SOLVENT EFFECTS ON EXCITED-STATE RELAXATION PHENOMENA

Solvent effects on excited state relaxation phenomena in binary solven t mixtures, studied by steady state and time-resolved fluorescence spe ctroscopy, are discussed in the frame of: electrostatic interactions, preferential solvation, weak associations with defined stoichiometry a nd structure and strongly bonded ground and excited state complex form ation. It is shown, that effects of hydrogen bonded complex formation can be discriminated from unspecific interactions in hydrocarbon - hyd roxylic binary solvent mixtures. The structure of such complexes and t heir role in altering excited state processes is discussed for some hy droxy- and amino- compounds (phenols, anilines, aliphatic tertiary ami nes, and aminocoumarins etc.).