INTRAMOLECULAR FORMATION OF EXCIMERS IN MODEL COMPOUNDS FOR POLYESTERS CONTAINING NAPHTHALENE UNITS - ALPHA,OMEGA-DIESTERS FROM 1-NAPHTHOIC ACID AND 5 GLYCOLS

The fluorescence of the α,ω-diesters of HO(CH2)mOH, m = 2-6, and 1-naphthoic acid has been characterized in dilute solution in solvents of different viscosity, η. The ratio of the intensity of the emission from intramolecular excimers and from individual naphthalene moieties, denoted by ID IM, depends on m and on η. Extrapolation to a medium of infinite η shows a lower equilibrium contribution to the formation of intramolecular excimers than that observed previously in an analogous series of α,ω-diesters based on 2-naphthoic acid. With the series based on 1-naphthoic acid, a weak odd-even effect is observed, with the maximum value of ID IM at m = 5. An equilibrium rotational isomeric state analysis can rationalize the observation of the odd-even effect and the occurrence of the maximum at m = 5. In media of low η, there is a substantial dynamic contribution to ID IM. © 1990.