Two monoclinic forms of diclofenac acid

Diclofenac acid, [2-(2,6-dichlorophenylamino)phenyl]acetic acid, C14H11Cl2NO2, crystallizes in two polymorphic forms in the monoclinic system. In both forms, molecules are linked to each other through the carboxyl groups giving rise to centrosymmetric dimers. No interaction among different dimers has been found.