Factors controlling the deactivation induced by hydrogen-bonding interaction: Steric and electronic effects on dual anisotropic relaxation processes

Abstract

The factors controlling deactivation from the intramolecular charge transfer excited states of aminoanthraquinones and aminofluorenones induced through intermolecular hydrogen-bonding interactions with alcohols such as p-substituted benzyl alcohols and bulky alcohols were investigated by steady-state and time-resolved fluorescence spectroscopy. The ratios of the Stern–Volmer constants for the fluorescence quenching by the alcohols to the contact molecular surface area of the hydroxy hydrogen were correlated well with the charge density of the hydroxy hydrogen of the alcohols. The rate constant of the forward process which forms a relaxed hydrogen-bonded complex in the excited state was revealed to depend on the contact molecular surface area of the hydroxy hydrogen, whereas the reverse process was mainly controlled by electronic effects which stabilize the relaxed hydrogen-bonded complex.