A porous Zn(ii)-coordination polymer based on a tetracarboxylic acid exhibiting selective CO2 adsorption and iodine uptake

Abstract

A porous Zn(II)-coordination polymer, namely {[Zn₂(μ₈-abtc)(betib)]·DMF}_n (1), was solvothermally synthesized from 3,3′,5,5′-azobenzenetetracarboxylate (abtc⁴⁻) and 1,4-bis(2-ethylimidazol-1-yl)butane (betib) ligands and {[Zn₂(μ₈-abtc)(betib)]·H₂O}_n (2) was obtained through the immersion of 1 in methanol. Compounds 1 and 2 were structurally characterized via numerous techniques. Both compounds displayed a 3D porous framework with a 3,6-connected sqc5381 net. Compound 2a obtained at 140 °C from 2 exhibited gas and iodine adsorption properties. Interestingly, the compound adsorbed selectively CO₂ with the uptake capacity of 54.02 cm³ g⁻¹ (13.26%) over N₂ (5.43 cm³ g⁻¹) and CH₄ (14.53 cm³ g⁻¹) at 273 K. The compound also adsorbed iodine with the weights of 19.99% and 30.26% in solution and vapor phases, respectively. The single crystal X-ray result and Raman spectra showed the presence of iodine units in the pores of the framework.