Polymorphism and the Phenomenon of Whole-Molecule Disorder Revealed in a Novel Dipodal Thiopyridine Ligand

We report two polymorphs (α and β) of a novel bipodal ligand, 1,4-bis(thiopyridine)benzene, which were isolated from the same methanolic solution. Single-crystal X-ray analyses revealed the phenomenon of positional whole-molecule disorder occurring in form α, which comes down to packing disorder. Computational calculations were carried out to compare the crystal lattice energies of the isolated polymorphs. The energetically more stable form β has a higher packing efficiency and shows an increased number of hydrogen bonds compared with both components of form α, the packing of which is dominated by van der Waals interactions. Supportive bulk studies, such as thermal analysis and powder X-ray diffraction, were also performed.