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

•A three-dimensional pillared-layer metal-organic framework has been synthesized.•The structural integrity of the framework is maintained after evacuation.•Gas adsorption studies were carried out for this MOF.•It shows significant CO2 adsorption over N2 and CH4.

A stable 3D MOF, {[Zn3(L)3(DPB)1.5]·6DMF·H2O}n{[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 273 K with an isosteric heat of adsorption of ∼21 kJ/mol, suggesting a strong interaction of the CO2 molecules with the framework walls.

Graphical abstractA robust 3D MOF was synthesized solvothermally using a partially methylated ligand and a pyridine based ditopic coligand. The MOF shows significant uptake of CO2 over N2 and CH4 at 273 K.Figure optionsDownload full-size imageDownload as PowerPoint slide