[Mg(H2O)4][(VO)2(PO4)2]: Crystal structure, DFT calculations, and catalytic activity

Abstract

[Mg(H2O)4][(VO)2(PO4)2] has been successfully synthesized in the M2+-V4+-P-O system through hydrothermal synthesis route. It was characterized using single-crystal X-ray diffraction, Fourier Transform Infrared Spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermal stability analysis (TG-DTA). [Mg(H2O)4][(VO)2(PO4)2] crystallizes in the tetragonal system (S.G.: I4/m), with the cell parameters: a = 6.2497(3), b = 6.2497(3), c = 13.4194(8) Å, V = 524.145 Å3, and Z = 2. The structure consists of vanadyl phosphate layers [VO(PO4)]2∞, constructed from O-vertices sharing [VO5]-square pyramids and [PO4] tetrahedral, which are separated by layers of [MgO6] octahedral linked to [VO5] by Mg–O–V bonds along c-axis. FT-IR and Raman studies confirmed the characteristic bands of phosphate and the vanadium (IV) groups. Thermogravimetric analysis of the compound was also used to study its thermal behavior. Furthermore, the catalytic efficiency of the title compound in the reduction by NaBH4 of three nitrophenol isomers (ortho-, meta-, and para-) to their corresponding aminophenols was tested. All three nitrophenol isomers could be reduced in 30 s in the presence of the title compound. First-principles calculations employing density functional theory (DFT) explored the structural, electronic, and optical properties. These computations were utilized to analyze the band structure, density of states, reflectivity, absorption coefficient, refractive index, and extinction coefficient. Examining the band structure and density of states (DOS) reveals that the material possesses a band gap of 2.79 eV.