New hybrid nanostructures based on keggin-type 12-tungstophosphate and some metal-semicarbazone complexes: Synthesis, x-ray crystal structures and spectroscopic studies

Abstract

Three novel inorganic-organic hybrid nanomaterials [Mn(HL)4Cl2](PW12O40)2.4CH3OH.8H2O (1), [Ni(L)2]2(PW12O40).2HCl.4CH3OH.8H2O (2) and [Cd(HL)6](PW12O40)2.3CH3OH.8H2O (3) have been synthesized by a simple one-pot reaction of phosphotungestic acid (H3PW12O40 abbreviated as PW12) and 2-pyridinecarbaldehyde semicarbazone ligand (HL). The synthesized hybrid nanomaterials were characterized by FT˗IR, UV˗Vis, powder and single crystal X˗ray diffraction (XRD), SEM, EDX and TGA. The FT-IR, UV–Vis, PXRD and TG results of nanomaterials 1–3 confirm their successful synthesis. Compound 1 with a monoclinic P21/c space group exhibits a three-dimensional (3D) framework composed Keggin-type PW12 clusters and discrete octahedral trans-[Mn(HL)4Cl2]. In compound 2, a 3D network constructed from octahedral [Ni(L)2] and individual PW12 clusters in the triclinic P-1 space group. Compound 3 crystallizes in the triclinic P-1 space group and displays a complicated 3D network built by the Keggin PW12 POM clusters and discrete tetrahedral [Cd(HL)4]2+complex subunits. In counds 1 and 3, the HL semicarbazone act as a O(CO)-donor monodentate ligand, while in the compound 2 the deprotonated L semicarbazone functions as a Npy,N,O(CO)-donor tridentate ligand. The crystal components in 1–3 are connected through numerous weak N/C–H⋯O(POM) and N/C–H⋯Cl hydrogen bonds to construct the three-dimensional networks. In 1–3, the 3D supramolecular networks are maintained through electrostatic and/or hydrogen bonding interactions. For compounds 1–3, both the simulated and experimental X-ray powder diffraction patterns match each other, indicating good phase purity of our samples. Furthermore, the performance of 1–3 in the removal of cationic methylene blue (MB) dye and anionic methyl orang (MO) dye from aqueous solutions was investigated.