Selective CO₂ Adsorption at Low Pressure in Nitrogen‐Rich Copper(II) Coordination Polymers

Abstract

Herein, a series of polymeric copper(II) complexes were obtained using four different triazoles: 3-amino-1,2,4-triazole (HL1), 3,5-diamino-1,2,4-triazole (HL2), 3-amino-1,2,4-triazole-5carboxylic acid (H 2 L3) and 1,2,4-triazole-3-carboxylic acid (H 2 L4); through solvothermal conditions, under controlled pressure and high temperature, following usual procedures described in the literature. These triazoles were chosen to exploit their different coordination modes to copper(II) metal centres to obtain interesting structures and varied gas adsorption selectivity. The isolated materials were characterized by common spectroscopic techniques (IR, diffuse reflectance UV-Vis, EPR), CHN analyses, X-ray diffraction (XRD), thermogravimetric analyses, and SQUID magnetometry to give an insight into their structure and composition. Besides, they had their BET surface area determined by nitrogen adsorption-desorption isotherms, to assess their porosity. At last, their capacity to adsorb carbon dioxide selectively was also evaluated, in line with those reported for similar systems in the literature. Although having small surface area, these compounds are able to adsorb CO 2 selectively at very low pressure (under 600 mbar).