(OC-6-23)-(7,12-Diethenyl-3,8,13,17-tetramethyl-21H,23H-porphine-2,18-dipropanoato(4-)-N(21),N(23),N(24))bis(pyridine)ferrate(2-) dihydrogen 15629-11-5 Protohemochrome Pyridine hemochrome Pyridine hemochromogen