2-[2-(4-nitro-2-sulphophenyl)vinyl]-5-[[4-[(4-sulphophenyl)azo]-1-naphthyl]-NNO-azoxy]benzenesulphonic acid

2-[2-(4-Nitro-2-sulfophenyl)ethenyl]-5-[[4-[(4-sulfophenyl)azo]naphthalen-1-yl]-NNO-azoxy]benzenesulfonic acid