ZINC(II) AND CADMIUM(II) METAL-ORGANIC FRAMEWORKS BASED ON THE AMIDE- FUNCTIONALIZED TETRACARBOXYLATE LIGAND: SYNTHESIS, CRYSTAL STRUCTURE, AND LUMINESCENT PROPERTIES

Abstract

By heating cadmium(II) and zinc(II) nitrates with 5-(3,5-dicarboxybenzoylamino)-isophthalic acid in mixed solvents [Cd2(H2O)3(nmp)(L)]·NMP (1), (H2NMe2)2[Cd3(L)2] (2), and (H2NMe2)2[Zn2.5(HL)(L)] (3) metal-organic frameworks are obtained. The compositions and structures of these compounds are determined by X-ray crystallography. Compound 1 has a layered structure, and isostructural 2 and 3 form 3D frameworks. Pores in compound 1 are filled with disordered solvent molecules, and in anionic 3D frameworks of 2 and 3 they contain dimethylammonium cations. The compositions of isostructural compounds 2 and 3 differ because the position of one of the zinc cations is half populated in 3, while the ligand in 3 is partially protonated. In 1, 5-(3,5-dicarboxybenzoylamino)-isophthalic ligands are in an eclipsed conformation; and in 2 and 3, they are in a crossed conformation. The photoluminescent properties are studied in the cadmium(II) and zinc(II) frameworks.