Synthesis and molecular structure of formylporphyrin. Intrinsic properties of porphyrin a

Abstract

Porphyrins having two electron negative formyl groups or one formyl and one vinyl group substituted on the diagonal pyrrole rings similar to that found in heme a have been synthesized and studied. The unique electronic spectra and redox potentials of the 4,8-substituted porphyrins were attributable to the strong π-interactions between the formyl group and the porphyrin ring. A detailed X-ray crystal structure of 4,8-diformyl-2,6-di-n-pentyl-1,3,5,7-tetramethylporphin is also reported. The inner nitrogen protons were found localized on the two opposite pyrrole rings not carrying the formyl groups.