Simultaneously achieving room-temperature phosphorescence(RTP) and multiple-stimuli responsiveness in a single-component system is of significance but remains challenging. Crystallization has been recognized to be a w...Simultaneously achieving room-temperature phosphorescence(RTP) and multiple-stimuli responsiveness in a single-component system is of significance but remains challenging. Crystallization has been recognized to be a workable strategy to fulfill the above task. However, how the molecular packing mode affects the intersystem crossing and RTP lifetime concurrently remains unclear so far. Herein, four economic small-molecular compounds, analogues of the famous drug raloxifene(RALO), are facilely synthesized and further explored as neat single-component and stimuli-responsive RTP emitters via crystallization engineering. Thanks to their simple structures and high ease to crystallize, these raloxifene analogues function as models to clarify the important role of molecular packing in the RTP and stimuliresponsiveness properties. Thorough combination of the single-crystal structure analysis and theoretical calculations clearly manifests that the tight antiparallel molecular packing mode is the key point to their RTP behaviors. Interestingly, harnessing the controllable and reversible phase transitions of the two polymorphs of RALO-OAc driven by mechanical force, solvent vapor, and heat, a single-component multilevel stimuli-responsive platform with tunable emission color is established and further exploited for optical information encryption. This work would shed light on the rational design of multi-stimuli responsive RTP systems based on single-component organics.展开更多
Charge transport characterization of single-molecule junctions is essential for the fundamental research of single-molecule physical chemistry and the development towards single-molecule electronic devices and circuit...Charge transport characterization of single-molecule junctions is essential for the fundamental research of single-molecule physical chemistry and the development towards single-molecule electronic devices and circuits. Among the single-molecule conductance characterization techniques,the single-molecule break junction technique is widely used in tens of worldwide research laboratories which can generate a large amount of experimental data from thousands of individual measurement cycles. However,data interpretation is a challenging task for researchers with different research backgrounds,and the different data analysis approaches sometimes lead to the misunderstanding of the measurement data and even reproducibility issues of the measurement. It is thus a necessity to develop a user-friendly all-in-one data analysis tool that automatizes the basic data analysis in a standard and widely accepted way. In this work,we present the XMe Code (Xiamen Molecular Electronics Code),an intelligent all-in-one data analysis tool for the comprehensive analysis of single-molecule break junction data. XMe code provides end-to-end data analysis that takes in the original experimental data and returns electronic characteristics and even charge transport mechanisms. We believe that XMe Code will promote the transparency of the data analysis in single-molecule electronics and the collaborations among scientists with different research backgrounds.展开更多
Folding of molecules is an essential process in nature,and various molecular machines achieve their chemical and mechanical function via controlled folding of molecular conformations.The electric field offers a unique...Folding of molecules is an essential process in nature,and various molecular machines achieve their chemical and mechanical function via controlled folding of molecular conformations.The electric field offers a unique strategy to drive the folding of molecular conformation and to control charge transport through single molecules but remains unexplored.The single-molecule break junction technique provides access to detect the conformational changes via the monitoring of single-molecule conductance,and the electric field between two metal electrodes with nanoscale spacing can provide an extremely strong to achieve in-situ control and detection of molecular folding at the single-molecule level.Here,we use the electric field to control the single-molecule folding using the scanning tunneling microscope break junction(STM-BJ)technique.The electric fields induced folding could lead to a∼1400%conductance change of the single-molecule junctions,and the folding/unfolding process can be in-situ switched at the scale of milliseconds.DFT calculations suggest the conformational control originates from the electric fieldinduced charge injection,and the formation of homoconjugated conformation with the overlapped orbitals.This work provides the first demonstration of electric field-driven molecular folding,which is essential for the understanding of molecular machines in nature and for the design of artificial molecular machines.展开更多
基金supported by the National Natural Science Foundation of China (21788102, 22275055, 22025503, 22220102004, 21875064, and 21790361)Shanghai Science and Technology Commission Basic Project Shanghai Natural Science Foundation (21ZR1417600)+5 种基金Shanghai Municipal Science and Technology Major Project (2018SHZDZX03)the Programme of Introducing Talents of Discipline to Universities (B16017)Shanghai Science and Technology Committee (17520750100)Science and Technology Commission of Shanghai Municipality (21JC1401700)the Fundamental Research Funds for the Central Universitiesthe support of Research Center of Analysis and Test of East China University of Science and Technology for the help on the characterization。
文摘Simultaneously achieving room-temperature phosphorescence(RTP) and multiple-stimuli responsiveness in a single-component system is of significance but remains challenging. Crystallization has been recognized to be a workable strategy to fulfill the above task. However, how the molecular packing mode affects the intersystem crossing and RTP lifetime concurrently remains unclear so far. Herein, four economic small-molecular compounds, analogues of the famous drug raloxifene(RALO), are facilely synthesized and further explored as neat single-component and stimuli-responsive RTP emitters via crystallization engineering. Thanks to their simple structures and high ease to crystallize, these raloxifene analogues function as models to clarify the important role of molecular packing in the RTP and stimuliresponsiveness properties. Thorough combination of the single-crystal structure analysis and theoretical calculations clearly manifests that the tight antiparallel molecular packing mode is the key point to their RTP behaviors. Interestingly, harnessing the controllable and reversible phase transitions of the two polymorphs of RALO-OAc driven by mechanical force, solvent vapor, and heat, a single-component multilevel stimuli-responsive platform with tunable emission color is established and further exploited for optical information encryption. This work would shed light on the rational design of multi-stimuli responsive RTP systems based on single-component organics.
基金supported by the National Natural Science Foundation of China(22325303,21973079,22032004)the National Key R&D Program of China(2017YFA0204902)+2 种基金the Fundamental Research Funds for the Central Universities in China(Xiamen University,20720190002)IRTSTFJ,National Science Foundation of Fujian Province(2018J06004)Beijing National Laboratory for Molecular Sciences(BNLMS202005).
文摘Charge transport characterization of single-molecule junctions is essential for the fundamental research of single-molecule physical chemistry and the development towards single-molecule electronic devices and circuits. Among the single-molecule conductance characterization techniques,the single-molecule break junction technique is widely used in tens of worldwide research laboratories which can generate a large amount of experimental data from thousands of individual measurement cycles. However,data interpretation is a challenging task for researchers with different research backgrounds,and the different data analysis approaches sometimes lead to the misunderstanding of the measurement data and even reproducibility issues of the measurement. It is thus a necessity to develop a user-friendly all-in-one data analysis tool that automatizes the basic data analysis in a standard and widely accepted way. In this work,we present the XMe Code (Xiamen Molecular Electronics Code),an intelligent all-in-one data analysis tool for the comprehensive analysis of single-molecule break junction data. XMe code provides end-to-end data analysis that takes in the original experimental data and returns electronic characteristics and even charge transport mechanisms. We believe that XMe Code will promote the transparency of the data analysis in single-molecule electronics and the collaborations among scientists with different research backgrounds.
基金the National Natural Science Foundation of China(Nos.22250003 and 22205084)National Key R&D Program of China(No.2017YFA0204902).
文摘Folding of molecules is an essential process in nature,and various molecular machines achieve their chemical and mechanical function via controlled folding of molecular conformations.The electric field offers a unique strategy to drive the folding of molecular conformation and to control charge transport through single molecules but remains unexplored.The single-molecule break junction technique provides access to detect the conformational changes via the monitoring of single-molecule conductance,and the electric field between two metal electrodes with nanoscale spacing can provide an extremely strong to achieve in-situ control and detection of molecular folding at the single-molecule level.Here,we use the electric field to control the single-molecule folding using the scanning tunneling microscope break junction(STM-BJ)technique.The electric fields induced folding could lead to a∼1400%conductance change of the single-molecule junctions,and the folding/unfolding process can be in-situ switched at the scale of milliseconds.DFT calculations suggest the conformational control originates from the electric fieldinduced charge injection,and the formation of homoconjugated conformation with the overlapped orbitals.This work provides the first demonstration of electric field-driven molecular folding,which is essential for the understanding of molecular machines in nature and for the design of artificial molecular machines.