Synthesis And Spectral Characteristics Of Novel A-D-A Compounds

Two-photon absorption materials have been receiving considerable interests due to their applications in 3D data storage,laser up-converted,optical limiting and photodynamic therapy.Ten new A-D-A compounds were designed and synthesized.The reaction mechanisms and a part of the reaction conditions were explored,the linear absorption and one-photon fluorescence properties were studied,the relationship between the molecular structures and spectral properties were discussed.Three new A-D-A type arylalkenyl aldehydes,2,5-dimethoxy-4-[(1E-2-(1H-benzimidazol-2-yl)ethenyl]benzaldehyde(7),2,5-dimethoxy-4-[(E)-2-(1H-benzoxazole-2-yl)ethenyl]benzaldehyde(8)and 2,5-dimethoxy-4-[(1 E)-2-(1 H-benzothiazole-2-yl)ethenyl]benzaldehyde(9),were synthesized by condension reaction of 2-methylbenzimidazole,2-methylbenzoxazole and 2-methylbenzothiazole with 2,5-dimethoxy-1,4-benzenedicarboxaldehyde.The yields were 75.2%,40.7%and 65.8%,respectively.The structures were conformed by IR and 1H NMR.Senven new A-D-A type s-triazine derivatives,2,4-dimethyl-6-{2,5-dimethoxy-4-[(1 E)-2-(1 H-benzimidazol-2-yl)ethenyl]styryl}-1,3,5-s-triazine(M1),2-methyl-4,6-{2,5-dimethoxy-4-[(1 E)-2-(1 H-benzimidazol-2-yl)ethenyl]styryl}-1,3,5-s-t:riazine(M2),2,4,6-tris {2,5-dimethoxy-4-[(1 E)-2-(1 H-benzimidazol-2-yl)ethenyl]styryl}-1,3,5-s-triazine(M3),2,4-dimethyl-6-{2,5-dimethoxy-4-[(1 E)-2-(1 H-benzoxazole-2-yl)ethenyl]styr yl}-1,3,5-s-triazine(El),2-methyl-4,6-{2,5-dimethoxy-4-[(1 E)-2-(1 H-benz oxazole-2-yl)ethenyl]styryl}-1,3,5-s-triazine(E2),2,4-dimethyl-6-{2,5-dim ethoxy-4-[(1 E)-2-(1 H-benzothiazole-2-yl)ethenyl]styryl}-1,3,5-s-triazine(S1),2-methyl-4,6-{2,5-dimethoxy-4-[(1 E)-2-(1 H-benzothiazole-2-yl)ethenyl]styryl}-1,3,5-s-triazine(S2),were synthesized by the condension reaction of 7,8 and 9 with trimethyl-s-triazine.The yields were 54.4%,45.5%,18.9%,43.4%,17.0%,32.5%and 34.8%,respectively.The structures were conformed by IR and 1H NMR.Ethyl acetimidate was synthesized from CH3CN,C2H5OH,and HCl.Then the trimethyl-s-trizaine was obtained after the trinerization of ethyl acetimidate using acetic acid as catalyst.The yield was 28.5%.Its structure was conformed by IR,1H NMR and MS.2-Methylbenzimidazole was synthesized from o-benzenediamine and glacial acetic acid.2-Methylbenzoxazole was synthesized from 2-aminophenol and glacial acetic acid using p-toluenesulfonic acid as the catalyst.The yields were 78.0%and 84.1%,respectively.The structures were conformed by IR and ’H NMR.1,4-Bis(bromomethyl)-2,5-dimethoxybenzene was synthesized from 1,4-dimethoxybenzene and paraformaldehyde.1,4-Dimethoxy-2,5-benzenedicarbaldehyde was synthesized by Sommelet reaction of 1,4-bis(bromomethyl)-2,5-dimethoxybenzene with hexamethylenetetramine.The yield was 34.0%.Its structure was conformed by IR and 1H NMR.A part of the reaction conditions were explored.The optimum reaction conditions for 7 were as followes:the refluxing temperature,the mole ratio of 2-methylbenzimidazole to 2,5-dimethoxy-1,4-benzenedicarboxaldehyde was 1.1:1,the reaction time was 20h.The optimum reaction conditions for M1 were as followes:the refluxing temperature,the mole ratio of trimethyl-s-triazine to 2,5-dimethoxy-4-[(1 E)-2-(1 H-benzimidazol-2-y l)ethenyl]benzaldehyde was 1.5:1,the reaction time was 10h.The optimum reaction conditions for 6 were as followes:the refluxing temperature,the mass percentage of acetic acid was 90%,the reaction time was 10h.The optimum reaction temperature for ethyl acetimidate hydrochloride was 20-30℃.The optimum mole ratio of glacial acetic acid to ethyl acetimidate was 0.08:1 in the trinerization.The linear absorption and one-photon fluorescence properties were investigated.The structure-property relationships were explored.From the results,we got the following conclusions:for the new A-D-A type arylalkenyl aldehydes,with the increase of the acceptor strength,the wavelengths show red-shift,and the single fluorescence intensity strengthen.For the new A-D-A type s-triazine derivatives,with the increase of branch number,the wavelengths show red-shift,and the single fluorescence intensity strengthen.