Synthesis of homologously pure bacteriochlorophyll-e and f analogues from BChls-c/d via transformation of the 7-methyl to formyl group and self-aggregation of synthetic zinc methyl bacteriopheophorbides-c/d/e/f in non-polar organic solvent

Homologously pure methyl bacteriopheophorbides-e and f (BPhes-e/fM) were prepared from modification of naturally occurring bacteriochlorophylls-c and d (BChls-c/d), respectively, by transformation of the methyl to formyl group at the 7-position. The absolute configuration of the 1-hydroxyethyl group at the 3-position of (Zn-)BPhes-e/fM was determined from comparison with structurally known BChl-c/d epimers. Visible spectra of synthetic (Zn-)BPhe-c/d/e/fM showed that the 71-oxidation and the 82/121/20-methylation affected Soret, Qx and Qy bands of both the monomeric (in a polar organic solvent) and oligomeric species (in a non-polar solvent).