Design Of New Molecular Wires And First Principle Studies On Their Charge Transport Properties

This thesis aims at designing novel molecular devices and understanding the electron transport and magnetic properties of the molecular devices. New types of molecular devices containing multiple metal core or conformation tunable structural unites were designed and their electronic and magnetic properties were studied by first-principle studies. The applications of the new devices in molecular rectifier, molecular switch and gas sensor were discussed.The main findings of the work are:1. New type of molecular wires based on metal complex has been designed for the first time. The electron transport properties of complex molecular wires can be tuned by the metal atoms. The complex molecular wires containing two different metal atoms exhibit rectification properties, and show reversible rectification effect in some bias range.2. Amine and nitryl substituted azobenzenes were designed as new molecular switches. These molecules have two stable conformations, which give different conductance. The two stable conductance states can be applied in designing new molecular switches..3. The electron transport properties of bipyridyl-dinitro dithiol (BPDN) have been studied. The experimental observation that BPDN has two stable conductance states is interpreted by it conformation change.4. The complex of a graphene like porphyrin sheet has been designed for the first time, and the electronic and magnetic properties of the sheets containing different magnetic metal ions were studied. The application for detecting NO gas based on the change of magnetic properties has been discussed.