A novel fluorescent thiol reagent: Syntheses and electronic spectra of N-(7-dimethylamino-4-methyl-3-coumarinyl)-maleimide (DACM-3) and the related compounds.

Abstract

Nitration of 7-dimethylaminocoumarin (1) afforded three isomers of the nitrocoumarins, two of which were by way of the amines converted to the corresponding maleimides and succinimides. Their absorption and fluorescence spectra were measured, and it was found that N-(7-dimethylamino-4-methyl-3-coumarinyl) maleimide (5a) has the requisite properties for serving as an useful fluorescence thiol reagent with regard to the fluorescent intensity, excitation wavelength, water solubility and the reactivity. Thus dimethylaminocoumarin is one of candidate fluorogenic groups of choice to be employed in organic fluorescence reagents.