4-[[2-[(E,3E)-3-[3-[(4-carboxyphenyl)methyl]-1-methyl-5-(trifluoromethyl)benzimidazol-2-ylidene]prop-1-enyl]-3-methyl-6-(trifluoromethyl)benzimidazol-3-ium-1-yl]methyl]benzoate