The molecule is a ring assembly consisting of two 5-amino-4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-2,7-disulfonic acid units joined by a 4,4'-linkage. The tetrasodium salt is the histological dye 'Pontamine sky blue 5B'. It has a role as a histological dye, a fluorochrome and a carcinogenic agent. It is a member of azobenzenes, a bis(azo) compound, a member of naphthols, an aminonaphthalenesulfonic acid, an aromatic ether and a ring assembly. It is a conjugate acid of a Pontamine sky blue 5B(4-).
5-amino-3-[[4-[4-[(8-amino-1-hydroxy-3,6-disulfonaphthalen-2-yl)diazenyl]-3-methoxyphenyl]-2-methoxyphenyl]diazenyl]-4-hydroxynaphthalene-2,7-disulfonic acid