Synthesis of 5,10-diphenylporphyrin

The synthesis and spectroscopic properties of hitherto unknown 5,10-diphenylporphyrin (3) are described. 2+2 and 3+1 Pathways were tested for the making of 5,10-diphenylporphyrin. The most successful method involved the condensation of an appropriately substituted dipyrromethane dicarbinol with dipyrromethane to provide the title compound in up to 20% yield. The structure of 3 was unambiguously established by H-1 and C-13 NMR spectroscopy. The UV-vis, fluorescence and NMR data of 5,10-diphenylporphyrin and its Zn(II) and Ni(II) complexes are described and contrasted with those for the isomeric 5,15-diphenyl- and 5,10,15,20-tetraphenylporphyrin. (C) 2002 Elsevier Science Ltd. All rights reserved.