In Situ Monitoring Of Electrochemistry Controlled Reactions At The Single Molecular Scale

The core of molecular electronics research is to study the charge transport mechanism of single molecule devices at the single molecule scale,as to achieve the construction of single molecule devices with various functions.With the development of single molecule manipulation techniques,molecular electronics has also provided an ideal research platform for exploring physical phenomena and chemical changes at the single molecule scale.Currently,in addition to studying charge transport mechanism,molecular electronics has made significant progress in the fields of biosensing,molecular recognition and chemical reactions,which opens up the application prospects of molecular electronics.In this paper,the experimental equipment of Electrochemical Scanning Tunneling Microscope Break Junction(ECSTM-BJ)with electrochemical regulated function was built on the basis of Scanning Tunneling Microscope Break Junction(STM-BJ),which was used to study the in-situ monitoring of electrochemistry-controlled reactions in single molecular junction.We’ve designed and synthesized organic molecule OPE-2OH with electrochemical activity.And electrochemical controlled chemical reactions of OPE-2OH molecular junctions were studied by ECSTM-BJ.What’ more,ECSTM-BJ was used to monitor in situ multi-step organic chemical reactions between OPE-2OH and L-cysteine.The specific work contents are as follows:1.ECSTM-BJ with electrochemical functions has been successfully built on the basis of STM-BJ.The experimental method for electrochemical gating and single molecule junction conduction testing has been improved.In addition,we have successfully improved the four electrode preparation processes of ECSTM-BJ,laying the foundation for subsequent research on electrochemical gating testing of single molecule junctions.2.The chemical reactions of the conjugated molecule OPE-2OH with hydroquinone as the core skeleton under electrochemical regulation were studied using ECSTM-BJ technique.The results of the single molecule junction conduction testing indicates that the oxidation reaction of the electrochemically active OPE-2OH molecule occurs under the electrochemical gating.The change of the molecular structure changes the quantum interference effect of the molecular junction,so that the process of oxidation reaction is presented through the change of the molecular junction conduction,which provides a new idea for the study of chemical reactions.3.ECSTM-BJ technique was used to monitor the multi-step organic chemical reaction of OPE-2OH and L-cysteine.This reaction consists of two processes: an electrochemical regulated oxidation reaction and a heterocyclic reaction between the quinone product formed in the first step and L-cysteine.The feasibility of using STMBJ technique to monitor the multi-step organic chemical reaction was verified by calculating the change of molecular junction transmittance.This work lays the foundation for further improvement of ECSTM-BJ equipment and further research on chemical reactions on single molecule junctions.