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

Abstract

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-naphthalenetricarboxylic acid-1,8-lactam-4,5-imides, was studied using both time-dependent density functional theory and semi-empirical approaches. It was found that the S0–S1 transition in lactamimides involves presumably HOMO–LUMO electron 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 S0–S1 transition. As a result, donor and acceptor side groups dramatically 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 electronic and steric factors. Three novel derivatives of lactamimides bearing donor and acceptor side groups were synthesized and characterized. Their UV–visible spectra confirmed the results of calculation. Copyright © 2000 John Wiley & Sons, Ltd.