Cd(II)-MOF: adsorption, separation, and guest-dependent luminescence for monohalobenzenes.

A series of isostructural 2-fold interpenetrating 2D Cd(II)-MOFs, namely G⊂CdL2(OTs)2 (G = THF (1), PhF (2), PhCl (3), PhBr (4), PhI (5), L = 1,2-bis[(3-(pyridin-4-yl)phenoxy]ethane, and OTs(-) = p-toluenesulfonate anion), have been successfully synthesized from the flexible ethylene glycol ether-bridging ligand L and Cd(OTs)2 in solution. The CdL2(OTs)2 framework contains squarelike nonpolar channels, and the encapsulated guest molecules can be removed by heating (150 °C) to generate a guest-free host framework which is able to reversibly adsorb monohalobenzenes PhX (X = F, Cl, Br, I) in the liquid phase under ambient conditions without loss of framework integrity. Furthermore, it can effectively separate these monohalobenzenes and exhibits a clear affinity for monohalobenzenes according to the following order: PhI > PhBr > PhCl > PhF. In addition, PhX⊂CdL2(OTs)2 exhibits guest-dependent luminescence properties.