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

Three novel inorganic-organic hybrid nanomaterials [Mn(HL) 4 Cl 2 ](PW 12 O 40 ) 2.4CH 3 OH.8H 2 O ( 1 ), [Ni(L) 2 ] 2 (PW 12 O 40 ).2HCl.4CH 3 OH.8H 2 O ( 2 ) and [Cd(HL) 6 ](PW 12 O 40 ) 2.3CH 3 OH.8H 2 O ( 3 ) have been synthesized by a simple one-pot reaction of phosphotungestic acid (H 3 PW 12 O 40 abbreviated as PW 12 ) 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 P2 1 /c space group exhibits a three-dimensional (3D) framework composed Keggin-type PW 12 clusters and discrete octahedral trans-[Mn(HL) 4 Cl 2 ]. In compound 2, a 3D network constructed from octahedral [Ni(L) 2 ] and individual PW 12 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 PW 12 POM clusters and discrete tetrahedral [Cd(HL) 4 ] 2+ complex subunits. In counds 1 and 3, the HL semicarbazone act as a O(C O)-donor monodentate ligand, while in the compound 2 the deprotonated L semicarbazone functions as a N py,N,O(C O)-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.