Linearly- and Cross-Conjugated Porphyrin Dimers: Synthesis and Characterization

Abstract

Acenes consisting of linearly fused benzene rings have been of great interest of study due to their unique electronic properties, in particular, their exceptionally high charge mobility, as well as their close relation to graphene.1-4 Although larger acenes are predicted to have even better electron mobility, larger acenes are not stable and soluble. Much effort has been devoted to the synthesis, stabilization/functionalization and characterization of acenes longer than pentacene in recent years.5-7 The fusion of an acene with two or more chromophores will greatly extend the pi-conjugation, and will likely produce electronically highly interactive multiporphyrinic systems. In this presentation, we present the synthesis and characterization of the pentacene-fused (linearly conjugated) and pentaquinone-fused (cross-conjugated) porphyrin oligomers. These pentacene-fused porphyrins are much more stable than their corresponding pentacene derivatives. The electronic absorption spectra and transit spectroscopy of these porphyrins indicate highly interactive multiple pi-systems. The electronic and optical properties of these i-extended porphyrins were measured using UV-Vis spectroscopy, life-time and steady state fluorescence spectroscopy, and cyclic voltammetry. DFT calculations were also performed for these porphyrins. S. S. Zade, M. Bendikov, J. Phys. Org. Chem. 2012 , 25, 452-461M. Bendikov, F. Wudl, D. F. Perepichka, Chem. Rev. 2004, 104, 4891-4945.Z. Sun, J. S. Wu, Aust. J. Chem. 2011, 64, 519-528J. E. Anthony, Chem. Rev. 2006, 106, 5028-5048J. E. Anthony, Angew. Chem. Int. Ed. 2008, 47, 452-483S. S. Zade, M. Bendikov, J. Phys. Org. Chem. 2012, 25, 452-461J. E. Anthony, A. Facchetti, M. Heeney, S. R. Marder, X. W. Zhan, Adv. Maters 2010, 22, 3876-3892 Figure 1