Layer-pillared zinc(II) metal–organic framework built from 4,4′-azo(bis)pyridine and 1,4-BDC

Novel layer-pillared metal–organic framework {[Zn2(OH)(AZPY)(BDC)1.5]·H2O}n (AZPY = 4,4′-azo(bis)pyridine; BDC = 1,4-benzenedicarboxylate) was prepared and characterized. The compound is formed by binuclear secondary building units of the composition [Zn2(OH)(BDC)0.5]2+, that are interconnected by AZPY and other BDC ligand giving neural (4,4)-grid-like polymeric sheets. Two adjacent sheets are pillared by 1,4-BDC2− anions forming bilayers, that are further interpenetrated. Wide-angle X-ray scattering experiments demonstrated that the framework structure of the coordination polymer is stable upon the removal of the water molecule by heating and the compound remains crystalline. The packing of the crystal is characteristic by the presence of voids and small structure channels that are propagated along [0 1 1] crystallographic direction. The adsorption studies reveal that prepared compound can adsorb nitrogen and carbon dioxide. The adsorption capacity for CO2 at 273 K, determined as amount of carbon dioxide adsorbed at p/p0 = 0.9, was 1.04 mmol/g.