1
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Flear EJ, Horst M, Yang J, Xia Y. Force Transduction Through Distant Force-Bearing Regioisomeric Linkages Affects the Mechanochemical Reactivity of Cyclobutane. Angew Chem Int Ed Engl 2024; 63:e202406103. [PMID: 38818671 DOI: 10.1002/anie.202406103] [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: 03/29/2024] [Revised: 05/24/2024] [Accepted: 05/29/2024] [Indexed: 06/01/2024]
Abstract
Fundamental understanding of mechanochemical reactivity is important for designing new mechanophores. Besides the core structure of mechanophores, substituents on a mechanophore can affect its mechanochemical reactivity through electronic stabilization of the intermediate or effectiveness of force transduction from the polymer backbone to the mechanophore. The latter factor represents a unique mechanical effect in considering polymer mechanochemistry. Here, we show that regioisomeric linkage that is not directly adjacent to the first cleaving bond in cyclobutane can still significantly affect the mechanochemical reactivity of the mechanophore. We synthesized three non-scissile 1,2-diphenyl cyclobutanes, varying their linkage to the polymer backbone via the o, m, or p-position of the diphenyl substituents. Even though the regioisomers share the same substituted cyclobutane core structure and similar electronic stabilization of the diradical intermediate from cleaving the first C-C bond, the p isomer exhibited significantly higher mechanochemical reactivity than the o and m isomers. The observed difference in reactivity can be rationalized as the much more effective force transduction to the scissile bond through the p-position than the other two substitution positions. These findings point to the importance of considering force-bearing linkages that are more distant from the bond to be cleaved when incorporating mechanophores into polymer backbones.
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Affiliation(s)
- Erica J Flear
- Department of Chemistry, Stanford University Stanford, California, 94305, United States
| | - Matías Horst
- Department of Chemistry, Stanford University Stanford, California, 94305, United States
| | - Jinghui Yang
- Department of Chemistry, Stanford University Stanford, California, 94305, United States
| | - Yan Xia
- Department of Chemistry, Stanford University Stanford, California, 94305, United States
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2
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Liao Y, Le Roi B, Zhang H, Diesendruck CE, Grolman JM. Facile Mechanophore Integration in Heterogeneous Biologically Derived Materials via "Dip-Conjugation". J Am Chem Soc 2024; 146:17878-17886. [PMID: 38899486 PMCID: PMC11229001 DOI: 10.1021/jacs.4c03534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Mechanical forces play critical roles in a wide variety of biological processes and diseases, yet measuring them directly at the molecular level remains one of the main challenges of mechanobiology. Here, we show a strategy to "Dip-conjugate" biologically derived materials at the chemical level to mechanophores, force-responsive molecular entities, using Click-chemistry. Contrary to classical prepolymerization mechanophore incorporation, this new protocol leads to detectable mechanochromic response with as low as 5% strain, finally making mechanophores relevant for many biological processes that have previously been inaccessible. Our results demonstrate the ubiquity of the technique with activation in synthetic polymers, carbohydrates, and proteins under mechanical force, with alpaca wool fibers as a key example. These results push the limits for mechanophore use in far more types of polymeric materials in applications ranging from molecular-level force damage detection to direct and quantitative 3D force measurements in mechanobiology.
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Affiliation(s)
- Yifan Liao
- Materials Science and Engineering Department, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Baptiste Le Roi
- Materials Science and Engineering Department, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Hang Zhang
- Shulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Charles E Diesendruck
- Shulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Joshua M Grolman
- Materials Science and Engineering Department, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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3
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Wang ZJ, Wang S, Jiang J, Hu Y, Nakajima T, Maeda S, Craig SL, Gong JP. Effect of the Activation Force of Mechanophore on Its Activation Selectivity and Efficiency in Polymer Networks. J Am Chem Soc 2024; 146:13336-13346. [PMID: 38697646 DOI: 10.1021/jacs.4c01879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
In recent decades, more than 100 different mechanophores with a broad range of activation forces have been developed. For various applications of mechanophores in polymer materials, it is crucial to selectively activate the mechanophores with high efficiency, avoiding nonspecific bond scission of the material. In this study, we embedded cyclobutane-based mechanophore cross-linkers (I and II) with varied activation forces (fa) in the first network of the double network hydrogels and quantitively investigated the activation selectivity and efficiency of these mechanophores. Our findings revealed that cross-linker I, with a lower activation force relative to the bonds in the polymer main chain (fa-I/fa-chain = 0.8 nN/3.4 nN), achieved efficient activation with 100% selectivity. Conversely, an increase of the activation force of mechanophore II (fa-II/fa-chain = 2.5 nN/3.4 nN) led to a significant decrease of its activation efficiency, accompanied by a substantial number of nonspecific bond scission events. Furthermore, with the coexistence of two cross-linkers, significantly different activation forces resulted in the almost complete suppression of the higher-force one (i.e., I and III, fa-I/fa-III = 0.8 nN/3.4 nN), while similar activation forces led to simultaneous activations with moderate efficiencies (i.e., I and IV, fa-I/fa-IV = 0.8 nN/1.6 nN). These findings provide insights into the prevention of nonspecific bond rupture during mechanophore activation and enhance our understanding of the damage mechanism within polymer networks when using mechanophores as detectors. Besides, it establishes a principle for combining different mechanophores to design multiple mechanoresponsive functional materials.
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Affiliation(s)
- Zhi Jian Wang
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo 001-0021, Japan
| | - Shu Wang
- Department of Chemistry, Duke University, Durham, North Carolina 27708-0346, United States
| | - Julong Jiang
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-8628, Japan
| | - Yixin Hu
- Department of Chemistry, Duke University, Durham, North Carolina 27708-0346, United States
| | - Tasuku Nakajima
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo 001-0021, Japan
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Satoshi Maeda
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo 001-0021, Japan
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-8628, Japan
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708-0346, United States
| | - Jian Ping Gong
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo 001-0021, Japan
- Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
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4
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Thai LD, Kammerer JA, Mutlu H, Barner-Kowollik C. Photo- and halochromism of spiropyran-based main-chain polymers. Chem Sci 2024; 15:3687-3697. [PMID: 38455007 PMCID: PMC10915860 DOI: 10.1039/d3sc06383f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 01/25/2024] [Indexed: 03/09/2024] Open
Abstract
Advanced functional polymeric materials based on spiropyrans (SPs) feature multi-stimuli responsive characteristics, such as a change in color with exposure to light (photochromism) or acids (halochromism). The inclusion of stimuli-responsive molecules in general - and SPs in particular - as main-chain repeating units is a scarcely explored macromolecular architecture compared to side chain responsive polymers. Herein, we establish the effects of substitution patterns on SPs within a homopolymer main-chain synthesized via head-to-tail Acyclic Diene METathesis (ADMET) polymerization. We unambiguously demonstrate that varying the location of the ester group (-OCOR) on the chromophore, which is essential to incorporate the SPs in the polymer backbone, determines the photo- and halochromism of the resulting polymers. While one polymer shows effective photochromism and resistance towards acids, the opposite - weak photochromism and effective response to acid - is observed for an isomeric polymer, simply by changing the position of the ester-linker relative to the benzopyran oxygen on the chromene unit. Our strategy represents a simple approach to manipulate the stimuli-response of main-chain SP bearing polymers and highlights the critical importance of isomeric molecular constitution on main-chain stimuli-sensitive polymers as emerging materials.
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Affiliation(s)
- Linh Duy Thai
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Jochen A Kammerer
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
| | - Hatice Mutlu
- Institut de Science des Matériaux de Mulhouse, UMR 7361 CNRS/Université de Haute Alsace 15 Rue Jean Starcky Mulhouse Cedex 68057 France
| | - Christopher Barner-Kowollik
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street Brisbane QLD 4000 Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
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5
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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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6
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Lin Y, Kouznetsova TB, Foret AG, Craig SL. Solvent Polarity Effects on the Mechanochemistry of Spiropyran Ring Opening. J Am Chem Soc 2024; 146:3920-3925. [PMID: 38308653 DOI: 10.1021/jacs.3c11621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2024]
Abstract
The spiropyran mechanophore (SP) is employed as a reporter of molecular tension in a wide range of polymer matrices, but the influence of surrounding environment on the force-coupled kinetics of its ring opening has not been quantified. Here, we report single-molecule force spectroscopy studies of SP ring opening in five solvents that span normalized Reichardt solvent polarity factors (ETN) of 0.1-0.59. Individual multimechanophore polymers were activated under increasing tension at constant 300 nm s-1 displacement in an atomic force microscope. The extension results in a plateau in the force-extension curve, whose midpoint occurs at a transition force f* that corresponds to the force required to increase the rate constant of SP activation to approximately 30 s-1. More polar solvents lead to mechanochemical reactions that are easier to trigger; f* decreases across the series of solvents, from a high of 415 ± 13 pN in toluene to a low of 234 ± 9 pN in n-butanol. The trend in mechanochemical reactivity is consistent with the developing zwitterionic character on going from SP to the ring-opened merocyanine product. The force dependence of the rate constant (Δx‡) was calculated for all solvent cases and found to increase with ETN, which is interpreted to reflect a shift in the transition state to a later and more productlike position. The inferred shift in the transition state position is consistent with a double-well (two-step) reaction potential energy surface, in which the second step is rate determining, and the intermediate is more polar than the product.
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Affiliation(s)
- Yangju Lin
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Alex G Foret
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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7
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Hu Y, Lin Y, Craig SL. Mechanically Triggered Polymer Deconstruction through Mechanoacid Generation and Catalytic Enol Ether Hydrolysis. J Am Chem Soc 2024; 146:2876-2881. [PMID: 38265762 DOI: 10.1021/jacs.3c10153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Polymers that amplify a transient external stimulus into changes in their morphology, physical state, or properties continue to be desirable targets for a range of applications. Here, we report a polymer comprising an acid-sensitive, hydrolytically unstable enol ether backbone onto which is embedded gem-dichlorocyclopropane (gDCC) mechanophores through a single postsynthetic modification. The gDCC mechanophore releases HCl in response to large forces of tension along the polymer backbone, and the acid subsequently catalyzes polymer deconstruction at the enol ether sites. Pulsed sonication of a 61 kDa PDHF with 77% gDCC on the backbone in THF with 100 mM H2O for 10 min triggers the subsequent degradation of the polymer to a final molecular weight of less than 3 kDa after 24 h of standing, whereas controls lacking either the gDCC or the enol ether reach final molecular weights of 38 and 27 kDa, respectively. The process of sonication, along with the presence of water and the existence of gDCC on the backbone, significantly accelerates the rate of polymer chain deconstruction. Both acid generation and the resulting triggered polymer deconstruction are translated to bulk, cross-linked polymer networks. Networks formed via thiol-ene cross-linking and subjected to unconstrained quasi-static uniaxial compression dissolve on time scales that are at least 3 times faster than controls where the mechanophore is not covalently coupled to the network. We anticipate that this concept can be extended to other acid-sensitive polymer networks for the stress-responsive deconstruction of gels and solvent-free elastomers.
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Affiliation(s)
- Yixin Hu
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Yangju Lin
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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8
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Thai LD, Fanelli J, Munaweera R, O'Mara ML, Barner-Kowollik C, Mutlu H. Main-chain Macromolecular Hydrazone Photoswitches. Angew Chem Int Ed Engl 2024; 63:e202315887. [PMID: 37988197 DOI: 10.1002/anie.202315887] [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: 10/20/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 11/23/2023]
Abstract
Hydrazones-consisting of a dynamic imine bond and an acidic NH proton-have recently emerged as versatile photoswitches underpinned by their ability to form thermally bistable isomers, (Z) and (E), respectively. Herein, we introduce two photoresponsive homopolymers containing structurally different hydrazones as main-chain repeating units, synthesized via head-to-tail Acyclic Diene METathesis (ADMET) polymerization. Their key difference lies in the hydrazone design, specifically the location of the aliphatic arm connecting the rotor of the hydrazone photoswitch to the aliphatic polymer backbone. Critically, we demonstrate that their main photoresponsive property, i.e., their hydrodynamic volume, changes in opposite directions upon photoisomerization (λ=410 nm) in dilute solution. Further, the polymers-independent of the design of the individual hydrazone monomer-feature a photoswitchable glass transition temperature (Tg ) by close to 10 °C. The herein established design strategy allows to photochemically manipulate macromolecular properties by simple structural changes.
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Affiliation(s)
- Linh Duy Thai
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Julian Fanelli
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
- Soft Matter Synthesis Laboratory, Institute for Biological Interfaces 3, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Rangika Munaweera
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland (UQ), 4067, St Lucia, QLD, Australia
| | - Megan L O'Mara
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland (UQ), 4067, St Lucia, QLD, Australia
| | - Christopher Barner-Kowollik
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, 4000, Brisbane, QLD, Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Hatice Mutlu
- Institut de Science des Matériaux de Mulhouse (IS2M), UMR 7361 CNRS/, Université de Haute Alsace (UHA), 15 rue Jean Starcky, 68057, Mulhouse Cedex, France
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9
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Chang HC, Liang MC, Luc VS, Davis C, Chang CC. Mechanochemical Reactivity of a 1,2,4-Triazoline-3,5-dione-Anthracene Diels-Alder Adduct. Chem Asian J 2024; 19:e202300850. [PMID: 37938167 DOI: 10.1002/asia.202300850] [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: 09/27/2023] [Revised: 10/31/2023] [Accepted: 11/05/2023] [Indexed: 11/09/2023]
Abstract
Force-responsive molecules that produce fluorescent moieties under stress provide a means for stress-sensing and material damage assessment. In this work, we report a mechanophore based on Diels-Alder adduct TAD-An of 4,4'-(4,4'-diphenylmethylene)-bis-(1,2,4-triazoline-3,5-dione) and initiator-substituted anthracene that can undergo retro-Diels-Alder (rDA) reaction by pulsed ultrasonication and compressive activation in bulk materials. The influence of having C-N versus C-C bonds at the sites of bond scission is elucidated by comparing the relative mechanical strength of TAD-An to another Diels-Alder adduct MAL-An obtained from maleimide and anthracene. The susceptibility to undergo rDa reaction correlates well with bond energy, such that C-N bond containing TAD-An degrades faster C-C bond containing MAL-An because C-N bond is weaker than C-C bond. Specifically, the results from polymer degradation kinetics under pulsed ultrasonication shows that polymer containing TAD-An has a rate constant of 1.59×10-5 min-1 , while MAL-An (C-C bond) has a rate constant of 1.40×10-5 min-1 . Incorporation of TAD-An in a crosslinked polymer network demonstrates the feasibility to utilize TAD-An as an alternative force-responsive probe to visualize mechanical damage where fluorescence can be "turned-on" due to force-accelerated retro-Diels-Alder reaction.
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Affiliation(s)
- Hao-Chun Chang
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, No. 1001, Daxue Rd. East Dist., Hsinchu City, 300093, Taiwan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Min-Chieh Liang
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, No. 1001, Daxue Rd. East Dist., Hsinchu City, 300093, Taiwan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Van-Sieu Luc
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, No. 1001, Daxue Rd. East Dist., Hsinchu City, 300093, Taiwan
- Sustainable Chemical Science and Technology (SCST), Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei, 11529, Taiwan
- Institute of Chemistry, Academia Sinica, Taipei, 11529, Taiwan
| | - Chelsea Davis
- Department of Mechanical Engineering, University of Delaware, Newark, Delaware, 19716, U.S.A
| | - Chia-Chih Chang
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, No. 1001, Daxue Rd. East Dist., Hsinchu City, 300093, Taiwan
- Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
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10
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Cai Y, Binder WH. Triggered Crosslinking of Main-Chain Enediyne Polyurethanes via Bergman Cyclization. Macromol Rapid Commun 2023; 44:e2300440. [PMID: 37877520 DOI: 10.1002/marc.202300440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 10/23/2023] [Indexed: 10/26/2023]
Abstract
Crosslinking chemistries occupy an important position in polymer modification with a particular importance when triggered in response to external stimuli. Enediyne (EDY) moieties are used as functional entities in this work, known to undergo a pericyclic Bergman cyclization (BC) to induce a triggered crosslinking of polyurethanes (PU) via the intermediately formed diradicals. Diamino-EDYs, where the distance between the enyne-moieties is known to be critical to induce a BC, are placed repetitively as main-chain structural elements in isophorone-based PUs to induce reinforcement upon heating, compression, or stretching. A 7-day compression under room temperature results in a ≈69% activation of the BC, together with the observation of an increase in tensile strength by 62% after 25 stretching cycles. The occurrence of BC is further proven by the decreased exothermic values in differential scanning calorimetry, together with characteristic peaks of the formed benzene moieties via IR spectroscopy. Purely heat-induced crosslinking contributes to 191% of the maximum tensile strength in comparison to the virgin PU. The BC herein forms an excellent crosslinking strategy, triggered by heat or force in PU materials.
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Affiliation(s)
- Yue Cai
- Macromolecular Chemistry, Institute of Chemistry, Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle (Saale), Germany
| | - Wolfgang H Binder
- Macromolecular Chemistry, Institute of Chemistry, Faculty of Natural Science II, Martin Luther University Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120, Halle (Saale), Germany
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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: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [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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Ritter VC, McDonald SM, Dobrynin AV, Craig SL, Becker ML. Mechanochromism and Strain-Induced Crystallization in Thiol-yne-Derived Stereoelastomers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302163. [PMID: 37399511 DOI: 10.1002/adma.202302163] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/19/2023] [Accepted: 06/30/2023] [Indexed: 07/05/2023]
Abstract
Most elastomers undergo strain-induced crystallization (SIC) under tension; as individual chains are held rigidly in a fixed position by an applied strain, their alignment along the strain field results in a shift from strain-hardening (SH) to SIC. A similar degree of stretching is associated with the tension necessary to accelerate mechanically coupled, covalent chemical responses of mechanophores in overstretched chains, raising the possibility of an interplay between the macroscopic response of SIC and the molecular response of mechanophore activation. Here, thiol-yne-derived stereoelastomers doped covalently with a dipropiolate-derivatized spiropyran (SP) mechanophore (0.25-0.38 mol%) are reported. The material properties of SP-containing films are consistent with undoped controls, indicating that the SP is a reporter of the mechanical state of the polymer. Uniaxial tensile tests reveal correlations between mechanochromism and SIC, which are strain-rate-dependent. When mechanochromic films are stretched slowly to the point of mechanophore activation, the covalently tethered mechanophore remains trapped in a force-activated state, even after the applied stress is removed. Mechanophore reversion kinetics correlate with the applied strain rate, resulting in highly tunable decoloration rates. Because these polymers are not covalently crosslinked, they are recyclable by melt-pressing into new films, increasing their potential range of strain-sensing, morphology-sensing, and shape-memory applications.
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Affiliation(s)
| | | | - Andrey V Dobrynin
- Department of Chemistry, University of North Carolina, Chapel Hill, NC, 27514, USA
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
| | - Matthew L Becker
- Department of Chemistry, Duke University, Durham, NC, 27708, USA
- Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, 27708, USA
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13
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McFadden ME, Barber RW, Overholts AC, Robb MJ. Naphthopyran molecular switches and their emergent mechanochemical reactivity. Chem Sci 2023; 14:10041-10067. [PMID: 37772118 PMCID: PMC10530568 DOI: 10.1039/d3sc03729k] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 08/23/2023] [Indexed: 09/30/2023] Open
Abstract
Naphthopyran molecular switches undergo a ring-opening reaction upon external stimulation to generate intensely colored merocyanine dyes. Their unique modularity and synthetic accessibility afford exceptional control over their properties and stimuli-responsive behavior. Commercial applications of naphthopyrans as photoswitches in photochromic ophthalmic lenses have spurred an extensive body of work exploring naphthopyran-merocyanine structure-property relationships. The recently discovered mechanochromic behavior of naphthopyrans has led to their emergent application in the field of polymer mechanochemistry, enabling advances in the design of force-responsive materials as well as fundamental insights into mechanochemical reactivity. The structure-property relationships established in the photochemical literature serve as a convenient blueprint for the design of naphthopyran molecular force probes with precisely tuned properties. On the other hand, the mechanochemical reactivity of naphthopyran diverges in many cases from the conventional photochemical pathways, resulting in unexpected properties and opportunities for deeper understanding and innovation in polymer mechanochemistry. Here, we highlight the features of the naphthopyran scaffold that render it a powerful platform for the design of mechanochromic materials and review recent advances in naphthopyran mechanochemistry.
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Affiliation(s)
- Molly E McFadden
- Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena California 91125 USA
| | - Ross W Barber
- Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena California 91125 USA
| | - Anna C Overholts
- Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena California 91125 USA
| | - Maxwell J Robb
- Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena California 91125 USA
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14
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Tang R, Gao W, Jia Y, Wang K, Datta BK, Zheng W, Zhang H, Xu Y, Lin Y, Weng W. Mechanochemically assisted morphing of shape shifting polymers. Chem Sci 2023; 14:9207-9212. [PMID: 37655017 PMCID: PMC10466301 DOI: 10.1039/d3sc02404k] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/03/2023] [Indexed: 09/02/2023] Open
Abstract
Morphing in creatures has inspired various synthetic polymer materials that are capable of shape shifting. The morphing of polymers generally relies on stimuli-active (typically heat and light active) units that fix the shape after a mechanical load-based shape programming. Herein, we report a strategy that uses a mechanochemically active 2,2'-bis(2-phenylindan-1,3-dione) (BPID) mechanophore as a switching unit for mechanochemical morphing. The mechanical load on the polymer triggers the dissociation of the BPID moiety into stable 2-phenylindan-1,3-dione (PID) radicals, whose subsequent spontaneous dimerization regenerates BPID and fixes the temporary shapes that can be effectively recovered to the permanent shapes by heating. A greater extent of BPID activation, through a higher BPID content or mechanical load, leads to higher mechanochemical shape fixity. By contrast, a relatively mechanochemically less active hexaarylbiimidazole (HABI) mechanophore shows a lower fixing efficiency when subjected to the same programing conditions. Another control system without a mechanophore shows a low fixing efficiency comparable to the HABI system. Additionally, the introduction of the BPID moiety also manifests remarkable mechanochromic behavior during the shape programing process, offering a visualizable indicator for the pre-evaluation of morphing efficiency. Unlike conventional mechanical mechanisms that simultaneously induce morphing, such as strain-induced plastic deformation or crystallization, our mechanochemical method allows for shape programming after the mechanical treatment. Our concept has potential for the design of mechanochemically programmable and mechanoresponsive shape shifting polymers.
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Affiliation(s)
- Rui Tang
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Wenli Gao
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Yulin Jia
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Kai Wang
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Barun Kumar Datta
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Wei Zheng
- College of Materials Science, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Huan Zhang
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Yuanze Xu
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
| | - Yangju Lin
- Department of Chemical Engineering, Stanford University 443 Via Ortega, Stanford California 94305 USA
| | - Wengui Weng
- Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University 422 South Siming Road Xiamen Fujian 361005 P. R. China
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15
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Clough JM, Kilchoer C, Wilts BD, Weder C. Hierarchically Structured Deformation-Sensing Mechanochromic Pigments. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2206416. [PMID: 36935363 PMCID: PMC10161078 DOI: 10.1002/advs.202206416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/23/2023] [Indexed: 05/06/2023]
Abstract
Mechanochromic materials alter their color in response to mechanical force and are useful for both fundamental studies and practical applications. Several approaches are used to render polymers mechanochromic, but they generally suffer from limitations in sensing range, capacity to provide quantitative information, and their capability to enable broad and simple implementation. Here, is it reported that these problems can be overcome by combining photonic structures, which alter their reflection upon deformation, with covalent mechanophores, whose spectral properties change upon mechanically induced bond scission, in hierarchically structured mechanochromic pigments. This is achieved by synthesizing microspheres consisting of an elastic polymer with spiropyran-based cross-links and non-close-packed silica nanoparticles. A strain of less than 1% can be detected in a shift of the reflection band from the photonic structure, while the onset strain for the conversion of the spiropyran into fluorescent merocyanine ranges from 30% to 70%, creating a broad strain detection range. The two responses are tailorable and synergistic, permitting the activation strain for the mechanophore response to be tuned. The mechano-sensing photonic pigments are demonstrated to be readily incorporated into different polymeric materials of interest and quantitatively probe spatially heterogeneous deformations over a large strain range.
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Affiliation(s)
- Jess M Clough
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, 1700, Switzerland
| | - Cédric Kilchoer
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, 1700, Switzerland
| | - Bodo D Wilts
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, 1700, Switzerland
- Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Strasse 2a, Salzburg, 5020, Austria
| | - Christoph Weder
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, Fribourg, 1700, Switzerland
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16
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Willis-Fox N, Watchorn-Rokutan E, Rognin E, Daly R. Technology pull: scale-up of polymeric mechanochemical force sensors. TRENDS IN CHEMISTRY 2023. [DOI: 10.1016/j.trechm.2023.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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17
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Mechanically gated formation of donor-acceptor Stenhouse adducts enabling mechanochemical multicolour soft lithography. Nat Chem 2023; 15:332-338. [PMID: 36690834 DOI: 10.1038/s41557-022-01126-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 12/14/2022] [Indexed: 01/24/2023]
Abstract
Stress-sensitive molecules called mechanophores undergo productive chemical transformations in response to mechanical force. A variety of mechanochromic mechanophores, which change colour in response to stress, have been developed, but modulating the properties of the dyes generally requires the independent preparation of discrete derivatives. Here we introduce a mechanophore platform enabling mechanically gated multicolour chromogenic reactivity. The mechanophore is based on an activated furan precursor to donor-acceptor Stenhouse adducts (DASAs) masked as a hetero-Diels-Alder adduct. Mechanochemical activation of the mechanophore unveils the DASA precursor, and subsequent reaction with a secondary amine generates an intensely coloured DASA. Critically, the properties of the DASA are controlled by the amine, and thus a single mechanophore can be differentiated post-activation to produce a wide range of functionally diverse DASAs. We highlight this system by establishing the concept of mechanochemical multicolour soft lithography whereby a complex multicolour composite image is printed into a mechanochemically active elastomer through an iterative process of localized compression followed by reaction with different amines.
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18
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Ducker RE, Brügge OS, Meijer AJHM, Leggett GJ. Tribochemical nanolithography: selective mechanochemical removal of photocleavable nitrophenyl protecting groups with 23 nm resolution at speeds of up to 1 mm s -1. Chem Sci 2023; 14:1752-1761. [PMID: 36819865 PMCID: PMC9931061 DOI: 10.1039/d2sc06305k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 01/14/2023] [Indexed: 01/18/2023] Open
Abstract
We describe the mechanochemical regulation of a reaction that would otherwise be considered to be photochemical, via a simple process that yields nm spatial resolution. An atomic force microscope (AFM) probe is used to remove photocleavable nitrophenyl protecting groups from alkylsilane films at loads too small for mechanical wear, thus enabling nanoscale differentiation of chemical reactivity. Feature sizes of 20-50 nm are achieved repeatably and controllably at writing rates up to 1 mm s-1. Line widths vary monotonically with the load up to 2000 nN. To demonstrate the capacity for sophisticated surface functionalisation provided by this strategy, we show that functionalization of nanolines with nitrilo triacetic acid enables site-specific immobilization of histidine-tagged green fluorescent protein. Density functional theory (DFT) calculations reveal that the key energetic barrier in the photo-deprotection reaction of the nitrophenyl protecting group is excitation of a π-π* transition (3.1 eV) via an intramolecular charge-transfer mechanism. Under modest loading, compression of the adsorbate layer causes a decrease in the N-N separation, with the effect that this energy barrier can be reduced to as little as 1.2 eV. Thus, deprotection becomes possible via either absorption of visible photons or phononic excitation transfer, facilitating fast nanolithography with a very small feature size.
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Affiliation(s)
- Robert E. Ducker
- Department of Chemistry, University of SheffieldBrook HillSheffield S3 7HFUK
| | - Oscar Siles Brügge
- Department of Chemistry, University of Sheffield Brook Hill Sheffield S3 7HF UK
| | | | - Graham J. Leggett
- Department of Chemistry, University of SheffieldBrook HillSheffield S3 7HFUK
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19
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Ouchi T, Bowser BH, Kouznetsova TB, Zheng X, Craig SL. Strain-triggered acidification in a double-network hydrogel enabled by multi-functional transduction of molecular mechanochemistry. MATERIALS HORIZONS 2023; 10:585-593. [PMID: 36484385 DOI: 10.1039/d2mh01105k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Recent work has demonstrated that force-triggered mechanochemical reactions within a polymeric material are capable of inducing measurable changes in macroscopic material properties, but examples of bulk property changes without irreversible changes in shape or structure are rare. Here, we report a double-network hydrogel that undergoes order-of-magnitude increases in acidity when strained, while recovering its initial shape after large deformation. The enabling mechanophore design is a 2-methoxy-gem-dichlorocyclopropane mechanoacid that is gated within a fused methyl methoxycyclobutene carboxylate mechanophore structure. This gated mechanoacid is incorporated via radical co-polymerization into linear and network polymers. Sonication experiments confirm the mechanical release of HCl, and single-molecule force spectroscopy reveals enhanced single-molecular toughness in the covalent strand. These mechanochemical functions are incorporated into a double-network hydrogel, leading to mechanically robust and thermally stable materials that undergo strain-triggered acid release. Both quasi-static stretching and high strain rate uniaxial compression result in substantial acidification of the hydrogel, from pH ∼ 7 to ∼5.
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Affiliation(s)
- Tetsu Ouchi
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
| | - Brandon H Bowser
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA.
| | | | - Xujun Zheng
- 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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20
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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: 20] [Impact Index Per Article: 20.0] [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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21
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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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22
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Luo SM, Barber RW, Overholts AC, Robb MJ. Competitive Activation Experiments Reveal Significantly Different Mechanochemical Reactivity of Furan–Maleimide and Anthracene–Maleimide Mechanophores. ACS POLYMERS AU 2022; 3:202-208. [PMID: 37065719 PMCID: PMC10103189 DOI: 10.1021/acspolymersau.2c00047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/01/2022] [Accepted: 11/01/2022] [Indexed: 11/23/2022]
Abstract
During the past two decades, our understanding of mechanochemical reactivity has advanced considerably. Nevertheless, an incomplete knowledge of structure-activity relationships and the principles that govern mechanochemical transformations limits molecular design. The experimental development of mechanophores has thus benefited from simple computational tools like CoGEF, from which quantitative metrics like rupture force can be extracted to estimate reactivity. Furan-maleimide (FM) and anthracene-maleimide (AM) Diels-Alder adducts are widely studied mechanophores that undergo retro-Diels-Alder reactions upon mechanical activation in polymers. Despite possessing significantly different thermal stability, similar rupture forces predicted by CoGEF calculations suggest that these compounds exhibit similar mechanochemical reactivity. Here, we directly probe the relative mechanochemical reactivity of FM and AM adducts through competitive activation experiments. Ultrasound-induced mechanochemical activation of bis-adduct mechanophores comprising covalently tethered FM and AM subunits reveals pronounced selectivity-as high as ∼13:1-for reaction of the FM adduct compared to the AM adduct. Computational models provide insight into the greater reactivity of the FM mechanophore, indicating a more efficient mechanochemical coupling for the FM adduct compared to the AM adduct. The methodology employed here to directly interrogate the relative reactivity of two different mechanophores using a tethered bis-adduct configuration may be useful for other systems where more common sonication-based approaches are limited by poor sensitivity.
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Affiliation(s)
- Stella M. Luo
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Ross W. Barber
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Anna C. Overholts
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Maxwell J. Robb
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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23
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Thazhathethil S, Muramatsu T, Tamaoki N, Weder C, Sagara Y. Excited State Charge-Transfer Complexes Enable Fluorescence Color Changes in a Supramolecular Cyclophane Mechanophore. Angew Chem Int Ed Engl 2022; 61:e202209225. [PMID: 35950260 PMCID: PMC9804172 DOI: 10.1002/anie.202209225] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Indexed: 01/05/2023]
Abstract
Mechanochromic mechanophores are reporter molecules that indicate mechanical events through changes of their photophysical properties. Supramolecular mechanophores in which the activation is based on the rearrangement of luminophores and/or quenchers without any covalent bond scission, remain less well investigated. Here, we report a cyclophane-based supramolecular mechanophore that contains a 1,6-bis(phenylethynyl)pyrene luminophore and a pyromellitic diimide quencher. In solution, the blue monomer emission of the luminophore is largely quenched and a faint reddish-orange emission originating from a charge-transfer (CT) complex is observed. A polyurethane elastomer containing the mechanophore displays orange emission in the absence of force, which is dominated by the CT-emission. Mechanical deformation causes a decrease of the CT-emission and an increase of blue monomer emission, due to the spatial separation between the luminophore and quencher. The ratio of the two emission intensities correlates with the applied stress.
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Affiliation(s)
- Shakkeeb Thazhathethil
- Department of Materials Science and EngineeringTokyo Institute of Technology2-12-1 OokayamaMeguro-ku, Tokyo152-8552Japan
- Research Institute for Electronic ScienceHokkaido UniversityN20, W10SapporoHokkaido001-0020Japan
| | - Tatsuya Muramatsu
- Department of Materials Science and EngineeringTokyo Institute of Technology2-12-1 OokayamaMeguro-ku, Tokyo152-8552Japan
| | - Nobuyuki Tamaoki
- Research Institute for Electronic ScienceHokkaido UniversityN20, W10SapporoHokkaido001-0020Japan
| | - Christoph Weder
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 41700FribourgSwitzerland
| | - Yoshimitsu Sagara
- Department of Materials Science and EngineeringTokyo Institute of Technology2-12-1 OokayamaMeguro-ku, Tokyo152-8552Japan
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24
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Wu M, Li Y, Yuan W, De Bo G, Cao Y, Chen Y. Cooperative and Geometry-Dependent Mechanochromic Reactivity through Aromatic Fusion of Two Rhodamines in Polymers. J Am Chem Soc 2022; 144:17120-17128. [PMID: 36070612 DOI: 10.1021/jacs.2c07015] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The unique topological features of Piezo proteins underlie the lever-like cellular mechanotransduction mechanism. This knowledge inspires us to seek topological/geometric control of mechanochromophores with unprecedentedly amplified, synergistic changes in polymers to serve as ideal stress probes. Here, by judicious placement of two spirolactam rings into aminobenzopyranoxanthene, a series of stereo- and regio-isomeric rhodamine-like mechanophores are developed. With two labile bonds closely coupled into one rigidified scaffold, these π-fused bis-mechanophores enable mechanochromic polymers, featuring cooperative bond scission, low rupture force (lower than rhodamine), and geometry-controlled ring-opening reactivity. Sonication, single-molecule force spectroscopy experiments, and density functional theory calculations provide insight into the force-color relationship and rationalize how the difference in reactivity of the four isomeric mechanophores is affected by their molecular geometry and thermodynamic equilibrium. Our strategy based on the aromatic fusion of bis-mechanophore promises a modular approach to isomeric mechanophores for cooperative bond scission. Also, important insights into internal and external factors governing tandem mechanochemical reactions are gained.
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Affiliation(s)
- Mengjiao Wu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.,Department of Chemistry, Tianjin University, Tianjin 300354, P. R. China
| | - Yiran Li
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Wei Yuan
- Department of Chemistry, Tianjin University, Tianjin 300354, P. R. China
| | - Guillaume De Bo
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Yi Cao
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Yulan Chen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
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25
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Thazhathethil S, Muramatsu T, Tamaoki N, Weder C, Sagara Y. Excited State Charge‐Transfer Complexes Enable Fluorescence Color Changes in a Supramolecular Cyclophane Mechanophore. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209225] [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)
- Shakkeeb Thazhathethil
- Hokkaido University Graduate School of Life Science: Hokkaido Daigaku Daigakuin Seimei Kagakuin Division of Life Science JAPAN
| | - Tatsuya Muramatsu
- Tokyo Institute of Technology: Tokyo Kogyo Daigaku Department of Materials Science and Engineering JAPAN
| | - Nobuyuki Tamaoki
- Hokkaido University Graduate School of Life Science: Hokkaido Daigaku Daigakuin Seimei Kagakuin Division of Life Science JAPAN
| | - Christoph Weder
- University of Fribourg: Universite de Fribourg Adolphe Merkle Institute JAPAN
| | - Yoshimitsu Sagara
- Tokyo Institute of Technology Department of Chemical Science and Engineering 2-12-1 Ookayama, Meguro-ku 152-8552 Tokyo JAPAN
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26
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Baumann C, Willis‐Fox N, Campagna D, Rognin E, Marten P, Daly R, Göstl R. Regiochemical effects for the mechanochemical activation of
9‐π‐extended anthracene‐maleimide Diels–Alder
adducts. JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1002/pol.20220342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Christoph Baumann
- DWI – Leibniz Institute for Interactive Materials Aachen Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University Aachen Germany
| | - Niamh Willis‐Fox
- Department of Engineering, Institute for Manufacturing University of Cambridge Cambridge UK
| | - Davide Campagna
- DWI – Leibniz Institute for Interactive Materials Aachen Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University Aachen Germany
| | - Etienne Rognin
- Department of Engineering, Institute for Manufacturing University of Cambridge Cambridge UK
| | - Paul Marten
- DWI – Leibniz Institute for Interactive Materials Aachen Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University Aachen Germany
| | - Ronan Daly
- Department of Engineering, Institute for Manufacturing University of Cambridge Cambridge UK
| | - Robert Göstl
- DWI – Leibniz Institute for Interactive Materials Aachen Germany
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27
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Raisch M, Reiter G, Sommer M. Determining Entanglement Molar Mass of Glassy Polyphenylenes Using Mechanochromic Molecular Springs. ACS Macro Lett 2022; 11:760-765. [PMID: 35612497 DOI: 10.1021/acsmacrolett.2c00238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molecular force transduction in tough and glassy poly(meta,meta,para-phenylene) (PmmpP) was investigated as a function of Mn using covalently incorporated mechanochromic donor-acceptor torsional springs based on an ortho-substituted diphenyldiketopyrrolopyrrole (oDPP). Blending oDPP-PmmpP probe chains with long PmmpP matrix chains allowed us to investigate molar-mass-dependent mechanochromic properties for a series of specimens having mechanically identical properties. In the strain-hardening regime, the mechanochromic response (Δλmax,em) was found to be a linear function of the acting stress and fully reversible, making oDPP-PmmpP a real-time and quantitative stress sensor. For entangled and nonentangled probe chains, distinctly different values of Δλmax,em were observed, yielding a critical molar mass of Mc ≈ 11 kg mol-1 for PmmpP. Once physical cross-linking of oDPP in the network of PmmpP was ensured, Δλmax,em was found to be independent of Mn. The resulting value of Mc is in very good agreement with results from rheology.
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Affiliation(s)
- Maximilian Raisch
- Institute for Chemistry, Polymer Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany
| | - Günter Reiter
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - Michael Sommer
- Institute for Chemistry, Polymer Chemistry, Chemnitz University of Technology, Straße der Nationen 62, 09111 Chemnitz, Germany
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28
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Qiu W, Scofield JMP, Gurr PA, Qiao GG. Mechanochromophore-linked Polymeric Materials with Visible Color Changes. Macromol Rapid Commun 2022; 43:e2100866. [PMID: 35338794 DOI: 10.1002/marc.202100866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/19/2022] [Indexed: 11/07/2022]
Abstract
Mechanical force as a type of stimuli for smart materials has obtained much attention in the past decade. Color-changing materials in response to mechanical stimuli have shown great potential in the applications such as sensors and displays. Mechanochromophore-linked polymeric materials, which are a growing sub-class of these materials, are discussed in detail in this review. Two main types of mechanochromophores which exhibit visible color change, summarized herein, involve either isomerization or radical generation mechanisms. This review focuses on their synthesis and incorporation into polymer matrices, the type of mechanical force used, factors affecting the mechanochromic properties, and their applications. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Wenlian Qiu
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Joel M P Scofield
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Paul A Gurr
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Greg G Qiao
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
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29
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Yamakado T, Saito S. Ratiometric Flapping Force Probe That Works in Polymer Gels. J Am Chem Soc 2022; 144:2804-2815. [PMID: 35108003 DOI: 10.1021/jacs.1c12955] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Polymer gels have recently attracted attention for their application in flexible devices, where mechanically robust gels are required. While there are many strategies to produce tough gels by suppressing nanoscale stress concentration on specific polymer chains, it is still challenging to directly verify the toughening mechanism at the molecular level. To solve this problem, the use of the flapping molecular force probe (FLAP) is promising because it can evaluate the nanoscale forces transmitted in the polymer chain network by ratiometric analysis of a stress-dependent dual fluorescence. A flexible conformational change of FLAP enables real-time and reversible responses to the nanoscale forces at the low force threshold, which is suitable for quantifying the percentage of the stressed polymer chains before structural damage. However, the previously reported FLAP only showed a negligible response in solvated environments because undesirable spontaneous planarization occurs in the excited state, even without mechanical force. Here, we have developed a new ratiometric force probe that functions in common organogels. Replacement of the anthraceneimide units in the flapping wings with pyreneimide units largely suppresses the excited-state planarization, leading to the force probe function under wet conditions. The FLAP-doped polyurethane organogel reversibly shows a dual-fluorescence response under sub-MPa compression. Moreover, the structurally modified FLAP is also advantageous in the wide dynamic range of its fluorescence response in solvent-free elastomers, enabling clearer ratiometric fluorescence imaging of the molecular-level stress concentration during crack growth in a stretched polyurethane film.
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Affiliation(s)
- Takuya Yamakado
- Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Shohei Saito
- Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
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30
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Kim D, Kwon MS, Lee CW. Mechanochromic polymers with a multimodal chromic transition: mechanophore design and transduction mechanism. Polym Chem 2022. [DOI: 10.1039/d2py00435f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This review presents the recent progress in multi-chromic polymers embedded with mechanophores concentrating on transduction mechanisms and design concepts.
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Affiliation(s)
- Daewhan Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Min Sang Kwon
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Chung Whan Lee
- Department of Chemistry, Gachon University, Seongnam 13120, Republic of Korea
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31
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Overholts AC, McFadden ME, Robb MJ. Quantifying Activation Rates of Scissile Mechanophores and the Influence of Dispersity. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c02232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anna C. Overholts
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Molly E. McFadden
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Maxwell J. Robb
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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32
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Wang T, Wang H, Shen L, Zhang N. Force-induced strengthening of a mechanochromic polymer based on a naphthalene-fused cyclobutane mechanophore. Chem Commun (Camb) 2021; 57:12675-12678. [PMID: 34779466 DOI: 10.1039/d1cc05305a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We discovered a force-induced strengthening of a mechanochromic polymer based on a naphthalene-fused cyclobutane mechanophore (NCD). Our results revealed that mechanically induced retro-cycloaddition of the NCD and subsequent crosslinking reactions between CC bonds were responsible for this peculiar strenghthening, and demonstrated the good possibility that the NCD can be applied in smart materials fields.
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Affiliation(s)
- Taisheng Wang
- School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167, P. R. China. .,Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing, 211167, P. R. China
| | - Haoxiang Wang
- School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167, P. R. China.
| | - Lei Shen
- School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167, P. R. China.
| | - Na Zhang
- School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167, P. R. China. .,Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology, Nanjing, 211167, P. R. China
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33
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Abstract
AbstractThis Account covers the recent progress made on heterocyclic mechanophores in the field of polymer mechanochemistry. In particular, the types of such mechanophores as well as the mechanisms and applications of their force-induced structural transformations are discussed and related perspectives and future challenges proposed.1 Introduction2 Types of Mechanophores3 Methods to Incorporate Heterocycle Mechanophores into Polymer Systems4 Mechanochemical Reactions of Heterocyclic Mechanophores4.1 Three-Membered-Ring Mechanophores4.2 Four-Membered-Ring Mechanophores4.3 Six-Membered-Ring Mechanophores4.4 Bicyclic Mechanophores5 Applications5.1 Cross-Linking of Polymer5.2 Degradable Polymer5.3 Mechanochromic Polymer6 Concluding Remarks and Outlook
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34
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He S, Stratigaki M, Centeno SP, Dreuw A, Göstl R. Tailoring the Properties of Optical Force Probes for Polymer Mechanochemistry. Chemistry 2021; 27:15889-15897. [PMID: 34582082 PMCID: PMC9292383 DOI: 10.1002/chem.202102938] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Indexed: 02/05/2023]
Abstract
The correlation of mechanical properties of polymer materials with those of their molecular constituents is the foundation for their holistic comprehension and eventually for improved material designs and syntheses. Over the last decade, optical force probes (OFPs) were developed, shedding light on various unique mechanical behaviors of materials. The properties of polymers are diverse, ranging from soft hydrogels to ultra-tough composites, from purely elastic rubbers to viscous colloidal solutions, and from transparent glasses to super black dyed coatings. Only very recently, researchers started to develop tailored OFP solutions that account for such material requirements in energy (both light and force), in time, and in their spatially detectable resolution. We here highlight notable recent examples and identify future challenges in this emergent field.
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Affiliation(s)
- Siyang He
- DWI - Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
- Institute of Technical and Macromolecular ChemistryRWTH Aachen UniversityWorringerweg 152074AachenGermany
| | - Maria Stratigaki
- DWI - Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
| | - Silvia P. Centeno
- DWI - Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific ComputingHeidelberg UniversityIm Neuenheimer Feld 20569120HeidelbergGermany
| | - Robert Göstl
- DWI - Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
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35
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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: 23] [Impact Index Per Article: 7.7] [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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36
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Gu F, Jiang T, Ma X. Visually Monitoring the Compactness of Polymer Matrixes Coded by Disparate Luminescence. ACS APPLIED MATERIALS & INTERFACES 2021; 13:43473-43479. [PMID: 34488339 DOI: 10.1021/acsami.1c15299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The intrinsic property disclosure of polymer systems by visual monitoring of photoluminescence behaviors is of great value in fundamental interest and promising applications. Three novel polymer films were obtained by simply doping methyl 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine-11-carboxylate (DPC) with three polymer materials. The photoluminescence behaviors of these films represented diverse fluorescence emissions from light orange to blue, especially room-temperature phosphorescence (RTP) emissions with ultralong lifetime, attributing to various configurations of DPC molecules provided by distinct microscopic environments in three polymer systems. The rigidity and regularity of polymer systems would be visually reflexed by luminescence regulation and temperature responses. In addition, irregular distribution of distinct polymer systems could be specifically monitored by both fluorescence and phosphorescence behaviors when doping different polymer materials into one blend film.
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Affiliation(s)
- Fan Gu
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China
| | - Tao Jiang
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China
| | - Xiang Ma
- Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research Center, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China
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37
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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: 5] [Impact Index Per Article: 1.7] [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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38
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Noh J, Peterson GI, Choi T. Mechanochemical Reactivity of Bottlebrush and Dendronized Polymers: Solid vs. Solution States. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Jinkyung Noh
- Department of Chemistry Seoul National University Seoul 08826 Republic of Korea
| | - Gregory I. Peterson
- Department of Chemistry Incheon National University 119 Academy-ro, Yeonsu-gu Incheon 22012 Republic of Korea
| | - Tae‐Lim Choi
- Department of Chemistry Seoul National University Seoul 08826 Republic of Korea
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39
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Noh J, Peterson GI, Choi TL. Mechanochemical Reactivity of Bottlebrush and Dendronized Polymers: Solid vs. Solution States. Angew Chem Int Ed Engl 2021; 60:18651-18659. [PMID: 34101320 DOI: 10.1002/anie.202104447] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/22/2021] [Indexed: 12/23/2022]
Abstract
We explored the mechanochemical degradation of bottlebrush and dendronized polymers in solution (with ultrasonication, US) and solid states (with ball-mill grinding, BMG). Over 50 polymers were prepared with varying backbone length and arm architecture, composition, and size. With US, we found that bottlebrush and dendronized polymers exhibited consistent backbone scission behavior, which was related to their elongated conformations in solution. Considerably different behavior was observed with BMG, as arm architecture and composition had a significant impact on backbone scission rates. Arm scission was also observed for bottlebrush polymers in both solution and solid states, but only in the solid state for dendronized polymers. Motivated by these results, multi-mechanophore polymers with bottlebrush and dendronized polymer architectures were prepared and their reactivity was compared. Although dendronized polymers showed slower arm-scission, the selectivity for mechanophore activation was much higher. Overall, these results have important implications to the development of new mechanoresponsive materials.
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Affiliation(s)
- Jinkyung Noh
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gregory I Peterson
- Department of Chemistry, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon, 22012, Republic of Korea
| | - Tae-Lim Choi
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
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40
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Kubota K, Toyoshima N, Miura D, Jiang J, Maeda S, Jin M, Ito H. Introduction of a Luminophore into Generic Polymers via Mechanoradical Coupling with a Prefluorescent Reagent. Angew Chem Int Ed Engl 2021; 60:16003-16008. [PMID: 33991023 DOI: 10.1002/anie.202105381] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/10/2021] [Indexed: 11/11/2022]
Abstract
Herein, we report a novel strategy for introducing a luminophore into generic polymers facilitated by mechanical stimulation. In this study, polymeric mechanoradicals were formed in situ under ball-milling conditions to undergo radical-radical coupling with a prefluorescent nitroxide-based reagent in order to incorporate a luminophore into the polymer main chains via a covalent bond. This method allowed the direct and conceptually simple preparation of luminescent polymeric materials from a wide range of generic polymers such as polystyrene, polymethyl methacrylate, and polyethylene. These results indicate that the present mechanoradical coupling strategy may help to transform existing commodity polymers into more valuable functional materials.
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Affiliation(s)
- Koji Kubota
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.,Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Naoki Toyoshima
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Daiyo Miura
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Julong Jiang
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Satoshi Maeda
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.,Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Mingoo Jin
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.,Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
| | - Hajime Ito
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan.,Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido, 060-8628, Japan
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41
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Kubota K, Toyoshima N, Miura D, Jiang J, Maeda S, Jin M, Ito H. Introduction of a Luminophore into Generic Polymers via Mechanoradical Coupling with a Prefluorescent Reagent. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202105381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Koji Kubota
- Division of Applied Chemistry Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Naoki Toyoshima
- Division of Applied Chemistry Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Daiyo Miura
- Division of Applied Chemistry Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Julong Jiang
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) Hokkaido University Sapporo Hokkaido 060-8628 Japan
- Department of Chemistry Faculty of Science Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Satoshi Maeda
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) Hokkaido University Sapporo Hokkaido 060-8628 Japan
- Department of Chemistry Faculty of Science Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Mingoo Jin
- Division of Applied Chemistry Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) Hokkaido University Sapporo Hokkaido 060-8628 Japan
| | - Hajime Ito
- Division of Applied Chemistry Graduate School of Engineering Hokkaido University Sapporo Hokkaido 060-8628 Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD) Hokkaido University Sapporo Hokkaido 060-8628 Japan
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42
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Peterson GI, Choi TL. The influence of polymer architecture in polymer mechanochemistry. Chem Commun (Camb) 2021; 57:6465-6474. [PMID: 34132272 DOI: 10.1039/d1cc02501e] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Polymer architecture is an important factor in polymer mechanochemistry. In this Feature Article, we summarize recent developments in utilizing polymer architecture to modulate mechanochemical reactions within polymers, or more specifically, the location and rates of bond scission events that lead to polymer fragmentation or mechanophore activation. Various well-defined architectures have been explored, including those of cyclic, intramolecularly cross-linked, dendritic, star, bottlebrush, and dendronized polymers. We primarily focus on describing the enhancement or suppression of mechanochemical reactivity, with respect to analogous linear polymers, as well as differences in solution- and solid-state behavior.
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Affiliation(s)
- Gregory I Peterson
- Department of Chemistry, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea.
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43
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Muramatsu T, Okado Y, Traeger H, Schrettl S, Tamaoki N, Weder C, Sagara Y. Rotaxane-Based Dual Function Mechanophores Exhibiting Reversible and Irreversible Responses. J Am Chem Soc 2021; 143:9884-9892. [PMID: 34162206 DOI: 10.1021/jacs.1c03790] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mechanochromic mechanophores permit the design of polymers that indicate mechanical events through optical signals. Here we report rotaxane-based supramolecular mechanophores that display both reversible and irreversible fluorescence changes. These responses are triggered by different forces and are achieved by exploiting the molecular shuttling function and force-induced dethreading of rotaxanes. The new rotaxane mechanophores are composed of a ring featuring a luminophore, which is threaded onto an axle with a matching quencher and two stoppers. In the stress-free state, the luminophore is preferentially located in the proximity of the quencher, and the emission is quenched. The luminophore slides away from the quencher when a force is applied and the fluorescence is switched on. This effect is reversible, unless the force is so high that the luminophore-carrying ring slips past the stopper and dethreading occurs. We show that the combination of judiciously selected ring and stopper moieties is crucial to attain interlocked structures that display such a dual response. PU elastomers that contain such doubly responsive rotaxanes exhibit reversible fluorescence changes over multiple loading-unloading cycles due to the shuttling function, whereas permanent changes are observed upon repeated deformations to high strains due to breakage of the mechanical bond upon dethreading of the ring from the axle. This response allows one, at least conceptually, to monitor the actual deformation of polymer materials and examine mechanical damage that was inflicted in the past on the basis of an optical signal.
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Affiliation(s)
- Tatsuya Muramatsu
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Yuji Okado
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Hanna Traeger
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Stephen Schrettl
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Nobuyuki Tamaoki
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Christoph Weder
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Yoshimitsu Sagara
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan.,JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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44
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Shieh P, Hill MR, Zhang W, Kristufek SL, Johnson JA. Clip Chemistry: Diverse (Bio)(macro)molecular and Material Function through Breaking Covalent Bonds. Chem Rev 2021; 121:7059-7121. [PMID: 33823111 DOI: 10.1021/acs.chemrev.0c01282] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In the two decades since the introduction of the "click chemistry" concept, the toolbox of "click reactions" has continually expanded, enabling chemists, materials scientists, and biologists to rapidly and selectively build complexity for their applications of interest. Similarly, selective and efficient covalent bond breaking reactions have provided and will continue to provide transformative advances. Here, we review key examples and applications of efficient, selective covalent bond cleavage reactions, which we refer to herein as "clip reactions." The strategic application of clip reactions offers opportunities to tailor the compositions and structures of complex (bio)(macro)molecular systems with exquisite control. Working in concert, click chemistry and clip chemistry offer scientists and engineers powerful methods to address next-generation challenges across the chemical sciences.
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Affiliation(s)
- Peyton Shieh
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Megan R Hill
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Wenxu Zhang
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Samantha L Kristufek
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jeremiah A Johnson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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45
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Bettens T, Eeckhoudt J, Hoffmann M, Alonso M, Geerlings P, Dreuw A, De Proft F. Designing Force Probes Based on Reversible 6π-Electrocyclizations in Polyenes Using Quantum Chemical Calculations. J Org Chem 2021; 86:7477-7489. [PMID: 33988028 DOI: 10.1021/acs.joc.1c00482] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conjugated π-system in polyenes can be interrupted by electrocyclic ring-closure reactions. In this work, this 6π-electrocylization is shown by means of density functional calculations to be reversible by the application of an external mechanical pulling force at the terminal ends of the interrupted polyene chain. The test systems were constrained in a fused ring system, thus locking the orientation of three π-bonds and generally promoting 6π-electrocyclic ring-closure reactions. For several systems, the forward reaction is exergonic and the corresponding reaction barrier is comparable to those reported in the literature. The reverse reaction is triggered by an external pulling force of 2 nN (nano-Newton) or less and also becomes exergonic in all investigated polyenes under these force conditions. Moreover, it proceeds via a low reaction barrier when a pulling force of 2 nN is active, indicating that the mechanical force is an efficient stimulus for triggering ring-opening reactions. Analysis of the strain energy induced by this mechanical force confirms an optimal activation of the corresponding C-C σ-bond that breaks upon ring opening when the pulling positions are located on the polyene chain.
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Affiliation(s)
- Tom Bettens
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Jochen Eeckhoudt
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Marvin Hoffmann
- Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 205A, D-69120 Heidelberg, Germany
| | - Mercedes Alonso
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Paul Geerlings
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, Ruprecht-Karls University, Im Neuenheimer Feld 205A, D-69120 Heidelberg, Germany
| | - Frank De Proft
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium
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46
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Affiliation(s)
- Panpan Li
- National Engineering Research Center for Colloidal Materials School of Chemistry and Chemical Engineering Shandong University Jinan Shandong 250100 P. R. China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry Shandong University Ministry of Education Jinan Shandong 250100 P. R. China
| | - Xu Wang
- National Engineering Research Center for Colloidal Materials School of Chemistry and Chemical Engineering Shandong University Jinan Shandong 250100 P. R. China
- Key Laboratory of Colloid and Interface Chemistry Shandong University Ministry of Education Jinan Shandong 250100 P. R. China
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47
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Sagara Y, Traeger H, Li J, Okado Y, Schrettl S, Tamaoki N, Weder C. Mechanically Responsive Luminescent Polymers Based on Supramolecular Cyclophane Mechanophores. J Am Chem Soc 2021; 143:5519-5525. [PMID: 33784073 DOI: 10.1021/jacs.1c01328] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A new approach to cyclophane-based supramolecular mechanophores is presented. We report a mechanically responsive cyclic motif that contains two fluorescent 1,6-bis(phenylethynyl)pyrene moieties that are capable of forming intramolecular excimers. The emission spectra of dilute solutions of this cyclophane and a polyurethane elastomer into which a small amount of the mechanophore (0.08 wt %) had been covalently integrated are dominated by excimer emission. Films of the cyclophane-containing polyurethane also display a considerable portion of excimer emission, but upon deformation, the fluorescence becomes monomer-dominated and a perceptible change from cyan to blue is observed. The response is instant, reversible, and consistent with a mechanically induced change of the molecular conformation of the mechanophore so that the excimer-promoting interactions between the luminophores are suppressed. In-depth investigations show a correlation between the applied strain and the emission color, which can conveniently be expressed by the ratio of monomer to excimer emission intensity. The current study suggests that cyclophanes can be utilized to develop various supramolecular mechanophores that detect and visualize weak forces occurring in polymeric materials or generated by living tissues.
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Affiliation(s)
- Yoshimitsu Sagara
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
- JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Hanna Traeger
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Jie Li
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-Ku, Sapporo, Hokkaido 001-0020, Japan
| | - Yuji Okado
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-Ku, Sapporo, Hokkaido 001-0020, Japan
| | - Stephen Schrettl
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Nobuyuki Tamaoki
- Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-Ku, Sapporo, Hokkaido 001-0020, Japan
| | - Christoph Weder
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
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48
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Qian H, Purwanto NS, Ivanoff DG, Halmes AJ, Sottos NR, Moore JS. Fast, reversible mechanochromism of regioisomeric oxazine mechanophores: Developing in situ responsive force probes for polymeric materials. Chem 2021. [DOI: 10.1016/j.chempr.2021.02.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
In mechanochemistry, molecules under tension can react in unexpected ways. The reactivity of mechanophores (mechanosensitive molecules) can be controlled using various geometric or electronic factors. Often these factors affect the rate of mechanical activation but sometimes give rise to alternative reaction pathways. Here we show that a simple isotope substitution (H to D) leads to a reversal of selectivity in the activation of a mechanophore. Remarkably this isotope effect is not kinetic in nature but emerges from dynamic effects in which deuteration reduces the ability of the reactant to follow a post-transition-state concerted trajectory on the bifurcated force-modified potential energy surface. These results give a new insight into the reactivity of molecules under tension.
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Affiliation(s)
- Robert Nixon
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Guillaume De Bo
- Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
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50
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Razgoniaev AO, Glasstetter LM, Kouznetsova TB, Hall KC, Horst M, Craig SL, Franz KJ. Single-Molecule Activation and Quantification of Mechanically Triggered Palladium-Carbene Bond Dissociation. J Am Chem Soc 2021; 143:1784-1789. [PMID: 33480680 DOI: 10.1021/jacs.0c13219] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Metal-complexed N-heterocyclic carbene (NHC) mechanophores are latent reactants and catalysts for a range of mechanically driven chemical responses, but mechanochemical scission of the metal-NHC bond has not been experimentally characterized. Here we report the single-molecule force spectroscopy of ligand dissociation from a pincer NHC-pyridine-NHC Pd(II) complex. The force-coupled rate constant for ligand dissociation reaches 50 s-1 at forces of approximately 930 pN. Experimental and computational observations support a dissociative, rather than associative, mechanism of ligand displacement, with rate-limiting scission of the Pd-NHC bond followed by rapid dissociation of the pyridine moiety from Pd.
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Affiliation(s)
- Anton O Razgoniaev
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Logan M Glasstetter
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Tatiana B Kouznetsova
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Kacey C Hall
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Matias Horst
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Stephen L Craig
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Katherine J Franz
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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