Synthesis And Properties Of New D-?-A Conjugated Small Molecules And Polymers Containing Carbazole Structure

The application of optoelectronic materials in life is becoming more and more extensive,showing great development prospects.Based on the literature and the preliminary work of our group,a series of D-?-A conjugated small molecules and conjugated polymers were designed and prepared,and their structures and properties were analyzed and characterized.The main work of this paper was as follows:Nucleophilic substitution reaction was carried out between carbazole and4-trifluoromethylcarbazole,and the N-(4-trifluoromethylphenyl)carbazole(M1)was obtained.Through Sonogashira coupling reaction,3-ethynyl-N-(4-trifluoromethylphenyl)carbazole(M2),6-diethynyl-N-[4-trifluoromethylphenyl]carbazole(M3),3-[4-(1,2,2-triphenylvinyl)phenylethynyl]-N-(4-trifluoromethylp--henyl)carbazole(M4)and 3,6-bis[4-(1,2,2-triphenylvinyl)phenylethynyl-N-(4-trifluoromethyl)Phenyl)carbazole(M5)was synthesized.The results showed that the UV-vis absorption wavelength and fluorescence emission wavelength of M4,M5 had a red shift phenomenon solid fluorescence intensity was significantly enhanced.M4,M5 exhibited aggregation-induced luminescence(AIE)effect.P1a-P1d was synthesized by Sonogashira coupling reaction of 3,6-diethynyl-N-(4-trifluoromethylphenyl)carbazole(M3),1,4-dibromobenzene,(E)-1,2-diphenyl-1,2-bis(4-bromophenyl)ethylene(8b),3,6-dibromo-9-bis(n-octyl)fluorene(8c)and4-(4-methoxyphenyl)-2,6-bis(4-bromophenyl)pyridine(8d).The results showed that the UV-vis absorption wavelength of P1a-P1d exhibits a red shift compared with M3.Compared with P1a,the fluorescence emission wavelengths of P1b and P1c exhibited a red-shift phenomenon,while P1d exhibits a blue-shift phenomenon.P1a also had showed a solvation effect.P1a-P1d were easily soluble in Py,DMF,THF at room temperature.At the same time,these prepared polymers had amorphous structure and high heat resistance with the decomposition temperature of 5%thermal weight loss as high as 380.5 ? in nitrogen atmosphere.Similarly,Sonogashira coupling reaction was carried out between3,6-diethynyl-N-(4-cyano)carbazole(11)and above-mentioned acceptor unit to produce four different D-?-A type conjugates P2a-P2d.The results showed that the UV-vis absorption wavelength of P2a-P2d had a red shift phenomenon compared with 11.In addition,the fluorescence emission wavelength of the acetone solution of P2b showed a significant blue shift.They had amorphous structure and were easily soluble in Py,DMF,THF at room temperature.In a nitrogen atmosphere,the decomposition temperature of 5%thermal weight loss can reach up to 337.5 ?,it showed that P2a-P2d had good thermal stability.