Exciplex emission for hydrocarbon—dimethylaniline systems in hydroxylic solvents

Abstract

Exciplex emission from pyrene-dimethylaniline (DMA) and anthracene-DMA systems appears at a much lower wavelenght in n-propanol (ε = 20.1) than in acetone (ε = 20.7). For all primary alcohols the exciplex emission appears at about the same position irrespective of the dielectric constants of the alcohols. However, the alcohols strongly quenched the exciplex emission in n-heptane and this quenching followed the Stern-Volmer relation. The quenching constants were found to follow the order primary> secondary> tertiary. These findings have been attributed to the stabilization of the non-bonding electrons at the nitrogen atom in DMA through hydrogen bonding with the alcohols.