The title compound, C20H20Br2N2O2, Coupler a tetradentate Schiff base, is the enantiomerically pure R,R-diastereomer of four possible stereoisomers.The molecular structure reveals two strong intramolecular O—H.N hydrogen bonds between the hydroxy O atom and the imino N atom, which each generate S(6) rings.In the crystal, molecules are stacked in columns along the a axis; when viewed down the b axis, successive columns are stacked in the opposite direction.
The structure reported herein is the monoclinic polymorph of the previously reported orthorhombic form [Yi & Hu (2009).Acta Cryst.E65, o2643], in which UC-II Collagen the complete molecule is generated by a crystallographic twofold axis.