Macrocycles continue to attract considerable attention because of their broad applications in the area of host-guest chemistry, in supramolecular chemistry, and in catalytic engineering.1 Fully conjugated macrocycles represent chain end-free p-systems, which can be advantageous in comparison to the respective linear oligomers. They often exhibit significant ring strain, and therefore dramatic ring size-dependent changes in the optical and electrochemical properties.2Boron-containing electron-deficient macrocycles could be of great potential significance due to the expected unusual linear and nonlinear optical properties and potential applications as electron-transport materials, emitters in OLEDs, etc.3 Of interest is also that tricoordinate organoborane compounds can serve as selective chemosensors for the recognition of samll anions. All these properties stem from the electron-deficient nature of boron and from conjugation of the empty pp orbital with p orbitals of attached p-conjugated moieties.4Recently, we have developed a selective and versatile route to fluoreneborane oligomers that are structurally well-controlled and defined in conjugation length.5 We describe herein the preparation and photophysical and electrochemical investigation of the first highly Lewis acidic bora-cyclophanes. Comparisons will be made to related aza-cyclophanes reported by Tanaka,6 which provide important insights into how the electronic structure correlates with the nature of the bridging atoms.  1. D. Ramaiah, P. P. Neelakandan, A. K. Nair, R. R. Avirah, Chem. Soc. Rev. 2010  , 39, 4158.2. T. Iwamoto,  S. Yamago, et al, J. Am. Chem. Soc. 2011  , 133, 8354.3. a) F. J�kle, Coord. Chem. Rev. 2006, 250, 1107; Chem. Rev. 2010  , 110, 3985;b) N. Matsumi, Y. Chujo, Polym. J. 2008  , 40, 77.4. C. D. Entwistle, T. B. Marder, Chem. Mater. 2004  , 16, 4574.5. P. Chen, R. A. Lalancette, F. J�kle, J. Am. Chem. Soc. 2011  , 133, 8802.6. A. Ito, K. Tanaka, et al, Angew. Chem. Int. Ed. 2010  , 49, 8205.

Synthesis and characterization of luminescent conjugated organoborane macrocycles

243rd National Meeting (2012)

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