Ground state charge transfer complex formation of some metalloporphyrins with aromatic solvents

Porphyrin derivatives are known to have absorption spectra in the visible region (400–700 nm). In the present Letter, a new (to the best of our knowledge) broad band is reported in the NIR region (700–900 nm) of the absorption spectra of zinc tetraphenylporphyrin, zinc octaethylporphyrin and magnesium octaethylporphyrin in aromatic solvents at high concentrations (∼10−4 mol/L). The broad absorption band in the NIR region is ascribed to be due to ground state charge transfer complex formation between the presently used metalloporphyrins and aromatic solvents.