Single-Electron Transfer Driven Cyanide Sensing: A New Multimodal Approach M. R. Ajayakumar and Pritam Mukhopadhyay* Supramolecular and Material Chemistry Lab, School of Physical Sciences, Jawaharlal Nehru UniVersity, New Delhi 110067, India Sarita Yadav and Subhasis Ghosh School of Physical Sciences, Jawaharlal Nehru UniVersity, New Delhi 110067, India m_pritam@mail.jnu.ac.in Received April 15, 2010 ABSTRACT A new SET-driven reaction-based strategy is reported for sensing of cyanide with indicators having low LUMO levels. The cyanide-specific reaction produces an air-stable radical anion marker and by virtue of its spin, charge, and the SOMO-LUMO-based electronic transition generates multimodal signal outputs. High selectivity and sensitivity (0.2-16 μM) were observed when compared to other reducing anions. This new indicator system exhibits regenerability and dip-stick sensing, and fabrication of an electronic sensing device for cyanide is demonstrated. There is continuous effort toward the design of anion sensors based on small molecules and their ensembles. 1 Among the anions, cyanide has evinced maximum interest due to its severe toxicity. Recently, reaction-based indicators/chemo- dosimeters have evolved as an attractive platform for sensing cyanide anions 2 and other analytes. 3 Cyanide sensors are also based on H-bonding, time-gated fluorescence, metal ion complexes, conformational changes, quantum dots, and thin- film sensing. 4a-h Cyanide sensing with reaction-based indicators utilizes the nucleophilic nature of the cyanide, and the design comprises a substrate and a reporter unit. Functional groups such as carbonyl/ene/imine 5 or Lewis acidic boranes 6 are used as substrates, while π-conjugated chromophores are used as the reporter units (Scheme 1a). (1) (a) Beer, P. D.; Gale, P. A. Angew. Chem., Int. Ed. 2001, 40, 486– 516. (b) Lavigne, J. J.; Anslyn, E. V. Angew. Chem., Int. Ed. 2001, 40, 3118–3130. (c) Martı ´nez-Ma ´ñez, R.; Sanceno ´n, F. Chem. ReV. 2003, 103, 4419–4476. (d) Sessler, J. L.; Seidel, D. Angew. Chem., Int. Ed. 2003, 42, 5134–5175. (e) Best, M. D.; Tobey, S. L.; Anslyn, E. V. Coord. Chem. ReV. 2003, 240, 3–15. (f) Martı ´nez-Ma ´ñez, R.; Sanceno ´n, F. Coord. Chem. ReV. 2006, 250, 3081–3093. (2) (a) Mohr, G. J. Chem.sEur. J. 2004, 10, 1082–1090. (b) Sessler, J. L.; Cho, D.-G. Chem. Soc. ReV. 2009, 38, 1647–1662. (3) (a) Kim, T.-H.; Swager, T. M. Angew. Chem. Int. Ed 2003, 42, 4803– 4806. (b) Zhang, S.-W.; Swager, T. M. J. Am. Chem. Soc. 2003, 125, 3420– 3421. (c) Nolan, E. M.; Lippard, S. J. Chem. ReV. 2008, 108, 3443–3480. (4) (a) Sun, S.-S.; Lees, A. J. Chem. Commun. 2000, 1687–1688. (b) Miyaji, H.; Sessler, J. L. Angew. Chem., Int. Ed. 2001, 40, 154–157. (c) Anzenbacher, P., Jr.; Tyson, D. S.; Jursikova ´, K.; Castellano, F. N. J. Am. Chem. Soc. 2002, 124, 6232–6233. (d) Badugu, R.; Lakowicz, J. R.; Geddes, C. D. J. Am. Chem. Soc. 2005, 127, 3635–3641. (e) Palomares, E.; Martı ´nez- Dı ´az, M. V.; Torres, T.; Coronado, E. AdV. Funct. Mater. 2006, 16, 1166– 1170. (f) Jo, J.; Lee, D. J. Am. Chem. Soc. 2009, 131, 16283–16291. (g) Shang, L.; Jin, L.; Dong, S. Chem. Commun. 2009, 3077–3079. (h) Gimeno, N.; Li, X.; Durrant, J. R.; Vilar, R. Chem.sEur. J. 2008, 14, 3006–3012. ORGANIC LETTERS 2010 Vol. 12, No. 11 2646-2649 10.1021/ol1008558  2010 American Chemical Society Published on Web 05/10/2010