Exciplex Studies. II. Indole and Indole Derivatives

摘要

An excitedhyphen;state solutemdash;solvent complex (exciplex) has been shown to be responsible for a large red shift and loss of vibrational structure in the fluorescence spectra of indole and indole derivatives in polar solvents. Solutemdash;solvent stoichiometry of 1:2 and 1:1 is observed with associating and nonassociating solvents, respectively. Hydrogen bonding between the indole Nsngbnd;H group and solvent is shown not to be responsible for the interaction. It is suggested that the exciplex state is a chargehyphen;transfer state and is an intermediate in the process of electron transfer from the solute to the solvent.