Synthesis of Tetraphenyltetraacenaphthoporphyrin: A New Highly Conjugated Porphyrin System with Remarkably Red-Shifted Electronic Absorption Spectra

摘要

Red-shifted porphyrinoid chromophores have been the subject of extensive studies over the last few years. This is due in part to their potential utility as photosensitizers in photodynamic therapy (PDT). However, these pigments have many additional applications including uses as fluorescent probes and near-infrared dyes, and as components of photosynthetic antenna arrays. A number of approaches for the construction of porphyrinoid systems with high-wavelength absorptions have been reported, includingthe synthesis of expanded porphyrins, porphyrin linkage isomers, and heterocyclic analogs. The intriguing observation that sterically crowded (and hence distorted) porphyrin structures, such as dodecaphenylpoiphyrin 1, have significantly red-shifted major absorption bands provides an alternative avenue to systems of this type. We have previously investigated the influence of fused aromatic subunits on the porphyrin chromophore. Regretfully, the influence of one or more fused naphthalene, phenanthrene,or 1,10-phenanthroline rings gave surprisingly small red shifts in the UV--vis absorption spectra, and even the highly symmetrical tetraphenanthroporphyrin 2 showed smaller bathochromic shiftsporphyrins and report, in striking contrast to the previous studies. on the extraordinarily red-shifted UV--vis absorption spectra exhibited by these tetraannelated porphyrins.