Design,Synthesis And Application Of Two Near-infrared Organic Fluorescent Small Molecule Based On S-containing Heterocycles

In recent years,potential applications of fluorescent materials with red light emission in flat panel displays,fluorescence sensors,photovoltaic cells,fluorescent probes,and bioimaging have attracted increasing attention by researchers.Such as the field of flat panel displays,it is one of the three primary colors of electroluminescence;in the field of bioimaging,it possesses superior advantages that other materials such as long wavelength excitation,strong light penetration ability,and large Stokes displacement are incomparable,to reach the purpose of deep bioimaging research at the low biological toxicity.However,the widths of forbidden of red and near-infrared materials are relatively narrow,and the non-radiative transition rate is significantly faster than that of green and blue light materials.Therefore,the fluorescence efficiency of red light materials is generally low,and in the aggregation state,the intermolecular strong dipoles effect will further destroy its fluorescence efficiency,which is very unfavorable for electroluminescence.Therefore,it is of great practical significance to develop new and highly efficient red luminescent materials.In this paper,we selected two kinds of sulfur-containing heterocyclic compounds,enzothiadiazole and cyano-substituted butenethiophene as acceptor units.Two kinds of D-A-D red organic fluorescent materials were designed and synthesized,their electroluminescent properties were systematically studied and biological application were preliminarily explored.In order to develop these two types of organic near-infrared fluorescent molecules with high efficiency,the following work has been done:1.The acceptor cyano-substituted vinylthiophene was connected with the modified phenothiazine derivative donor unit to obtain the target product TBPPTZ.The powder has an emission peak at 660 nm and a fluorescence efficiency of 29%.The energy level structure was studied by theoretical calculation and cyclic voltammogram,which showed a narrow band gap,different solutions of UV-Vis absorption and fluorescence spectra were used to study the aggregation behavior,indicating that the product have obvious charge-transfer and aggregation-induced luminescence properties,doped and nondoped OLEDspreparedby TBPPTZ light-emitting layer have excellent performance of higher maximum external quantum efficiency and lower device roll-off2.The introduction of thiophene groups on the bandgap adjustment of the red light material TPATCN realizes the regulation of the luminescent behavior of the material,We successfully obtained a near-red material TPATHCNE.The emission peak of the solid powder was red shifted from the 670 nm to the near-infrared region of 736 nm.Through the study of its photophysical,thermal,and electrical properties,heteroatom sulfur was discovered,The introduction of the element can effectively reduce the band gap,but it also can quenches the fluorescence to reduce the solid state luminous efficiency.The maximum brightness of the device is 210 cd m^-2,and the maximum external quantum efficiency is0.199%,but undoped OLED performs well in its corresponding spectral range.3.Nanoparticles made of TPATHCNE and bovine serum albumin were used to culture yeast cells,and the nanoparticles were initially judged to be phagocytosed by cells.DLS distribution and Zefa potential data were used to characterize the particles have good granulation and biological stability,these indicates that the Near-Infrared material has potential application value of biological imaging.