A three-dimensional pillared-layer metal-organic framework: Synthesis, structure and gas adsorption studies

Abstract

A stable 3D MOF, {[Zn3(L)3(DPB)1.5]·6DMF·H2O}n was synthesized using a partially methylated linear rigid linker (LH2) in the presence of the co-linker DPB (1,4-dipyridylbenzene) under solvothermal condition. The complex was found to have channels along the crystallographic a-axis with the pore surfaces aligned with –CH3 groups that resulted in a hydrophobic environment inside the cavity. Thermogravimetric analysis and variable temperature powder X-ray diffraction show high thermal stability of the framework. The solvent molecules in the cavity can be evacuated maintaining the structural integrity of the framework to afford a porous structure. Gas (N2, CH4, CO2 and H2) adsorptions were carried out for this MOF. The desolvated framework shows significant CO2 adsorption over N2 and CH4 at 273K with an isosteric heat of adsorption of ∼21kJ/mol, suggesting a strong interaction of the CO2 molecules with the framework walls.