Chicago Sky Blue 6B

sodium (6Z,6'Z)-6,6'-(2,2'-(3,3'-dimethoxy-[1,1'-biphenyl]-4,4'-diyl)bis(hydrazin-2-yl-1-ylidene))bis(4-amino-5-oxo-5,6-dihydronaphthalene-1,3-disulfonate)

O=C1C(C(C=C/C1=N/NC(C(OC)=C2)=CC=C2C3=CC=C(C(OC)=C3)N/N=C4C(C(C(C=C\4)=C5S([O-])(=O)=O)=C(C(S([O-])(=O)=O)=C5)N)=O)=C6S([O-])(=O)=O)=C(C(S([O-])(=O)=O)=C6)N.[Na+].[Na+].[Na+].[Na+]