Heterometallic trinuclear cluster-based microporous metal-organic framework with high adsorption selectivity of CO₂ over N₂

A new metal-organic compound, [Zn2Ca(bdc)(3)(H2O)(2)](n)center dot x(solvent) (1 H(2)bdc = terephthalic acid), has been successfully constructed via the solvothermal reactions of H(2)bdc, Zn(NO3)(2)center dot 6H(2)O and Ca(NO3)(2)center dot 4H(2)O. Two symmetry-related Zn(II) ions and one Ca(II) are bridged by six bis-monodentate carboxylate groups together to form a heterometallic trinuclear [Zn2Ca(COO)(6)] cluster subunit. The linear bdc(2-) ligands further connected these trinuclear clusters into a 3D porous framework with 6-connected pcu topology. Remarkably, this porous compound can be stable up to 256 degrees C verified by the thermogravimetric analysis and powder X-ray diffraction analysis. Gas adsorption property investigations demonstrated that it shows high adsorption selectivity for CO2 over N-2 at ambient conditions.