A new terbium(III) chelate as an efficient singlet oxygen fluorescence probe

A terbium(III) chelate fluorescence probe for detection of singlet oxygen (102) in aqueous media, NNN',N-[2,6-bis(3'-aminomethyl-l'pyrazolyi)-4-(9-anthryl)pyridine] tetrakis (acetate)-Tb3+ (PATA-Tb3+), was designed and synthesized. The new chelate is highly water soluble, is almost nonfluorescent, and can specifically react with O-1(2) to yield a strongly fluorescent chelate, the endoperoxide of PATA-Tb3+, accompanied by a remarkable increase in the fluorescence quantum yield from 0.46 to 10.5%. The long fluorescence lifetime of the endoperoxide (2.76 ms) allows the probe to be used favorably for time-resolved fluorescence detection Of O-1(2). The studies of fluorescence property and reaction specificity indicate that the new probe is highly sensitive and selective for O-1(2). The probe was used for quantitative detection Of O-1(2) generated from a MoO42--H2O2 system to give a detection limit of 10.8 nM. In addition, the good applicability of the probe was demonstrated by the real-time monitoring of the kinetic process of O-1(2) generation in a horseradish peroxidase-catalyzed oxidation system of indole-3-acetic acid in a weakly acidic buffer. (c) 2006 Elsevier Inc. All rights reserved.