Coordination-driven self-assembly of a series of dinuclear M 2 L 2 mesocates with a bis-bidentate pyridylimine ligand.

Four isostructural dinuclear M2L2 mesocates of the general formula [M2(NCS)4(L)2]·4.5MeOH (1M; M = Mn, Fe, Co, Zn) were constructed by using the coordination-driven self-assembly of the [M(NCS)2] precursor and the flexible bis-bidentate pyridylimine Schiff base ligand L (L = 4,4'-(1,4-phenylenebis(oxy))bis(N-(pyridin-2-ylmethylene)aniline). The centrosymmetric M2L2 mesocate forms through the side-by-side coordination of two L ligands to a pair of M(ii) ions. The mesocates exhibit a reversible temperature induced desolvation-solvation behavior without losing their structural integrity. The activated 1Co, as the representative M2L2 mesocate, shows an exceptionally high MeOH vapour uptake capacity of 481.9 cm3 g-1 (68.8 wt%) at STP with good recyclability. Notably, it also exhibits CO2 adsorption with an uptake capacity of 20.2 cm3 g-1 (3.6 wt%) at room temperature and 1 bar.