Coordination-driven self-assembly of a series of dinuclear M2L2 mesocates with a bis-bidentate pyridylimine ligand

Abstract

Four isostructural dinuclear M₂L₂ mesocates of the general formula [M₂(NCS)₄(L)₂]·4.5MeOH (1_M; 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 1_Co, 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.