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

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.