The Preparation And Characterization Of Organic Photo-functional Materials Based-on Pyridal[2,1,3] Thiadiazole And Its Derivatives

With2,1,3-benzothiadiazole as analogue, pyridal[2,1,3]thiadiazole, a more electron-deficient receptor fragments of polymer, and its derivatives was designed and synthesized. Using4-hydroxy pyridine as its initial raw materials, the target compound was synthesized via6steps, and each process of the reactions and the synthesis conditions and methods were optimized and selected to improve the yield of the reaction. The intermadiate of each reaction was characterized by1N MR,13C NMR, FR-IR to make sure they are right, finally, with12.2%of the total yield of target product and its derivatives was got.With successful synthesis of the donors and acceptors, a series of repeat D-A type conjugated polymers were synthesized with the classic blue fluorescent material monomer fluorene, carbazole and phenothiazine as donor segment and with5,8-dibromo-2,3-dimethylpyrido[3,4-b]pyrazine as the acceptor unit through suzuki cross-coupling reactions. The properties of all the polymers were characterized by NMR spectroscopy and GPC. Besides their thermal, optical, and electrochemical properties, acid effects to their optical properties were explored and made a systematically research of the properties of the polymers.We can draw the following conclusion by measuring the optical properties of polymer:UV-vis absorption spectrum of polymer based on phenothiazine red-shift obviously, of which spectrum carbazole and fluorene are similar; polymer based on fluorene has the largest fluorescence quantum efficiency and reach28%from the fluorescence spectrum. In addition, after adding lewis acid or Bronston acid to chloroform solution of the polymers, great effects on the photochemical properties of polymer could be observed, UV-vis spectrum red-shift obviously and fluorescence spectrum has significant quenching phenomenon, accompanied by fluorescence color changing.Through the introduction of acceptor units in the polymer, the solvent has little affect on ultraviolet and fluorescence spectrum of polymers. As polarity of the solvent increasing, the ultraviolet and fluorescence emission wavelength changes a little, we cannot draw the conclusion that electron-withdraw fragment in the polymer chains can significantly increase the charge transfer, we denote the reason for low molecular weight of the polymer.By cyclic voltammograms, HOMO energy levels and band gap of the three polymer were obtained. Introducing acceptor fragment, band gap of polymers decreased significantly, which indirectly denote that the ability of electron transfer enhance. If adjusting receptor and donor segments in the polymer to the appropriate proportion, the polymers can be used as light-emitting material of holes and electrons transfer.