STILBENE AMINE EXCIPLEXES - SUBSTITUENT EFFECTS

Fluorescence is observed for 24 exciplexes formed between excited para-substituted trans-stilbene (X H, CN, Cl, CH3 CH(CH3)2 and CH3O) and four tertiary amines (triethylamine, diisopropylmethylamine, diisopropylethylamine and N,N-dimethylaniline) in n-hexane at room temperature. The maximum fluorescence energies are well correlated with the Rehm and Weller theoretical values with the exception of the triethylamine systems. The systematic shift in exciplex energy also correlates well with the Hammett σp constant; however, for the triethylamine-stilbene systems, the correlation is less linear. The thermodynamic stability of the exciplex determines the degree of linearity in the Hammett correlation. Investigations of the products, Stern-Volmer quenching, dipole moments and exciplex lifetimes were also carried out to determine the structure-reactivity relationship. © 1990.