Screening Search for Fluorescent Thiol Reagents : Syntheses of N-Naphthylmaleimide Derivatives with a Dimethylamino or a Methoxy Group as an Auxochrome and Their Electronic Spectra

In order to search useful fluorescent thiol reagents, a naphthalene ring with a dimethylamino or methoxy group was selected as a fundamental fluorogenic group. On the basis of the design to combine such a fluorogenic and a maleimide group, 11 and 15 were synthesized as the candidate thiol reagents. Analogous model compounds (13 and 17) were also prepared. Their absorption and fluorescence spectra were measured, and the structural requirements for the candidate fluorogenic groups were discussed. Some of dimethylaminonaphthylmaleimides were found to be potential fluorescent thiol reagents.