The molecule is an organosulfonate oxoanion obtained by deprotonation of the sulfo group of 4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonic acid. It is a conjugate base of a 4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonic acid.
4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonate