Formation and behavior of intramolecular N- (styrylalkyl)aniline exciplexes

The photophysical and photochemical behavior of several aniline spacer - st yrene molecules in which the spacer is a short polymethylene chain has been investigated. Long wavelength excitation selectively excites the aniline c hromophore which undergoes intramolecular quenching by the styrene to yield an intramolecular exciplex. Exciplex fluorescence is observed for both of the tertiary anilines investigated and for one of the three secondary anili nes. More rapid exciplex formation in nonpolar vs. polar solvents is attrib uted to the necessity of desolvating the polar aniline singlet in polar sol vents. Intramolecular adduct formation is the major photochemical process f or the secondary anilines, but is highly inefficient for the tertiary anili nes. The behavior of the intramolecular aniline-styrene exciplexes is compa red to that of the styrene-amine exciplexes previously investigated in this laboratory.