Anions, solvents and spacer ligands assisted hydrogen-bonding coordination frameworks from tripodal ntb ligands

Four new hydrogen-bonding (HB) coordination frameworks were synthesized and structurally characterized by using tris(2-benzimidazoylmethyl)amine (ntb) to react with different transition metal salts, which show diversified coordination motifs and hydrogen extending modes due to the contribution of counter-anions, methanol solvents, or spacer ligands, respectively. Among which, complexes 1 and 2 show mononuclear coordination units, connected by abundant N-H⋯N and N-H⋯O bonds formed between the units with trifluoromethanesulfonate (OTf^-), azide (N₃^-) anions or methanol solvents into 2D sheets, which are further connected by C-H⋯O or π⋯π interactions into 3D topological nets; while in complexes 3 and 4, the spacer ligands 4-(pyridin-4-yl)pyridine (4′4-bipy) or 4,4′-bipyridine 1,1′-dioxide (dbpo) also participate in the coordination, resulting in either dinuclear coordination units linked by hydrogen-bonding into (4, 4) net or two different kinds of mononuclear units further extended by hydrogen-bonding into array of helical chains.