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Two POM@MOF hybrid materials composed of a copper-based metal–organic framework (MOF) [Cu3(C9H3O6)2(H2O)3]n (HKUST-1) encapsulating vanadium-substituted Keggin polyoxometalates (POM), [α-PVW11O40]4− (PVW11) and [α-PV2W10O40]5− (PV2W10), were prepared and characterized. PVW11@HKUST-1 and PV2W10@HKUST-1 were synthesized hydrothermally by self-assembly of HKUST-1 in the presence of the preformed POMs, [α-PVW11O40]4− and [α-PV2W10O40]5−, respectively. The two POM@MOF composites were characterized by X-ray diffraction, TGA, BET surface area analysis and FT-IR and Raman spectroscopy. The electronic structure of the POM@MOF materials and their respective constituents is surveyed using solid state UV-vis reflectance spectroscopy. The UV-vis spectra order the oxidizing strength of the POM constituents ([α-PV2W10O40]5− > [α-PVW11O40]4−) and reveal the distinct electronic structure of the POM@MOF materials obtained by synthetic encapsulation of mono- and di-vanadium substituted Keggin polyoxotungstates in HKUST-1. [ABSTRACT FROM AUTHOR]

Organofunctionalized tetranuclear clusters [(MIICl)2(VIVO)2{((HOCH2CH2)(H)N(CH2CH2O))(HN(CH2CH2O)2)}2] (1, M=Co, 2: M=Zn) containing an unprecedented oxometallacyclic {M2V2Cl2N4O8} (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo‐alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single‐crystal X‐ray diffraction structure analysis. The isostructural clusters are formed of edge‐sharing octahedral {VO5N} and trigonal bipyramidal {MO3NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of 1 and 2 in an unusual two‐mode fashion, unobserved previously. In the crystalline state, the clusters of 1 and 2 are joined by hydrogen bonds to form a three‐dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [Jiso(VIV−VIV)=−5.4(1); −3.9(2) cm−1], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [Jiso (VIV−CoII)=−12.6 and −7.5 cm−1] contained in 1. [ABSTRACT FROM AUTHOR]

Molecular metal oxide cluster, K5[α-1,2-PV2W10O40] (PV2W10), was found to have intrinsic catalytic activity for the oxidative dehydrogenation of propane with high selectivity (> 80%) to propylene at low propane conversion (0.3%). Synthesis of dispersed PV2W10 in non-reducible supports, γ-Al2O3 and SiO2, was done by incipient wetness impregnation. The supported catalysts were characterized by IR, Raman spectroscopy, nitrogen adsorption, x-ray powder diffraction (PXRD), elemental analysis, hydrogen temperature-programmed reduction (H2–TPR), and ammonia temperature-programmed desorption (NH3–TPD). Catalytic testing of the supported PV2W10 at equimolar cluster concentration revealed that when supported in γ-Al2O3 it is more active (sevenfold increase in propane conversion) but in SiO2 it is more selective to propylene (94%). The observed performance was due to both an increase in reducibility and higher concentration of strong acid sites for PV2W10 supported in γ-Al2O3 versus SiO2. Lastly, PV2W10 was shown to remain intact under reaction conditions indicating its thermal and oxidative stability. [ABSTRACT FROM AUTHOR]

Two POM@MOF hybrid materials composed of a copper-based metal-organic framework (MOF) [Cu 3 (C 9 H 3 O 6 ) 2 (H 2 O) 3 ] n (HKUST-1) encapsulating vanadium-substituted Keggin polyoxometalates (POM), [α-PVW 11 O 40 ] 4- ( PVW 11 ) and [α-PV 2 W 10 O 40 ] 5- ( PV 2 W 10 ), were prepared and characterized. PVW 11 @HKUST-1 and PV 2 W 10 @HKUST-1 were synthesized hydrothermally by self-assembly of HKUST-1 in the presence of the preformed POMs, [α-PVW 11 O 40 ] 4- and [α-PV 2 W 10 O 40 ] 5- , respectively. The two POM@MOF composites were characterized by X-ray diffraction, TGA, BET surface area analysis and FT-IR and Raman spectroscopy. The electronic structure of the POM@MOF materials and their respective constituents is surveyed using solid state UV-vis reflectance spectroscopy. The UV-vis spectra order the oxidizing strength of the POM constituents ([α-PV 2 W 10 O 40 ] 5- > [α-PVW 11 O 40 ] 4- ) and reveal the distinct electronic structure of the POM@MOF materials obtained by synthetic encapsulation of mono- and di-vanadium substituted Keggin polyoxotungstates in HKUST-1.

Organofunctionalized tetranuclear clusters [(M II Cl) 2 (V IV O) 2 {((HOCH 2 CH 2 )(H)N(CH 2 CH 2 O))(HN(CH 2 CH 2 O) 2 )} 2 ] (1, M=Co, 2: M=Zn) containing an unprecedented oxometallacyclic {M 2 V 2 Cl 2 N 4 O 8 } (M=Co, Zn) framework have been prepared by solvothermal reactions. The new oxo-alkoxide compounds were fully characterized by spectroscopic methods, magnetic susceptibility measurement, DFT and ab initio computational methods, and complete single-crystal X-ray diffraction structure analysis. The isostructural clusters are formed of edge-sharing octahedral {VO 5 N} and trigonal bipyramidal {MO 3 NCl} units. Diethanolamine ligates the bimetallic lacunary double cubane core of 1 and 2 in an unusual two-mode fashion, unobserved previously. In the crystalline state, the clusters of 1 and 2 are joined by hydrogen bonds to form a three-dimensional network structure. Magnetic susceptibility data indicate weakly antiferromagnetic interactions between the vanadium centers [J iso (V IV -V IV )=-5.4(1); -3.9(2) cm -1 ], and inequivalent antiferromagnetic interactions between the cobalt and vanadium centers [J iso (V IV -Co II )=-12.6 and -7.5 cm -1 ] contained in 1., (© 2023 Wiley-VCH GmbH.)