Effect of Binding and Conformation on Fluorescence Quenching in New 2‘,7‘-Dichlorofluorescein Derivatives

Abstract
[structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nitrogen atoms cooperatively and reversibly suppress the fluorescence of the chromophore.