2-[4-[2-(4-Nitro-2-sulfophenyl)ethenyl]-3-sulfophenyl]-2H-naphtho[1,2-d]triazole-5-sulfonic acid

2-[4-[2-(4-nitro-2-sulphophenyl)vinyl]-3-sulphophenyl]-2H-naphtho[1,2-d]triazole-5-sulphonic acid