Achieving efficient adsorption and desorption processes by controllably tuning the properties of adsorbents at different technical stages is extremely attractive.However,it is difficult for traditional adsorbents to r...Achieving efficient adsorption and desorption processes by controllably tuning the properties of adsorbents at different technical stages is extremely attractive.However,it is difficult for traditional adsorbents to reach the target because of their fixed active sites.Herein,we report on the fabrication of a smart adsorbent,which was achieved by introducing photoresponsive azobenzene derivatives with cis/trans isomers to Ce-doped mesoporous silica.These photoresponsive groups serve as “molecular switches”by sheltering and exposing active sites,leading to efficient adsorption and desorption.Ce is also doped to provide additional active sites in order to enhance the adsorption performance.The results show that the cis isomers effectively shelter the active sites,leading to the selective adsorption of methylene blue(MB)over brilliant blue(BB),while the trans isomers completely expose the active sites,resulting in the convenient release of the adsorbates.Both selective adsorption and efficient desorption can be realized controllably by these smart adsorbents through photostimulation.Moreover,the performance of the obtained materials is well maintained after five cycles.展开更多
In this assay, a label-free fluorescent sensing platform based on triple-helix molecular switch（THMS） and G-quadruplex was developed for the detection of tetracycline. We demonstrated this approach by using THMS, wh...In this assay, a label-free fluorescent sensing platform based on triple-helix molecular switch（THMS） and G-quadruplex was developed for the detection of tetracycline. We demonstrated this approach by using THMS, which consists of a central section with a shortened 8-mer aptamer sequence with high affinity to tetracycline and flanked by two arm segments. G-rich oligonucleotide can specifically bind to thioflavin T（Th T） as a signal transduction probe（STP）. In the absence of tetracycline, THMS remains stable, the fluorescence of background is low. By the addition of target tetracycline, the aptamer-target binding results in the formation of a structured aptamer-target complex, which disassembles the THMS and releases the STP. The free STP self-assembles into G-quadruplex and specifically binds to Th T which generates a obvious fluorescence enhancement. Using the triple-helix molecular switch, the developed aptamer-based fluorescent sensing platform showed a linear relationship with the concentration of tetracycline ranging from 0.2 to 20.0 nmol/L. The detection limit of tetracycline was determined to be970.0 pmol/L. The assay avoids complicated modifications or chemical labeling, making it simple and cost-effective. So, it is expected that this aptamer-based fluorescent assay could be extensively applied in the field of food safety inspection.展开更多
Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limite...Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.展开更多
Based on the nonequilibrium Green function method and density functional theory calculations, we theoretically investigate the effect of chirality on the electronic transport properties of thioxanthene-based molecular...Based on the nonequilibrium Green function method and density functional theory calculations, we theoretically investigate the effect of chirality on the electronic transport properties of thioxanthene-based molecular switch. The molecule comprises the switch which can exhibit different chiralities, that is, cis-form and trans-form by ultraviolet or visible irradiation. The results clearly reveal that the switching behaviors can be realized when the molecule converts between cis-form and trans-form. ~urthermore, the on-off ratio can be modulated by the chirality of the carbon nanotube electrodes. The maximum on-off ratio can reach 109 at 0.4 V for the armchair junction, suggesting potential applications of this type of junctions in future design of functional molecular devices.展开更多
Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine （PSBH） were studied using the DFT-B3LYP/6-31G＊ method. The results confirmed that the electrical co...Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine （PSBH） were studied using the DFT-B3LYP/6-31G＊ method. The results confirmed that the electrical conductivity of the closed form of considered molecular switch is higher than that of the open form. NBO electric charges on heavy atoms of biphenyl unit revealed that the positive charge on sulfur atoms reinforced, which caused the collapse of disulfide bond.展开更多
Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated.It was found that fluorescence intensity and optical rotation of the new chi...Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated.It was found that fluorescence intensity and optical rotation of the new chiral hymecromone derivatives could be regulated by light.This property has potential significance for developing a new type of dual-mode molecular switch.展开更多
Using nonequilibrium Green＇s function formalism combined first-principles density functional theory, we analyze the transport properties of a 4,4-dimethyl-6-（4-nitrophenyl）-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-en...Using nonequilibrium Green＇s function formalism combined first-principles density functional theory, we analyze the transport properties of a 4,4-dimethyl-6-（4-nitrophenyl）-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene molecular optical switch. The title molecule can convert between closed and open forms by visible or ultraviolet irradiation. The I-V characteristics, differential conductance, on-off ratio, electronic transmission coefficients, spatial distribution of molecular projected self-consistent Hamiltonian orbitals, HOMO-LUMO gaps, effect of electrode materials Y（111）（Y =Au, Ag and Pt） on electronic transport and different molecular geometries corresponding to the closed and open forms through the molecular device are discussed in detail. Based on the results, as soon as possible the open form translates to the closed form, and there is a switch from the ON state to the OFF state（low resistance switches to high resistance）. Theoretical results show that the donor/acceptor substituent plays an important role in the electronic transport of molecular devices. The switching performance can be improved to some extent through suitable donor and acceptor substituents.展开更多
It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuc...It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuclear DNA fragments could enhance the expression activity of LDH/DNA and the amount of expressed LDH (1 5) is in proportion to the amount of dissociable LDH (1 5) on the LDH/DNA. With the integration of 14C Leu to the proteins, it is also observed that the addition of LDH (1 5) ...nNAD + can suppress the in vitro expression activity of LDH/DNA. AFM observation shows that the regulation sequence at the both ends of active genes may be bound with such active factors as proteins encoded by the genes which probably is the main molecular switch of gene expression and regulation we have been always searching for. Our work shows the prospective application of the combination of AFM and isotope labeling in the research of biological reaction.展开更多
Plants activate complex signaling networks in response to pathogen attacks,orchestrating defense responses both locally and in distant and systemic tissues.The systemic activation of plant immunity,termed systemic acq...Plants activate complex signaling networks in response to pathogen attacks,orchestrating defense responses both locally and in distant and systemic tissues.The systemic activation of plant immunity,termed systemic acquired resistance(SAR),was first observed in the 1960s in tobacco plants infected with the tobacco mosaic virus.A defining feature of SAR is the accumulation of pathogenesis-related(PR)proteins,are sometimes also referred to as the molecular markers for this process(Durrant and Dong,2004).展开更多
Electrical switching of a single-molecule junction provides a practical module to perform sophisticated operations in electronic devices.However,designing an all-electrically-driven molecular switch is a great challen...Electrical switching of a single-molecule junction provides a practical module to perform sophisticated operations in electronic devices.However,designing an all-electrically-driven molecular switch is a great challenge.Here,we experimentally and theoretically investigated the charge transport characteristics of isoindigo(ISO)-molecules at the single-molecule level using the scanning tunneling microscope break junction technique.We find that the single-molecule junctions of ISO-molecules display bias voltage-driven switching characteristics.These switches are realtime,reversible,and nondestructive under low-bias voltages.Experimental results show that the mechanism of the switch is not the transition from nonresonant charge transport to resonant charge transport,but it is the shift of the frontier orbital energy levels of ISO-molecules and the change of the interfacial electronic coupling with bias voltage.Our results will advance the design of high-performance bias voltage-driven molecular switches.展开更多
The multifaceted switches are part of our everyday life from the macroscopic to the molecular world.A molecular switch operating in the solution and in the crystalline state is very different.In this review,we summari...The multifaceted switches are part of our everyday life from the macroscopic to the molecular world.A molecular switch operating in the solution and in the crystalline state is very different.In this review,we summarize the state-of-the-art of smart molecular crystal switches based on molecular martensites.These crystal switches respond to external stimuli and reversibly change between states,retaining their macroscopic integrity.The operation of the switches predominantly relies on temperature alterations or mechanical stress,with emerging methods based on photothermal effects,photoisomerization,and host-vip chemistry.The capability of changing the molecular orientation and interaction in smart molecular crystal switches offers opportunities in several applications,including actuators,reversibly shaping structural materials,optoelectronic and magnetic materials,as well as switchable porous materials.Smart molecular crystal switches have vast potential in modern scientific and technological progress.The ongoing research shapes a rich landscape for innovation and future scientific exploration across diverse disciplines.展开更多
Molecular switches that can undergo reversible switching between two or more different states in response to external stimuli have been used in the fabrication of various optoelectronic devices and smart materials for...Molecular switches that can undergo reversible switching between two or more different states in response to external stimuli have been used in the fabrication of various optoelectronic devices and smart materials for many decades, and also found many applications in sensing, molecular self-assembly and photo-controlled biological systems. Recently, mechanically interlocked molecules, such as rotaxanes and catenanes, and molecular rotary motors based on overcrowded alkenes have emerged as two new kinds of molecular switches. Some novel applications of above-mentioned molecular switches have been discovered. In this mini review, we mainly highlight noticeable achievements over the past decade in this field, and summarize the applications of new types of molecular switches, for instance, controlling the chiral space to regulate catalytic reaction as organocatalysts, controlling molecular motions, synthesizing a peptide in a sequence-specific manner and modulating the wettability of the self-assembled monolayers.展开更多
In contrast to the static operations of conventional semiconductor devices,the dynamic conformational freedom in molecular devices opens up the possibility of using individual molecules as new types of devices such as...In contrast to the static operations of conventional semiconductor devices,the dynamic conformational freedom in molecular devices opens up the possibility of using individual molecules as new types of devices such as a molecular conformational switch or for molecular data storage.Bistable molecules such as those having two stable cis and trans isomeric confi gurations could provide,once clamped between two electrodes,a switching phenomenon in the non-equilibrium current response.Here,we model molecular switch junctions formed at silicon contacts and demonstrate the potential of such tunable molecular switches in electrode/molecule/electrode confi gurations.Using the non-equilibrium Green function(NEGF)approach implemented with the density-functional-based tight-binding(DFTB)theory,a series of properties such as electron transmissions,current voltage characteristics in the different isomer conformations,and potential energy surfaces(PESs)as a function of the reaction coordinates along the trans to cis transition were calculated for two azobenzene-based model compounds.Furthermore,in order to investigate the stability of molecular switches under ambient conditions,molecular dynamics(MD)simulations at room temperature were performed and time-dependent fl uctuations of the conductance along the MD pathways were calculated.Our numerical results show that the transmission spectra of the cis isomers are more conductive than trans counterparts inside the bias window for both model compounds.The currentvoltage characteristics consequently show the same trends.Additionally,calculations of the time-dependent transmission fluctuations along the MD pathways have shown that the transmission in the cis isomers is always signifi cantly larger than that in their trans counterparts,showing that molecular switches can be expected to work as robust molecular switching components.展开更多
By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Th...By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.展开更多
A simple-structured 4-（2-pyridylazo）resorcinol （PAR） system presents interesting properties with dual fluorescent outputs. Modulated by solution pH two kinds of reversible switch behaviors, ＂ON-OFF＂ and ＂OFF-ON...A simple-structured 4-（2-pyridylazo）resorcinol （PAR） system presents interesting properties with dual fluorescent outputs. Modulated by solution pH two kinds of reversible switch behaviors, ＂ON-OFF＂ and ＂OFF-ON＂, were realized with the PAR system. Stimulated by different combination of external stimulus, such as metal ions, UV ir- radiation and solution pH, the PAR system could perform multiple logic functions including three inputs AND, two inputs INHIBIT and combinatorial ＂NOR/AND＂ in parallel. The operation of the designed system is very simple and detected with a high sensitive fluorescent signal.展开更多
A novel pH-responsive[2]pseudorotaxane based on ethylated pillar[6]arene and bis(1,2,3-triazolium)butane cation was constructed.The dethreading and rethreading could be reversibly controlled by adding base and acid,i....A novel pH-responsive[2]pseudorotaxane based on ethylated pillar[6]arene and bis(1,2,3-triazolium)butane cation was constructed.The dethreading and rethreading could be reversibly controlled by adding base and acid,i.e.,the deprotonation and reprotonation of the vip.In contrast,such responsible switching behavior does not occur for the complexation between the vip and ethylated pillar[5]arene,since both the cationic axle and the deprotonated one can be strongly bound by ethylated pillar[5]arene.Furthermore,the bis(1,2,3-triazolium)butane⊂pillar[6]-arene-[2]pseudorotaxane can also disassemble upon the addition of competitive ethylated pillar[5]arene.展开更多
Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular...Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.展开更多
LepA, the highly conserved translational GTPase (trGTPase), triggers one-codon back-movement of the elongating ribosome. Here we identify a new enzymatic activity
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
基金This work was supported by the National Science Fund for Excellent Young Scholars(21722606)the National Natural Science Foundation of China(21676138,21878149,21808110,and 21576137)+1 种基金the China Postdoctoral Science Foundation(2018M632295)the Six Talent Plan(2016XCL031).
文摘Achieving efficient adsorption and desorption processes by controllably tuning the properties of adsorbents at different technical stages is extremely attractive.However,it is difficult for traditional adsorbents to reach the target because of their fixed active sites.Herein,we report on the fabrication of a smart adsorbent,which was achieved by introducing photoresponsive azobenzene derivatives with cis/trans isomers to Ce-doped mesoporous silica.These photoresponsive groups serve as “molecular switches”by sheltering and exposing active sites,leading to efficient adsorption and desorption.Ce is also doped to provide additional active sites in order to enhance the adsorption performance.The results show that the cis isomers effectively shelter the active sites,leading to the selective adsorption of methylene blue(MB)over brilliant blue(BB),while the trans isomers completely expose the active sites,resulting in the convenient release of the adsorbates.Both selective adsorption and efficient desorption can be realized controllably by these smart adsorbents through photostimulation.Moreover,the performance of the obtained materials is well maintained after five cycles.
基金supported by National Natural Science Foundation of China (Nos. 21205142, 31370104)The Research Innovation Program for Graduates of Central South University (No. 2016zzts580)
文摘In this assay, a label-free fluorescent sensing platform based on triple-helix molecular switch（THMS） and G-quadruplex was developed for the detection of tetracycline. We demonstrated this approach by using THMS, which consists of a central section with a shortened 8-mer aptamer sequence with high affinity to tetracycline and flanked by two arm segments. G-rich oligonucleotide can specifically bind to thioflavin T（Th T） as a signal transduction probe（STP）. In the absence of tetracycline, THMS remains stable, the fluorescence of background is low. By the addition of target tetracycline, the aptamer-target binding results in the formation of a structured aptamer-target complex, which disassembles the THMS and releases the STP. The free STP self-assembles into G-quadruplex and specifically binds to Th T which generates a obvious fluorescence enhancement. Using the triple-helix molecular switch, the developed aptamer-based fluorescent sensing platform showed a linear relationship with the concentration of tetracycline ranging from 0.2 to 20.0 nmol/L. The detection limit of tetracycline was determined to be970.0 pmol/L. The assay avoids complicated modifications or chemical labeling, making it simple and cost-effective. So, it is expected that this aptamer-based fluorescent assay could be extensively applied in the field of food safety inspection.
基金funded by the National Natural Science Foundation of China(No.31801620).
文摘Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.
基金Supported by the National Natural Science Foundation of China under Grant No 11004156the Natural Science Foundation of Shaanxi Province under Grant No 2014JM1025+2 种基金the Science and Technology Star Project of Shaanxi Province under Grant No2016KJXX-38the Special Foundation of Key Academic Subjects Development of Shaanxi Province under Grant No 2008-169the Xi'an Polytechnic University Young Scholar Supporting Plan under Grant No 2013-06
文摘Based on the nonequilibrium Green function method and density functional theory calculations, we theoretically investigate the effect of chirality on the electronic transport properties of thioxanthene-based molecular switch. The molecule comprises the switch which can exhibit different chiralities, that is, cis-form and trans-form by ultraviolet or visible irradiation. The results clearly reveal that the switching behaviors can be realized when the molecule converts between cis-form and trans-form. ~urthermore, the on-off ratio can be modulated by the chirality of the carbon nanotube electrodes. The maximum on-off ratio can reach 109 at 0.4 V for the armchair junction, suggesting potential applications of this type of junctions in future design of functional molecular devices.
基金Supported by the Young Researchers Club of Islamic Azad University, Shahrood Branch
文摘Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine （PSBH） were studied using the DFT-B3LYP/6-31G＊ method. The results confirmed that the electrical conductivity of the closed form of considered molecular switch is higher than that of the open form. NBO electric charges on heavy atoms of biphenyl unit revealed that the positive charge on sulfur atoms reinforced, which caused the collapse of disulfide bond.
基金the National Natural Science Foundation of China for financial suppoa(No.29972033)
文摘Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated.It was found that fluorescence intensity and optical rotation of the new chiral hymecromone derivatives could be regulated by light.This property has potential significance for developing a new type of dual-mode molecular switch.
基金Supported by the Damghan University,the Ferdowsi University of Mashhad and the Islamic Azad University of Shahrood
文摘Using nonequilibrium Green＇s function formalism combined first-principles density functional theory, we analyze the transport properties of a 4,4-dimethyl-6-（4-nitrophenyl）-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene molecular optical switch. The title molecule can convert between closed and open forms by visible or ultraviolet irradiation. The I-V characteristics, differential conductance, on-off ratio, electronic transmission coefficients, spatial distribution of molecular projected self-consistent Hamiltonian orbitals, HOMO-LUMO gaps, effect of electrode materials Y（111）（Y =Au, Ag and Pt） on electronic transport and different molecular geometries corresponding to the closed and open forms through the molecular device are discussed in detail. Based on the results, as soon as possible the open form translates to the closed form, and there is a switch from the ON state to the OFF state（low resistance switches to high resistance）. Theoretical results show that the donor/acceptor substituent plays an important role in the electronic transport of molecular devices. The switching performance can be improved to some extent through suitable donor and acceptor substituents.
文摘It is observed by in situ stain that LDH (1 5) ...nNAD + can probably enter the nucleopore and can be bound bound specifically with the genes that encode them. During the in vitro expression, the dilution of heart nuclear DNA fragments could enhance the expression activity of LDH/DNA and the amount of expressed LDH (1 5) is in proportion to the amount of dissociable LDH (1 5) on the LDH/DNA. With the integration of 14C Leu to the proteins, it is also observed that the addition of LDH (1 5) ...nNAD + can suppress the in vitro expression activity of LDH/DNA. AFM observation shows that the regulation sequence at the both ends of active genes may be bound with such active factors as proteins encoded by the genes which probably is the main molecular switch of gene expression and regulation we have been always searching for. Our work shows the prospective application of the combination of AFM and isotope labeling in the research of biological reaction.
基金supported by a grant from the National Research Foundation of Korea(NRF)funded by the Ministry of Education,Science,and Technology(grant no.RS-2023-00248352)。
文摘Plants activate complex signaling networks in response to pathogen attacks,orchestrating defense responses both locally and in distant and systemic tissues.The systemic activation of plant immunity,termed systemic acquired resistance(SAR),was first observed in the 1960s in tobacco plants infected with the tobacco mosaic virus.A defining feature of SAR is the accumulation of pathogenesis-related(PR)proteins,are sometimes also referred to as the molecular markers for this process(Durrant and Dong,2004).
基金supported by the National Natural Science Foundation of China(grant nos.21875279,22075080,and 52273176)the Shanghai Municipal Science and Technology Major Project(grant no.2018SHZDZX03)the Fundamental Research Funds for the Central Universities,and East China University of Science and Technology.
文摘Electrical switching of a single-molecule junction provides a practical module to perform sophisticated operations in electronic devices.However,designing an all-electrically-driven molecular switch is a great challenge.Here,we experimentally and theoretically investigated the charge transport characteristics of isoindigo(ISO)-molecules at the single-molecule level using the scanning tunneling microscope break junction technique.We find that the single-molecule junctions of ISO-molecules display bias voltage-driven switching characteristics.These switches are realtime,reversible,and nondestructive under low-bias voltages.Experimental results show that the mechanism of the switch is not the transition from nonresonant charge transport to resonant charge transport,but it is the shift of the frontier orbital energy levels of ISO-molecules and the change of the interfacial electronic coupling with bias voltage.Our results will advance the design of high-performance bias voltage-driven molecular switches.
基金supported by the National Natural Science Foundation of China(51773077 and 52173164 H.Z)the Natural Science Foundation of Jilin Province(20230101038JC,H.Z)+1 种基金a fund from New York University Abu Dhabi(P.N)This material is based upon works supported by Tamkeen under NYUAD RRC Grant No.CG011.
文摘The multifaceted switches are part of our everyday life from the macroscopic to the molecular world.A molecular switch operating in the solution and in the crystalline state is very different.In this review,we summarize the state-of-the-art of smart molecular crystal switches based on molecular martensites.These crystal switches respond to external stimuli and reversibly change between states,retaining their macroscopic integrity.The operation of the switches predominantly relies on temperature alterations or mechanical stress,with emerging methods based on photothermal effects,photoisomerization,and host-vip chemistry.The capability of changing the molecular orientation and interaction in smart molecular crystal switches offers opportunities in several applications,including actuators,reversibly shaping structural materials,optoelectronic and magnetic materials,as well as switchable porous materials.Smart molecular crystal switches have vast potential in modern scientific and technological progress.The ongoing research shapes a rich landscape for innovation and future scientific exploration across diverse disciplines.
基金supported by the National Natural Science Foundation of China(21272073,21421004,21190033)the National Basic Research Program of China(2011CB808400)+1 种基金the Fok Ying Tong Education Foundation(121069)the Fundamental Research Funds for the Central Universities,and the Innovation Program of Shanghai Municipal Education Commission
文摘Molecular switches that can undergo reversible switching between two or more different states in response to external stimuli have been used in the fabrication of various optoelectronic devices and smart materials for many decades, and also found many applications in sensing, molecular self-assembly and photo-controlled biological systems. Recently, mechanically interlocked molecules, such as rotaxanes and catenanes, and molecular rotary motors based on overcrowded alkenes have emerged as two new kinds of molecular switches. Some novel applications of above-mentioned molecular switches have been discovered. In this mini review, we mainly highlight noticeable achievements over the past decade in this field, and summarize the applications of new types of molecular switches, for instance, controlling the chiral space to regulate catalytic reaction as organocatalysts, controlling molecular motions, synthesizing a peptide in a sequence-specific manner and modulating the wettability of the self-assembled monolayers.
基金by the Volkswagen Foundation by the Deutsche Forshuhgsgemeinschaft(DFG)under Contracts No.CU 44/5-2,CU 44/8-1,and CU 44/3-3by the WCU(World Class University)program through the Korea Science and Engineering Foundation funded by the Ministry of Education,Science and Technology(Project No.R31-2008-000-10100-0).
文摘In contrast to the static operations of conventional semiconductor devices,the dynamic conformational freedom in molecular devices opens up the possibility of using individual molecules as new types of devices such as a molecular conformational switch or for molecular data storage.Bistable molecules such as those having two stable cis and trans isomeric confi gurations could provide,once clamped between two electrodes,a switching phenomenon in the non-equilibrium current response.Here,we model molecular switch junctions formed at silicon contacts and demonstrate the potential of such tunable molecular switches in electrode/molecule/electrode confi gurations.Using the non-equilibrium Green function(NEGF)approach implemented with the density-functional-based tight-binding(DFTB)theory,a series of properties such as electron transmissions,current voltage characteristics in the different isomer conformations,and potential energy surfaces(PESs)as a function of the reaction coordinates along the trans to cis transition were calculated for two azobenzene-based model compounds.Furthermore,in order to investigate the stability of molecular switches under ambient conditions,molecular dynamics(MD)simulations at room temperature were performed and time-dependent fl uctuations of the conductance along the MD pathways were calculated.Our numerical results show that the transmission spectra of the cis isomers are more conductive than trans counterparts inside the bias window for both model compounds.The currentvoltage characteristics consequently show the same trends.Additionally,calculations of the time-dependent transmission fluctuations along the MD pathways have shown that the transmission in the cis isomers is always signifi cantly larger than that in their trans counterparts,showing that molecular switches can be expected to work as robust molecular switching components.
基金supported by the National Natural Science Foundation of China (Grant No. 11004156)the National Basic Research Program of China (Grant No. 2009CB929204)+1 种基金the Education Department Foundation of Shaanxi Province, China (Grant No. 09JK461)the Fundament Research of Xi’an Polytechnic University (Grant No. 09XG09)
文摘By applying nonequilibrium Green's function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of the dihydroazulene optical molecular switch. Three kinds of adsorption sites including the hollow, bridge and top sites are studied. The two forms of this molecule, namely the open form and the closed form, can reversibly switch from each other upon photoexcitation. Their transmission spectra are remarkably distinctive. Theoretical results show that the current of the closed form is always significantly larger than that of the open form for all three adsorption sites, which promises this system as possibly one of the good candidates for optical switches due to its unique advantage, and which may have some potential applications in the future molecular circuit.
基金The authors kindly thank the financial support from National Natural Science Foundation of China，973 Project
文摘A simple-structured 4-（2-pyridylazo）resorcinol （PAR） system presents interesting properties with dual fluorescent outputs. Modulated by solution pH two kinds of reversible switch behaviors, ＂ON-OFF＂ and ＂OFF-ON＂, were realized with the PAR system. Stimulated by different combination of external stimulus, such as metal ions, UV ir- radiation and solution pH, the PAR system could perform multiple logic functions including three inputs AND, two inputs INHIBIT and combinatorial ＂NOR/AND＂ in parallel. The operation of the designed system is very simple and detected with a high sensitive fluorescent signal.
文摘A novel pH-responsive[2]pseudorotaxane based on ethylated pillar[6]arene and bis(1,2,3-triazolium)butane cation was constructed.The dethreading and rethreading could be reversibly controlled by adding base and acid,i.e.,the deprotonation and reprotonation of the vip.In contrast,such responsible switching behavior does not occur for the complexation between the vip and ethylated pillar[5]arene,since both the cationic axle and the deprotonated one can be strongly bound by ethylated pillar[5]arene.Furthermore,the bis(1,2,3-triazolium)butane⊂pillar[6]-arene-[2]pseudorotaxane can also disassemble upon the addition of competitive ethylated pillar[5]arene.
基金supported by the National Natural Science Foundation of China (Grant No. 60471042)Natural Science Foundation of Shandong Province, China (Grant No. ZR2009AL004)
文摘Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.
文摘LepA, the highly conserved translational GTPase (trGTPase), triggers one-codon back-movement of the elongating ribosome. Here we identify a new enzymatic activity
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.
