Photoelectrochemical oxidation of a turn-on fluorescent probe mediated by a surface MnII catalyst covalently attached to TiO2 nanoparticles

• Published in: Journal of catalysis 2014-02, Vol.310, p.37-44
• Main Authors: Durrell, Alec C., Li, Gonghu, Koepf, Matthieu, Young, Karin J., Negre, Christian F.A., Allen, Laura J., McNamara, William R., Song, Hee-eun, Batista, Victor S., Crabtree, Robert H., Brudvig, Gary W.
• Format: Article
• Language: English
• Subjects: Dye-sensitized photoelectrochemical cell; Manganese; Manganese compounds; Nanoparticles; Oxidation; Photoanode; Photocatalysis; Photooxidation; Studies; Titanium dioxide; Turn-on fluorescence
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2013.07.001

[Display omitted] •H2DCF is an effective fluorescence sensor to evaluate anode performance in photocatalytic cells.•We show that increased photocurrent does not necessarily correlate with increased catalysis.•Redox-active Mn photoanodes outperform redox-inactive Zn anodes. A manganese complex covalently attached to a TiO2 electrode via a light-absorbing organic linker (L) was used in the photooxidation of 2′,7′-dihydrodichlorofluorescein (H2DCF). Significant and sustained photocurrent was observed upon visible-light illumination of the fully assembled anode in the presence of the substrate. The two-electron, two-proton oxidation of H2DCF yields the fluorescent compound, 2′,7′-dichlorofluorescein (DCF). Our studies suggest that the MnII–L–TiO2 architecture is an effective photoanode for multielectron chemistry, as production of DCF under visible-light illumination exceeds yields observed for bare TiO2 as well as ZnII–L–TiO2 anodes. The turn-on fluorescent behavior of H2DCF upon oxidation makes it an excellent substrate for the study of new photoanodes. The high fluorescence quantum yield of DCF allows for nanomolar sensitivity and real-time monitoring of substrate oxidation.