The photophysics of some tertiary aliphatic amines in solution

Abstract

The absorption and fluorescence properties of some N-methyl alicyclic amines are reported. Absorption maxima, fluorescence emission wavelength maxima, and fluorescence lifetimes are highly dependent upon amine structure. The Stokes shift is also dependent upon amine structure and this is suggested as being a reflection of the extent to which the amino group is pyramidal in the ground state. In many cases, change of solvent from cyclohexane to tetrahydrofuran causes a large red shift in wavelength for maximum fluorescence intensity, but often has little effect upon fluorescence lifetime, which indicates that solvent effects upon non-radiative processes occur largely before the solvated planar state of the amine is created. Examples of the quenching of amine fluorescence by hydroxy groups and of excited amines forming exciplexes with benzene are presented.