PHOTOPHYSICAL PROPERTIES OF TETRAHYDROISOQUINOLINE - EVIDENCE FOR FLIPPED INTRAMOLECULAR CHARGE-TRANSFER (FICT) EMISSION

Photophysical properties of tetrahydroisoquinoline (THIQ) have been st udied in various solvents. It has been found that in aprotic solvents a secondary amine THIQ shows a charge transfer emission band in additi on to the expected locally excited xylene type emission band, though t here is no corresponding charge transfer band in the absorption spectr um. It is ascribed to a charge transfer process in the excited state a fter flipping the N-atom across the average molecular plane. The ratio of FICT emission to locally excited xylene type emission is sensitive to the pH of the solution. This is due to the blocking of the lone pa ir of the nitrogen atom of THIQ by H+. (C) 1997 Elsevier Science B.V.