Dynamics and equilibrium for the formation of fluorescent Lewis acid-base exciplexes and triplexes between 9-aminophenanthrene and aliphatic amines.

The excited singlet states of 9-aminophenanthrene and its N-aminoalkyl derivatives are strongly fluorescent in cyclohexane. Addition of low concentrations of Et(3)N, Pr(2)NH, or PrNH(2) results in a red shift of the emission maximum and moderately decreased fluorescence intensity. Analysis of the fluorescence behavior using a combination of singular value decomposition with self-modeling and kinetic analysis provides evidence for the sequential formation of 1 : 1 (exciplex) and 1 : 2 (triplex) complexes between the excited 9-aminophenanthrene and ground-state alkylamine, both of which are strongly fluorescent.