Maize 1: A Trimorphic Azo Pigment

We report the discovery of a trimorphic azo pigment, 2-[(2-chloro-phenyl)-hydrazono]-3-oxo-N-o-tolyl-butyramide (Maize 1) and spectroscopic and thermal properties of its forms. Single-crystal X-ray diffraction reveals that the three polymorphs all crystallize in the space group P1̄, with forms I and III packing in sheets and form II having a herringbone packing pattern. This pigment exists as the keto-hydrazone tautomer and is nearly planar in...