Time-resolved spectroscopy of 2-naphthol-triethylamine charge-transfer complexes in polar and non-polar solvents

Abstract

Hydrogen-bonded complexes of 2-naphthol-triethylamine have been studied in different polar and non-polar solvents. The ground-state equilibrium constants and the excited-state Stern-Volmer quenching rates have been calculated and both have been found to be greater in non-polar solvents. Decay-associated spectra and excitation spectra have shown that in non-polar solvents the exciplex is totally non-emitting while the ground-state hydrogen-bonded complex gives rise to a solvent-stabilised red-shifted ion-pair spectrum. In polar solvents, the usual excited-state proton transfer reaction takes place in which a risetime in the decay curve of solvent-separated ion pairs and a large red-shift in the spectrum are observed.