INTRAMOLECULAR FLUORESCENCE SELF-QUENCHING OF FLUORESCEINAMINE

In this paper, the intramolecular self-quenching of fluoresceinamine has been investigated. The ubiquitous use of fluorescein dyes as labels and indicators requires a thorough understanding of their properties. This fluorescein derivative has a quantum yield of 0.015 and exhibits none of fluorescein's indicator properties until the amine's electron lone pair is made unavailable for electron transfer through covalent or electrostatic binding process. A series of acyl and sulfonyl halides react with fluoresceinamine to produce highly fluorescent products with the spectral and indicator properties of fluorescein. A secondary quenching mechanism can be imposed on the molecule in derivatives formed by reaction with nitrobenzoyl chlorides. In these cases the degree of quenching is influenced by the nitro group position. Complexation of fluoresceinamine with a cationic surfactant, cetyltrimethylammonium bromide, also regenerated the fluorescence. The ability to regenerate the quenched fluorescence provides a remarkable example of electron density acting as a switch in the control of fluorescence. Fluoresceinamine can be quenched systematically by two different processes, offering the potential for studying quenching mechanisms and their distance and spatial requirements. © 1993, IEEE. All rights reserved. © 1990, American Chemical Society. All rights reserved.