Synthesis, Structures, And Properties Of Amine Substituted-Benzothiazole Compounds

Organic electroluminescent devices (OLEDs) have attracted a worldwide interest due to their high emission efficiency, low operating voltage and flexibility properies that can be employed to fabricate new generation panel displays. The exploitation of OLEDs materials and optimization of device structure have had great progress during recent two decades. Many new materials with red (R), green (G) or blue (B) emission color have been developed for full color OLEDs. Generally, to achieve a full color display, the R, G and B emission materials, which possessed strictly different molecular structures, have to be used. Therefore, the full color OLEDs were established based on the complexes and high cost organic syntheses. To achieve a full color electroluminescent material system through simple molecular modification is an important issue for OLEDs display. Recently, molecules with characteristics of excited-state intramolecular proton-transfer (ESIPT) have attracted wide attentions, especially the ESIPT emission materials in solid state due to their high quantum yields and promising applications. The amino substituted 2-(2'-hydroxyphenyl) benzothiazole (BTZ) compounds with remarkable ESIPT characteristics showed obvious contrary emission shifts (4-substituted and 5-substituted compounds showed orange red and blue-green fluorescence, respectively) and great deal efforts have been invested in the ESIPT compounds. Therefore, we have designed and synthesized 6 new amine substituted hydroxyphenyl benzothiazole compounds by modifing the 4- and 5-position of BTZ (namely m-OH and p-OH respectively). What's more, we have synthesized a series of zinc and beryllium complexes with p-OH as ligands. On the other hand, we have characterized their structures, properities and structure-property relationship, respectively. 1. In chapter II. We modified 4- and 5- position of BTZ with three simple subsitituted aminoes including dimethylamino, diphenylamino and carbazole groups, respectively, in which the benzothiazole moiety as an electron accepter and the substituted amino group as an electron donor. By X-ray diffraction method, we found their crystal structures all show enol-tautomer which should be a necessary condition for ESIPT.2. In chapter III. We invested photophysical properties of amine substituted hydrophenyl benzothiazole compounds in solvents and solid states and they both showed obvious long-wavelength emission which due to ESIPT. By theorical calculation, we understound that the luminescent effects of ESIPT. Their thermal properties mainly resulted from the molecular weights and structural conjugation and plannarity. In the end, we, consider their full color photoluminescence, designed a series of simple organic electroluminescent devices to study their electroluminescent properties, which also showed full color emitting.3. In chapter IV. Metallic complexes based on hydroxyphenyl benzothiazole are also an important organic emtting and electron transporting materials. Therefore, we synthesized 6 new zinc and beryllium complexes with p-OH as ligands, and characterized one crystal structure of beryllium complex. Moreover, we investigated their thermal, photoluminescent and electrochemical properties systematically. These metallic complexes all showed obviously broard and red-shifted emission peaks compared with their ligands, high thermal stability and good reversibility of electrochemical reduction, all of which were the very important factors for OLEDs.In conclusion, we have designed and synthesized amine substituted hydroxyphenyl benzothiazole compounds and some zinc and beryllium complexes. The fromer compounds show obvious ESIPT emission and relevant properties, and what most important thing is that they have full color solid PL and EL in OLEDs. As to the later complexes, they own better thermal stability and reduction reversibility, showing potential value for application in futher.