Simple Pb-II fluorescent probe based on Pb-II-catalyzed hydrolysis of phosphodiester

A new fluorescent probe for Pb-II, p-nitrophenyl 3H-phenoxazin-3-one-7-yl phosphoric acid (NPPA), was designed and synthesized by linking resorufin (serving as a fluorophore and electron acceptor) to p-nitrophenol (serving as a fluorescence quencher and electron donor) through phosphodiester bonds. When NPPA was irradiated with light, intramolecular fluorescence self-quenching took place because of the photoinduced electron transfer from the donor to the acceptor. However, upon the addition of Pb-II, the phosphate ester bonds in the probe were cleaved and the fluorophore was released, accompanying the retrievement of fluorescence. (C) 2003 Wiley Periodicals, Inc.