Synthesis, structures and properties of new hybrid solids containing ruthenium complexes and polyoxometalates

Two new organic-inorganic hybrid solids containing Keggin ions and ruthenium complexes have been synthesized and characterized by FT-IR, UV-vis, luminescence, X-ray, and TG analysis. In KNa[Ru(bpy)₃]₂[H₂W₁₂O₄₀]·8H₂O (1), the [Ru(bpy)₃]²⁺ (bpy=2,2′-bipyridine) complex ions are located in between the infinite one-dimensional double-chains formed by adjacent Keggin anions [H₂W₁₂O₄₀]⁶⁻ linked through {KO₇} and {NaO₆} polyhedra, while in K₆[Ru(pzc)₃]₂[SiW₁₂O₄₀]•12H₂O (2), the [Ru(pzc)₃]⁻ (pzc=pyrazine-2-carboxylate) complex anions are confined by layered networks of the [SiW₁₂O₄₀]⁴⁻ clusters connected by potassium ions. Both compounds exhibit three-dimensional frameworks through noncovalent interactions such as hydrogen bonds and anion?π interactions. Additionally, compound 1 shows strong luminescence at 604 nm in solid state at room temperature.     

Syntheses, structures and properties of 3D inorganic-organic hybrid frameworks constructed from lanthanide polymer and Keggin-type tungstosilicate

Inorganic-organic hybrid frameworks, namely [Ce(H₂O)₃(pdc)]₄[SiW₁₂O₄₀]·6H₂O 1, [M(H₂O)₄(pdc)]₄[SiW₁₂O₄₀]·2H₂O (M=Ce for 2a, La for 2b, Nd for 2c; H₂pdc=pyridine-2,6-dicarboxylic acid) were assembled through incorporation of Keggin-type heteropolyanion [SiW₁₂O₄₀]⁴⁻ within the voids of lanthanides-pdc network as pillars or guests under hydrothermal condition. Single-crystal X-ray analyses of these crystals reveal that compound 1 presents 3D pillar-layered framework with the [SiW₁₂O₄₀]⁴⁻ anions located on the square voids of the two-dimensional Ce-pdc bilayer. Compounds 2a-c are isostructural and constructed from 3D Ln-pdc-based metal-organic framework (MOF) incorporating noncoordinating guests Keggin structure [SiW₁₂O₄₀]⁴⁻. Solid-state properties of compounds 1 and 2a-c such as thermal stability and photoluminescence have been further investigated.     

Assembly of a Supramolecular Architecture Based on Keggin POMs and Lanthanide Coordination Cations

Two new compounds based on Keggin polyoxometalates (POMs) [SiW₁₂O₄₀]⁴⁻ (SiW₁₂), [Na(H₂O)₃(H₂L)SiW₁₂O₄₀](H₂L)₂   6H₂O (1), and [Ce(H₂O)₃(HL)₂(H₂L)]₂[SiW₁₂O₄₀]₂ 10H₂O (2) (HL = C₆H₅NO₂ = isonicotinic acid), have been conventionally synthesized and characterized by routine methods. Compound 1 possesses a 1D right-handed helical structure constructed by SiW₁₂O₄₀ ⁴⁻ {SiW₁₂} and [Na(H₂O)₃(HL)] complexes. Interestingly, these right-handed helical chains are linked together via H-bonds forming a novel chiral layer. By using the similar synthesis method to that for compound 1, except for employing Ce³⁺ cations in instead of La³⁺ cations, a 3D supramolecular compound 2 based on SiW₁₂ and Ce³⁺ coordination cations has been obtained, which contains 1D channels along a axis. Additionally, the luminescence properties of 2 were studied. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A series of Wells-Dawson and Keggin-based compounds with uncoordinated S donors as fluorescence sensors to Hg2+

Abstract

Through using a S-containing ligand 2,2’-dimethyl-4,4’-bithiazole (dbt), a series of Wells-Dawson and Keggin-based compounds, {Zn(dbt)₃}{Zn(dbt)₂(H₂O)}₂{HP₂W^VW^VI₁₇O₆₂}·4H₂O (1), {Cd(dbt)₂(H₂O) (HP₂W^VW^VI₁₇O₆₂)}{Cd(dbt)₃}{Cd(dbt)₂(H₂O)}·13H₂O (2), {Cd₂(dbt)₄Cl} {PW₁₂O₄₀} (3) and {Cd₂(dbt)₄}{SiW₁₂O₄₀} (4), were synthesized under hydrothermal conditions and structurally characterized. In 1, there are three dissociated subunits: Wells-Dawson anion, {Zn(dbt)₃}²⁺ and {Zn(dbt)₂(H₂O)}²⁺. In 2, the mono-supporting Wells-Dawson anions exhibit abundant hydrogen bonding interactions with discrete {Cd(dbt)₃}²⁺ and {Cd(dbt)₂(H₂O)}²⁺ mononuclear coordination complexes, constructing a supramolecular layer. Compound 3 has a binuclear Cd cluster {Cd₂(dbt)₄Cl}⁴⁺ with a Cl as a bridging atom. The Keggin anions link these binuclear Cd clusters alternately to build a 1D chain. In 4, a pair of {Cd(dbt)₂}²⁺ subunits connect adjacent Keggin anions and a 1D chain is formed. In these four compounds, only the N donors coordinate with Zn or Cd and the S atoms are uncoordinated. These compounds show good fluorescence sensing performance to Hg²⁺. We also studied the electrochemical and photocatalytic properties of 1–4. These compounds also can act as electrochemical sensors for the detection of nitrite.     

A series of new organic–inorganic compounds templated by the [SiW12O40]4− polyanion

Two couples of new compounds templated by the polyanion [SiW₁₂O₄₀]^4?,[Hbix][Cu^I(bix)]₃[SiW₁₂O₄₀]·4H₂O (1) and [Cu^II(H₂O)(Hbix)₂(bix)]₂[Cu^II(H₂O)₂(Hbix)₂(bix)][SiW₁₂O₄₀]₃·4H₂O (2) (bix = 1,4-Bis(imidazol-1-ylmethyl)benzene), [Cu^I(bbi)]₄[SiW₁₂O₄₀]·2H₂O (3) and [Cu^II(bbi₂)]₂[SiW₁₂O₄₀] (4) (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) were hydrothermally synthesized, and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses and single X-ray diffraction. Compounds 1 and 2 were synthesized from the same reactants but exhibited distinct structures which could be ascribed to the different ratios of the reactant bix to Cu^II. In compound 1, the higher ratio of bix results in the transformation of the Cu^II to Cu^I, the [SiW₁₂O₄₀]^4? templates direct the Cu^I–bix coordination polymers to form a 3D supramolecular framework with grid-like channels along two directions. The [SiW₁₂O₄₀]^4? templates in compound 2 locate in the voids of the 3D supramolecular network constructed by Cu^II–bix coordination polymers, which exhibits the interdigitation fashion in both the formation of the 2D layer and the 3D framework. Compounds 3 and 4 were synthesized similar to 1 and 2, except for the change of bix to bbi. In compound 3, the Cu^I–bbi polymers form a supramolecular metal–organic host framework with rhombic channels in which the SiW₁₂ templates reside. Compound 4 shows a framework with hexagonal channels constructed by Cu^II–bbi coordination polymers which accommodated the SiW₁₂ templates.     

Water-induced reversible dissolution/reorganization transformations of Cu(Ⅱ)-K(I) heterometallic coordination polymers

Three new heterometallic coordination compounds, namely, [KCu(I3)(L)2(H2O)2]n(1), [KCu(I3)(L)2(H2O)]n(2) and [CuK4(I3)2(L′)4]n(3), were prepared and characterized(HL=5-methylpyrazine-2-carboxylic acid, HL′=p-tolylacetic acid). Structural studies revealed that 1 and 2 exhibit 3D frameworks with rectangular channels occupied by triiodide ions. Both compounds can be symbolized as a 5-connected net with pcu topology. In compound 3, a one-dimensional polyhedral chain is connected by hexanuclear mask like clusters [Cu2K4O8]. These chains are further linked each other via rare(1,1,3,3)-triiodide ion-bridging units to generate a 3D(4,5,6)-connected net with the point symbol of {12}2{4·122}4{46}{48·62}4{49·66}4. It is noteworthy that water-induced reversible dissolution/reorganization processes occur between 1/2 and [Cu(L)2(H2O)]n·3nH2O. The thermal and photoluminescence properties of compounds 1, 2, and 3 were investigated as well.     

A multi-functional 3D polymolybdate-based copper(II) complex based on an asymmetric pyridyl-amide ligand: synthesis,structure and properties

A polymolybdate-based metal–organic compound {H₂[Cu₂(L)₂(Mo₈O₂₇)(H₂O)₄]} (1) [L = N-(pyridin-3-yl)isonicotinamide] has been synthesized under solvothermal (methanol–water mixed solvent) conditions and structurally characterized by single-crystal X-ray diffraction. Compound 1 exhibits a 3D metal–organic network containing unusual 1D [Mo₈O₂₇] _n ^6n? inorganic chains, with adjacent 1D chains connected by Cu(II) atoms and L ligands to form a 3D framework with a trinodal 4,4,6-connected {4².6³.8}₂{4⁴.6⁸.8³} topology. The electrocatalytic activities of compound 1 and its photocatalytic properties for the degradation of organic dyes have also been investigated.     

Synthesis, structural characterization and properties of a 3D infinitely extended structural rare earth coordination compound of K3{[Sm(H2O)7]2Na[α-SiW11O39Sm(H2O)4]2} · 14 H2O· 14 H2O

A 3D infinitely extended structural rare earth coordination compound with a formula of K₃{[Sm(H₂O)₇]₂Na[α-SiW₁₁O₃₉Sm(H₂O)₄]₂}·14H₂O has been synthesized by reaction of Sm₂O₃, HClO₄, NaOH with α-K₈SiW₁₁O39·nH₂O, and characterized by IR, UV spectra, ICP, TG-DTA, cyclic voltammetry, variable-temperature magnetic susceptibility and X-ray single-crystal diffraction. X-ray single-crystal diffraction indicates that the title compound crystallizes in a triclinic lattice, Pī space group, with a = 1.2462(3) nm, b = 1.2652(3) nm, c = 1.8420(4) nm, α = 87.45(3)°, β = 79.91(3)°, γ= 82.57(3)°, Z = 1, R₁ = 0.0778, wR₂ = 0.1610. Structural analysis reveals that Sm³⁺(1) coordination cation has incorporated into the vacant site of [α-SiW11O₃₉]⁸⁻ entity, forming the [α- SiW₁₁O₃₉Sm(H₂O)₄]⁵⁻ subunit. The two adjacent [α-SiW₁₁O₃9Sm(H₂O)4]⁵⁻ subunits are combined with each other through two Sm(1)-O-W bridges accompanying the formation of dimmer structural unit [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ of the title compound. The neighboring dimmer structural units [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ are linked to form the 1D chainlike structure by means of two Sm³⁺(2) and a Na⁺(1) coordination cations. The K⁺(1) cations connect the 1D packing chains constructing the 2D netlike structure, and adjacent netlike layers are also grafted by K⁺(2) cations to build the novel 3D infinitely extended structure. The result of TG-DTA curves manifests that the decomposition temperature of the title polyanionic framework is 554°C. The cyclic voltammetry measurements show that the title polyanion has the two-step redox processes in aqueous solution with pH = 3.1. Variable temperature magnetic susceptibility indicates the title compound obeys the Cruie-Weiss Law in the higher temperature range from 110 to 300 K, while in the lower temperature range from 2 to 110 K the comparatively strong antiferromagnetism interactions can be observed.     

Layer-by-layer self-assembly and electrocatalytic properties of poly(ethylenimine)-silicotungstate multilayer composite films

Hybrid multilayer films composed of poly(ethylenimine) and the Keggin-type polyoxometalates [ SiW₁₁O₃₉ ]^{8 -} ( SiW₁₁ ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{{\hbox{O}}_{{39}}}} \right]^{{8} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}} \right) and [ SiW₁₁Co^II( H₂O )O₃₉ ]^{6 -} ( SiW₁₁Co ) {\left[ {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{C}}{{\hbox{o}}^{\rm{II}}}\left( {{{\hbox{H}}_2}{\hbox{O}}} \right){{\hbox{O}}_{{39}}}} \right]^{{6} - }}\left( {{\hbox{Si}}{{\hbox{W}}_{{11}}}{\hbox{Co}}} \right) were prepared on glassy carbon electrodes by layer-by-layer self-assembly, and were characterized by cyclic voltammetry and scanning electron microscopy. UV-vis absorption spectroscopy of films deposited on quartz slides was used to monitor film growth, showing that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of bilayers. Cyclic voltammetry indicates that the electrochemical properties of the polyoxometalates are maintained in the multilayer films, and that the first tungsten reduction process for immobilized SiW₁₁ and SiW₁₁Co is a surface-confined process. Electron transfer to [ Fe( CN )₆ ]^{3 - /4 -} {\left[ {{\hbox{Fe}}{{\left( {\hbox{CN}} \right)}_6}} \right]^{{3} - /{4} - }} and [ Ru( NH₃ )₆ ]^{3 + /2 +} {\left[ {{\hbox{Ru}}{{\left( {{\hbox{N}}{{\hbox{H}}_3}} \right)}_6}} \right]^{{3} + /{2} + }} as electrochemical probes was also investigated by cyclic voltammetry. The (PEI/SiW₁₁Co)_n multilayer films showed excellent electrocatalytic reduction properties towards nitrite, bromate and iodate.     

Synthesis,structures, luminescent and dielectric properties of lanthanide coordination polymers

Under hydrothermal conditions, four lanthanide coordination polymers were synthesized based on 4-(4,5-dicarboxy-1H-imidazol-2-yl)pyridine 1-oxide (H₃DCImPyO), with the molecular forumulas [Eu(HDCImPyO)·(H₂O)₂·(CHO₂)]_n (1), [Sm(HDCImPyO)·(H₂O)₂·(HCO₂)]_n (2), {[La(HDCImPyO)·(H₂O)·(HCO₂)]·O₂}_n (3) and {[Y(HDCImPyO)·(C₂O₄)·(H₂O)₂]·H₂O}_n (4). With diverse coordination modes, they were further characterized by elemental analysis, infrared spectroscopy, dielectric measurement, and single-crystal X-ray structural analysis. Complexes 1 and 2 were isostructural and had similar structures with {4⁴, 6²} topology. Complex 1 exhibited strong fluorescent emission in the solid state at room temperature. In 3, HDCImPyO^2? adopted μ₄-kO, O′: kO′, O′′: O′′′: O′′′′ coordination to bridge four La(III) ions to form a 3-D framework with {4. 5²}₂{4². 5¹⁰. 6¹². 7. 8³} topology. In 4, both HDCImPyO^2? ligands and Y³⁺ cations were simplified as linkers to form an interpenetrating 3-D framework with {4¹³. 6²}₂{4²². 6⁶} topology.     

Solvent-tuned polyoxometalate-based supramolecular hybrids constructed from different metal-organic motifs: Various structures and adsorption properties for dyes

Three polyoxometalate-based supramolecular hybrids with different metal-organic motifs have been synthesized by tuning the solvents, which show various adsorption activities for different organic dyes.     

Ionothermal syntheses of three transition-metal-containing polyoxotungstate hybrids exhibiting the photocatalytic and electrocatalytic properties

Employing the ionothermal synthesis approach, three new transition-metal-containing polyoxotungstate hybrids: [Dmim]₂Na₃[SiW₁₁O₃₉Fe(H₂O)]·H₂O (Dmim=1,3-Dimethylimidazole) (1), [Emim]₉Na₈[(SiW₉O₃₄)₃{Fe₃(μ₂-OH)₂(μ₃-O)}₃(WO₄)]·0.5H₂O(Emim=1-Ethyl-3-meth-ylimidazole) (2) and [Dmim]2[HMim]Na₆[(AsW₉O₃₃)₂{Mn^III(H₂O)}₃]·3H₂O (Dmim=1,3-Dimethylimidazole; Mim=1-Methylimidazole) (3) have been synthesized in 1-ethyl-3-methyl imidazolium bromide ([Emim]Br) ionic liquids (ILs). Compound 1 possesses a 3-D open framework constructed from the mono-iron^III-substituted α-Keggin-type anion and the organic cations [Dmim]+ through the hydrogen bond interactions. Compound 2 contains a [{Fe^III₃(μ₂-OH)₂(μ₃-O)}₃(μ₄-WO₄)] cluster surrounded by three [SiW₉O₃₄]¹⁰⁻ ligands, eight sodium cations and nine dissociative [Emim]⁺ cations around the polyoxoanion. The polyoxoanion of 3 consists of a high-valent trinuclear-manganese (III)-substituted sandwiching polyoxoanion based on the [α-AsW₉O₃₃]⁹⁻ units. All the compounds are characterized by elemental analyses, IR, UV-vis spectra, TG-DTA and XRD analyses. The XPS and EPR spectra of Mn^III in 3 were studied. The photocatalytic and electrocatalytic properties, as well as the stabilities of 1-3 were also investigated.     

Keggin‐Type Polyoxometalate‐Based Metal–Organic Networks for Photocatalytic Dye Degradation

The reaction of Keggin‐type polyoxometalate (POM) units, transition‐metal (TM) ions, and a rigid bis(imidazole) ligand (1,4‐bis(1‐imidazolyl)benzene (bimb)) in a hydrothermal environment led to the isolation of four new POM‐based metal–organic networks, [H₂L][CuL][SiW₁₂O₄₀]?2 H₂O ( 1 ), [H₂L]₂[Co(H₂O)₃L][SiW₁₁CoO₃₉]?6 H₂O ( 2 ), KH[CuL]₂[SiW₁₁CoO₃₉(H₂O)]?2 H₂O ( 3 ), and [CuL]₄[GeW₁₂O₄₀]?H₂O ( 4 ; L=bimb). All four compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compounds 1 and 3 are new 3D networks with 1D channels. Compounds 2 and 4 contain 2D networks, which further stack into 3D supramolecular networks. The contributions of pH value, the negative charge of the POM, and the TM coordination modes to the construction of 3D networks were elucidated by comparing the synthetic conditions and structures of compounds 1 – 4 . The photocatalytic properties of compounds 1 – 4 were investigated using methylene blue (MB) degradation under UV light. All compounds showed good catalytic activity and structural stability. The possible catalytic mechanism was discussed on the basis of active‐species trapping experiments. The different photocatalytic activities of compounds 1 – 4 were explained by comparison of the band gaps of different POM species and different packing modes of POM units in these hybrid compounds.     

Syntheses, characterizations and crystal structures of three new organically templated or organically bonded zinc selenates

Three new organically templated or organically bonded zinc selenates, namely, {H₂bipy}Zn(SeO₄)₂(H₂O)₂1 (bipy=4,4′-bipyridine), {H₂pip}{Zn(SeO₄)₂(H₂O)₄}·2H₂O 2 (pip=piprazine), and Zn(SeO₄)(phen)(H₂O)₂3 (phen=1,10-phenanthroline) have been synthesized by hydrothermal reactions. The structure of compound 1 features a 1D chain composed of [Zn(SeO₄)₂(H₂O)₂]²⁻ anions. Compound 2 has a 2D layer structure built from {Zn(SeO₄)₂(H₂O)₄}²⁻ anions that are cross-linked by doubly protonated piperazine cations via N-H?O hydrogen bonds. The structure of compound 3 contains a 1D chain of Zn(SeO₄)(phen)(H₂O)₂, such chains are further interlinked by hydrogen bonds and π?π interactions to form a 〈200〉 layer. The different roles the templates played have also been discussed.     

Hydrothermal syntheses and structural characterization of two new supramolecular compounds: (H2bbi)2[Mo8O26] and (H2bbi)2[SiW12O40]·2H2O [bbi = 1,1′-(1,4-butanediyl)bis(imidazole)]

Two new inorganic–organic hybrid supramolecular compounds based on imidazolium and POMs formulated as (H₂bbi)₂[Mo₈O₂₆] (1) and (H₂bbi)₂[SiW₁₂O₄₀]·2H₂O (2) [bbi = 1,1′-(1,4-butanediyl)bis(imidazole)] have been prepared under hydrothermal conditions and characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. The two compounds consist of protonated bbis together with POMs. [Mo₈O₂₆]^4? and [SiW₁₂O₄₀]^4? are linked through H₂bbi into a three-dimensional (3D) network via hydrogen bonds, respectively. Compound 1 is the first example of 3D two-fold interpenetrating hydrogen bond-supported supramolecular assembly from octamolybdate one-dimensional (1D) chain and imidazolium. The fascinating structural feature of compound 2 is that the anions and the protonated bbi ligands formed a 3D (4, 8) supramolecular network by hydrogen bonds. Compound 2 has been used as a solid bulk-modifier to fabricate three-dimensional bulk-modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior and electrocatalysis of compound 2 modified CPE (2-CPE) have been studied.     

Three coordination polymers constructed from succinic acid and 1,4-bis(1H-imidazol-4-yl)benzene: synthesis,crystal structures,and properties

Three coordination polymers involving transition metals, namely [Co(suc)(1,4-bib)(H₂O)₂]_n (1), [Mn(suc)(1,4-bib)(H₂O)₂]_n (2), [Cd(suc)(1,4-bib)]_n (3) (H₂suc?=?succinic acid, 1,4-bib?=?1,4-bis(1H-imidazol-4-yl)benzene), have been synthesized under solvothermal conditions. All three compounds were characterized by single-crystal X-ray diffraction, elemental analysis, FTIR, UV–Vis spectroscopy, powder X-ray diffraction and thermogravimetric analyses. Compounds 1 and 2 show 2D metal–organic layers with the point symbol of {4⁴·6²}. The 3D framework of compound 3 displays a 4-connected dia net with the point symbol of {6⁶} topology. Magnetic susceptibility studies of compound 1 indicate weak antiferromagnetic coupling between the Co(II) centers. The adsorption experiment results show that compound 3 exhibits rapid and selective separation of congo red over methylene blue and rhodamine B.     

Syntheses and electrochemical properties of three supramolecular architectures based on Keggin silicontungstates and different metal-organic units

Three new compounds [Mn(H₂O)₂(bimb)₂(H₃SiW₁₂O₄₀)₂](bimb)₄ (1), [Zn₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (2), and [Ni₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (3) (bimb = 1,3-bis(1-imidazoly)benzene) have been synthesized under the same hydrothermal reaction except for tuning the metal cations (Mn²⁺, Zn²⁺, and Ni²⁺). Structural characterizations show that the three compounds possess distinct structural motives. Compound 1 displays a supramolecular one-dimensional (1 D) chain formed by π···π interactions that occur among the almost parallel bimb ligands from adjacent [Mn(H₂O)₂(bimb)₂(SiW₁₂O₄₀)₂] dimers. Compound 2 shows a supramolecular two-dimensional (2D) layer achieved by intermolecular (C–H···O) hydrogen bondings between the Zn₂(bimb)₄ molecular loops and the SiW₁₂ anions. Compound 3 also exhibits a supramolecular 2D layer, but it is different from 2, which is generated by the π···π interactions among adjacent 1D polymeric chains. The distinct structural features of the three compounds suggest that the metal cations should play a significant role in the process of assembly. Additionally, the electrochemical properties of compounds 1–3 have been investigated, and the results indicate that compounds 1–3 possess excellent electrocatalytic activity toward reduction of both iodated and nitrite molecules.     

dl-Serine covalently modified multinuclear lanthanide-implanted arsenotungstates with fast photochromism

A series of dl-serine covalently modified multinuclear lanthanide implanted arsenotungstates K₂[{Ln(H₂O)₇}₂{As₄W₄₄O₁₃₇(OH)₁₈(H₂O)₂(dl-Ser)₂}{Ln₂(H₂O)₅(dl-Ser)}₂]·65H₂O (dl-Ser = dl-serine, Ln = La (1), Ce (2), Pr (3)) are obtained. Crystal structure analysis shows that these compounds are isomorphic and contain the basic [{As₄W₄₄O₁₃₇(OH)₁₈(H₂O)₂(dl-Ser)₂}{Ln₂(H₂O)₅(dl-Ser)}₂]^8– polyoxoanion constituted by two {As₂W₁₉O₅₉(OH)₈(H₂O)}^6? subunits, a [W₆O₂₃(OH)₂(dl-Ser)₂]^14? fragment, and two embedded [Ln₂(H₂O)₅(dl-Ser)]⁵⁺ groups, which further build into one dimensional linear chainlike structure via two peripheral Ln³⁺ ions. Most remarkably, these compounds exhibit rapid photochromic behaviors, which changed color quickly from white (1), yellow (2), green (3) to blue (1), brown (2) and glaucous (3) in ten minutes under UV irradiation, and that the colors gradually recovered in the dark for approximately 22 h.     

Determination of kinetic parameters of inorganic metalporphyrins

The thermal properties of four heteropoly complexes α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1.5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) and α-[(C₄H₉)₄N]_3.5H_2.5[SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) were studied by means of TG, DTA and DSC. The activation energy and reaction order of the thermal decomposition reaction of these complexes have been calculated.

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Zusammenfassung Mittels TG, DTA und DSC wurden die thermischen Eigenschaften der vier heteropolaren Komplexe α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1,5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) und α-[(C₄H₉)₄N]_3.5H_2,5 [SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) untersucht. Die Aktivierungsenergie und Reaktionsordnung der thermischen Zersetzungsreaktion dieser Komplexe wurde berechnet.

     

Two Bisupporting Keggin-Type POM-Based Hybrids Decorated by [Zn(phen)2]2+ Fragments

Two bisupporting Keggin-type polyoxoanion-based hybrids decorated by [Zn(phen)₂]²⁺ complexes, [Zn(phen)₂]₂(PW ₁₁ ^VI W^VO₄₀) (1) and K[Zn(phen)₂(H₂O)]₂(OH) (SiW₁₂O₄₀)·H₂O (2) (phen = 1,10′-phenanthroline), have been hydrothermally synthesized, and characterized by elemental analysis, IR spectra, UV–Vis spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and single-crystal X-ray diffraction. The structural analyses reveal that compound 1 consists of a 0D bisupporting Keggin-type heteropoly blue cluster obtained by using reductant glucose, which is grafted by two [Zn(phen)₂]²⁺ fragments; compound 2 presents a 1D infinite chain, which is constructed from bisupporting [SiW₁₂O₄₀]^4? polyoxoanions decorated by [Zn(phen)₂(H₂O)]²⁺ fragments and K⁺ ions. Additionally, the electrochemical behaviors of two compounds were studied.