10.1021/ol2019983 r 2011 American Chemical Society Published on Web 08/24/2011 ORGANIC LETTERS 2011 Vol. 13, No. 18 4918–4921 Synthesis of Subphthalocyanines as Probes for the Accessibility of Silica Nanochannels Mine Ince, † Nando Gartmann, ‡ Christian G. Claessens, † Tom  as Torres,* ,†,§ and Dominik Br € uhwiler* ,‡ Departamento de Quı´mica Org  anica, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain, Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland, and IMDEA-Nanociencia, Facultad de Ciencias, Cantoblanco, 28049 Madrid, Spain tomas.torres@uam.es; bruehwi@aci.uzh.ch Received July 25, 2011 ABSTRACT The synthesis of a new subphthalocyanine is reported. Its structural and photophysical properties are ideal for probing the accessibility of arrays of silica nanochannels. Subphthalocyanines 1 (SubPcs) are lower homologues of phthalocyanines, 2 comprising a 14-π electron nonplanar aromatic macrocycle made of three diiminoisoindole units N-fused around a central boron atom. 3 Unlike the related planar phthalocyanines, SubPcs possess a peculiar conical structure which provides them with relatively high solu- bility and low tendency to aggregate. SubPcs exhibit a number of unique properties that allow a wide range of applications in fields such as nonlinear optics, 4 LEDs, 5 photovoltaics, 6 photodynamic therapy, 7 supramolecular chemistry, 8 as well as in photosynthetic models for study- ing energy- and electron-transfer processes. 9 SubPcs have also been employed as intermediates in the synthesis of unsymmetrically substituted phthalocyanines through a ring expansion reaction. 10 † Universidad Autonoma de Madrid. ‡ University of Zurich. § IMDEA-Nanociencia. (1) (a) Torres, T. Angew. Chem., Int. Ed. 2006, 45, 2834. (b) Claessens, C. G.; Gonz alez-Rodrı´guez, D.; Torres, T. Chem. Rev. 2002, 102, 835. (2) de la Torre, G.; Claessens, C. G.; Torres, T. Chem. Commun. 2007, 2000. (3) Meller, A.; Ossko, A. Monatsh. Chem. 1972, 103, 150. (4) del Rey, B.; Keller, U.; Torres, T.; Rojo, G.; Agull o-L opez, F.; Nonell, S.; Marti, C.; Brasselet, S.; Ledoux, I.; Zyss, J. J. Am. Chem. Soc. 1998, 120, 12808. (5) Dı´az, D. D.; Bolink, H. J.; Capelli, L. M.; Claessens, C. G.; Coronado, E.; Torres, T. Tetrahedron Lett. 2007, 48, 4657. (6) Gommans, H.; Aernouts, T.; Verreet, B.; Heremans, P.; Medina, A.; Claessens, C. G.; Torres, T. Adv. Funct. Mater. 2009, 19, 3435. (7) Rubio, N.; Jim enez-Banzo, A.; Torres, T.; Nonell, S. J. Photochem. Photobiol. A. 2007, 185, 214. (8) Claessens, C. G.; Vicente-Arana, M. J.; Torres, T. Chem. Commun. 2008, 6378. (9) Gonz alez-Rodrı´guez, D.; Carbonell, E.; De Miguel Rojas, G.; Atienza Castellanos, C.; Guldi, D. M.; Torres, T. J. Am. Chem. Soc. 2010, 132, 16488. (10) (a) Kobayashi, N.; Kondo, R.; Nakajima, S.; Osa, T. J. Am. Chem. Soc. 1990, 112, 9640. (b) Sastre, A.; del Rey, B.; Torres, T. J. Org. Chem. 1996, 61, 8591. (11) (a) Yanagisawa, T.; Shimizu, T.; Kuroda, K.; Kato, C. Bull. Chem. Soc. Jpn. 1990, 63, 988. (b) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli, J. C.; Beck, J. S. Nature 1992, 359, 710.