(E)-4-Bromo-2-[(Phenylimino)Methyl]Phenol: A New Polymorph And Thermochromism

A new polymorph of (E)-4-bromo-2-[(phenylimino)methyl]phenol, C13H10BrNO, is reported, together with a low-temperature structure determination of the previously published polymorph. Both polymorphs were found to have an intramolecular O-H center dot center dot center dot N hydrogen bond between the phenol OH group and the imine N atom, forming an S(6) ring. The crystals were observed to have different colours at room temperature, with the previously published polymorph being more orange and the new polymorph more yellow. The planarity of the molecule in the two polymorphs was found to be significantly different, with dihedral angles (Phi) between the two aromatic rings for the previously published 'orange' polymorph of Phi = 1.8 (2)degrees at 120 K, while the new 'yellow' polymorph had Phi = 45.6 (1)degrees at 150 K. It was also observed that both polymorphs displayed some degree of thermochromism and upon cooling the 'orange' polymorph became more yellow, while the 'yellow' polymorph became paler upon cooling.