Synthesis and two-dimensional correlation infrared spectroscopy study of an organic–inorganic hybrid compound constructed by [Mo5P2O23] and Cu-imidazole components

Abstract A novel compound, (Himi)(H 3 O) [Cu(imi) 2 ] 2 [P 2 Mo 5 O 23 ]·H 2 O 1 (imi = imidazole), was synthesized by hydrothermal method and characterized by X-ray single analysis, ESR spectrum, one-dimensional (1D) infrared spectroscopy and two-dimensional (2D) correlation infrared spectroscopy under thermal and magnetism perturbation. Crystal data for the compound 1 : orthorhombic system, space group Pnma , a  = 14.580(3) A, b  = 21.073(4) A, c  = 16.664(3) A, Z  = 4. It consists of the Mo–Cu building-blocks [Cu(imi) 4 ] 2 [P 2 Mo 5 O 23 ] 2− , protonated imidazole cations and water molecules. In the Mo–Cu building-blocks, [Mo 5 P 2 O 23 ] 6− clusters are linked by {Cu(imi) 4 } 2+ group to form a two-dimension parallelogram griddling structure. From the 2D IR correlation spectroscopy analyses, it is discovered that the intensity changes of Mo O and P–O band are sensitive to the temperature variation, whereas the Mo–O bond linking to Cu 2+ can be remarkably affected by the magnetism variation. Furthermore, the intensity changes of P–O bands occur prior to that of the Mo O band during the temperature elevation.