3H-​Indolium, 2-​[3-​[1-​[6-​[[3-​(11,​12-​didehydrodibenz[b,​f]​azocin-​5(6H)​-​yl)​-​3-​oxopropyl]​amino]​-​6-​oxohexyl]​-​1,​3-​dihydro-​3,​3-​dimethyl-​5-​sulfo-​2H-​indol-​2-​ylidene]​-​1-​propen-​1-​yl]​-​3,​3-​dimethyl-​5-​sulfo-​1-​(3-​sulfopropyl