10.1021/ol2022627 r 2011 American Chemical Society Published on Web 09/29/2011 ORGANIC LETTERS 2011 Vol. 13, No. 20 5532–5535 Toward the Development of the Direct and Selective Detection of Nitrates by a Bioinspired MoÀCu System Hanit Marom, Yanay Popowski, Svetlana Antonov, and Michael Gozin* Department of Chemistry, Raymond and Beverly Sackler Faculty of Exact Science, Tel-Aviv University, Tel Aviv 69978, Israel cogozin@mgchem.tau.ac.il Received August 21, 2011 ABSTRACT The development of a new platform for the direct and selective detection of nitrates is described. Two thioether-based chemosensors and the corresponding sulfoxides and sulfones were prepared, and their photophysical properties were evaluated. Upon selective sulfoxidation of these thioethers with nitrates via an oxygen-transfer reaction promoted by a bioinspired MoÀCu system, significant fluorescence shifts were measured. A selective response of these systems, discriminating between nitrate salts and H 2 O 2 , was also shown. Nitrates are the world’s most widespread groundwater contaminant, mainly resulting from crop fertilization, live- stock wastes, and organic wastes (nitrates that are formed from organic nitrogen-containing compounds found in manure). 1 Excessive consumption of nitrates can lead to a fatal medical condition called methemoglobinemia and other problems, such as spontaneous abortion and birth defects in the central nervous system. 2 A variety of analytical methods have been developed for the determination of nitrates. Most of them are based on spectrophotometry, 3 ion chromatography, 4 flow-injection analysis, 5 electrochemistry, 6 and capillary electrophoresis. 7 Spectroscopic methods are the most commonly used be- cause of their low detection limits and convenient sample- preparation protocols. A broad range of spectroscopic techniques (in many cases in conjunction with suitable chemical reactions) are applicable, including UVÀvis, 8 chemoluminescence, 9 fluorescence, 10 IR, 11 Raman, 12 and molecular-cavity emission spectroscopies. 13 However, these (1) Johnson, C. J.; Kross, B. C. Am. J. Ind. Med. 1990, 18, 449. (2) Manassaram, D. M.; Backer, L. C.; Moll, D. M. Environ. Health Perspect. 2006, 114, 320. (3) (a) Zhag, M.; Yuan, D. X.; Chen, G. H.; Li, Q. L.; Zhang, Z.; Liang, Y. Microchim. Acta 2008, 160, 461. (b) L opez Pasquali, C. E.; Gallego-Pic o, A.; Fern andez Hernando, P.; Velasco, M.; Durand Alegrı´a, J. S. Microchem. J. 2010, 94, 79. (4) (a) Abha, C.; Anil, K. B.; Gupta, V. K. Talanta 2001, 55, 789. (b) Tirumalesh, K. Talanta 2008, 74, 1428. (5) Gamboa, J. C. M.; Pe na, R. C.; Paix ao, T. R. L. C.; Bertotti, M. Talanta 2009, 80, 581. (6) (a) Li, H. L.; Chambers, J. Q.; Hobbs, D. T. J. Appl. Electrochem. 1988, 18, 454. (b) Moorcroft, M. J.; Nei, L.; Davis, J.; Compton, R. G. Anal. Lett. 2000, 33, 3127. (c) Mori, V.; Bertotti, M. Anal. Lett. 1999, 32, 25. (d) Bouamrane, F.; Tadjeddine, A.; Butler, J. E.; Tenne, R.; Levy- Clement, C. J. Electroanal. Chem. 1996, 405, 95. (e) Reuben, C.; Galun, E.; Cohen, H.; Tenne, R.; Kalish, R.; Muraki, Y.; Hashimoto, K.; Fujishima, A.; Butler, J. M.; Levy-Clement, C. J. Electroanal. Chem. 1995, 396, 233. (7) Bord, N.; Cretier, G.; Rocca, J. L.; Bailly, C.; Souchez, J. P. J. Chromatogr., A 2005, 1100, 223. (8) (a) Stanley, M. A.; Maxwell, J.; Forrestal, M.; Doherty, A. P.; MacCraith, B. D.; Diamond, D.; Vos, J. G. Anal. Chim. Acta 1994, 299, 8. (b) Takeda, K.; Fujiwara, K. Anal. Chim. Acta 1993, 276, 25. (9) (a) Yang, F.; Troncy, E.; Francoeur, M.; Vinet, B.; Vina, P.; Czaika, G.; Blaise, G. Clin. Chem. 1997, 43, 657. (b) Aoki, T.; Fukuda, S.; Hosoi, Y.; Mukai, H. Anal. Chim. Acta 1997, 349, 11. (c) Yoshizumi, K.; Aoki, K. Anal. Chem. 1985, 57, 737. (d) He, Z. K.; Fuhrmann, B.; Spohn, U. Fresenius’ J. Anal. Chem. 2000, 367, 264. (10) (a) Ohta, T.; Arai, Y.; Takitani, S. J. Pharm. Sci. 1987, 76, 531. (b) Lee, S. H.; Field, L. R. Anal. Chem. 1984, 56, 2647. (c) Huang, Z.; Korenaga, T.; Helaleh, M. I. H. Mikrochim. Acta 2000, 134, 179. (d) Buldt, A.; Karst, U. Anal. Chem. 1999, 71, 3003. (e) Geetha, K.; Balasubramanian, N. Anal. Lett. 2000, 33, 1869. (11) Jiao, G.; Lips, S. H. J. Plant Nutr. 2000, 23, 79. (12) Aker, P. M.; Zhang, J.; Nichols, W. J. Chem. Phys. 1999, 110, 2202. (13) (a) Celik, A.; Henden, E. Analyst 1989, 114, 563. (b) Al-Zamil, I. Z.; Townshend, A. Anal. Chim. Acta 1982, 142, 151.