2-[2-(4-Nitro-2-sulfophenyl)ethenyl]-5-[[4-[(4-sulfophenyl)azo]phenyl]-ONN-azoxy]benzenesulfonic acid

2-[2-(4-nitro-2-sulphophenyl)vinyl]-5-[[4-[(4-sulphophenyl)azo]phenyl]-O,N,N-azoxy]benzenesulphonic acid