Selective CO2adsorption in four zinc(ii)-based metal organic frameworks constructed using a rigid N,N′-donor linker and various dicarboxylate ligands

Abstract

Four new Zn(II)-based metal organic frameworks (MOFs), namely, [Zn(tdc)(4-bpmh)]n·n(H2O) (1), [Zn(2-NH2BDC)(4-bpmh)]n·n(EtOH) (2), [Zn(NDC)(4-bpmh)]n (3) and {[Zn(ADPA)(4-bpmh)(H2O)](ClO4)}n·n(MeOH) (4) (tdc = 2,5-thiophene dicarboxylic acid, 2-NH2BDC = 2-aminoterephthalic acid, NDC = 2,6-naphthalene dicarboxylic acid, ADPA = adipic acid, 4-bpmh = N,N-bis-pyridin-4-ylmethylene-hydrazine) have been synthesized through the slow diffusion technique using a 4-bpmh linker and different dicarboxylic acids. Structural analysis reveals that compounds 1–3 have 3D networks with diamondoid (dia) topologies whereas compound 4 has a 2D pillared-trilayer framework with sql/Shubnikov tetragonal plane net topology. Compounds 1–2 have 6-fold interpenetrated nets and compound 3 is a 7-fold interpenetrated net. Gas adsorption studies reveal that all the compounds 1–4 show selective adsorption of CO2 over other gases (N2, CH4) at low temperature, and the uptake amount of compound 2 is almost double in comparison with those of compounds 1, 3 and 4.