Porphocyanine: An Expanded Tetrapyrrolic Macrocycle
David Dolphin, Rettig, S.J., Tang, H., Wijesekera, T., and Xie, L.Y.
J. Am. Chem. Soc.
Self-condensation of a 5,5'-bis(aminomethyl)dipyrromethane with the loss of ammonia followed by aerial oxidation gives a new 22 π-electron aromatic system called porphocyanine. Octaethylporphocyanine (I) has a typical porphyrin-like absorption spectrum with a Soret band at 457 nm and the longest wavelength absorption at 797 nm. Upon protonation the Soret band sharpens and the long wavelength band exhibits a hypsochromic shift. A single crystal x-ray structure of the zinc complex II shows the porphocyanine molecule to be completely flat.