label: (R)-(Z)-stereoisomer of 3-ethenyl-2,7,12,18-tetramethyl-8-(2-oxoethylidene)-21H,23H-porphine-13,17-dipropanoic acid
label_lc: (r)-(z)-stereoisomer of 3-ethenyl-2,7,12,18-tetramethyl-8-(2-oxoethylidene)-21h,23h-porphine-13,17-dipropanoic acid