet or green fluorescent solid phases, as well as tunable thermal and mechanofluorochromic (MFC) transitions. These compounds harness "soft" non-covalent control to achieve polymorphism: the electronic substituent effect of the ester groups weakens the fluoroarene-arene (ArF-ArH) interactions that typically direct crystal packing of this class of compounds, increasing competitiveness of other interactions. Small structural modifications tip this balance and shift the prevalence of violet- or green-emitting polymorphs. Compounds with short alkyl chain lengths show both violet and various green fluorescent polymorphs, while the violet fluorescent form dominates with alkyl lengths longer than butyl. Further, thermally induced green-to-violet fluorescent crystal-to-crystal transitions occur for single crystals of CO2-1 and CO2-3. Finally, the PEs show reversible violet-to-green mechanofluorochromism (MFC), with temperature required for reversion of this MFC decreasing with alkyl chain length. We therefore present this design of directional but weak interactions as a strategy to access polymorphs and tunable stimuli-responsive behavior in solids.
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Affiliation(s)
- Seth A Sharber
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA
| | - Arielle Mann
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA
| | - Kuo-Chih Shih
- Department of Chemical & Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, Storrs, CT 06269, USA
| | - William J Mullin
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA
| | - Mu-Ping Nieh
- Department of Chemical & Biomolecular Engineering, University of Connecticut, 97 North Eagleville Road, Storrs, CT 06269, USA
| | - Samuel W Thomas
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA 02155, USA
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Sharber SA, Thomas SW. Small Changes With Big Consequences: Swapping Two Atoms In Side Chains Changes Phenylene-Ethynylene Packing And Fluorescence. Chemistry 2018; 24:16987-16991. [PMID: 30281848 DOI: 10.1002/chem.201804648] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Indexed: 11/06/2022]
Abstract
Engineering the properties of conjugated materials in the solid state is an unsolved, ongoing challenge important to fundamental understanding of how non-covalent interactions dictate packing and key properties, as well as the development of technologies based in organic optoelectronics. The most common design paradigm of such materials divide them into a "main chain" with extended conjugation, the chemical structure of which determines optoelectronic properties, and "side chains" not conjugated to the backbone, which provide solubility when they are long alkyl chains. This paper describes comparisons between phenylene-ethynylene molecules in which slight changes to the structure of "side chains"-swapping hydrogen and fluorine atomic position on an aromatic ring-results in unexpectedly large changes in the solid-state optical properties. In a pair of anisyl-terminated three-ring phenylene-ethynylenes, switching the side chain arenes of benzyl esters from 2,4,6-trifluoro to 2,3,6-trifluoro results in a shift in fluorescence emission spectra of over 100 nm, as well as the opposite direction of force-induced shifting of emission. Through a combination X-ray crystal structures, electronic structure calculations, and comparisons with other derivatives, we describe how the 2,4,6-trifluorinated side chains yield cofacial fluoroarene-arene stacking interactions that twist the PE backbone out of conjugation, while the 2,3,6-trifluoro side chains do not stack, instead yielding more coplanar PE backbones that form intermolecular aggregates. Overall, this work demonstrates how slight modifications to parts of conjugated materials normally considered ancillary to optoelectronic properties can determine their solid-state properties, epitomizing the challenge of rational design but at the same time offering opportunities for materials discovery and improved understanding of non-covalent interactions.
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Affiliation(s)
- Seth A Sharber
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA, 02155, USA
| | - Samuel W Thomas
- Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, MA, 02155, USA
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Sharber SA, Shih KC, Mann A, Frausto F, Haas TE, Nieh MP, Thomas SW. Reversible mechanofluorochromism of aniline-terminated phenylene ethynylenes. Chem Sci 2018; 9:5415-5426. [PMID: 30009013 PMCID: PMC6009520 DOI: 10.1039/c8sc00980e] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/23/2018] [Indexed: 01/24/2023] Open
Abstract
Seven three-ring phenylene-ethynylene (PE) structural analogs, differing only in the lengths of alkyl chains on terminal aniline substituents, show 50-62 nm bathochromic shifts in emission maxima in response to mechanical force (mechanofluorochromism, MC). These shifts are fully reversible with heat or solvent fuming. Shearing of these solids yields a transition from green-emitting crystalline phases to orange-emitting amorphous phases as established by differential scanning calorimetry and X-ray diffraction. Molecules with shorter alkyl chain lengths required higher temperatures to recover the hypsochromically shifted crystalline phases after grinding, while the recovery with chain lengths longer than butyl occurred at room temperature. In addition to this structure-dependent thermochromism, these compounds retain their MC properties in polymer hosts to various extents. The crystalline phases of these materials have PE chromophores that are twisted due to non-covalent perfluoroarene-arene (ArF-ArH) interactions involving perfluorophenyl pendants and the terminal rings of the PE chromophore, resulting in interrupted conjugation and an absence of chromophore aggregation. The MC behavior of an analog without the perfluoroarene rings is severely attenuated. This work demonstrates the general utility of twisted PEs as stimuli-responsive moieties and reveals clear structure-property relationships regarding the effects of alkyl chain length on these materials.
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Affiliation(s)
- Seth A Sharber
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , MA 02155 , USA .
| | - Kuo-Chih Shih
- Department of Chemical & Biomolecular Engineering , University of Connecticut , 97 North Eagleville Road, Storrs , CT 06269 , USA
| | - Arielle Mann
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , MA 02155 , USA .
| | - Fanny Frausto
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , MA 02155 , USA .
| | - Terry E Haas
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , MA 02155 , USA .
| | - Mu-Ping Nieh
- Department of Chemical & Biomolecular Engineering , University of Connecticut , 97 North Eagleville Road, Storrs , CT 06269 , USA
| | - Samuel W Thomas
- Department of Chemistry , Tufts University , 62 Talbot Avenue , Medford , MA 02155 , USA .
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Sharber SA, Baral RN, Frausto Arellano F, Haas TE, Müller P, Thomas Iii SW. Substituent Effects That Control Conjugated Oligomer Conformation through Non-covalent Interactions. J Am Chem Soc 2017; 139:5164-5174. [PMID: 28362486 DOI: 10.1021/jacs.7b00878] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although understanding the conformations and arrangements of conjugated materials as solids is key to their prospective applications, predictive power over these structural factors remains elusive. In this work, substituent effects tune non-covalent interactions between side-chain fluorinated benzyl esters and main-chain terminal arenes, in turn controlling the conformations and interchromophore aggregation of three-ring phenylene-ethynylenes (PEs). Cofacial fluoroarene-arene (ArF-ArH) interactions cause twisting in the PE backbone, interrupting intramolecular conjugation as well as blocking chromophore aggregation, both of which prevent the typically observed bathochromic shift observed upon transitioning PEs from solution to solid. This work highlights two structural factors that determine whether the ArF-ArH interactions, and the resulting twisted, unaggregated chromophores, occur in these solids: (i) the electron-releasing characteristic of substituents on ArH, with more electron-releasing character favoring ArF-ArH interactions, and (ii) the fluorination pattern of the ArF ring, with 2,3,4,5,6-pentafluorophenyl favoring ArF-ArH interactions over 2,4,6-trifluorophenyl. These trends indicate that considerations of electrostatic complementarity, whether through a polar-π or substituent-substituent mechanism, can serve as an effective design principle in controlling the interaction strengths, and therefore the optoelectronic properties, of these molecules as solids.
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Affiliation(s)
- Seth A Sharber
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | - Rom Nath Baral
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | | | - Terry E Haas
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
| | - Peter Müller
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Samuel W Thomas Iii
- Department of Chemistry, Tufts University , Medford, Massachusetts 02155, United States
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