Models for the photosynthetic reaction center: preparation, spectroscopy, and crystal and molecular structures of cofacial bisporphyrins linked by cis-1, 2- and trans-1,2-ethene bridges and of 1,1-carbinol-bridged bisporphyrins

A single-step reductive coupling of metal(II) 5-formyloctaethylporphyrins produces both cis-1,2- and trans-1,2-ethene-bridged bisporphyrins. Pi-pi aggregation of the monomeric subunits is significant in the formation of cis-ethene-bridged bisporphyrins. Crystal structures of the cis-dimer exhibit both intra- and intermolecular aggregation and the cis-dimers having cofacial bisporphyrins have significant overlap of the pi-system. X-ray and spectroscopic studies help determine the molecular structures of 1, 1-carbinol-bridged bisporphyrins and the trans-1,2-ethene-bridged bisporphyrin.