1H-Benz[e]indolium, 2-[3-[3-(5-carboxypentyl)-1,3-dihydro-1,1-dimethyl-6,8-disulfo-2H-benz[e]indol-2-ylidene]-1-propen-1-yl]-3-ethyl-1,1-dimethyl-6,8-disulfo-, inner salt

1H-Benz[e]indolium, 2-[3-[3-(5-carboxypentyl)-1,3-dihydro-1,1-dimethyl-6,8-disulfo-2H-benz[e]indol-2-ylidene]-1-propen-1-yl]-3-ethyl-1,1-dimethyl-6,8-disulfo-, inner salt