不同分子对称性的对氨基四苯基卟啉的合成及其发光特性

合成了具有不同数目的对氨基苯基取代的卟吩衍生物,其中包括5-(对-氨苯基)-10,15,20-三苯基卟吩,5,10-二(对-氨苯基)-15,20-二苯基卟吩,5,15-二(对-氨苯基)-10,20-二苯基卟吩;5,10,15-三(对-氨苯基)-20-苯基卟吩和5,10,15,20-四(对-氨苯基)卟吩等,并对它们的电子吸收和发射光谱以及荧光寿命进行了测量,所得实验结果表明:由取代基引起的分子对称性的改变对它们的光谱和动态特性有一定的影响,分子对称性降低时,可使吸收振子强度增大和荧光衰变过程加速,这一效应对对称禁戒的A1g-B2u和A1g-B3u的电子跃迁的影响尤为显著,这一发现启发了人们,即使是和发色基相互作用不大的基团中的非对称取代也有可能使电子跃迁的对称性禁戒松弛。

SYNTHESIS OF p-AMINOPHENYLPORPHINES OF DI DIFFERENT SYMMETRY AND THEIR SPECTRAL CHARACTERISTICS

The porphines with different number of p-aminophenyl substituents including 5-(p-aminophenyl)-10,15,20-triphtnylporphine;5-10-di(p-aminophenyl) -15,20-diphenylporphine; 5,15-di(p-aminophenyl)-10,20-diphenylporphine; 5, 10,15-tri(p-aminophenyl)-20-phenylporphine and 5,10,15,20-tetra (p-ami-nophenyl)porphine have been synthesized.Their absorption,fluorescence spectra as well as fluorescence lifetimes have been measured. The results obtained reveal that substitution-induced change in molecular symmetry has a detectable effect on their spectral as well as temporal characteristics. The reduction of molecular symmetry leads to an increase in oscillator strength and an accelaration in fluorescence decay and this substitution effect manifests more clearly for the symmetry-forbidden A1g?B2u and A1g?B3n transitions. This finding implies that the asymmetrical substitution even in the groups which do not interact much with the chromcphore seems to be able to relax the symmetry restriction posed on the electronic transitions as well.