Polyoxometalate-based Inorganic Organic Hybrid Research Articles

Two new Keggin-type polyoxometalate-based organic-inorganic hybrid compounds with metal ions and chelate ligands

Two new hybrid compounds with chemical formulas [Co(L1)2(H2O)2]2[SiW12O40]·6H2O (1) and [Cu2(C9H22 N)2(L2)2][SiW12O40]·2H2O (2) (L1 = 3,3′-diamino-5,5′-bis(1H-1,2,4-triazole), L2 = 1,2-bis(3-(2-pyridyl)pyrazole-1-ylmethyl)benzene, C9H22 N = tripropylamine) were prepared in a hydrothermal reaction system containing Keggin-type polyoxometalates (POMs), transition metal (TM) salts (cobalt salts and copper salts), and chelate L1/L2 ligands. X-ray structural analysis reveals that 1 and 2 possess 3-D supramolecular host frameworks with large cavities and the polyoxoanions SiW12 reside in these cavities as the guest templates. The photocatalytic activities of 1 and 2 were investigated. Both compounds show efficient catalytic activity for degradation of RhB with 1 > 2. The loading amount of the POM units and the structural features of these POM-based organic-inorganic hybrid compounds may be necessary factors that affect the activity of catalysts in the photocatalytic degradation.

One Pot Synthesis of Octahydroquinazolinone Derivatives Using (Me (Im)12) H4CuPW11O39 as a Surfactant Type Catalyst

This study is aimed at proposing a practical green procedure for the synthesis of octahydroquinazolinone derivatives using benzaldehyde, dimedone and urea under microwave irradiation in water. A surfactant type polyoxometalate-based organic–inorganic hybrid was able to efficiently catalyze this synthesis. The catalyst was prepared and characterized by Fourier transform infrared, UV–Vis, X-ray diffraction, and thermogravimetric analysis. The employed catalyst exerted a synergistic effect; the anion part acted as a catalyst while the cation part acted as a surfactant in order to increase the concentration of organic reactants in water. The main advantage of this method is its remarkable yield in short reaction periods, which results in the rendering of products with high purity. Moreover, this heterocatalyst is capable of being easily recovered and reused several times. The influences of reaction conditions were studied systematically, and a possible catalysis mechanism was proposed for understanding the highly efficient heterogeneous catalytic behavior.

Visible light photodegradation of organic dyes, reduction of CrVI and catalytic oxidative desulfurization by a class of polyoxometalate-based inorganic-organic hybrid compounds

A new family of polyoxometalates-based inorganic–organic hybrid compounds, namely, [Ag4(H2O)(L)3(SiW12O40)] (1), [Zn(L)(H2O)]2[SiW12O40]·3H2O (2), [Cu(L)(H2O)]2[SiW12O40] (3), and [Cu2(L)2(HPWVI10WV2O40)]·4H2O (4), have been synthesized (L = 1,4–bis(3-(2-pyridyl)pyrazol)butane). This series of inorganic–organic hybrid compounds exhibit variable supramolecular architectures. The photodegradation of organic dyes malachite green and methylene blue with the use of compounds 1–4 as photocatalysts was studied under visible light irradiation. Strikingly, the photocatalytic result demonstrates that compound 1 is an efficient photocatalyst for the removal of malachite green and methylene blue. Remarkably, compound 1 serves as an active and recyclable photocatalyst for the reduction of CrVI with isopropanol as scavenger at ambient temperature. The catalytic oxidative desulfurization of thioanisole was also investigated with the use of compounds 1–4 as catalysts and tert-butyl hydroperoxide as oxidant. The catalytic results indicate that compounds 3 and 4 behave high catalytic performance for the oxidation of the thioanisole.

Crystal Structure and Band Gap Engineering in Polyoxometalate-Based Inorganic-Organic Hybrids.

We have demonstrated engineering of the electronic band gap of the hybrid materials based on POMs (polyoxometalates), by controlling its structural complexity through variation in the conditions of synthesis. The pH- and temperature-dependent studies give a clear insight into how these experimental factors affect the overall hybrid structure and its properties. Our structural manipulations have been successful in effectively tuning the optical band gap and electronic band structure of this kind of hybrids, which can find many applications in the field of photovoltaic and semiconducting devices. We have also addressed a common crystallographic disorder observed in Keggin-ion (one type of heteropolyoxometalate [POMs])-based hybrid materials. Through a combination of crystallographic, spectroscopic, and theoretical analysis of four new POM-based hybrids synthesized with tactically varied reaction conditions, we trace the origin and nature of the disorder associated with it and the subtle local structural coordination involved in its core picture. While the crystallography yields a centrosymmetric structure with planar coordination of Si, our analysis with XPS, IR, and Raman spectroscopy reveals a tetrahedral coordination with broken inversion symmetry, corroborated by first-principles calculations.

Two hybrid compounds constructed from Ni-tris(imidazolyl) complexes and Keggin clusters: Syntheses, structures and electrochemical properties

By introducing different polyoxotungstates into the Ni-tib (tib = 1, 3, 5-tris (1-imidazolyl)benzene) system, two new polyoxometalate-based inorganic-organic hybrids with distinct architectures, [Ni(Htib)4][PW12O40]2 (1) and [Nitib]2(H2O)4](GeW12O40)·2H2O (2) have been synthesized under the same hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) patterns and thermogravimetic (TG) analyses. Structural analyses show that compound 1 is a dimer, in which two neighboring mono-connected [PW12O40]3- (PW12) clusters are linked together by a [Ni(Htib)4] complex cation. In contrast to compound 1, compound 2 presents a 2D grid layer formed by bi-connected [GeW12O40]4- (GeW12) clusters and [Ni2(H2O)4(tib)2] complex cations, and the adjacent layers are further linked together by the hydrogen bondings to form a highly opened 3D framework. The distinct structural features of two hybrids suggest that the charge of the Keggin anions should play a key role in the process of assembly. Additionally, the electrochemical properties of compounds 1 and 2 have been investigated, and the results indicated that 1 and 2 have good electrocatalytic activities towards reduction of nitrite and oxidation of ascorbic acid.

Room-temperature mechanochemical preparation and electrochemistry properties of polyoxometalate-based inorganic-organic hybrid

Based on the Keggin-type silicotungstic acid and thiourea, a new inorganic-organic hybrid with lamellar shape has been synthesized by a mechanochemical route at room temperature. The heteropolyanions still retained the Keggin-type structure in the hybrid. It was designed as a carbon paste electrode to investigate its electrochemical properties. The sample shows the characteristic electrochemical properties of Keggin-type polyanions, holding three couples of stable and reversible redox peaks in the range of −0.15~−0.73V, which may arise from the maintenance of Keggin-type polyanions and the pore structure of lamina. This work proposed a new synthetic route for polyoxometalates-based hybrid, and offered an effective method to investigate the property of polyoxometalate-based hybrid under the solid state condition.

A new type of photomagnetic system: photoinduced charge transfer in polyoxometalate-based organic-inorganic hybrid.

Herein, we show a new photomagnetic system that gives rise to the magnetic transformation from diamagnetism to paramagnetism by photoinduced intramolecular charge transfer in the polyoxometalate-based organic-inorganic hybrid, [(VMo6O22)2{O2C(CH2)2CO2}3] (1).

A polyoxometalate-based inorganic–organic hybrid polymer constructed from silver-Schiff base building block and Keggin-type cluster: Synthesis, crystal structure and photocatalytic performance for the degradation of rhodamine B

One polyoxometalate-based inorganic–organic hybrid polymer [Ag3L4(PMo12O40)(CH3OH)]·CH3OH (1), where L is N,N′-bis(furan-2-ylmethylene)hydrazine, has been synthesized at room temperature and structurally characterized by infrared spectroscopy, ultraviolet–visible spectroscopy, elemental analysis, X-ray powder diffraction and X-ray single-crystal crystallography. The structure of 1 exhibits a crystalline one-dimensional polymer constructed by the connections of Keggin-type [PMo12O40]3− anions and [Ag3L4]3+ units, in which each Ag(I) center adopted a distorted square pyramidal environment. The spectroscopic experiments show that polymer 1 not only is potential semiconductor materials but also displays the obvious photocatalytic performance for the degradation of rhodamine B.

A polyoxometalate-based inorganic–organic hybrid material: synthesis, characterization structure and photocatalytic study

Abstract A new polyoxometalate (POM)-based inorganic–organic hybrid compound, [Ag2(bib)3][H2SiW12O40] (1), has been hydrothermally synthesized and characterized by routine methods. Single-crystal X-ray diffraction analysis reveals that inorganic supramolecular chains constructed of POM and [Ag2(bib)3] subunits are fused together via the Ag cations forming a 3D supramolecular structure. The structure possesses the moganite-type topology. The photocatalytic properties have been investigated through the oxidative decomposition of Rhodamine-B dye.

Assembly and properties of a high dimensional and high connective Preyssler polyoxometalate modified by Ag(I) coordination polymers

Through using AgNO 3 , K 12.5 Na 1.5 [NaP 5 W 30 O 110 ]·15H 2 O and flexible ligand 1,1'-bis(3,5-dimethyl- 1 H -pyrazolate)methane (H 2 bdpm) as reactants, a novel Ag-encapsulated Preyssler-type polyoxometalate-based organic-inorganic hybrid compound, [Ag 13 (H 2 bdpm) 8 (H 2 O) 5 (HAgP 5 W 30 O 110 )]·2H 2 O ( 1 ), has been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectrum, TG analyses and single crystal X-ray diffraction. Crystal structure analysis shows that compound 1 crystallizes in the triclinic system, space group P 1 , a =19.135(5) A, b =20.313(5) A, c =28.400(5) A, Z =2, R 1 =0.0550, wR 2 =0.1542. Compound 1 contains a rare Preyssler-type polyoxoanion with Ag(I) as a center, which is linked by other Ag ions to form a 2D inorganic layer. Adjacent layer are further connected by various Ag-H 2 bdpm subunits to construct a 3D framework. The structural feature of 1 rests on the high connectivity of the Preyssler polyoxoanion (18-connected) and the diverse coordination modes of Ag I .

Polyoxometalate-based organic-inorganic hybrid compounds containing transition metal mixed-organic-ligand complexes of N-containing and pyridinecarboxylate ligands.

Five new organic–inorganic hybrid compounds based on the Keggin-type polyoxoanion [SiW12O40]4−, namely [Cu3(2,2′-bpy)3(inic)(μ2-OH)(H2O)][SiW12O40]·2H2O (1), [Cu6(phen)6(μ3-Cl)2(μ2-Cl)2Cl2(inic)2][SiW12O40]·6H2O (2), [Cu2(hnic)(2,2′-bpy)2Cl]2[H2SiW12O40] (3), [Cu2(nic)(phen)2Cl2]2[SiW12O40] (4) and [Cu2(pic)(2,2′-bpy)2Cl]2[SiW12O40] (5) (inic = isonicotinic acid, hnic = 2-hydroxy-nicotinic acid, nic = nicotinic acid, pic = picolinic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been synthesized and characterized by IR, UV-Vis, XPS, XRD, cyclic voltammetric measurements, photoluminescence analysis and single crystal X-ray diffraction analysis. Crystal analysis reveals that compound 1 exhibits a 2-D double layered framework structure constructed from [SiW12O40]4− and copper-aqua-2,2′-bipy-hydroxyl-isonicotinate complexes. Compound 2 is a 0-D discrete structure formed by [SiW12O40]4− and copper-chloro-isonicotinate-phenanthroline complexes. Compound 3 shows a 1-D single chain structure based on the linkage of copper-2,2-bpy-chloro-2-hydroxy-nicotinate complexes and [SiW12O40]4−. Compounds 4 and 5 both contain polyoxometalate supported transition metal complexes, one is a polyoxometalate supported copper-chloro-nicotinate-phenanthroline complex in 4, and the other is a polyoxometalate supported copper-2,2-bpy-chloro-nicotinate complex in 5. It should be noted that nicotinic, isonicotinic and picolinic acids are structural isomers and 2-hydroxy-nicotinic acid is an in situ hydroxylated product of nicotinic acid. In addition, photocatalytic degradation of Rhodamine B (RhB) by compounds 1–5 has been investigated in aqueous solutions.

Planar {Ni6} cluster-containing polyoxometalate-based inorganic-organic hybrid compound and its extended structure.

Two {Ni6} cluster-containing inorganic-organic hybrid compounds have been successfully synthesized in the presence of organic amine under hydrothermal conditions, and they were characterized by powder and single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and IR spectroscopy. Structural analysis indicates that [Ni0.5(H2O)3][{Ni6(μ3-OH)3en(H2O)10}(H2P2W15O56)]·10H2O (1, en = ethylenediamine) is a triangular inorganic {Ni6} cluster substituted polyoxotungstate with only one en to stabilize the {Ni6} cluster. However, [Ni(dap)2]{[Ni1.5(dap)1.5(H2O)3][Ni6(μ3-OH)3(dap)2(en)(H2O) {O2C(CH2)2CO2}0.5(CH3COO)(P2W15O56)]}·15H2O (2, dap = 1,2-diaminopropane) is a three-dimensional inorganic-organic hybrid compound linked by succinic acid. The magnetic properties of both compounds were studied. In addition, the adsorption properties of compound 2 have also been investigated.

ChemInform Abstract: Two New Helical Compounds Based on Keggin Clusters and N‐Donor Multidentate Ligand: Syntheses, Structures and Properties.

AbstractKeggin‐type polyoxometalate‐based inorganic‐organic hybrids [CuH3L2(GeMo12O40)] ·2H2O (I) and [CuH3L2(SiMo12O40)] ·2H2O (II) (L: 2,4,5‐tri(4‐pyridyl)‐imidazole) are prepared from Cu(O‐Ac)2, GeO2 or Na2SiO3, Na2MoO4, and L under hydrothermal conditions (autoclave, 170 °C, 5 d, 44% and 18% yield, resp.).

Anion-induced supramolecular isomerism in two Preyssler P5W30 polyoxometalate-based hybrid materials.

Two extended Preyssler P5W30 polyoxometalate-based inorganic-organic hybrid materials exhibiting anion-induced supramolecular isomerism were reported. Because of the cis-trans isomerism in the octahedral CoN2O4 coordination geometry, the Preyssler P5W30 polyoxometalates are extended by double O-Co-O bridges in 1α and a single O-Co-O bridge in 1β to form the isomeric 2D 4-connected 4(4)-sql and 3D 8-connected bcu networks, respectively. Both compounds show electrocatalytic abilities on the reduction of H2O2.

Modulating the polyoxometalate-based inorganic–organic hybrids from simple chains to complicated frameworks via changing POM clusters

Investigation into a hydrothermal reaction system with a copper salt, 1-(imidazo-1-ly)-4-(1,2,4-triazol-1-ylmethyl)benzene) (itb) ligand and three types of polyoxometalates (POMs) led to the preparation of three new coordination polymers, [Cu2(itb)4(H4P2W18O62)]·H2O (1), [Cu(itb)4(HPW12O40)]·4H2O (2) and [Cu2(itb)2(Mo8O26)]·6H2O (3). The three coordination polymers were characterized by elemental analyses, single-crystal X-ray diffraction, powder X-ray diffraction, XPS and IR spectra. Structural analyses show that with modulating the type of POM anions from [Mo8O26]4− and [PW12O40]3− to [P2W18O62]6−, the three coordination polymers possess distinct structural motifs: simple one-dimensional (1D) chain (1), 1D + 1D → 2D interdigitated architectures (2) and complicated 3D frameworks consisting of both meso-helixes and left/right-helixes (3). The distinct structural features of the three coordination polymers suggest that the POM anions should play a significant role in the process of assembly. The electrocatalytic and luminescent properties for coordination polymers 1–3 have been investigated.

Spontaneous resolution of polyoxometalate-based inorganic-organic hybrids driven by solvent and common ion.

Three single-sided, triol-functionalized Anderson POM hybrids were successfully synthesized. With suitable solvents and the effect driven by common-ion synergy, enantiopure crystals were obtained when the spontaneous resolution of enantiomers occurred upon crystallization. The chirality of POM-organic hybrids was confirmed by single-crystal X-ray diffraction and solid-state CD spectrum. A reversible, spontaneous resolution process for POM-based inorganic-organic hybrids was observed in this work.

Two new helical compounds based on Keggin clusters and N-donor multidentate ligand: Syntheses, structures and properties

Two isostructural polyoxometalate-based inorganic–organic hybrids with 1D helical chain, [CuH3L2(GeMo12O40)]·2H2O (1) and [CuH3L2(SiMo12O40)]·2H2O (2), where L=2,4,5-tri(4-pyridyl)-imidazole have been synthesized under hydrothermal conditions. It is the first time to use the L ligand to synthesis the Keggin-type polyoxometalate-based inorganic–organic hybrids. The two compounds possess the left- and right-handed helical chains and the POMs as pendants attach in the helical chains through Cu–O bonds. The two compounds have been characterized by elemental analyses, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA) and photoluminescent spectroscopy. Moreover, nitrogen adsorption−desorption measurement, electrochemical and photocatalysis properties for degradation of methylene blue (MB) upon a UV irradiation of compound 1 have been examined.

Assembly of Polyoxometalate-Based Hybrids with Different Helical Channels upon Subtle Ligand Variation

Self-assembly of multiple components into well-defined and predictable structures remains one of the foremost challenges in chemistry. Here, upon subtle ligand variation, we reported on the assembly of three new polyoxometalate-based organic–inorganic hybrid compounds with different helical channel, [Ag3(H2pyttz-I)2][PMo12O40] (1), [Ag6(H2pyttz-II)4][CoW12O40]·2H2O (2), and [Ag7(Hpyttz-II)3(H2pyttz-II)][GeW12O40]·7H2O (3) (H2pyttz-I/II = 4-/3-pyrid-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, POM = polyoxometalates). X-ray diffraction analysis shows that compound 1 is constructed by “butterfly-like” Ag5(H2pyttz-I)2 subunits and POMs clusters, which are assembled into close helical channels impregnated with the components selves. Both compounds 2 and 3 are constructed by “paddle-wheel like” Ag4(H2pyttz-II)4 motifs and POMs clusters, which bring into being the larger helical channels (10.5% and 12.5% of the cell volume, respectively). Note that the only difference in compounds 2 and 3 is that the former conta...

Crystal structures and spectral properties of two polyoxometalate-based inorganic–organic compounds from silver–azine building blocks with bis-bidentate and tridentate ligands

Two polyoxometalate-based inorganic–organic hybrid compounds constructed from silver(I)-L species and saturated Keggin type polyoxoanion, [Ag2L21]2(SiMo12O40)·1.5DMF·0.5CH3OH⋅H2O 1 and [{Ag4L22(DMF)5}(SiMo12O40)] 2 (L1=phenyl 2-pyridyl ketone azine, L2=3-phenyltriazolo[1,5-a]pyridine), have been synthesized and structurally characterized by IR, UV, elemental analysis, XRPD and complete single crystal structure analyses, where the ligands L1 and L2 are bis-bidentate and tridentate azines synthesized with the same materials under different conditions. The structure of 1 exhibits a dinuclear double-helicate with [SiMo12O40]4− anions as counter ions, where all of the Ag centers coordinate to bis-bidentate chelating ligands. Compound 2 displays a two-dimensional sheet formed by the Ag–organic infinite chains and the [SiMo12O40]4− alternately arranged in a “rail-like” fashion. The luminescent properties of 1 and 2 in the solid state were investigated.

Hydrothermal Synthesis, Crystal Structure, and Luminescent Properties of One New Inorganic-organic Hybrid Compound (ClBzQl)3[PMo12O40] (ClBzQl = 1- (4′-Cl-benzyl)quinolinium cation)

A new polyoxometalate-based inorganic-organic hybrid compound (ClBzQl)3[PMo12O40] 1 (ClBzQl = 1-(4′-Cl-benzyl)quinoli- nium cation) has been synthesized by hydrothermal method and characterized by IR, elemental analysis, and X-ray crystallography. Analysis of the crystal structure of 1 suggests that there are multiform intermolecular C−H···O hydrogen bonds between polyoxoanions and organic cations and obvious face-to-face π−π interactions involving quinoline rings of adjacent cations. The luminescent properties of the compound 1 in the solid state at room temperature were investigated.