The fluorescence properties of polymethylene bis-b-naphthoates I (n = 2, 3, 4, 5, 10) in poor solvents such as DMSO-water and ethylene glycol-water were measured under stationary and nonstationary conditions at various temps. Hydrophobic interactions bring the two chromophores of I (n = 3, 4, 5, 10) into a sandwich arrangement in ground state, thus promote intramol. excimer formation upon excitation. The perfect overlapping structure for I (n = 2) can not be formed in ground state because of the eclipsed conformation of two methylene groups in such a sandwich arrangement. The favorable conformation for I (n = 2) is the structure in which the two naphthyl rings are in proximity. The activation energy, ethalpy and entropy changes for excimer formation of I (n = 2) were calculated from the fluorescence decay parameters.

Key words: WATER, REACTION KINETICS, PHOTOCHEMISTRY, CARBOXYLIC ACID ESTER, DMSO, ETHANEDIOL P, CHROMOPHOR, FLUOROSPECTROPHOTOMETRY, CONFORMATION, FLUORSCENCE DECAY