4-Chloro-2-[(E)-({4-[N-(3,4-dimethyl­isoxazol-5-yl)sulfamo­yl]phen­yl}iminio)meth­yl]phenolate

The title compound, C(18)H(16)ClN(3)O(4)S, is a Schiff base ligand in which the H atom of the hydr­oxy group has moved to the N atom of the imine group, resulting in a zwitterion. The structure is stabilized by an intra­molecular (N—H⋯O) and five inter­molecular (C—H⋯O, C—H⋯N and N—H⋯O) hydrogen bonds. The mol­ecules are linked to each other by hydrogen bonds and form a three-dimensional polymeric network. In addition, the aromatic rings are also involved in π–π inter­actions [centroid–centroid distance between aromatic rings = 3.7525 (11) Å].