Synthesis And Properties Of The Novel Schiff Bases Containing Carbazolyl Group

Schiff base is a class of organic compounds which contain characteristic imine or azomethine group (-C=N-). The Schiff base aroused the interest of scholars both home and abroad, because of its various coordination forms, strong coordination ability, good biological activities and optical properties. Some of them have been widely applied in medicine, catalysis and photoelectric materials. In this paper, fifteen novel carbazol-containing Schiff bases were synthesized, and also characterized by 1H NMR, MS, IR, and elemental analyses. The works mainly include:(1) The chiral amino alcohols and 3-formacyl-N-ethyl carbazole as the key intermediates were synthesized with the carbazole and natural amino-acid as the materials, and the synthesis conditions of 3-formacyl-N-ethyl carbazole were optimizated. The results show that the best yield of sing-formylation was obtained, when the volume ratio of N-ethyl carbazole, POCl3 and DMF is 1:10:10.Six novel chiral amino alcohol Schiff bases were synthesized by the solvent-free reaction for the first time. The influence of the different organic solvent system (THF, EtOH, AcH, EtOH-AcH) and solvent-free system on the yields of the target chiral amino alcohol Schiff bases was studied in detail. The experimental results show that the synthesis conditions of the target chiral amino alcohol Schiff bases are mild in the organic solvent system, but the products are purified very difficultly. Compared with the previous method, the solvent-free method possess such advantages as short reaction time, without adding catalyst, high yield and only simple recrystallization purification in mixed solvent. The yield of the target chiral amino alcohol Schiff base was up to 87%, when the reaction temperature was at 95℃and the reaction time was 40 min.The effect of the structure of the chiral amino alcohol on the spectral propertie of the target chiral amino alcohol Schiff bases was studied. The results indicat that the structure of the chiral amino alcohol have significant influence on their fluorescence, and the Schiff base L1 has the best fluorescence intensity. Because L-phenylglycinol possesses the aromatic rings, the conjugation effect of the molecular structure of the Schiff base L1 are improved, and its energy transfer efficiency is enhanced, its fluorescence intensity is increased.(2) Nine novel carbazol-containing diacylhydrazone Schiff bases were synthesized with the carbazole, 2-naphthol, methyl salicylate, p-nitrobenzoic acid, and ethyl benzoate as the raw materials. And explored were the synthesis conditions of Friedel-Crafts acylation of N-alkyl carbazole and carbazol-containing diacylhydrazone Schiff bases. The experimental results show that the best yield of di-acetylation is obtained when the volume ratio of 9-alkyl carbazole, acetyl chloride, and catalyst is 1:5:4; the best yields of the target diacylhydrazone Schiff base is obtained when the volume ratio of ethanol and glacial acetic acid is 10:2. The spectral propertie of the target diacylhydrazone Schiff bases was studied, and the results indicat that Schiff base L7 and L8 have the best fluorescence intensity.