Synthesis and energy band characterization of hybrid molecular materials based on organic–polyoxometalate charge-transfer salts

Tetrabutyl Ammonium Salts of Keggin-Type Vanadium-Substituted Phosphomolybdates and Phosphotungstates for Selective Aerobic Catalytic Oxidation of Benzyl Alcohol

A series of tetrabutyl ammonium (TBA) salts of V-included Keggin-type polyoxoanions with W (TBA4PW11V1O40 and TBA5PW10V2O40) and Mo (TBA4PMo11V1O40 and TBA5PMo10V2O40) as addenda atoms were prepared using a hydrothermal method. These synthesized materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance (DRS UV-Vis), thermogravimetric analysis (TGA), CHN elemental analysis (EA), inductively coupled plasma spectrometry (ICP-MS), and N2 physisorption techniques to assess their physicochemical/textural properties and correlate them with their catalytic performances. According to FT-IR and DRS UV-Vis, (PVXW(Mo)12−XO40)(3+X)− anions are the main species present in the TBA salts. Additionally, CHN-EA and ICP-MS revealed that the desired stoichiometry was obtained. Their catalytic activities in the liquid-phase aerobic oxidation of benzyl alcohol to benzaldehyde were studied at 5 bar of O2 at 170 °C. Independently of the addenda atom nature, the catalytic activity increased with the number of V in the Keggin anion structure. For both series of catalysts, TBA salts of polyoxometalates with the highest V-substitution degree (TBA5PMo10V2O40 and TBA5PW10V2O40) showed higher activity. The maximum benzyl alcohol conversions obtained were 93% and 97% using (TBA)5PMo10V2O40 and (TBA)5PW10V2O40 as catalysts, respectively. In all the cases, the selectivity toward benzaldehyde was higher than 99%.

The corrosion inhibition of stainless steel by ferrocene–polyoxometalate hybrid molecular materials – experimental and first principles studies

The corrosion inhibition mechanism for SS316 coated with FcPMo hybrid material is shown.

Hydrothermal synthesis and crystal structure of a bisupporting Keggin-polyoxometalate hybrid compound decorated with a copper(II) complex unit

A bisupporting Keggin-type polyoxometalate compound, {[CuII(phen)2]2[(HBW12O40)]}[CuIICl2(phen)]2· 2H2O (phen=1,10-phenathroline) (1), has been synthesized through the hydrothermal method and characterized by IR spectroscopy, elemental analysis, UV/Vis/NIR spectroscopy, and powder and single crystal X-ray diffraction. The bisupporting Keggin-polyoxometalate consists of one Keggin-type [HBW12O40]4−core and two covalently linked copper(II) complex fragments [Cu(phen)2]2+. In the crystal structure π···π interactions, C–H···Cl, O–H···Cl, O–H···O and C–H···O hydrogen bonds lead to a three-dimensional supramolecular structure.