1
|
Lee CK, Gangadharappa C, Fahrenbach AC, Kim DJ. Harnessing Radicals: Advances in Self-Assembly and Molecular Machinery. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2408271. [PMID: 39177115 DOI: 10.1002/adma.202408271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 07/25/2024] [Indexed: 08/24/2024]
Abstract
Radicals, with their unpaired electrons, exhibit unique chemical and physical properties that have long intrigued chemists. Despite early skepticism about their stability, the discovery of persistent radicals has opened new possibilities for molecular interactions. This review examines the mechanisms and applications of radically driven self-assembly, focusing on key motifs such as naphthalene diimides, tetrathiafulvalenes, and viologens, which serve as models for radical assembly. The potential of radical interactions in the development of artificial molecular machines (AMMs) are also discussed. These AMMs, powered by radical-radical interactions, represent significant advancements in non-equilibrium chemistry, mimicking the functionalities of biological systems. From molecular switches to ratchets and pumps, the versatility and unique properties of radically powered AMMs are highlighted. Additionally, the applications of radical assembly in materials science are explored, particularly in creating smart materials with redox-responsive properties. The review concludes by comparing AMMs to biological molecular machines, offering insights into future directions. This overview underscores the impact of radical chemistry on molecular assembly and its promising applications in both synthetic and biological systems.
Collapse
Affiliation(s)
| | | | - Albert C Fahrenbach
- School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia
- Australian Centre for Astrobiology, University of New South Wales, Sydney, NSW, 2052, Australia
- UNSW RNA Institute, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Dong Jun Kim
- School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia
| |
Collapse
|
2
|
Chen X, Chen H, Fraser Stoddart J. The Story of the Little Blue Box: A Tribute to Siegfried Hünig. Angew Chem Int Ed Engl 2023; 62:e202211387. [PMID: 36131604 PMCID: PMC10099103 DOI: 10.1002/anie.202211387] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Indexed: 02/02/2023]
Abstract
The tetracationic cyclophane, cyclobis(paraquat-p-phenylene), also known as the little blue box, constitutes a modular receptor that has facilitated the discovery of many host-guest complexes and mechanically interlocked molecules during the past 35 years. Its versatility in binding small π-donors in its tetracationic state, as well as forming trisradical tricationic complexes with viologen radical cations in its doubly reduced bisradical dicationic state, renders it valuable for the construction of various stimuli-responsive materials. Since the first reports in 1988, the little blue box has been featured in over 500 publications in the literature. All this research activity would not have been possible without the seminal contributions carried out by Siegfried Hünig, who not only pioneered the syntheses of viologen-containing cyclophanes, but also revealed their rich redox chemistry in addition to their ability to undergo intramolecular π-dimerization. This Review describes how his pioneering research led to the design and synthesis of the little blue box, and how this redox-active host evolved into the key component of molecular shuttles, switches, and machines.
Collapse
Affiliation(s)
- Xiao‐Yang Chen
- Department of ChemistryNorthwestern University2145 Sheridan RoadEvanstonIllinois 60208USA
| | - Hongliang Chen
- Stoddart Institute of Molecular ScienceDepartment of ChemistryZhejiang UniversityHangzhou310027China
- ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou311215China
| | - J. Fraser Stoddart
- Department of ChemistryNorthwestern University2145 Sheridan RoadEvanstonIllinois 60208USA
- Stoddart Institute of Molecular ScienceDepartment of ChemistryZhejiang UniversityHangzhou310027China
- ZJU-Hangzhou Global Scientific and Technological Innovation CenterHangzhou311215China
- School of ChemistryUniversity of New South WalesSydneyNSW 2052Australia
| |
Collapse
|
3
|
Au-Yeung HY, Deng Y. Distinctive features and challenges in catenane chemistry. Chem Sci 2022; 13:3315-3334. [PMID: 35432874 PMCID: PMC8943846 DOI: 10.1039/d1sc05391d] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/04/2022] [Indexed: 11/21/2022] Open
Abstract
From being an aesthetic molecular object to a building block for the construction of molecular machines, catenanes and related mechanically interlocked molecules (MIMs) continue to attract immense interest in many research areas. Catenane chemistry is closely tied to that of rotaxanes and knots, and involves concepts like mechanical bonds, chemical topology and co-conformation that are unique to these molecules. Yet, because of their different topological structures and mechanical bond properties, there are some fundamental differences between the chemistry of catenanes and that of rotaxanes and knots although the boundary is sometimes blurred. Clearly distinguishing these differences, in aspects of bonding, structure, synthesis and properties, between catenanes and other MIMs is therefore of fundamental importance to understand their chemistry and explore the new opportunities from mechanical bonds.
Collapse
Affiliation(s)
- Ho Yu Au-Yeung
- Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
- State Key Laboratory of Synthetic Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Yulin Deng
- Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| |
Collapse
|
4
|
Peng WC, Wang H, Zhang DW, Li ZT. Folding and Aggregation of Oligoviologens in Water and Cucurbit[ n]uril ( n=7, 8) Modulation. CHINESE J ORG CHEM 2022. [DOI: 10.6023/cjoc202108025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
5
|
Chen X, Mao H, Feng Y, Cai K, Shen D, Wu H, Zhang L, Zhao X, Chen H, Song B, Jiao Y, Wu Y, Stern CL, Wasielewski MR, Stoddart JF. Radically Enhanced Dual Recognition. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiao‐Yang Chen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Haochuan Mao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute for Sustainability and Energy at Northwestern Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yuanning Feng
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Kang Cai
- Department of Chemistry Nankai University 94 Weijin Road, Nankai District Tianjin 300071 China
| | - Dengke Shen
- Institutes of Physical Science and Information Technology Anhui University Hefei 230601 China
| | - Huang Wu
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Long Zhang
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Xingang Zhao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Hongliang Chen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Bo Song
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yang Jiao
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Yong Wu
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Charlotte L. Stern
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Michael R. Wasielewski
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute for Sustainability and Energy at Northwestern Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - J. Fraser Stoddart
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
- Stoddart Institute of Molecular Science Department of Chemistry Zhejiang University Hangzhou 310027 China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou 311215 China
| |
Collapse
|
6
|
Chen XY, Mao H, Feng Y, Cai K, Shen D, Wu H, Zhang L, Zhao X, Chen H, Song B, Jiao Y, Wu Y, Stern CL, Wasielewski MR, Stoddart JF. Radically Enhanced Dual Recognition. Angew Chem Int Ed Engl 2021; 60:25454-25462. [PMID: 34342116 DOI: 10.1002/anie.202109647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Indexed: 11/08/2022]
Abstract
Complexation between a viologen radical cation (V.+ ) and cyclobis(paraquat-p-phenylene) diradical dication (CBPQT2(.+) ) has been investigated and utilized extensively in the construction of mechanically interlocked molecules (MIMs) and artificial molecular machines (AMMs). The selective recognition of a pair of V.+ using radical-pairing interactions, however, remains a formidable challenge. Herein, we report the efficient encapsulation of two methyl viologen radical cations (MV.+ ) in a size-matched bisradical dicationic host - namely, cyclobis(paraquat-2,6-naphthalene)2(.+) , i.e., CBPQN2(.+) . Central to this dual recognition process was the choice of 2,6-bismethylenenaphthalene linkers for incorporation into the bisradical dicationic host. They provide the space between the two bipyridinium radical cations in CBPQN2(.+) suitable for binding two MV.+ with relatively short (3.05-3.25 Å) radical-pairing distances. The size-matched bisradical dicationic host was found to exhibit highly selective and cooperative association with the two MV.+ in MeCN at room temperature. The formation of the tetrakisradical tetracationic inclusion complex - namely, [(MV)2 ⊂CBPQN]4( .+) - in MeCN was confirmed by VT 1 H NMR, as well as by EPR spectroscopy. The solid-state superstructure of [(MV)2 ⊂CBPQN]4( .+) reveals an uneven distribution of the binding distances (3.05, 3.24, 3.05 Å) between the three different V.+ , suggesting that localization of the radical-pairing interactions has a strong influence on the packing of the two MV.+ inside the bisradical dicationic host. Our findings constitute a rare example of binding two radical guests with high affinity and cooperativity using host-guest radical-pairing interactions. Moreover, they open up possibilities of harnessing the tetrakisradical tetracationic inclusion complex as a new, orthogonal and redox-switchable recognition motif for the construction of MIMs and AMMs.
Collapse
Affiliation(s)
- Xiao-Yang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Haochuan Mao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yuanning Feng
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Kang Cai
- Department of Chemistry, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, China
| | - Dengke Shen
- Institutes of Physical Science and Information Technology, Anhui University, Hefei, 230601, China
| | - Huang Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Long Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Xingang Zhao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Hongliang Chen
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Bo Song
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yang Jiao
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Yong Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Charlotte L Stern
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.,School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 311215, China
| |
Collapse
|
7
|
Cai K, Zhang L, Astumian RD, Stoddart JF. Radical-pairing-induced molecular assembly and motion. Nat Rev Chem 2021; 5:447-465. [PMID: 37118435 DOI: 10.1038/s41570-021-00283-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2021] [Indexed: 12/25/2022]
Abstract
Radical-pairing interactions between conjugated organic π-radicals are relative newcomers to the inventory of molecular recognition motifs explored in supramolecular chemistry. The unique electronic, magnetic, optical and redox-responsive properties of the conjugated π-radicals render molecules designed with radical-pairing interactions useful for applications in various areas of chemistry and materials science. In particular, the ability to control formation of radical cationic or anionic species, by redox stimulation, provides a flexible trigger for directed assembly and controlled molecular motions, as well as a convenient means of inputting energy to fuel non-equilibrium processes. In this Review, we provide an overview of different examples of radical-pairing-based recognition processes and of their emerging use in (1) supramolecular assembly, (2) templation of mechanically interlocked molecules, (3) stimuli-controlled molecular switches and, by incorporation of kinetic asymmetry in the design, (4) the creation of unidirectional molecular transporters based on pumping cassettes powered by fuelled switching of radical-pairing interactions. We conclude the discussion with an outlook on future directions for the field.
Collapse
|
8
|
Hanozin E, Mignolet B, Martens J, Berden G, Sluysmans D, Duwez AS, Stoddart JF, Eppe G, Oomens J, De Pauw E, Morsa D. Radical-Pairing Interactions in a Molecular Switch Evidenced by Ion Mobility Spectrometry and Infrared Ion Spectroscopy. Angew Chem Int Ed Engl 2021; 60:10049-10055. [PMID: 33561311 PMCID: PMC8251753 DOI: 10.1002/anie.202014728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/07/2021] [Indexed: 12/11/2022]
Abstract
The digital revolution sets a milestone in the progressive miniaturization of working devices and in the underlying advent of molecular machines. Foldamers involving mechanically entangled components with modular secondary structures are among the most promising designs for molecular switch‐based applications. Characterizing the nature and dynamics of their intramolecular network following the application of a stimulus is the key to their performance. Here, we use non‐dissociative electron transfer as a reductive stimulus in the gas phase and probe the consecutive co‐conformational transitions of a donor‐acceptor oligorotaxane foldamer using electrospray mass spectrometry interfaced with ion mobility and infrared ion spectroscopy. A comparison of collision cross section distributions for analogous closed‐shell and radical molecular ions sheds light on their respective formation energetics, while variations in their respective infrared absorption bands evidence changes in intramolecular organization as the foldamer becomes more compact. These differences are compatible with the advent of radical‐pairing interactions.
Collapse
Affiliation(s)
- Emeline Hanozin
- Mass Spectrometry Laboratory, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - Benoit Mignolet
- Theoretical Physical Chemistry, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - Jonathan Martens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, The Netherlands
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, The Netherlands
| | - Damien Sluysmans
- NanoChemistry and Molecular Systems, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - Anne-Sophie Duwez
- NanoChemistry and Molecular Systems, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - J Fraser Stoddart
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA.,Stoddart Institute of Molecular Science, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou, 311215, China.,School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Gauthier Eppe
- Mass Spectrometry Laboratory, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, The Netherlands.,van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 908, 1098XH, Amsterdam, The Netherlands
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, UR MolSys, University of Liège, 4000, Liège, Belgium
| | - Denis Morsa
- Mass Spectrometry Laboratory, UR MolSys, University of Liège, 4000, Liège, Belgium.,Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525, ED, Nijmegen, The Netherlands
| |
Collapse
|
9
|
Hanozin E, Mignolet B, Martens J, Berden G, Sluysmans D, Duwez A, Stoddart JF, Eppe G, Oomens J, De Pauw E, Morsa D. Radical‐Pairing Interactions in a Molecular Switch Evidenced by Ion Mobility Spectrometry and Infrared Ion Spectroscopy. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Emeline Hanozin
- Mass Spectrometry Laboratory UR MolSys University of Liège 4000 Liège Belgium
| | - Benoit Mignolet
- Theoretical Physical Chemistry UR MolSys University of Liège 4000 Liège Belgium
| | - Jonathan Martens
- Institute for Molecules and Materials FELIX Laboratory Radboud University Toernooiveld 7 6525 ED Nijmegen The Netherlands
| | - Giel Berden
- Institute for Molecules and Materials FELIX Laboratory Radboud University Toernooiveld 7 6525 ED Nijmegen The Netherlands
| | - Damien Sluysmans
- NanoChemistry and Molecular Systems UR MolSys University of Liège 4000 Liège Belgium
| | - Anne‐Sophie Duwez
- NanoChemistry and Molecular Systems UR MolSys University of Liège 4000 Liège Belgium
| | - J. Fraser Stoddart
- Department of Chemistry Northwestern University Evanston IL 60208 USA
- Stoddart Institute of Molecular Science Department of Chemistry Zhejiang University Hangzhou 310027 China
- ZJU-Hangzhou Global Scientific and Technological Innovation Center Hangzhou 311215 China
- School of Chemistry University of New South Wales Sydney NSW 2052 Australia
| | - Gauthier Eppe
- Mass Spectrometry Laboratory UR MolSys University of Liège 4000 Liège Belgium
| | - Jos Oomens
- Institute for Molecules and Materials FELIX Laboratory Radboud University Toernooiveld 7 6525 ED Nijmegen The Netherlands
- van't Hoff Institute for Molecular Sciences University of Amsterdam Science Park 908 1098XH Amsterdam The Netherlands
| | - Edwin De Pauw
- Mass Spectrometry Laboratory UR MolSys University of Liège 4000 Liège Belgium
| | - Denis Morsa
- Mass Spectrometry Laboratory UR MolSys University of Liège 4000 Liège Belgium
- Institute for Molecules and Materials FELIX Laboratory Radboud University Toernooiveld 7 6525 ED Nijmegen The Netherlands
| |
Collapse
|
10
|
Nakamura T, Mori Y, Naito M, Okuma Y, Miyagawa S, Takaya H, Kawasaki T, Tokunaga Y. Rotaxanes comprising cyclic phenylenedioxydiacetamides and secondary mono- and bis-dialkylammonium ions: effect of macrocyclic ring size on pseudorotaxane formation. Org Chem Front 2020. [DOI: 10.1039/c9qo01359h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[2]Rotaxanes, stabilized through multiple and cooperative hydrogen bonding system, were synthesized from dialkylammonium ions and macrocycle possessing two phenylenedioxydiacetamide units and appropriate spacers.
Collapse
Affiliation(s)
- Takanori Nakamura
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| | - Yuka Mori
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| | - Masaya Naito
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| | - Yukari Okuma
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| | - Shinobu Miyagawa
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| | - Hikaru Takaya
- International Research Center for Elements Science
- Institute for Chemical Research
- Kyoto University
- Uji 611-0011
- Japan
| | - Tsuneomi Kawasaki
- Department of Applied Chemistry
- Tokyo University of Science
- Tokyo 162-8601
- Japan
| | - Yuji Tokunaga
- Department of Materials Science and Engineering
- Faculty of Engineering
- University of Fukui
- Fukui 910-8507
- Japan
| |
Collapse
|
11
|
Zhou HY, Zong QS, Han Y, Chen CF. Recent advances in higher order rotaxane architectures. Chem Commun (Camb) 2020; 56:9916-9936. [PMID: 32638726 DOI: 10.1039/d0cc03057k] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Despite dramatic advances in the template-directed synthesis of archetypal [2]rotaxanes, higher order rotaxanes with multiple molecular components (rings or dumbbells) are relatively daunting subjects owing to their synthetic challenges. With unique interlocked architectures, higher order rotaxanes have found applications in artificial molecular machines. In this feature article, we will focus on the recent advances in higher order rotaxanes with well-defined structures. Different types of rotaxane architectures will be described, and their synthetic approaches will be highlighted. Moreover, the stimuli-responsive molecular motion with increasing complexity in these diverse architectures will also be discussed.
Collapse
Affiliation(s)
- He-Ye Zhou
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qian-Shou Zong
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, China
| | - Ying Han
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
| | - Chuan-Feng Chen
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. and University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
12
|
Schröder HV, Schalley CA. Electrochemically switchable rotaxanes: recent strides in new directions. Chem Sci 2019; 10:9626-9639. [PMID: 32110308 PMCID: PMC7020790 DOI: 10.1039/c9sc04118d] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 10/03/2019] [Indexed: 12/13/2022] Open
Abstract
Are they still electrifying? Electrochemically switchable rotaxanes are well known for their ability to efficiently undergo changes of (co-)conformation and properties under redox-control. Thus, these mechanically interlocked assemblies represent an auspicious liaison between the fields of molecular switches and molecular electronics. Since the first reported example of a redox-switchable molecular shuttle in 1994, improved tools of organic and supramolecular synthesis have enabled sophisticated new architectures, which provide precise control over properties and function. This perspective covers recent advances in the area of electrochemically active rotaxanes including novel molecular switches and machines, metal-containing rotaxanes, non-equilibrium systems and potential applications.
Collapse
Affiliation(s)
- Hendrik V Schröder
- Institut für Chemie und Biochemie , Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany .
| | - Christoph A Schalley
- Institut für Chemie und Biochemie , Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany .
| |
Collapse
|
13
|
Hanozin E, Morsa D, De Pauw E. Two-Parameter Power Formalism for Structural Screening of Ion Mobility Trends: Applied Study on Artificial Molecular Switches. J Phys Chem A 2019; 123:8043-8052. [PMID: 31449411 DOI: 10.1021/acs.jpca.9b06121] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recent literature provides increasing samples of structural studies relying on ion mobility coupled to mass spectrometry in view of characterizing gas-phase conformation and energetics properties of biomolecular ions. A typical framework consists in experimentally monitoring the collisional cross sections for various experimental conditions and using them as references to select appropriate candidate structures issued from theoretical modeling. Although it has proved successful for structural assignment, this process is resource costly and lengthy, namely due to intricacies in the selection of appropriate input geometries. In the present work, we propose simplified methodologies dedicated to the systematic screening of ion mobility data acquired on systems built from repetitive subunits and detail their application to challenging artificial molecular switch systems. Capitalizing on coarse-grained design, we first demonstrate how the assimilation of subunits into adequately assembled building-blocks can be used for fast assignments of a system topology. Further focusing on topology-specific differential ion mobility trends, we show that the building-block assemblies can be fused into single fully convex solid figure models, i.e., sphere and cylinder, whose projected areas follow a two-parameter power formalism A × nB. We show that the fitting parameters A and B were assigned as structural descriptors respectively associated with the dimensions of each constitutive subunit, i.e., size parameter, and with their assembled tridimensional arrangement, i.e., shape parameter. The present work provides a ready-to-use method for the screening of IM-MS data sets that is expected to facilitate the eventual design of input structures whenever advanced modeling calculations are required.
Collapse
Affiliation(s)
- Emeline Hanozin
- Mass Spectrometry Laboratory, MolSys Research Unit , University of Liège , 4000 Liège , Belgium
| | - Denis Morsa
- Mass Spectrometry Laboratory, MolSys Research Unit , University of Liège , 4000 Liège , Belgium
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, MolSys Research Unit , University of Liège , 4000 Liège , Belgium
| |
Collapse
|
14
|
Schröder HV, Stein F, Wollschläger JM, Sobottka S, Gaedke M, Sarkar B, Schalley CA. Accordion‐Like Motion in Electrochemically Switchable Crown Ether/Ammonium Oligorotaxanes. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813265] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Hendrik V. Schröder
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Felix Stein
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Jan M. Wollschläger
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Sebastian Sobottka
- Institut für Chemie und BiochemieFreie Universität Berlin Fabeckstraße 34/36 14195 Berlin Germany
| | - Marius Gaedke
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
| | - Biprajit Sarkar
- Institut für Chemie und BiochemieFreie Universität Berlin Fabeckstraße 34/36 14195 Berlin Germany
| | - Christoph A. Schalley
- Institut für Chemie und BiochemieFreie Universität Berlin Takustraße 3 14195 Berlin Germany
- School of Life SciencesNorthwestern Polytechnical University 127 Youyi Xilu, Xi'an Shaanxi 710072 P. R. China
| |
Collapse
|
15
|
Schröder HV, Stein F, Wollschläger JM, Sobottka S, Gaedke M, Sarkar B, Schalley CA. Accordion-Like Motion in Electrochemically Switchable Crown Ether/Ammonium Oligorotaxanes. Angew Chem Int Ed Engl 2019; 58:3496-3500. [PMID: 30623543 DOI: 10.1002/anie.201813265] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Indexed: 12/13/2022]
Abstract
Reversible oxidation reactions in electrochemically switchable oligorotaxanes with tetrathiafulvalene (TTF) decorated 24-crown-8 ether wheels generate intramolecular mixed-valence and radical-cation interactions between the wheels. This induces shuttling of the wheels and a contraction of inter-wheel distances. Further oxidation generates repulsive forces between the TTFs and maximizes the inter-wheel distances instead. These interactions and co-conformational changes were not observed for structurally similar controls in which acetyl groups along the axle prevent translational motion of the wheels. This operation mode of oligorotaxanes, which is reminiscent of an accordion-like motion, is promising for functional materials and nanodevices such as piston-type rotaxane motors.
Collapse
Affiliation(s)
- Hendrik V Schröder
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Felix Stein
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Jan M Wollschläger
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Sebastian Sobottka
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Marius Gaedke
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34/36, 14195, Berlin, Germany
| | - Christoph A Schalley
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195, Berlin, Germany.,School of Life Sciences, Northwestern Polytechnical University, 127 Youyi Xilu, Xi'an, Shaanxi, 710072, P. R. China
| |
Collapse
|
16
|
Schröder HV, Witte F, Gaedke M, Sobottka S, Suntrup L, Hupatz H, Valkonen A, Paulus B, Rissanen K, Sarkar B, Schalley CA. An aryl-fused redox-active tetrathiafulvalene with enhanced mixed-valence and radical-cation dimer stabilities. Org Biomol Chem 2019; 16:2741-2747. [PMID: 29594290 DOI: 10.1039/c8ob00415c] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Molecular recognition of stable organic radicals is a relatively novel, but important structural binding motif in supramolecular chemistry. Here, we report on a redox-switchable veratrole-fused tetrathiafulvalene derivative VTTF which is ideally suited for this purpose and for the incorporation into stimuli-responsive systems. As revealed by electrochemistry, UV/Vis measurements, X-ray analysis, and electrocrystallisation, VTTF can be reversibly oxidised to the corresponding radical-cation or dication which shows optoelectronic and structural propterties similar to tetrathiafulvalene and tetrakis(methylthio)tetrathiafulvalene. However, theoretical calculations, variable temperature EPR, and NIR spectroscopy indicate that the dispersion-driven binding in the mixed-valence dimer (VTTF2)˙+ (KMV = 69 M-1 in CH2Cl2) and the radical-cation dimer (VTTF˙+)2 (KRC = 38 M-1 in CH3CN) is significantly enhanced by the additional veratrole π-surface in comparison to pristine tetrathiafulvalene.
Collapse
Affiliation(s)
- Hendrik V Schröder
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Wang Y, Cheng T, Sun J, Liu Z, Frasconi M, Goddard WA, Stoddart JF. Neighboring Component Effect in a Tri-stable [2]Rotaxane. J Am Chem Soc 2018; 140:13827-13834. [PMID: 30253106 DOI: 10.1021/jacs.8b08519] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The redox properties of cyclobis(paraquat- p-phenylene)cyclophane (CBPQT4+) render it a uniquely variable source of recognition in the context of mechanically interlocked molecules, through aromatic donor-acceptor interactions in its fully oxidized state (CPBQT4+) and radical-pairing interactions in its partially reduced state (CBPQT2(•+)). Although it is expected that the fully reduced neutral state (CBPQT(0)) might behave as a π-donating recognition unit, resulting in a dramatic change in its binding properties when compared with the other two redox states, its role in rotaxanes has not yet been investigated. To address this challenge, we report herein the synthesis of a tri-stable [2]rotaxane in which a CBPQT4+ ring is mechanically interlocked with a dumbbell component containing five recognition sites-(i) a bipyridinium radical cation (BIPY(•+)) located centrally along the axis of the dumbbell, straddled by (ii) two tetrafluorophenylene units linked to (iii) two triazole rings. In addition to the selective recognition between (iv) the CBPQT4+ ring and the triazole units, and (v) the CBPQT2(•+) ring and the reduced BIPY(•+) unit in the dumbbell component, investigations in solution have now confirmed the presence of additional non-covalent bonding interactions between the CBPQT(0) ring, acting as a donor in its neutral state, and the two tetrafluorophenylene acceptors in the dumbbell component. The unveiling of this piece of molecular recognition in a [2]rotaxane is reminiscent of the existence in much simpler, covalently linked, organic molecules of neighboring group participation (anchimeric assistance giving way to transannular interactions) in small-, medium-, and large-membered rings.
Collapse
Affiliation(s)
- Yuping Wang
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - Tao Cheng
- Materials and Process Simulation Center , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125 , United States
| | - Junling Sun
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States
| | - Zhichang Liu
- School of Science , Westlake University , 18 Shilongshan Road , Hangzhou 310024 , China
| | - Marco Frasconi
- Department of Chemical Sciences , University of Padova , Via Marzolo 1 , Padova 35131 , Italy
| | - William A Goddard
- Materials and Process Simulation Center , California Institute of Technology , 1200 East California Boulevard , Pasadena , California 91125 , United States
| | - J Fraser Stoddart
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , United States.,Institute for Molecular Design and Synthesis , Tianjin University , 92 Weijin Road , Nankai District, Tianjin 300072 , China.,School of Chemistry , University of New South Wales , Sydney , NSW 2052 , Australia
| |
Collapse
|
18
|
Nguyen MT, Ferris DP, Pezzato C, Wang Y, Stoddart JF. Densely Charged Dodecacationic [3]- and Tetracosacationic Radial [5]Catenanes. Chem 2018. [DOI: 10.1016/j.chempr.2018.07.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
19
|
Chen L, Lim KJC, Babra TS, Taylor JO, PiŽl M, Evans R, Chippindale AM, Hartl F, Colquhoun HM, Greenland BW. A macrocyclic receptor containing two viologen species connected by conjugated terphenyl groups. Org Biomol Chem 2018; 16:5006-5015. [PMID: 29946600 DOI: 10.1039/c8ob00919h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A macrocyclic receptor molecule containing two viologen species connected by conjugated terphenyl groups has been designed and synthesised. The single-crystal X-ray structure shows that the two viologen residues have a transannular NN separation of ca. 7.4 Å. Thus, the internal cavity dimensions are suitable for the inclusion of π-electron-rich species. The macrocycle is redox active, and can accept electrons from suitable donor species including triethylamine, resulting in a dramatic colour change from pale yellow to dark green as a consequence of the formation of a paramagnetic bis(radical cationic) species. Cyclic voltammetry shows that the macrocycle can undergo two sequential and reversible reduction processes (E1/2 = -0.65 and -0.97 V vs. Fc/Fc+). DFT and TD-DFT studies accurately replicate the structure of the tetracationic macrocycle and the electronic absorption spectra of the three major redox states of the system. These calculations also showed that during electrochemical reduction, the unpaired electron density of the radical cations remained relatively localised within the heterocyclic rings. The ability of the macrocycle to form supramolecular complexes was confirmed by the formation of a pseudorotaxane with a guest molecule containing a π-electron-rich 1,5-dihydroxynaphthalene derivative. Threading and dethreading of the pseudorotaxane was fast on the NMR timescale, and the complex exhibited an association constant of 150 M-1 (±30 M-1) as calculated from 1H NMR titration studies.
Collapse
Affiliation(s)
- Long Chen
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Pezzato C, Nguyen MT, Kim DJ, Anamimoghadam O, Mosca L, Stoddart JF. Controlling Dual Molecular Pumps Electrochemically. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803848] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Cristian Pezzato
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Minh T. Nguyen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Dong Jun Kim
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Ommid Anamimoghadam
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Lorenzo Mosca
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - J. Fraser Stoddart
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute of Molecular Design and Synthesis Tianjin University Nankai District Tianjin 300072 China
| |
Collapse
|
21
|
Pezzato C, Nguyen MT, Kim DJ, Anamimoghadam O, Mosca L, Stoddart JF. Controlling Dual Molecular Pumps Electrochemically. Angew Chem Int Ed Engl 2018; 57:9325-9329. [DOI: 10.1002/anie.201803848] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Cristian Pezzato
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Minh T. Nguyen
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Dong Jun Kim
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Ommid Anamimoghadam
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - Lorenzo Mosca
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
| | - J. Fraser Stoddart
- Department of Chemistry Northwestern University 2145 Sheridan Road Evanston IL 60208 USA
- Institute of Molecular Design and Synthesis Tianjin University Nankai District Tianjin 300072 China
| |
Collapse
|
22
|
Lipke MC, Wu Y, Roy I, Wang Y, Wasielewski MR, Stoddart JF. Shuttling Rates, Electronic States, and Hysteresis in a Ring-in-Ring Rotaxane. ACS CENTRAL SCIENCE 2018; 4:362-371. [PMID: 29632882 PMCID: PMC5879476 DOI: 10.1021/acscentsci.7b00535] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Indexed: 06/08/2023]
Abstract
The trisradical recognition motif between a 4,4'-bipyridinium radical cation and a cyclo-bis-4,4'-bipyridinium diradical dication has been employed previously in rotaxanes to control their nanomechanical and electronic properties. Herein, we describe the synthesis and characterization of a redox-active ring-in-ring [2]rotaxane BBR·8PF6 that employs a tetraradical variant of this recognition motif. A square-shaped bis-4,4'-bipyridinium cyclophane is mechanically interlocked around the dumbbell component of this rotaxane, and the dumbbell itself incorporates a smaller bis-4,4'-bipyridinium cyclophane into its covalently bonded structure. This small cyclophane serves as a significant impediment to the shuttling of the larger ring across the dumbbell component of BBR8+ , whereas reduction to the tetraradical tetracationic state BBR4(+•) results in strong association of the two cyclophanes driven by two radical-pairing interactions. In these respects, BBR·8PF6 exhibits qualitatively similar behavior to its predecessors that interconvert between hexacationic and trisradical tricationic states. The rigid preorganization of two bipyridinium groups within the dumbbell of BBR·8PF6 confers, however, two distinct properties upon this rotaxane: (1) the rate of shuttling is reduced significantly relative to those of its predecessors, resulting in marked electrochemical hysteresis observed by cyclic voltammetry for switching between the BBR8+/BBR4(+•) states, and (2) the formally tetraradical form of the rotaxane, BBR4(+•) , exhibits a diamagnetic ground state, which, as a result of the slow shuttling motions within BBR4(+•) , has a long enough lifetime to be characterized by 1H NMR spectroscopy.
Collapse
Affiliation(s)
- Mark C. Lipke
- Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854, United States
| | - Yilei Wu
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Indranil Roy
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Yuping Wang
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Michael R. Wasielewski
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|
23
|
Burgess M, Hernández-Burgos K, Schuh JK, Davila J, Montoto EC, Ewoldt RH, Rodríguez-López J. Modulation of the Electrochemical Reactivity of Solubilized Redox Active Polymers via Polyelectrolyte Dynamics. J Am Chem Soc 2018; 140:2093-2104. [PMID: 29369622 DOI: 10.1021/jacs.7b08353] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Redox active polymers (RAPs) are electrochemically versatile materials that find key applications in energy storage, sensing, and surface modification. In spite of the ubiquity of RAP-modified electrodes, a critical knowledge gap exists in the understanding of the electrochemistry of soluble RAPs and their relation to polyelectrolyte dynamics. Here, we explore for the first time the intersection between polyelectrolyte behavior and the electrochemical response that highly soluble and highly substituted RAPs with viologen, ferrocene, and nitrostyrene moieties elicit at electrodes. This comprehensive study of RAP electrolytes over several orders of magnitude in concentration and ionic strength reveals distinct signatures consistent with surface confined, colloidal, and bulk-like electrochemical behavior. These differences emerge across polyelectrolyte packing regimes and are strongly modulated by changes in RAP coil size and electrostatic interactions with the electrode. We found that, unlike monomer motifs, simple changes in the ionic strength caused variations over 1 order of magnitude in the current measured at the electrode. In addition, the thermodynamics of adsorbed RAP films were also affected, giving rise to standard reduction potential shifts leading to redox kinetic effects as a result of the mediating nature of the RAP film in equilibrium with the solution. Full electrochemical characterization via transient and steady-state techniques, including the use of ultramicroelectrodes and the rotating disk electrode, were correlated to dynamic light scattering, ellipsometry, and viscometric analysis. These methods helped elucidate the relationship between electrochemical behavior and RAP coil size, film thickness, and polyelectrolyte packing regime. This study underscores the role of electrostatics in modulating the reactivity of redox polyelectrolytes.
Collapse
Affiliation(s)
- Mark Burgess
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | | | - Jonathon K Schuh
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | | | - Elena C Montoto
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | - Randy H Ewoldt
- Joint Center for Energy Storage Research , Argonne, Illinois 60439, United States
| | | |
Collapse
|
24
|
Hanozin E, Mignolet B, Morsa D, Sluysmans D, Duwez AS, Stoddart JF, Remacle F, De Pauw E. Where Ion Mobility and Molecular Dynamics Meet To Unravel the (Un)Folding Mechanisms of an Oligorotaxane Molecular Switch. ACS NANO 2017; 11:10253-10263. [PMID: 28881131 DOI: 10.1021/acsnano.7b04833] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
At the interface between foldamers and mechanically interlocked molecules, oligorotaxanes exhibit a spring-like folded secondary structure with remarkable mechanical and physicochemical properties. Among these properties, the ability of oligorotaxanes to act as molecular switches through controlled modulations of their spatial extension over (un)folding dynamics is of particular interest. The present study aims to assess and further characterize this remarkable feature in the gas phase using mass spectrometry tools. In this context, we focused on the [4]5NPR+12 oligorotaxane molecule complexed with PF6- counterion and probed its co-conformational states as a function of the in-source-generated charge states. Data were interpreted in light of electronic secondary structure computations at the PM6 and DFT levels. Our results highlight two major co-conformational groups associated either with folded compact structures, notably stabilized by intramolecular π-π interactions and predominant for low charge states or with fully stretched structures resulting from significant Coulombic repulsions at high charge states. Between, the oligorotaxane adopts intermediate folded co-conformations, suggesting a stepwise unfolding pathway under increasing repulsive Coulombic constraints. The reversibility of this superstructural transition was next interrogated under electron-driven (nondissociative electron transfer) and heat-driven (collision-induced unfolding) activation stimuli. The outcomes support the feasibility to either unfold or (partially) refold the oligorotaxane foldamer on purpose in the gas phase. Our results show that the balance between the stabilizing π-π interactions and the versatile Coulomb interactions dictates the elongation state of the foldamer in the gas phase and emphasizes the adequacy of mass spectrometry tools for the superstructural characterization of desolvated prototypical artificial molecular machines.
Collapse
Affiliation(s)
| | | | | | | | | | - J Fraser Stoddart
- Mechanostereochemistry Group, Northwestern University , Evanston, Illinois 60208, United States
| | | | | |
Collapse
|
25
|
Wang Y, Frasconi M, Stoddart JF. Introducing Stable Radicals into Molecular Machines. ACS CENTRAL SCIENCE 2017; 3:927-935. [PMID: 28979933 PMCID: PMC5620985 DOI: 10.1021/acscentsci.7b00219] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Indexed: 06/07/2023]
Abstract
Ever since their discovery, stable organic radicals have received considerable attention from chemists because of their unique optical, electronic, and magnetic properties. Currently, one of the most appealing challenges for the chemical community is to develop sophisticated artificial molecular machines that can do work by consuming external energy, after the manner of motor proteins. In this context, radical-pairing interactions are important in addressing the challenge: they not only provide supramolecular assistance in the synthesis of molecular machines but also open the door to developing multifunctional systems relying on the various properties of the radical species. In this Outlook, by taking the radical cationic state of 1,1'-dialkyl-4,4'-bipyridinium (BIPY•+) as an example, we highlight our research on the art and science of introducing radical-pairing interactions into functional systems, from prototypical molecular switches to complex molecular machines, followed by a discussion of the (i) limitations of the current systems and (ii) future research directions for designing BIPY•+-based molecular machines with useful functions.
Collapse
Affiliation(s)
- Yuping Wang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Marco Frasconi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, Padova 35131, Italy
| | - J. Fraser Stoddart
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|
26
|
Gautam R, Astashkin AV, Chang TM, Shearer J, Tomat E. Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers. Inorg Chem 2017; 56:6755-6762. [PMID: 28497967 DOI: 10.1021/acs.inorgchem.7b01030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ability of tetrapyrrolic macrocycles to stabilize unpaired electrons and engage in π-π interactions is essential for many electron-transfer processes in biology and materials engineering. Herein, we demonstrate that the formation of π dimers is recapitulated in complexes of a linear tripyrrolic analogue of naturally occurring pigments derived from heme decomposition. Hexaethyltripyrrindione (H3TD1) coordinates divalent transition metals (i.e., Pd, Cu, Ni) as a stable dianionic radical and was recently described as a robust redox-active ligand. The resulting planar complexes, which feature a delocalized ligand-based electronic spin, are stable at room temperature in air and support ligand-based one-electron processes. We detail the dimerization of neutral tripyrrindione complexes in solution through electron paramagnetic resonance (EPR) and visible absorption spectroscopic methods. Variable-temperature measurements using both EPR and absorption techniques allowed determination of the thermodynamic parameters of π dimerization, which resemble those previously reported for porphyrin radical cations. The inferred electronic structure, featuring coupling of ligand-based electronic spins in the π dimers, is supported by density functional theory (DFT) calculations.
Collapse
Affiliation(s)
- Ritika Gautam
- Department of Chemistry and Biochemistry, The University of Arizona , Tucson, Arizona 85721, United States
| | - Andrei V Astashkin
- Department of Chemistry and Biochemistry, The University of Arizona , Tucson, Arizona 85721, United States
| | - Tsuhen M Chang
- Department of Chemistry and Biochemistry, The University of Arizona , Tucson, Arizona 85721, United States
| | - Jason Shearer
- Department of Chemistry, University of Nevada , Reno, Nevada 89577, United States
| | - Elisa Tomat
- Department of Chemistry and Biochemistry, The University of Arizona , Tucson, Arizona 85721, United States
| |
Collapse
|
27
|
Zhan TG, Wu L, Zhao Z, Zhou ZB, Yun MY, Wei J, Zheng ST, Yin HH, Zhang KD. Reversible conversion between a pleated oligo-tetrathiafulvalene radical foldamer and folded donor-acceptor [3]pseudorotaxane under redox conditions. Chem Commun (Camb) 2017; 53:5396-5399. [PMID: 28451683 DOI: 10.1039/c7cc02526b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Linear tetrathiafulvalene (TTF) oligomers were synthesized, which could not only form a pleated TTF˙+ radical cation foldamer under oxidation conditions, but also interlocked with CBPQT4+ to form folded donor-acceptor [3]pseudorotaxane in the neutral state of TTF. Moreover, switchable transformation between these two folded supramolecular structures was achieved under the alternative regulation of the redox states of TTF units.
Collapse
Affiliation(s)
- Tian-Guang Zhan
- College of Chemistry and Life Science, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China.
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Wang Y, Sun J, Liu Z, Nassar MS, Botros YY, Stoddart JF. Radically promoted formation of a molecular lasso. Chem Sci 2017; 8:2562-2568. [PMID: 28553488 PMCID: PMC5431688 DOI: 10.1039/c6sc05035b] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/15/2017] [Indexed: 12/15/2022] Open
Abstract
Two potential viologen-based molecular lasso precursors-both composed of a 4,4'-bipyridinium (BIPY2+) unit as part of a rope appended to a cyclobis(paraquat-p-phenylene) (CBPQT4+) loop-that have been designed to mimic the threading/unthreading motion of lasso peptides, have been synthesised and characterised. Solution and solid-state experiments reveal that, when the BIPY2+ unit in the rope and the CBPQT4+ loop are connected by a bulky linker, no lasso-like conformational transformation is observed between the different redox states on account of steric effects. In sharp contrast, when the linker size is small, the molecule can be switched between (i) a free rope-like conformation in its fully oxidised state and (ii) a self-entangled lasso-like conformation under reducing conditions employing either chemical or electrochemical stimuli: the BIPY˙+ unit in the rope resides inside the cavity of the CBPQT2(˙+) loop, forming a pseudo[1]rotaxane. The switching process is reversible and stereochemically unambiguous. This research shows how tiny structural differences can induce significantly different self-complexing properties and sheds light on designing functional artificial actuators.
Collapse
Affiliation(s)
- Yuping Wang
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; Tel: +1-847-491-3793
| | - Junling Sun
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; Tel: +1-847-491-3793
| | - Zhichang Liu
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; Tel: +1-847-491-3793
| | - Majed S Nassar
- Joint Center of Excellence in Integrated Nano-Systems (JCIN) , King Abdul-Aziz City for Science and Technology (KACST) , P. O. Box 6086 , Riyadh 11442 , Saudi Arabia
| | - Youssry Y Botros
- Joint Center of Excellence in Integrated Nano-Systems (JCIN) , King Abdul-Aziz City for Science and Technology (KACST) , P. O. Box 6086 , Riyadh 11442 , Saudi Arabia
- PanaceaNano, Inc. , 2265 East Foothill Boulevard , Pasadena , California 91107 , USA
| | - J Fraser Stoddart
- Department of Chemistry , Northwestern University , 2145 Sheridan Road , Evanston , Illinois 60208 , USA . ; Tel: +1-847-491-3793
| |
Collapse
|
29
|
Lipke MC, Cheng T, Wu Y, Arslan H, Xiao H, Wasielewski MR, Goddard WA, Stoddart JF. Size-Matched Radical Multivalency. J Am Chem Soc 2017; 139:3986-3998. [DOI: 10.1021/jacs.6b09892] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Mark C. Lipke
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tao Cheng
- Materials
and Process Simulation Center, California Institute of Technology, 1200 California Boulevard, Pasadena, California 91125, United States
| | - Yilei Wu
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Hasan Arslan
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Hai Xiao
- Materials
and Process Simulation Center, California Institute of Technology, 1200 California Boulevard, Pasadena, California 91125, United States
| | - Michael R. Wasielewski
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - William A. Goddard
- Materials
and Process Simulation Center, California Institute of Technology, 1200 California Boulevard, Pasadena, California 91125, United States
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|
30
|
Wang Y. Can Persistent Organic Radicals Find Function? Chem 2017. [DOI: 10.1016/j.chempr.2017.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
31
|
Kahlfuss C, Denis-Quanquin S, Calin N, Dumont E, Garavelli M, Royal G, Cobo S, Saint-Aman E, Bucher C. Electron-Triggered Metamorphism in Porphyrin-Based Self-Assembled Coordination Polymers. J Am Chem Soc 2016; 138:15234-15242. [PMID: 27766847 DOI: 10.1021/jacs.6b09311] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Viologen-centered electron transfer is used to trigger a complete dissociation of a porphyrin-based supramolecular architecture. In the oxidized state, self-assembly is induced by iterative association of individual porphyrin-based tectons. Dissociation of the self-assembled species is actuated upon changing the redox state of the bipyridium units involved in the tectons from their dicationic state to their radical cation state, the driving force of the disassembling process being the formation of an intramolecularly locked conformation partly stabilized by π-dimerization of both viologen cation radicals.
Collapse
Affiliation(s)
- Christophe Kahlfuss
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| | - Sandrine Denis-Quanquin
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| | - Nathalie Calin
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| | - Elise Dumont
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| | - Marco Garavelli
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France.,Dipartimento di Chimica "G. Ciamician", Università di Bologna , V. F. Selmi 2, 40126 Bologna, Italy
| | - Guy Royal
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire (UMR 5250), F38400 Grenoble, France
| | - Saioa Cobo
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire (UMR 5250), F38400 Grenoble, France
| | - Eric Saint-Aman
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire (UMR 5250), F38400 Grenoble, France
| | - Christophe Bucher
- Univ Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342 Lyon, France
| |
Collapse
|
32
|
Li X, Yuan X, Deng P, Chen L, Ren Y, Wang C, Wu L, Feng W, Gong B, Yuan L. Macrocyclic shape-persistency of cyclo[6]aramide results in enhanced multipoint recognition for the highly efficient template-directed synthesis of rotaxanes. Chem Sci 2016; 8:2091-2100. [PMID: 28451329 PMCID: PMC5399641 DOI: 10.1039/c6sc04714a] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 11/21/2016] [Indexed: 12/16/2022] Open
Abstract
Examples of using two-dimensional shape-persistent macrocycles, i.e. those having noncollapsible and geometrically well-defined skeletons, for constructing mechanically interlocked molecules are scarce, which contrasts the many applications of these macrocycles in molecular recognition and functional self-assembly. Herein, we report the crucial role played by macrocyclic shape-persistency in enhancing multipoint recognition for the highly efficient template-directed synthesis of rotaxanes. Cyclo[6]aramides, with a near-planar conformation, are found to act as powerful hosts that bind bipyridinium salts with high affinities. This unique recognition module, composed of two macrocyclic molecules with one bipyridinium ion thread through the cavity, is observed both in the solid state and in solution, with unusually high binding constants ranging from ∼1013 M-2 to ∼1015 M-2 in acetone. The high efficacy of this recognition motif is embodied by the formation of compact [3]rotaxanes in excellent yields based on either a "click-capping" (91%) or "facile one-pot" (85%) approach, underscoring the great advantage of using H-bonded aromatic amide macrocycles for the highly efficient template-directed synthesis of mechanically interlocked structures. Furthermore, three cyclo[6]aramides bearing different peripheral chains 1-3 demonstrate high specificity in the synthesis of a [3]rotaxane from 1 and 2, and a [2]rotaxane from 3via a "facile one-pot" approach, in each case as the only isolated product. Analysis of the crystal structure of the [3]rotaxane reveals a highly compact binding mode that would be difficult to access using other macrocycles with a flexible backbone. Leveraging this unique recognition motif, resulting from the shape-persistency of these oligoamide macrocycles, in the template-directed synthesis of compact rotaxanes may open up new opportunities for the development of higher order interlocked molecules and artificial molecular machines.
Collapse
Affiliation(s)
- Xiaowei Li
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Xiangyang Yuan
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Pengchi Deng
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Lixi Chen
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Yi Ren
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Chengyuan Wang
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Lixin Wu
- State Key Laboratory of Supramolecular Structure and Materials , Jilin University , Changchun 130012 , China
| | - Wen Feng
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| | - Bing Gong
- Department of Chemistry , The State University of New York , Buffalo , New York 14260 , USA
| | - Lihua Yuan
- College of Chemistry , Key Laboratory for Radiation Physics and Technology of Ministry of Education , Analytical & Testing Center , Sichuan University , Chengdu 610064 , Sichuan , China . ; ; Tel: +86-28-85412890
| |
Collapse
|
33
|
Fernando IR, Frasconi M, Wu Y, Liu WG, Wasielewski MR, Goddard WA, Stoddart JF. Sliding-Ring Catenanes. J Am Chem Soc 2016; 138:10214-25. [DOI: 10.1021/jacs.6b04982] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isurika R. Fernando
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Marco Frasconi
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova 35131, Italy
| | - Yilei Wu
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Argonne-Northwestern
Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - Wei-Guang Liu
- Materials
and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
| | - Michael R. Wasielewski
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Argonne-Northwestern
Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - William A. Goddard
- Materials
and Process Simulation Center, California Institute of Technology, Pasadena, California 91125, United States
- NanoCentury
KAIST Institute and Graduate School of EEWS (WCU), Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong Dong, Yuseong Gu, Daejeon 305-701, Republic of Korea
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|
34
|
Cheng C, Cheng T, Xiao H, Krzyaniak MD, Wang Y, McGonigal PR, Frasconi M, Barnes JC, Fahrenbach AC, Wasielewski MR, Goddard WA, Stoddart JF. Influence of Constitution and Charge on Radical Pairing Interactions in Tris-radical Tricationic Complexes. J Am Chem Soc 2016; 138:8288-300. [DOI: 10.1021/jacs.6b04343] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Chuyang Cheng
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Tao Cheng
- Materials
and Process Simulation Center (MC 139-74), California Institute of Technology, Pasadena, California 91125, United States
| | - Hai Xiao
- Materials
and Process Simulation Center (MC 139-74), California Institute of Technology, Pasadena, California 91125, United States
| | - Matthew D. Krzyaniak
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Argonne-Northwestern
Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - Yuping Wang
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Paul R. McGonigal
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department
of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Marco Frasconi
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova 35131, Italy
| | - Jonathan C. Barnes
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department
of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Avenue, Cambridge, Massachusetts 02139, United States
| | - Albert C. Fahrenbach
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Department
of Molecular Biology and Center for Computational and Integrative
Biology, Massachusetts General Hospital, Howard Hughes Medical Institute, 185 Cambridge Street, Boston, Massachusetts 02114, United States
- Earth-Life
Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Michael R. Wasielewski
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Argonne-Northwestern
Solar Energy Research (ANSER) Center, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - William A. Goddard
- Materials
and Process Simulation Center (MC 139-74), California Institute of Technology, Pasadena, California 91125, United States
| | - J. Fraser Stoddart
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| |
Collapse
|