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

A

1g

?

B

2u

and

A

1g

?

B

3n

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.