ELECTRONIC-STRUCTURES AND SPECTRA OF AMINOACETOPHENONES AND RELATED COMPOUNDS

The Sn←S0 and Sn←Sx transition bands were measured with m- and p dimethylaminoacetophenones and related compounds in order to clarify the characters of the excited singlet states. The observed spectra were reasonably interpreted by the use of the theoretical results based on the composite molecule method. The longest wavelength band (S1←S0) of the meta isomer has mainly the local excitation (LE) character of aniline (1B2← 1A1), while that of the para isomer is ragarded as the intramolecular charge-transfer band. In the para isomer the LE transition corresponding to 1B2←1A1 is covered by the intense CT band. The Sn←Si transitions of the meta isomer are almost of LE character, whereas those of the para isomer are of back GT nature. This is mainly attributed to the difference in the character of.