Novel substituted 1-amino-4,5,8-naphthalenetricarboxylic acid-1,8-lactam-4,5-imides: Experimental and theoretical study

The electronic structure of the ground and the first singlet excited state of a novel class of fluorescent dyes, substituted 1-amino-4,5,8-naphthalene tricarboxylic acid-1,8-lactam-4,5-imides, was studied using both time-depen dent density functional theory and semi-empirical approaches. It was found that the So-Si transition in lactamimides involves presumably HOMO-LUMO ele ctron promotion. Strong intramolecular charge transfer from lactam nitrogen , C-2 and C-4 atoms to C-6 and C-7 atoms of the naphthalene ring occurs on S-0-S-1 transition. As a result, donor and acceptor side groups dramaticall y affect the long-wave absorption maximum, allowing control of its position over a range of more than 100 nm. Positions 2 and 7 are most sensitive to the electronic effects of the side groups owing to the combination of elect ronic and steric factors. Three novel derivatives of lactamimides bearing d onor and acceptor side groups were synthesized and characterized. Their UV- visible spectra confirmed the results of calculation. Copyright (C) 2000 Jo hn Wiley & Sons, Ltd.