Intramolecular excited charge-transfer states in donor–acceptor derivatives of naphthalene and azanaphthalenes

Abstract

Electronic structure and molecular conformation of selected donor–acceptor isomeric derivatives of naphthalene, quinoline and quinazoline as well as a family of isomeric triazanaphthalenes containing N,N-dimethylaniline as an electron donor in the excited charge transfer singlet (¹CT) states have been investigated. The mechanism of the ¹CT←S₀ absorption and ¹CT → S₀ emission is discussed in terms of the Mulliken–Murrell model of the CT complexes and the Marcus formalism of radiative charge transfer. The determination of the electronic transition dipole moments corresponding to the CT absorption and fluorescence and the band-shape analysis of the corresponding spectra lead to the quantities relevant for the ¹CT → S₀ charge recombination in the Marcus inverted region. It is shown that some of the photophysical properties of the compounds can be predicted in terms of a simple LCAO MO description from the properties of individual chromophores.