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
each form. The molecular conformation in the crystal is similar to its diarylide pigment analogues. In contrast to
many other polymorphic pigments, the color differs very little among forms of Maize 1.