Investigation Of Charge Transport Through Hydrogen Bond And Chiral Recognition Via Single-Molecule Electrical Measurement Technique

Molecular electronics proposes the applications of a single or a few molecules as basic electrical components to assemble integrated circuits in a "bottom-up" manner.To realize the conductance measurement for single-molecule is a prerequisite for study in this field.After decades of development,single-molecule electrical characterization technique represented by Mechanically Controllable Break Junction(MCBJ)and Scanning Tunneling Microscope Break Junction(STM-BJ)provided a platform for the investigation of molecular electronics.Hydrogen bonds widely exist in nature,such as DNA,peptides and protein molecules in life science.Most studies have shown that biomacromolecules with non-conjugated structures are often non-conductive,while electrons can be transported through DNA chains of up to tens of nanometers to achieve specific biological functions,for example,repair and signal delivery of base pair.Although scientists from the area of biology,chemistry and physics have conducted in-depth studies on these issues,they still find that there are great obstacles to investigate long-range electrical transports in nature.The study of the charge transport through hydrogen bond at single-molecule scale can help answer these questions.Therefore,the charge transport through single and double hydrogen-bonded junction series have been studied at the single-molecule level.In addition,this thesis also uses STM-BJ technique to realize a series of chiral amino alcohols based on hycdrogen bond interaction,and developed a chiral recognition method based on single-molecule level.In conclusion,the research contents and results of this thesis are as follows:1.Based on the self-built STM-BJ single-molecule conductivity test platform,we have constructed a dimeric supramolecular junction using an amino group as an anchor group to form a double or single hydrogen bond bridge through a carboxyl group or a hydroxyl group,respectively.Using the statistical methods from data mining,I have realized the study of the electrical properties of series of hydrogen bond dimers.2.Using STM-BJ technique,we compare the conductance of the linear alkane supramolecules through the double hydrogen bond.It is found that the conductance of this double hydrogen bond series decay with the molecular lengths,and the tunneling decay constant is much lower than that of linear alkane,which means the double hydrogen bond dimer excellent electrical transport properties.3.Furthermore,we characterize the transport properties of single hydrogen bond dimers for the first time,and found that it has a more lower tunneling decay constant than that from double hydrogen bond series,which brings more excellent long-range charge transfer properties.Using DFT theoretical calculations,it is revealed that the introduction of hydrogen bonds will generate a new resonant tunneling orbital near the Fermi level,and it is presumed that the introduction of hydrogen bonds leads to a decrease in the tunneling decay constant.4.We employ chiral probe molecule with biphenyl naphthol as the main component and thioacetyl group as anchor group as molecular sensor.The specificity of the amino alcohol enantiomer based on hydrogen bond interaction was realized by STM-BJ technology.The chiral recognition method advances the chiral recognition technique into a single-molecule scale.