The Fluorescence of Indoles and its Application in Drug Analysis

Abstract

The literature on fluorescence of indoles and its application is briefly reviewed. The effect of polar solvents such as n-butanol, methanol, cyclohexanol, borneol, tert~butanol, 3-ethyl-3-pentanol, acetonitrile, tetrahydrofuran, pyrrolidine, cyclohexylamine, triethylamine, quinuclidine, triethylenediamine and acetic acid on the fluorescence of some indole derivatives such as unsubstituted indole; 2, 3-cyclodecamethyleneindole; 2,3-dimethylindole; 2-Butyl-3-propylindole; 2-methylindole; 2-tertbutylindole;3-methylindole; tryptophol; 7-methylindole; 5-methylindole;5-methoxyindole;5-fluoroindole; 6,7-dimethyl-1,2,3,4-tetrahydrocarbazole;6-methyl-1,2,3,4-tetrahydrocarbazole; 6-n-butyl-1,2,3, 4-tetrahydrocarbazole;6-methoxy-1,2,3,4-tetrahydrocarbazole; 6,8-dimethyl-1,2,3, 4-tetrahydrocarbazole;8,9-cyclotrimethylene-1,2,3,4-tetrahydrocarbazole; 1,2,3 7trimethylindole; 1,2-dimethylindole and 1,3-dimethylindole in cyclohexane is reported. It was noted that the formation of an exciplex is dependent upon electronic and steric effects of both solvent and indole structures. The nature of the exciplex is discussed and a dipole-dipole with some charge transfer interaction is proposed for the mechanism of exciplex formation. The synthesis of some of the above indoles is described. The analysis of drugs such as 5-Hydroxyindole-3-acetic acid, 5-Hydroxytryptophan,indomethacin and oxypertine by native fluorescence, O-phthalaldehyde reaction and gas chromatography methods is described.