Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission(AIE) luminogens(i.e...Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission(AIE) luminogens(i.e., AIEgens) has been witnessed. The combination of AIEgens and rotaxanes leads to the successful construction of a novel type of luminescent rotaxanes with many attractive features. In particular, the unique controllable dynamic feature of rotaxanes endows the resultant AIEgen-based rotaxanes precisely tunable emissions under external stimuli, leading to the construction of a novel type of smart luminescent materials. In this minireview, the recent progress of AIEgen-based rotaxanes has been summarized, with an emphasis on the design strategy and potential applications.展开更多
Natural molecular machines have inspired the development of artificial molecular machines,which have the potential to revolutionize several areas of technology.Artificial molecular machines commonly employ molecular s...Natural molecular machines have inspired the development of artificial molecular machines,which have the potential to revolutionize several areas of technology.Artificial molecular machines commonly employ molecular switches,molecular motors,and molecular shuttles as fundamental building blocks.The observation of artificial molecular machines constructed by these building blocks can be highly challenging due to their small sizes and intricate behaviors.The use of modern instrumentation and advanced observational techniques plays a crucial role in the observation and characterization of molecular machines.Furthermore,a well-designed molecular structure is also a critical factor in making molecular ma-chines more observable.This review summarizes the common methods from diverse perspectives used to observe molecular machines and emphasizes the significance of comprehending their behaviors in the design of superior artificial molecular machines.展开更多
Oligo[n]rotaxanes are one of the most extensively studied categories of mechanically bonded macromolecules.In this study,a supramolecular oligo[2]rotaxane is successfully constructed driven by platinum(Ⅱ)metallacycle...Oligo[n]rotaxanes are one of the most extensively studied categories of mechanically bonded macromolecules.In this study,a supramolecular oligo[2]rotaxane is successfully constructed driven by platinum(Ⅱ)metallacycle and pillar[5]arene-based host–vip interactions in an orthogonal way.The supramolecular oligo[2]rotaxane is further applied in fabricating a light harvesting system.展开更多
The condensation reaction ofω-aminoalkyleneamide-functionalized pillar[5]arenes with 2-(4-([2,2’:6’,2〃-terpyridin]-4’-yl)phenoxy)acetic acid or 4-(4-([2,2’:6’,2"-terpyridin]-4’-yl)phenoxy)butanoic acid in...The condensation reaction ofω-aminoalkyleneamide-functionalized pillar[5]arenes with 2-(4-([2,2’:6’,2〃-terpyridin]-4’-yl)phenoxy)acetic acid or 4-(4-([2,2’:6’,2"-terpyridin]-4’-yl)phenoxy)butanoic acid in dry chloroform at room temperature under the catalysis of HOBT/EDCl resulted in novel pillar[5]arene diamido-bridged terpyridine derivatives.~1 H NMR and 2 D NOESY spectra clearly indicated that the interesting[1]rotaxanes were formed by longer alkylene such as propylene,butylene and hexylenediamido chains threading into the cavity of the pillar[5]arene and with larger terpyridine acting as the stopper.However,the shorter ethylenediamido chain only exists outer of cavity of pillar[5]arene and the molecule exist on free form.展开更多
Styrene-butadiene rubber(SBR)is an indispensable material in modern society,and the necessity for enhanced mechanical properties in SBR persists,particularly to withstand the rigors of challenging environmental condit...Styrene-butadiene rubber(SBR)is an indispensable material in modern society,and the necessity for enhanced mechanical properties in SBR persists,particularly to withstand the rigors of challenging environmental conditions.To surmount the limitations of conventional cross-linking modes,mechanical bonds stabilized by host-vip recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks(MINs).Compared with covalently cross-linked network,the representative MIN exhibits superior mechanical performance in terms of elongation(1392%)and breaking strength(4.6 MPa),whose toughness has surged by 17 times.Dissociation of host-vip recognition and subsequent sliding motion provide an effective energy dissipation mechanism,and the release of hidden length is also beneficial to enhance toughness.Furthermore,the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties,which can return to initial state with one minute rest interval.We aspire that this direct introduction method can serve as a blueprint,offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials.展开更多
The concept of“robust dynamics”describes the incorporation of mechanically interlocked molecules(MIMs)into metal-organic framework(MOF)materials such that large amplitude motions(e.g.,rotation or translation of a ma...The concept of“robust dynamics”describes the incorporation of mechanically interlocked molecules(MIMs)into metal-organic framework(MOF)materials such that large amplitude motions(e.g.,rotation or translation of a macrocycle)can occur inside the free volume pore of the MOF.To aid in the preparation of such materials,reticular synthesis was used herein to design rigid molecular building blocks with predetermined ordered structures starting from the well-known MOF NOTT-101.New linkers were synthesized that have a T-shape,based on a triphenylene tetra-carboxylate strut,and their incorporation into Cu(II)-based MOFs was investigated.The single-crystal structures of three new MOFs,UWCM-12(fof),β-UWCM-13(loz),UWCM-14(lil),with naked T-shaped linkers were determined;β-UWCM-13 is the first reported example of the loz topology.A fourth MOF,UWDM-14(lil)is analogous to UWCM-14(lil)but contains a[2]rotaxane linker.Variable-temperature,^(2)H solid-state NMR was used to probe the dynamics of a 24-membered macrocycle threaded onto the MOF skeleton.展开更多
Using the strategy of ligand fine-tuning by steric hindrance, we successfully obtained Solomon links(4_(1)^(2)) and figure-eight knots(4_(1)) with half-sandwich organometallic unit and amino-acid embedded ligands. The...Using the strategy of ligand fine-tuning by steric hindrance, we successfully obtained Solomon links(4_(1)^(2)) and figure-eight knots(4_(1)) with half-sandwich organometallic unit and amino-acid embedded ligands. The two curved bidentate ligands exhibit subtle differences, whereas they result in totally distinct entanglement modes. An alcoholysis reaction with the ligands leads to the formation of a molecular tweezer. Notably, unsymmetrical ligands were utilized in the self-assembly process to explore the formation of directional molecules, and the reactions exhibited selectivity due to comprehensive π interactions and multiple hydrogen bonds. The topologies and behavior of the above structures were confirmed through single-crystal X-ray diffraction,nuclear magnetic resonance techniques and mass spectrometry.展开更多
Mechanically interlocked polymers(MIPs)are promising candidates for the construction of elastomeric materials with desirable mechanical performance on account of their abilities to undergo inherent rotational and tran...Mechanically interlocked polymers(MIPs)are promising candidates for the construction of elastomeric materials with desirable mechanical performance on account of their abilities to undergo inherent rotational and translational mechanical movements at the molecular level.However,the investigations on their mechanical properties are lagging far behind their structural fabrication,especially for linear polyrotaxanes in bulk.Herein,we report stretchable poly[2]rotaxane elastomers(PREs)which integrate numerous mechanical bonds in the polymeric backbone to boost macroscopic mechanical properties.Specifically,we have synthesized a hydroxyfunctionalized[2]rotaxane that subsequently participates in the condensation polymerization with diisocyanate to form PREs.Benefitting from the peculiar structural and dynamic characteristics of the poly[2]rotaxane,the representative PRE exhibits favorable mechanical performance in terms of stretchability(∼1200%),Young’s modulus(24.6 MPa),and toughness(49.5 MJ/m^(3)).Moreover,we present our poly[2]rotaxanes as model systems to understand the relationship between mechanical bonds and macroscopic mechanical properties.It is concluded that the mechanical properties of our PREs are mainly determined by the unique topological architectures which possess a consecutive energy dissipation pathway including the dissociation of host−vip interaction and consequential sliding motion of the wheel along the axle in the[2]rotaxane motif.展开更多
The properties of coordination complexes are dictated by both the metals and the ligands.The use of molecular receptors as second-sphere ligands enables significant modulation of the chemical and physical properties o...The properties of coordination complexes are dictated by both the metals and the ligands.The use of molecular receptors as second-sphere ligands enables significant modulation of the chemical and physical properties of coordination complexes.In this minireview,we highlight recent advances in functional systems based on molecular receptors as second-sphere coordination ligands,as applied in molecular recognition,synthesis of mechanically interlocked molecules,separation of metals,catalysis,and biomolecular chemistry.These functional systems demonstrate that second-sphere coordination is an emerging and very promising strategy for addressing societal challenges in health,energy,and the environment.展开更多
Aiming at the construction of novel multistate circularly polarized luminescence(CPL)switches,dual stimuli-responsive chiral[2]rotaxanes towards anions and light have been designed and constructed.Through the light-co...Aiming at the construction of novel multistate circularly polarized luminescence(CPL)switches,dual stimuli-responsive chiral[2]rotaxanes towards anions and light have been designed and constructed.Through the light-controlled on/off F?rster resonance energy transfer(FRET)switching between the emissive stoppers and anion-induced controllable motions of the chiral wheel for the precise regulations of chirality information transfer from the chiral wheel to the emissive stoppers,precisely switching between four CPL emission states with varied emission wavelengths and dissymmetry factors has been successfully realized,making them a promising platform for practical uses such as information storage and encryption.This proof-of-concept study not only provides a novel design strategy for multistate CPL switching but also contributes excellent candidates for the construction of novel smart chiral luminescent materials.展开更多
Based on a[2]rotaxane precursor with exchangeable pentafluorophenyl ester stoppers,a new wheelassembling approach has been successfully developed for the precise sequence control of hetero[3]rotaxanes,leading to the f...Based on a[2]rotaxane precursor with exchangeable pentafluorophenyl ester stoppers,a new wheelassembling approach has been successfully developed for the precise sequence control of hetero[3]rotaxanes,leading to the facile and efficient synthesis of both sequence isomers of hetero[3]rotaxanes.More importantly,taking advantage of the chirality retention along with the wheel-assembling process,corresponding sequence isomers of chiral AIEgenfunctionalized hetero[3]rotaxanes were further precisely synthesized.Impressively,the resultant hetero[3]rotaxanes revealed remarkable sequencedependent aggregation-induced emission(AIE)behavior and circularly polarized luminescence performance with large dissymmetry factors up to 0.012,highlighting the great power of the newly coined sequence engineering concept in developing novel AIE-active chiroptical materials.This proof-ofconcept study lays the foundation for investigation of the structure-property relationships of heterorotaxanes that can further direct the rational design and precise synthesis of sequence-defined heterorotaxanes with desirable properties for practical applications.展开更多
Artificial molecular muscles undergo well-controlled contractile and extensile motions upon external stimulation,leading to remarkable length changes.Evaluating such length changes at the molecular level is essential ...Artificial molecular muscles undergo well-controlled contractile and extensile motions upon external stimulation,leading to remarkable length changes.Evaluating such length changes at the molecular level is essential to the design of integrated artificial molecular muscles that mimic biological muscles.Taking advantage of the strong contrast of platinum(Pt)atoms in high-angle annular dark-field scanning transmission electron microscopy images,we imaged Pt-containing molecular[c2]daisy chains directly by employing metal atom markers.The length changes and associated conformational transformations of these newly developed artificial molecular muscles have been measured experimentally in combination with theoretical calculations.The contraction ratios of these two molecular muscles with the TEMPO or pyrene anchoring group were calculated to be 21.0%or 15.7%respectively,suggesting a substantial anchoring effect.This study demonstrates the experimental measurement of the length changes of artificial molecular muscles and provides a new avenue for investigating the motion of artificial molecular machines.展开更多
基金financial support sponsored by the National Natural Science Foundation of China(No.22001073)the Fundamental Research Funds for the Central Universitiesthe Research Fund Program of Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices(No.2020-GDKLFSHMD-07)。
文摘Aiming at the construction of novel rotaxanes with desired luminescent properties for practical applications, recently the rapid development of rotaxanes decorated with aggregation-induced emission(AIE) luminogens(i.e., AIEgens) has been witnessed. The combination of AIEgens and rotaxanes leads to the successful construction of a novel type of luminescent rotaxanes with many attractive features. In particular, the unique controllable dynamic feature of rotaxanes endows the resultant AIEgen-based rotaxanes precisely tunable emissions under external stimuli, leading to the construction of a novel type of smart luminescent materials. In this minireview, the recent progress of AIEgen-based rotaxanes has been summarized, with an emphasis on the design strategy and potential applications.
基金supported by“Zhishan”Scholars Programs of Southeast University,Jiangsu Innovation Team Program,and the Fundamental Research Funds for the Central Universities.
文摘Natural molecular machines have inspired the development of artificial molecular machines,which have the potential to revolutionize several areas of technology.Artificial molecular machines commonly employ molecular switches,molecular motors,and molecular shuttles as fundamental building blocks.The observation of artificial molecular machines constructed by these building blocks can be highly challenging due to their small sizes and intricate behaviors.The use of modern instrumentation and advanced observational techniques plays a crucial role in the observation and characterization of molecular machines.Furthermore,a well-designed molecular structure is also a critical factor in making molecular ma-chines more observable.This review summarizes the common methods from diverse perspectives used to observe molecular machines and emphasizes the significance of comprehending their behaviors in the design of superior artificial molecular machines.
基金financially supported by the National Natural Science Foundation of China(Nos.22001214,21662031,21661028,22061039)the Science Fund for Distinguished Young Scholars of Gansu Province(No.22JR5RA131)+3 种基金the Longyuan Innovation and Entrepreneurship Talent Project of Gansu Provincethe Major Project Cultivation Program of Northwest Normal University(No.NWNU-LKZD2022-01)the Top Leading Talents Project of Gansu Province,the Key R&D Program of Gansu Province(No.21YF5GA066)Gansu Province College Industry Support Plan Project(No.2022CYZC-18)。
文摘Oligo[n]rotaxanes are one of the most extensively studied categories of mechanically bonded macromolecules.In this study,a supramolecular oligo[2]rotaxane is successfully constructed driven by platinum(Ⅱ)metallacycle and pillar[5]arene-based host–vip interactions in an orthogonal way.The supramolecular oligo[2]rotaxane is further applied in fabricating a light harvesting system.
基金financially supported by the National Natural Science Foundation of China (No.21871227)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘The condensation reaction ofω-aminoalkyleneamide-functionalized pillar[5]arenes with 2-(4-([2,2’:6’,2〃-terpyridin]-4’-yl)phenoxy)acetic acid or 4-(4-([2,2’:6’,2"-terpyridin]-4’-yl)phenoxy)butanoic acid in dry chloroform at room temperature under the catalysis of HOBT/EDCl resulted in novel pillar[5]arene diamido-bridged terpyridine derivatives.~1 H NMR and 2 D NOESY spectra clearly indicated that the interesting[1]rotaxanes were formed by longer alkylene such as propylene,butylene and hexylenediamido chains threading into the cavity of the pillar[5]arene and with larger terpyridine acting as the stopper.However,the shorter ethylenediamido chain only exists outer of cavity of pillar[5]arene and the molecule exist on free form.
基金the financial support of the National Natural Science Foundation of China(22071152 and 22122105)the financial support of the National Natural Science Foundation of China(22305150)+4 种基金the financial support from the National Natural Science Foundation of China(22101175 and 52333001)Natural Science Foundation of Shanghai(22dz1207603)supported by the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study(SN-ZJU-SIAS-006)State Key Laboratory of Polyolefins and Catalysis and Shanghai Key Laboratory of Catalysis Technology for Polyolefins(SKL-LCTP-202301)the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22SG11)。
文摘Styrene-butadiene rubber(SBR)is an indispensable material in modern society,and the necessity for enhanced mechanical properties in SBR persists,particularly to withstand the rigors of challenging environmental conditions.To surmount the limitations of conventional cross-linking modes,mechanical bonds stabilized by host-vip recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks(MINs).Compared with covalently cross-linked network,the representative MIN exhibits superior mechanical performance in terms of elongation(1392%)and breaking strength(4.6 MPa),whose toughness has surged by 17 times.Dissociation of host-vip recognition and subsequent sliding motion provide an effective energy dissipation mechanism,and the release of hidden length is also beneficial to enhance toughness.Furthermore,the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties,which can return to initial state with one minute rest interval.We aspire that this direct introduction method can serve as a blueprint,offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials.
基金S.J.L.acknowledges the Natural Sciences and Engineering Research Council of Canada for support of a Discovery Grant(101694)and a Canada Research Chair.R.W.S.is also grateful for support from NSERC,the Canadian Foundation for Innovation,the Ontario Innovation Trust,the University of Windsor for the development and maintenance of the SSNMR centre,and for funding from the Florida State University and the National High Magnetic Field Laboratory(NHMFL),which is funded by the National Science Foundation Cooperative Agreement(DM R-1644779)and by the State of Florida.The authors acknowledge M.Revington for technical assistance with solution NM Rspectroscopy and J.Auld for technical assistance with high resolution mass spectrometry.
文摘The concept of“robust dynamics”describes the incorporation of mechanically interlocked molecules(MIMs)into metal-organic framework(MOF)materials such that large amplitude motions(e.g.,rotation or translation of a macrocycle)can occur inside the free volume pore of the MOF.To aid in the preparation of such materials,reticular synthesis was used herein to design rigid molecular building blocks with predetermined ordered structures starting from the well-known MOF NOTT-101.New linkers were synthesized that have a T-shape,based on a triphenylene tetra-carboxylate strut,and their incorporation into Cu(II)-based MOFs was investigated.The single-crystal structures of three new MOFs,UWCM-12(fof),β-UWCM-13(loz),UWCM-14(lil),with naked T-shaped linkers were determined;β-UWCM-13 is the first reported example of the loz topology.A fourth MOF,UWDM-14(lil)is analogous to UWCM-14(lil)but contains a[2]rotaxane linker.Variable-temperature,^(2)H solid-state NMR was used to probe the dynamics of a 24-membered macrocycle threaded onto the MOF skeleton.
基金supported by the National Natural Science Foundation of China (22031003, 21720102004)Shanghai Science Technology Committee (19DZ2270100)。
文摘Using the strategy of ligand fine-tuning by steric hindrance, we successfully obtained Solomon links(4_(1)^(2)) and figure-eight knots(4_(1)) with half-sandwich organometallic unit and amino-acid embedded ligands. The two curved bidentate ligands exhibit subtle differences, whereas they result in totally distinct entanglement modes. An alcoholysis reaction with the ligands leads to the formation of a molecular tweezer. Notably, unsymmetrical ligands were utilized in the self-assembly process to explore the formation of directional molecules, and the reactions exhibited selectivity due to comprehensive π interactions and multiple hydrogen bonds. The topologies and behavior of the above structures were confirmed through single-crystal X-ray diffraction,nuclear magnetic resonance techniques and mass spectrometry.
基金supported by grants from the National Natural Science Foundation of China(22122105,22071152,and 21901161)Natural Science Foundation of Shanghai(20ZR1429200 and 22YF1400800)supported by the Starry Night Science Fund of Zhejiang University Shanghai Institute for Advanced Study(SN-ZJU-SIAS-006).
文摘Mechanically interlocked polymers(MIPs)are promising candidates for the construction of elastomeric materials with desirable mechanical performance on account of their abilities to undergo inherent rotational and translational mechanical movements at the molecular level.However,the investigations on their mechanical properties are lagging far behind their structural fabrication,especially for linear polyrotaxanes in bulk.Herein,we report stretchable poly[2]rotaxane elastomers(PREs)which integrate numerous mechanical bonds in the polymeric backbone to boost macroscopic mechanical properties.Specifically,we have synthesized a hydroxyfunctionalized[2]rotaxane that subsequently participates in the condensation polymerization with diisocyanate to form PREs.Benefitting from the peculiar structural and dynamic characteristics of the poly[2]rotaxane,the representative PRE exhibits favorable mechanical performance in terms of stretchability(∼1200%),Young’s modulus(24.6 MPa),and toughness(49.5 MJ/m^(3)).Moreover,we present our poly[2]rotaxanes as model systems to understand the relationship between mechanical bonds and macroscopic mechanical properties.It is concluded that the mechanical properties of our PREs are mainly determined by the unique topological architectures which possess a consecutive energy dissipation pathway including the dissociation of host−vip interaction and consequential sliding motion of the wheel along the axle in the[2]rotaxane motif.
基金The authors thank Northwestern University(NU)for their support of this work,which was also funded by the Center for Sustainable Separation of Metals(CSSM)and part of a National Science Foundation(NSF)Center for Chemical Innovation(CCI):grant number CHE1925708.
文摘The properties of coordination complexes are dictated by both the metals and the ligands.The use of molecular receptors as second-sphere ligands enables significant modulation of the chemical and physical properties of coordination complexes.In this minireview,we highlight recent advances in functional systems based on molecular receptors as second-sphere coordination ligands,as applied in molecular recognition,synthesis of mechanically interlocked molecules,separation of metals,catalysis,and biomolecular chemistry.These functional systems demonstrate that second-sphere coordination is an emerging and very promising strategy for addressing societal challenges in health,energy,and the environment.
基金financial support sponsored by the National Natural Science Foundation of China(92356307)financial support sponsored by the National Natural Science Foundation of China(92056203)+4 种基金financial support sponsored by the National Natural Science Foundation of China(22201077)Shanghai Pilot Program for Basic Research(TQ20240205)Natural Science Foundation of Shanghai(23ZR1419600)Science and Technology Commission of Shanghai Municipality(21520710200)the National Key R&D Program of China(2021YFA1501600)。
文摘Aiming at the construction of novel multistate circularly polarized luminescence(CPL)switches,dual stimuli-responsive chiral[2]rotaxanes towards anions and light have been designed and constructed.Through the light-controlled on/off F?rster resonance energy transfer(FRET)switching between the emissive stoppers and anion-induced controllable motions of the chiral wheel for the precise regulations of chirality information transfer from the chiral wheel to the emissive stoppers,precisely switching between four CPL emission states with varied emission wavelengths and dissymmetry factors has been successfully realized,making them a promising platform for practical uses such as information storage and encryption.This proof-of-concept study not only provides a novel design strategy for multistate CPL switching but also contributes excellent candidates for the construction of novel smart chiral luminescent materials.
基金support by the National Natural Science Foundation of China(grant nos.92356307 and 22001073)the Natural Science Foundation of Shanghai(grant no.23ZR1419600)+3 种基金support by the National Natural Science Foundation of China(grant no.92056203)the Science and Technology Commission of Shanghai Municipality(grant no.21520710200)the National Key R&D Program of China(grant no.2021YFA1501600)support by the National Natural Science Foundation of China(grant no.22201077).
文摘Based on a[2]rotaxane precursor with exchangeable pentafluorophenyl ester stoppers,a new wheelassembling approach has been successfully developed for the precise sequence control of hetero[3]rotaxanes,leading to the facile and efficient synthesis of both sequence isomers of hetero[3]rotaxanes.More importantly,taking advantage of the chirality retention along with the wheel-assembling process,corresponding sequence isomers of chiral AIEgenfunctionalized hetero[3]rotaxanes were further precisely synthesized.Impressively,the resultant hetero[3]rotaxanes revealed remarkable sequencedependent aggregation-induced emission(AIE)behavior and circularly polarized luminescence performance with large dissymmetry factors up to 0.012,highlighting the great power of the newly coined sequence engineering concept in developing novel AIE-active chiroptical materials.This proof-ofconcept study lays the foundation for investigation of the structure-property relationships of heterorotaxanes that can further direct the rational design and precise synthesis of sequence-defined heterorotaxanes with desirable properties for practical applications.
基金financial support by the National Natural Science Foundation of China(grant no.92056203)the Science and Technology Commission of Shanghai Municipality(grant no.21520710200)+8 种基金the National Key R&D Program of China(grant no.2021YFA1501600)the Innovation Program of Shanghai Municipal Education Commission(grant no.2019-01-07-00-05-E00012)W.W.acknowledges the financial support by the National Natural Science Foundation of China(grant no.22001073)the Natural Science Foundation of Shanghai(grant no.23ZR1419600)L.H.acknowledges the financial support by the National Nature Science Foundation of China(grant no.22103062)the Shanghai Pujiang Program(grant no.22PJ1402800)the Fundamental Research Funds for the Central UniversitiesX.-Q.W.acknowledges the financial support by the National Natural Science Foundation of China(grant no.22201077)W.-J.L.is grateful to the China Postdoctoral Science Foundation(grant nos.BX2021103 and 2021M700044)for financial support.
文摘Artificial molecular muscles undergo well-controlled contractile and extensile motions upon external stimulation,leading to remarkable length changes.Evaluating such length changes at the molecular level is essential to the design of integrated artificial molecular muscles that mimic biological muscles.Taking advantage of the strong contrast of platinum(Pt)atoms in high-angle annular dark-field scanning transmission electron microscopy images,we imaged Pt-containing molecular[c2]daisy chains directly by employing metal atom markers.The length changes and associated conformational transformations of these newly developed artificial molecular muscles have been measured experimentally in combination with theoretical calculations.The contraction ratios of these two molecular muscles with the TEMPO or pyrene anchoring group were calculated to be 21.0%or 15.7%respectively,suggesting a substantial anchoring effect.This study demonstrates the experimental measurement of the length changes of artificial molecular muscles and provides a new avenue for investigating the motion of artificial molecular machines.
