The coordination chemistry and supramolecular interactions of 2-(2'-Pyridyl)imidazole ligand: a comprehensive review with theoretical insight

This review explores the role of 2-(2'-Pyridyl) imidazole (PyimH) as a coordinating ligand and also its role as a supramolecular agent through hydrogen bonding and pi...pi interaction. Two N coordination sites make 2-(2'-Pyridyl)imidazole an analogous ligand to 2,2'-bipyridine. The syn orientation of imidazole and pyridine sp(2) nitrogen makes it a bidentate chelating ligand. PyimH mainly produces discrete coordination complexes (0D), but in a few cases, 1D coordination polymers are observed due to bridging co-ligands like oxalate, dicyanamide, tricyanomethanide, croconate, thiocyanate, and iso-thiocyanate. These discrete coordination units and co-ligand bridged 1D coordination polymers are further augmented to higher dimensional supramolecular systems having linear, zig-zag, ladder-shaped, ribbon-like, and helical geometry. These supramolecular structures are stabilized by intermolecular hydrogen bonding interaction (N-H center dot center dot center dot N, N-H center dot center dot center dot O, O-H center dot center dot center dot N, O-H center dot center dot center dot O, and C-H center dot center dot center dot O) and p.p interaction capability of PyimH ligand. PyimH generally acts as an excellent chelating ligand for a range of metal ions and is also a capable supramolecular glueing agent due to hydrogen bonding and pi-stacking ability.