Study On Synthesis And Properties Of T-Shaped Organic Conjugates Based On Monopyridazinotetrathiafulvalene

Tetrathiafulvalene (TTF) and its derivatives have been used in many research fields such as supramolecular science, materials science and nanotechnology result from their great advantages in electron donating properties and reversible redox properties. However, because of the strong electron donating properties, TTF and its derivatives are sensitive to moisture and oxygen, which led to the degradation of the materials when they are used as semiconductor materials. As a result, conjugated structure and strong electron-withdrawing groups are usually introduced to the skeleton of TTF and to improve the stability of the semiconductor materials.In this paper, pyridazine group with electron-donating properties was fused to TTF, based on which a series of T-shaped pyridazine-tetrathiafulvalene derivatives were synthesized at the first time and their photophysical and electrochemical properties and charge mobility were also studied. The following are the main aspects of this work in this paper:1. A series of precursors of T-shaped organic conjugates-3,6-disubstituted pyridazine-fused tetrathiafulvalene (TMA1-TMA7), their photophysical and electrochemical properties were studied through UV-Vis spectroscopy and cyclic voltammetry. Their HOMO and LUMO energy levels were worked out to be respectively in the range from-4.88eV to-5.07eV and-2.23eV to-2.61eV, and the energy gap in the range from2.43eV to2.79eV from the electrochemical data and UV-Vis data, which suggest that this series of compounds may be used as hole of organic semiconductor materials. Density functional theory calculations have proved the existence of intramolecular charge transfer between the pyridazine part and TTF unit in the ground state. Single crystals of TMA1, TMA5, TMA6and TMA7were prepared by solvent diffusion, and by whose X-Ray data the structure were analyzed.2. In order to enhance π-π accumulation and self-assembling properties to obtain semiconductor materials with high charge mobility,3-and6-of pyridazine ring in pyridazine-fused tetrathiafulvalene introduced phenyl, biphenyl or N-phenyl carbazole to prepare T-type conjugated system (TMB1-TMB8). The system can enhance the intermolecular interactions, leading to the formation of better packing of molecules. Through studies of cyclic voltammetry and UV-Vis spectra, their HOMO and LUMO energy levels were calculated out to be respectively in the range from-4.85eV to-5.09eV and-3.17eV to-3.2eV, and the energy gap to be2.51eV～2.55 eV. Introduction of phenyl group, biphenyl and N-phenyl carbazole effectively can effectively reduce the HOMO energy levels, which are suitable the requirements of p-type and n-type semiconductor. The field effect transistor test showed that these compounds have hole transport properties, among which the thin-film field-effect transistor monility of the lamellar liquid crystal compound TMB4with longer alkyl chain (R=n-C18H37) was4.5x10-5·cm2/V·s. Single crystal of TMB4was prepared by solvent diffusion, and by whose X-Ray data the structure was analyzed.3. In order to reduce the HOMO and LUMO energy levels to obtain organic semiconductor with high electron mobility, F atoms and dicyanovinyl with electron-withdrawing properties were introduced to combine with the two benzene rings in TMB1to synthesis anonther T-type organic conjugated system (TMC1-TMC13). The studies showed that the compounds showed excellent thermal stability, their HOMO and LUMO energy levels were estimated to be obout-5.15eV and-3.60eV, which are suitable the requirements for the p-channel and n-channel field effect transistors. The measurement of thin-film field effect tansistor indicated that the conjugated molecule TMC1-TMC8with dicycanovinyl diaplayed high electeon mobility, among which the mobility of TMC1was up to1.3cm2/V·s.