Tuned synthesis of two coordination polymers of Cd(ii) using substituted bent 3-pyridyl linker and succinate: structures and their applications in anion exchange and sorption properties

Abstract

Two new Cd(II) coordination polymers, namely [Cd(3-bpdh)₂(ClO₄)₂]_n (1) and {[Cd(3-bpdh)(suc)(H₂O)]·3(H₂O)}_n (2), have been synthesized using a substituted bent N,N′-donor ligand 2,5-bis-(3-pyridyl)-3,4-diaza-2,4-hexadiene (3-bpdh) and aliphatic dicarboxylate disodium succinate (suc) with Cd(II) perchlorate salts at room temperature by a slow diffusion technique for the exploration of our previous reported work. Both the structures were determined by single-crystal X-ray diffraction analysis and also by other physicochemical methods. Structure analysis revealed that complex 1 is a 1D chain structure containing coordinated perchlorate with a metal centre, and complex 2 shows a porous 3D framework with encapsulation of lattice water molecules into the void along the crystallographic a-axis. The PXRD study shows the bulk purity of both the complexes and TGA analysis of 2 exhibits that the structure is thermally stable up to 250 °C. Complex 1 shows a nice anion exchange property with replacement of weakly coordinated perchlorate with the inclusion of new anions; and the anion exchanged solids were characterised by FT-IR, PXRD and photoluminescence properties. The desolvated framework of 2 exhibits sorption of CO₂ and water vapor and surface adsorption of N₂ corroborating with the nature of the pore environment present in 2. The photoluminescence study has been also done for both complexes in the solid state which exhibits ligand based emissions at room temperature.