(2Z)-4-butyl-2-[[4-butyl-5-[[3-butyl-5-[(Z)-(4-butyl-3,5-dimethyl-pyrrol-2-ylidene)methyl]-4-methyl-1H-pyrrol-2-yl]methyl]-3-methyl-1H-pyrrol-2-yl]methylene]-3,5-dimethyl-pyrrole dihydrobromide