A Cu(II)-organic framework with hxl topology as an efficient adsorbent for methylene blue

The present work demonstrates the synthesis of a Cu-pyrazinedicarboxylate derived coordination polymer (CP), {[Cu(pzdca)2](Me2NH2)2}n (HT-2) (H2pzdca = 2,3-Pyrazindicarboxylic acid). The coordination polymer has been characterized using FTIR, PXRD, TGA, SEM and single crystal X-ray analysis. HT-2 crystallizes in a monoclinic system with the P21/c space group. The asymmetrical unit of HT-2, [Cu(pzdca)](Me2NH2) is composed of single Cu ion, one coordinated linker (pdca2−) and one free dimethyl aminium cation. The coordination sphere of the CP is anionic which is counter balanced by two dimethyl ammonium cations. The crystallography indicates that the structure around Cu2+ ion is octahedral and the topological analysis discloses that the valence-bonded MOFs for the HT-2 results in underlying 2,4-c net with the hxl topology. The present polymer has been assessed for environmental remediation as an adsorbent for hazardous aromatic dyes. The HT-2 effectively adsorbs the cationic dye (MB) from the mixture of the cationic (MB) and anionic (MO) dyes under ambient temperature and pH. Thus, the present CP is an intriguing example of the structure-property relationship for tuning the adsorption capacities towards hazardous environmental pollutants.