Novel Isopolyoxotungstate [H₂W₁₁O₃₈]^8– Based Metal Organic Framework: As Lewis Acid Catalyst for Cyanosilylation of Aromatic Aldehydes

A novel polyoxometalate-based metal organic framework (POMOF) constructed from isolated isopolyoxotungstate [H₂W₁₁O₃₈]^8– cluster, {[Cu₂(bpy)­(H₂O)_5.5]₂[H₂W₁₁O₃₈]·3H₂O·0.5CH₃CN} (<b>1</b>, where bpy = 4,4′-bpydine), has been synthesized under solvothermal conditions and charaterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. In <b>1</b>, {W₁₁} clusters are alternately linked by two [Cu(2)­(H₂O)_1.5(O_t)₃(N)]²⁺ cations in an unexpected end-to-end fashion leading to a one-dimensional (1D) chain. Adjacent 1D chains are linked through Cu(1)–bpy–Cu(2) in an opposite direction to form a two-dimensional (2D) wavelike sheet along the <i>ab</i> plane. These 2D sheets are further stacked in a parallel fashion giving rise to the 1D channels with copper­(II) cations aligned in the channels. The resulting POMOF acted as a Lewis acid catalyst through a heterogeneous manner to prompt cyanosilylation with excellent efficiency

Beat over the Old Ground with New Strategy: Engineering As···As Interaction in Arsenite-Based Dawson Cluster β‑[W₁₈O₅₄(AsO₃)₂]^6–

By reaction of [As₂W₁₉O₆₇(H₂O)]^14–, NiCl₂·6H₂O, and phen under hydrothermal conditions, a new organic–inorganic tungstoarsenate hybrid [Ni­(phen)₃]₄[As₂W₁₈O₆₀]­{[Ni­(phen)₂]­[H₂As₂W₁₈O₆₀]}·12H₂O (where phen = 1,10-phenanthroline) (<b>1</b>) was obtained via self-assembly and characterized by elemental analysis, infrared (IR) spectroscopy, solid UV–vis absorption spectrum, and single-crystal X-ray diffraction (XRD). An unprecedented 18-tungstoarsenate Dawson cluster, β-[W₁₈O₅₄(AsO₃)₂]^6–, encapsulating two pyramidal arsenite AsO₃^3– anions as templates and exhibiting interesting intramolecular As···As interaction is first achieved. <b>1</b> displays a one-dimensional (1D) chain architecture constructed by alternating β-[W₁₈O₅₄(AsO₃)₂]^6– and nickel­(II) complexes [Ni­(phen)₂)]²⁺. The resulting hybrid can act as a photocatalyst to prompt the degradation of Rhodamine B (RhB) with excellent efficiency

Novel Isopolyoxotungstate [H₂W₁₁O₃₈]^8– Based Metal Organic Framework: As Lewis Acid Catalyst for Cyanosilylation of Aromatic Aldehydes

A novel polyoxometalate-based metal organic framework (POMOF) constructed from isolated isopolyoxotungstate [H₂W₁₁O₃₈]^8– cluster, {[Cu₂(bpy)­(H₂O)_5.5]₂[H₂W₁₁O₃₈]·3H₂O·0.5CH₃CN} (<b>1</b>, where bpy = 4,4′-bpydine), has been synthesized under solvothermal conditions and charaterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction. In <b>1</b>, {W₁₁} clusters are alternately linked by two [Cu(2)­(H₂O)_1.5(O_t)₃(N)]²⁺ cations in an unexpected end-to-end fashion leading to a one-dimensional (1D) chain. Adjacent 1D chains are linked through Cu(1)–bpy–Cu(2) in an opposite direction to form a two-dimensional (2D) wavelike sheet along the <i>ab</i> plane. These 2D sheets are further stacked in a parallel fashion giving rise to the 1D channels with copper­(II) cations aligned in the channels. The resulting POMOF acted as a Lewis acid catalyst through a heterogeneous manner to prompt cyanosilylation with excellent efficiency

Metal–Organic Frameworks with Phosphotungstate Incorporated for Hydrolytic Cleavage of a DNA-Model Phosphodiester

Five phosphotungstate-incorporated metal–organic frameworks {[Eu₄(dpdo)₉(H₂O)₁₆PW₁₂O₄₀]}­(PW₁₂O₄₀)₂·(dpdo)₃·Cl₃ (<b>1</b>); {ZnNa₂(μ-OH)­(dpdo)₄(H₂O)₄[PW₁₂O₄₀]}·3H₂O (<b>2</b>); {Zn₃(dpdo)₇}­[PW₁₂O₄₀]₂·3H₂O (3); and [Ln₂H­(μ-O)₂(dpdo)₄(H₂O)₂]­[PW₁₂O₄₀]·3H₂O (Ln = Ho for <b>4</b> and Yb for <b>5</b>) (dpdo = 4,4′-bipyridine-<i>N</i>,<i>N</i>′-dioxide) have been synthesized through a one-step hydrothermal reaction and characterized by elemental analyses, infrared (IR) spectroscopy, photoluminescence, and single-crystal X-ray diffraction (XRD). The structural analyses indicate that <b>1</b>–<b>5</b> display diversity structure from one-dimensional (1D) to three-dimensional (3D) series of hybrids. Kinetic experiments for the hydrolytic cleavage of DNA-model phosphodiester BNPP (bis­(<i>p</i>-nitrophenyl)­phosphate) were followed spectrophotometrically for the absorbance increase at 400 nm in EPPS (4-(2-hydroxyethyl)­piperazine-1-propane sulfonic acid) buffer solution, because of the formation of <i>p</i>-nitrophenoxide with <b>1</b>–<b>5</b> under conditions of pH 4.0 and 50 °C. Ultraviolet (UV) spectroscopy indicate that the cleavage of the phosphodiester bond proceeds with the pseudo-first-order rate constant in the range of 10^–7–10^–6 s^–1, giving an inorganic phosphate and <i>p</i>-nitrophenol as the final products of hydrolysis. The results demonstrate that <b>1</b>–<b>5</b> have good catalytic activity and reusability for hydrolytic cleavage of BNPP

Metal–Organic Frameworks with Phosphotungstate Incorporated for Hydrolytic Cleavage of a DNA-Model Phosphodiester

Five phosphotungstate-incorporated metal–organic frameworks {[Eu₄(dpdo)₉(H₂O)₁₆PW₁₂O₄₀]}­(PW₁₂O₄₀)₂·(dpdo)₃·Cl₃ (<b>1</b>); {ZnNa₂(μ-OH)­(dpdo)₄(H₂O)₄[PW₁₂O₄₀]}·3H₂O (<b>2</b>); {Zn₃(dpdo)₇}­[PW₁₂O₄₀]₂·3H₂O (3); and [Ln₂H­(μ-O)₂(dpdo)₄(H₂O)₂]­[PW₁₂O₄₀]·3H₂O (Ln = Ho for <b>4</b> and Yb for <b>5</b>) (dpdo = 4,4′-bipyridine-<i>N</i>,<i>N</i>′-dioxide) have been synthesized through a one-step hydrothermal reaction and characterized by elemental analyses, infrared (IR) spectroscopy, photoluminescence, and single-crystal X-ray diffraction (XRD). The structural analyses indicate that <b>1</b>–<b>5</b> display diversity structure from one-dimensional (1D) to three-dimensional (3D) series of hybrids. Kinetic experiments for the hydrolytic cleavage of DNA-model phosphodiester BNPP (bis­(<i>p</i>-nitrophenyl)­phosphate) were followed spectrophotometrically for the absorbance increase at 400 nm in EPPS (4-(2-hydroxyethyl)­piperazine-1-propane sulfonic acid) buffer solution, because of the formation of <i>p</i>-nitrophenoxide with <b>1</b>–<b>5</b> under conditions of pH 4.0 and 50 °C. Ultraviolet (UV) spectroscopy indicate that the cleavage of the phosphodiester bond proceeds with the pseudo-first-order rate constant in the range of 10^–7–10^–6 s^–1, giving an inorganic phosphate and <i>p</i>-nitrophenol as the final products of hydrolysis. The results demonstrate that <b>1</b>–<b>5</b> have good catalytic activity and reusability for hydrolytic cleavage of BNPP

Metal–Organic Frameworks with Phosphotungstate Incorporated for Hydrolytic Cleavage of a DNA-Model Phosphodiester

Five phosphotungstate-incorporated metal–organic frameworks {[Eu₄(dpdo)₉(H₂O)₁₆PW₁₂O₄₀]}­(PW₁₂O₄₀)₂·(dpdo)₃·Cl₃ (<b>1</b>); {ZnNa₂(μ-OH)­(dpdo)₄(H₂O)₄[PW₁₂O₄₀]}·3H₂O (<b>2</b>); {Zn₃(dpdo)₇}­[PW₁₂O₄₀]₂·3H₂O (3); and [Ln₂H­(μ-O)₂(dpdo)₄(H₂O)₂]­[PW₁₂O₄₀]·3H₂O (Ln = Ho for <b>4</b> and Yb for <b>5</b>) (dpdo = 4,4′-bipyridine-<i>N</i>,<i>N</i>′-dioxide) have been synthesized through a one-step hydrothermal reaction and characterized by elemental analyses, infrared (IR) spectroscopy, photoluminescence, and single-crystal X-ray diffraction (XRD). The structural analyses indicate that <b>1</b>–<b>5</b> display diversity structure from one-dimensional (1D) to three-dimensional (3D) series of hybrids. Kinetic experiments for the hydrolytic cleavage of DNA-model phosphodiester BNPP (bis­(<i>p</i>-nitrophenyl)­phosphate) were followed spectrophotometrically for the absorbance increase at 400 nm in EPPS (4-(2-hydroxyethyl)­piperazine-1-propane sulfonic acid) buffer solution, because of the formation of <i>p</i>-nitrophenoxide with <b>1</b>–<b>5</b> under conditions of pH 4.0 and 50 °C. Ultraviolet (UV) spectroscopy indicate that the cleavage of the phosphodiester bond proceeds with the pseudo-first-order rate constant in the range of 10^–7–10^–6 s^–1, giving an inorganic phosphate and <i>p</i>-nitrophenol as the final products of hydrolysis. The results demonstrate that <b>1</b>–<b>5</b> have good catalytic activity and reusability for hydrolytic cleavage of BNPP

Engineering Chiral Polyoxometalate Hybrid Metal–Organic Frameworks for Asymmetric Dihydroxylation of Olefins

Chiral metal–organic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^5– and the chiral group, l- or d-pyrrolidin-2-ylimidazole (<b>PYI</b>), into one single framework, the two enantiomorphs Ni-<b>PYI</b>1 and Ni-<b>PYI</b>2 were obtained via self-assembly, respectively. The channels of Ni-<b>PYI</b>s were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity

Engineering Chiral Polyoxometalate Hybrid Metal–Organic Frameworks for Asymmetric Dihydroxylation of Olefins

Chiral metal–organic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^5– and the chiral group, l- or d-pyrrolidin-2-ylimidazole (<b>PYI</b>), into one single framework, the two enantiomorphs Ni-<b>PYI</b>1 and Ni-<b>PYI</b>2 were obtained via self-assembly, respectively. The channels of Ni-<b>PYI</b>s were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity

Engineering Chiral Polyoxometalate Hybrid Metal–Organic Frameworks for Asymmetric Dihydroxylation of Olefins

Chiral metal–organic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^5– and the chiral group, l- or d-pyrrolidin-2-ylimidazole (<b>PYI</b>), into one single framework, the two enantiomorphs Ni-<b>PYI</b>1 and Ni-<b>PYI</b>2 were obtained via self-assembly, respectively. The channels of Ni-<b>PYI</b>s were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity

Engineering Chiral Polyoxometalate Hybrid Metal–Organic Frameworks for Asymmetric Dihydroxylation of Olefins

Chiral metal–organic frameworks (MOFs) with porous and tunable natures have made them feasible for performing a variety of chemical reactions as heterogeneous asymmetric catalysts. By incorporating the oxidation catalyst [BW₁₂O₄₀]^5– and the chiral group, l- or d-pyrrolidin-2-ylimidazole (<b>PYI</b>), into one single framework, the two enantiomorphs Ni-<b>PYI</b>1 and Ni-<b>PYI</b>2 were obtained via self-assembly, respectively. The channels of Ni-<b>PYI</b>s were enlarged through a guest exchange reaction to remove the cationic chiral templates and were well modulated with hydrophilic/hydrophobic properties to allow molecules of both H₂O₂ and olefin ingress and egress. The coexistence of both the chiral directors and the oxidants within a confined space provided a special environment for the formation of reaction intermediates in a stereoselective fashion with high selectivity. The resulting MOF acted as an amphipathic catalyst to prompt the asymmetric dihydroxylation of aryl olefins with excellent stereoselectivity