Synthesis,Characterization And Electrochemical Properties Of Molecular Wires Bridged By Oligofurans

In recent years,the research about molecular electronics which intrinsically study on the molecular level of electronic devices,has become the hot topics in the field of chemistry mixed with materials.As the most fundamental circuit element,it plays a role in transmitting information and wiring,so further development of molecular wires has profound significance.Organometallic compounds bearing conjugated organic bridging ligands between redox active metal complexes were studied extensively not only due to their superior electronic properties but also can be used to simulate electron transport properties.There are many factors that affect the molecular wires on the electron transport properties,such as the structures of bridging ligands,solvent effects and so on.The systematic research on the factors affecting the performance of molecular wires plays an important role in reference value for designing and selecting predominant molecular conductors.Since furan has the advantage of cheap and readily available,high reactivity,readily biodegradable,good solubility and good planarity,etc.The author systematically inspects the influence on the electronic transmission performance of ruthenium metal complexes molecular wire which the furan ring unit number with furanyl as the bridging ligand and how bimetallic ruthenium complexes play a role by bridging.The specific research contents are as follows:1.In order to study the effect of furan ring's numbers on single ruthenium compounds,we synthesized four to furyl bridged single metal ruthenium compounds(1-a,2-a,3-a and 4-a).(1).These compounds were characterized by NMR,1-a is confirmed by X-ray crystal diffraction.(2).All of the compounds are studied by conventional electrochemical techniques,UV-Vis and situ UV-Vis-NIR spectroscopy technique.Research shows that,with the increasing of the furan ring of the number,the oxidation potentials are more negative and their oxidation potential difference can reach to 240 mV.At the same time,the redox process of the metal center is reversible to quasi reversible,and the stability of the molecular wire after oxidation is reduced.2.In order to study the effect of the number of furan ring on the interaction between the bimetal ruthenium compounds,we synthesized five with furanyl based bimetallic bridged ruthenium compounds(1-b,2-b,3-b,4-b,5-b).(1).These compounds were characterized by NMR,1-b is confirmed by X-ray crystal diffraction.(2).All of the compounds are studied by conventional electrochemical techniques,UV-Vis,NIR and situ UV-Vis-NIR spectroscopy technique.Research shows that show complex 1-b?4-b have undergone successive two-step lose electronic process with the number of the furan ring units increasing and gradually increasing the distance of the two metal centers,leading to weakening of the interaction between the two metals.(3).The study of NIR and situ UV-Vis-NIR spectroscopy technique indicate that mixed-valence compounds are formed after the molecular wires are oxided,the charge state delocalized over the entire molecule.When the number of furan ring reaches to a certain degree,part of the charge localized on the bridging ligand.