Preparation Of Novel Aggregate Induced Luminescence Materials And Their Applications In Molecular Electronics

Organic semiconductor materials have become one of the research hotspots of advanced functional materials in this century because of their advantages in film forming and device size.However,most traditional organic luminous materials emit light efficiently in dilute solution,but when they are prepared as solid films or nanoparticles,the effect of aggregation-caused quenching(ACQ)occurs when they are prepared.However,there are still some unsolved basic scientific problems and challenges in the research of AIE,such as the theoretical system of AIE to be further studied and the development of new materials to be broken through.From the perspective of single molecule,this paper systematically studies the application of AIE material system in the field of molecular electronics,in order to explore the luminescence mechanism of aggregation-induced luminescence materials by using single molecule conductance measurement technology,and guide the development of new materials with high efficiency aggregation-induced luminescence.The main research contents are as follows:(1).The construction of traditional single-molecule devices requires the introduction of anchoring groups at both ends of the molecule,such as sulfhydryl group,mercaptomethyl group,amino group,etc.Different anchoring groups will affect the electrical transport capacity of the molecular junction.Previous studies have found that the spatial conjugation of hexaphenylbenzene can not only improve molecular conductance,but also increase the stability of molecular devices.Therefore,based on the hexaphenylbenzene system,we designed and synthesized two new single-molecule wires.The propeller structure formed by the middle benzene ring of hexaphenylbenzene and the surrounding six benzene rings is used to form a strong interaction with the gold motor.This effect can be used as the anchor group of molecular wires for the construction of monomolecular device systems.This study of electric transport using spatial conjugation properties provides a new idea for the construction of novel metal/molecule/metal junctions.(2).Keto-salicylaldehyde hydrazine is a novel AIE fluorescent probe motif based on intramolecular proton transfer effect.We designed and synthesized a series of salicylic aldehyde derivatives based on keto-salicylic aldehyde hydrazine,and regulated the electric transport properties of the molecules by introducing methoxy and hydroxyl groups,so as to verify the luminescence mechanism of AIE materials.It was found that because the hydroxyl group in the molecule and the lone pair electron on N formed an intermolecular hydrogen bond,forming a stable ring structure,the molecular devices constructed with hydroxyl molecules have higher conductance than other molecules.The influence of the introduction of methoxy group and hydroxyl group on intramolecular electrical transport is further studied by theoretical calculation.The introduction of methoxy group leads to destructive quantum interference,and the introduction of hydroxyl group leads to creative quantum interference.These results are consistent with the results of conductance measurement.(3).Based on the typical AIE tetraphenylvinyl,we designed and synthesized molecular wires of different electrical transmission types by introducing different number of anchoring groups and thiophene aromatic rings.It was found that multiple anchoring groups in TPE-(SMe)4 inhibited molecular rotation by interaction with gold electrodes,and multiple electrical transmission paths were formed at the same time.So the conductivity is significantly higher than other molecular wires.In addition,the introduction of 2-5-dimethylthiophene significantly reduced the molecular conductance of tetraphenylvinyl system.Theoretical studies found that the introduction of 2-5-dimethylthiophene led to destructive quantum interference,so the molecular conductance appeared low phenomenon.