Orthorhombic polymorph of 4-(2,2':6',2''-terpyridin-4'-yl)aniline.

Crystallographic data for the title compound, C21H16N4, are reported herein. The compound was recrystallized from a methanol/aceto-nitrile solvent system at 298 K. It crystallizes in the Pca21 space group at 100 K compared to the previously reported monoclinic polymorph and displays inter-molecular hydrogen bonding, through N-H⋯N contacts, and π-π inter-actions. None of the rings in the structure is coplanar - dihedral angles defined by atoms of the peripheral rings with the central pyridine range from -7.1 (3) to 29.8 (3)°.