Ligation of the quinolone antibacterial agent pipemidic acid to Keggin polyoxotungstates

Three new drug molecules modifying Keggin polyoxometallate compounds have been synthesized under hydrothermal conditions and structurally characterized by routine techniques. Single-crystal X-ray diffraction analysis shows that compound 1 is constructed by a Keggin cluster and two [Cu(PPA)₂] drug complexes, formulated as [Cu(PPA)₂]₂·[PW₁₂O₄₀]·6H₂O. Compound 2 consists of a Cd substituted Keggin cluster [PW₁₁CdO₃₉] and five isolated HPPA drug molecules, formulated as [HPPA]₅·[PW₁₁CdO₃₉]·2H₂O. Compound 3 consists of a full oxidised Keggin [PW₁₂O₄₀] cluster and three isolated HPPA drug molecules, formulated as [HPPA]₃·[PW₁₂O₄₀]·2H₂O. Additionally, the antitumor activity of the three new compounds and their parent components in vitro were studied by a MTT experiment. The results show that introduction of TM-PPA/PPA into the polyoxoanion surface could increase their antitumor activity and make the compounds penetrate into the cells easily. Furthermore, the antitumor activity of the compounds can be modulated by their different structures.     

Construction and properties of drug molecules modifying octamolybdate hybrid compounds

By introducing antibacterial drug pipemidic acid into octamolybdates, two new compounds, (HPPA)₄[Mo₈O₂₆] 2H₂O (1) and [Ni₂(PPA)₂(H₂O)₄] [Mo₈O₂₆] 3H₂O (2) (PPA?=?8-ethyl-5,8-dihydro-5-oxo-2-(1-piperazinyl)pyrido(2,3-d)pyrimidine-6-carboxylic acid), have been synthesized and characterized by physical methods. Single-crystal X-ray analysis reveal that 1 and 2 crystallize in the triclinic system, space group P-1, in which supramolecular interactions play vital roles in stabilizing the structure of 1 and 2. The results of their antitumor activities in vitro show that the compounds exhibit good anti-SGC7901 and anti-SMMC7721 activities, which indicates that the antitumor activities of Polyoxometalates can be modulated by the surface modification with drugs.     

A one-dimensional organic–inorganic hybrid constructed by saturated Keggin polyoxoanions and [CuI(4,4′-bipy)] n n + chains

A one-dimensional (1-D) organic–inorganic hybrid compound {(H₃O)[Cu^I(4,4′-bipy)]₃[SiW₁₂O₄₀]} · 1.5H₂O (1) has been synthesized from hydrothermal reaction of Keggin polyoxometalate, cupric nitrate and 4,4′-bipyridine (4,4′-bipy). Single crystal X-ray diffraction shows 1-D zigzag chains built up of saturated Keggin polyoxoanions and infinite [Cu^I(4,4′-bipy)] _n ^{n +} units. Zipper-like arrangement of adjacent zigzag chains by hydrogen-bonding interactions leads to a 2-D layer and π–π interactions of 4,4′-bipy ligands from adjacent layers further result in the 3-D structure of 1. All Cu atoms in 1 are three-coordinated with “T-type” geometries, indicating they are univalent in the resultant compound. This result has further been confirmed by the absence of signal in the EPR spectrum of 1.     

Assembly of an unprecedented metal-pipemidic acid complex modifying octamolybdates containing like DNA spiral chain

By introducing antibacterial drugs pipemidic acid into the octamolybdates, an unprecedented compound, [Zn(PPA)₂(H₂O)]₂·[Mo₈O₂₆]·3.5H₂O (1) (PPA = pipemidic acid), has been synthesized and characterized by routine physical methods. Single-crystal X-ray diffraction analysis reveals that the title compound contains the right- and left-double-stranded like DNA helical chains, which are assembled together via sharing the β-Mo₈ clusters forming the fascinating double intertwined inverted helices. The result of the antitumor activities shows that the title compound possesses higher antitumor activity and selectivity.     

pH-controlled assembly of two new supramolecular hybrid compounds based on Keggin polyoxotungstates

Two supramolecular compounds based on Keggin polyoxotungstates, (4,4′-H₂bpy){[Cu(4,4′-bpy)]₂[SiW₁₂O₄₀]} (1) and (4,4′-H₂bpy)₂[SiW₁₂O₄₀]·2H₂O (2) have been synthesized and characterized by elemental analyses, IR, UV, XPS spectra, TG analyses, and single crystal X-ray diffraction analyses. Compound 1 exhibits an infinite 1-D ladder like structure, which is further interconnected into a 3-D supramolecular framework via hydrogen bonding interactions. Compound 2 contains 4,4′-bipyridine (4,4′-bpy), pseudo-Keggin polyoxoanions [SiW₁₂O₄₀]^4?, and water molecules. Polyoxoanions together with water molecules in 2 construct a 3-D inorganic supramolecular network through O···O and O···Ow(1) interactions. The electrochemical behaviors and photocatalytic properties of 1 and 2 have been investigated.     

Two New 2D and 1D Ni(II) Coordination Polymers Bridged by Vanadium-Substituted Keggin Polyoxotungstophosphates: Hydrothermal Synthesis and Crystal Structure

Two coordination polymers based on vanadium-substituted Keggin polyoxotungstophosphates as bridging ligands, {[Ni(4,4′-bipy)_1.5(OH)(H₂O)]₂[H₃PW₁₀V₂O₄₀]}·4H₂O (4,4′-bpy = 4,4′-bipyridine) 1 and {[Ni(dpa)₂][Ni(dpa)(H₂O)₃]₂[PW₉V₃O₄₀]}·4H₂O (dpa = 2,2′-dipyridylamine) 2, have been obtained by hydrothermal reactions and characterized by elemental analysis, IR, XRD, TGA and single-crystal X-ray Diffraction analysis. Compound 1 is a 2D layered structure built from 1D infinite zigzag {Ni₂(4,4′-bipy)₃(OH)₂(H₂O)₂}_n²⁺ chains bridged via [H₃PW₁₀V₂O₄₀]²⁻ anions. Compound 2 exhibits a one-dimensional chain-like structure constructed from [Ni(dpa)₂]²⁺ fragments bridged via bis-supported Keggin polyoxoanions [Ni(dpa)(H₂O)₃]₂[PW₉V₃O₄₀]²⁻. The two examples demonstrate that vanadium-substituted Keggin polyoxometalates have greater coordination capability.     

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 new Keggin-type heteropolyanion decorated with dinuclear copper-organic coordination ions: {[Cu(Phen)(μ-Cl)Cu(Phen)<Subscript>2</Subscript>]<Subscript>2</Subscript>[SiW<Subscript>12</Subscript>O<Subscript>40</Subscript>]} · H<Subscript>2</Subscript>O

A new Keggin-type heteropolyanion decorated with dinuclear copper-organic coordination ions, {[Cu(Phen)(μ-Cl)Cu(Phen)₂]₂[SiW₁₂O₄₀]}· H₂O (I), has been hydrothermally synthesized and structurally characterized by IR spectroscopy and single-crystal X-ray diffraction. X-ray crystallography analysis showed that two dinuclear copper-organic [Cu(Phen)(μ-Cl)Cu(Phen)₂]³⁺ units are supported on the reduced α-Keggin polyoxoanion [SiW₁₂O₄₀]^6? via two terminal oxygen atoms from opposite sides of the Keggin polyoxoanion, and I further acts as a neutral molecular unit for the construction of a one-dimensional chain-like framework by \(C - H \cdots Cl\) hydrogen bonds and π-π-stacking interactions.     

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.     

The state of palladium in the system potassium palladium-11-tungstosilicate on aluminosilicate as studied by DRIFT spectroscopy

The influence of redox treatments on the state of palladium in the heteropoly acid K₆[SiW₁₁PdO₃₉] supported on amorphous aluminosilicate was studied by diffuse-reflectance IR spectroscopy using CO as a probe molecule. A bulk sample of the K₆[SiW₁₁PdO₃₉]·11H₂O heteropoly compound (HPC) was studied for comparison. The deposition of the bulk sample on aluminosilicate leads to the partial decomposition of Keggin structure and to the removal of palladium cations from the HPC framework. The metal introduced into the K₆[SiW₁₁PdO₃₉]/SiO₂-Al₂O₃ system within HPC displays higher thermal stability in redox cycles compared to that of the bulk HPC. A highly dispersed state of palladium persists up to 573 K.     

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.     

两个新颖的铜-二氮杂菲和钼(磷, 硒)杂多酸组成的有机-无机杂合化合物: 合成和晶体结构

水热法合成了两个新颖的有机-无机杂合化合物{[Cu(o-phen)(H₂O)]₃[Mo₅P₂O₂₃]}•4.5H₂O (1) 和{[Cu(o-phen)- (H₂O)]₂[Mo₅Se₂O₂₁]} (2) (o-phen＝1,10-phenanthroline). 通过红外光谱和单晶X射线衍射分析确定了它们的结构. 结构分析表明两个分子结构中的相邻[Mo₅P₂O₂₃]^6－或[Mo₅Se₂O₂₁]^4－阴离子均由两个桥式的[Cu(o-phen)(H₂O)]单元连接成分别为风车状和双侧桥联状一维聚合链, 化合物1的双金属链又通过若干链间氢键形成层状堆积结构. 讨论了钼杂多酸阴离子和第二种金属-配体亚单元阳离子之间的相互匹配关系.     

A complex based on a decorated Keggin-type cluster from Cu(II) and 4,4′-dimethyl-2,2′-bipyridine: synthesis,structure and proton conductivity

A proton-conductive complex based on decorated Keggin-type cluster, {[Cu(dmbipy)(H₂O)₃]₂[SiW₁₂O₄₀]}·7H₂O (where dmbipy is 4,4′-dimethyl-2,2′-bipyridine) (1), was synthesized by reaction of CuSiW₁₂O₄₀·nH₂O and dmbipy at room temperature. The product was characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis at 293 K revealed that 1 crystallized in the monoclinic space group C2/c and has a 3-D supramolecular network with 1-D hydrophilic channels constructed by a decorated Keggin-type cluster, [Cu(dmbipy)(H₂O)₃]₂SiW₁₂O₄₀, and solvent water molecules via hydrogen-bonding interactions. Thermogravimetric analysis suggests that 1 has high-thermal stability and good water binding in 1-D hydrophilic channels from 20 to 100 °C. Compound 1 exhibits good proton conductivities (over 10^?3 S cm^?1) at 100 °C in the relative humidity range 35–98%.     

Diverse structures,magnetism and photoluminescence of four transition metal coordination compounds based on the semirigid 4-(pyridin-3-yloxy)-phthalic acid

Four transition metal coordination compounds, {[Co(PPDA)(H₂O)₂]}_n (1), {[Ni(HPPDA)₂]}_n (2), {[Cd(PPDA)(H₂O)]?H₂O}_n (3), and {Zn(HPPDA)₂(H₂O)₄}_n (4), were synthesized by assembling transition metal salts with a semirigid ligand 4-(pyridin-3-yloxy)-phthalic acid (H₂PPDA) under hydrothermal conditions. The compounds have been characterized by elemental analyses, IR spectra, TGA, powder X-ray diffraction, and single-crystal X-ray crystallography. Compound 1 exhibits a three-connected 2-D layered structure, 2 shows a (3,6)-connected 2-D layered structure, 3 displays a (3,6)-connected 2-D layered framework based on binuclear units, and 4 is a mononuclear structure, connected to generate a 3-D supramolecular architecture by hydrogen bonds. Compound 2 is thermally stable up to 300 °C. The magnetic properties of 1 and photoluminescent properties of 3 and 4 have been explored.     

A water chain with trimeric/hexameric clusters trapped in a POM/Ln compound

A new 3-D supramolecular compound based on a Keggin polyoxometalate and lanthanide (Ln) coordination cations [Ce(H₂O)₃L₃]₂[HSiMo₁₂O₄₀]₂[L] ? 7H₂O (1) (L = isonicotinic acid) has been synthesized and characterized by routine methods. Compound 1 has a water chain with trimeric and hexameric water clusters trapped in the network. The isonicotinic acid plays a key role in forming the 1-D water chains. Compound 1 shows intense photoluminescence at room temperature.     

Syntheses,characterization, and luminescent properties of four alkaline earth metal–organic frameworks based on two similar N-containing carboxylates

Four coordination polymers {[Ca(3-pa)₂(H₂O)₂]·3H₂O} (1), {[Sr(3-pa)₂(H₂O)₂]·3H₂O} (2), {[Ca(4-pa)₂(H₂O)₄]} (3) and {[Sr(4-pa)(H₂O)₆]·[4-pa]} (4), (3-pa = pyridine-3-carboxylate, 4-pa = pyridine-4-carboxylate) have been synthesized and structurally characterized. Lots of noncovalent interactions were found in the four compounds, aiding the formation of high-dimensional architectures from the low-dimensional structures. Complex 1 and 2 feature similar 1-D chain structures, which adopt face-to-face orientation to form an interesting 2-D network with pipe-like motif. Chain-like water clusters consisting of infinite tetragonal unit are trapped and stabled in the vacuums of the pipelines. The 2-D sheets are further connected into 3-D architecture by noncovalent interactions. Complex 3 has a discrete mononuclear structure, which is further connected into a 3-D framework by hydrogen bonds and π···π interactions. In complex 4, the zigzag-like chain structure units are parallel to each other and pack in ABAB mode to give rise to a 2-D network, which is stabled by π···π stacking and hydrogen bonds. The counteranions in 4 are hosted between the nets and act as “glue” linking the 2-D networks into a 3-D architecture. In addition, the photoluminescence properties of the compounds have been investigated.     

Stepwise synthesis of two inorganic–organic hybrids based on the manganese monosubstituted Keggin polyanion chains

Two new hybrid compounds based on the manganese monosubstituted Keggin polyanion chains, [H₂bpy][Ag(bpy)]₂[HPMnMo₁₁O₃₉] (1) and [H₂bpy]₂[Hbpy][PMnMo₁₁O₃₉]·H₂O (2), (bpy = 4,4′-bipyridine) have been stepwise synthesized under hydrothermal condition and characterized by elemental analyses, IR spectra, thermogravimetry, and single-crystal X-ray diffraction technique. Structural characterization reveals that although both 1 and 2 contain manganese monosubstituted Keggin polyanion chains, the polyanion chains are not in the full consistent way. In 1, the neighboring manganese monosubstituted Keggin clusters are connected via sharing the para position oxygen atoms of the clusters to form a linear polyanion chain in which the monosubstituted Keggin clusters are further grafted by silver coordination polymer chains forming a 2D network. Whereas the polyanion chain in 2 exhibits a zigzag structure, which is formed by sharing the metaposition terminal oxygen atoms of the clusters, rather than para position terminal oxygen atoms as that in 1. Each zigzag chain contacts with four adjacent chains along four directions through short interspecies contacts, forming a 3D supramolecular framework. The protonated Hbipy⁺ and H₂bipy²⁺ molecules as the counter cations exist in voids of the supramolecular framework in 2. Furthermore, photocatalytic experiments indicate that 1 has good activities for photocatalytic degradation of RhB under UV irradiation.     

Polyoxometalate‐Based Entangled Coordination Networks Induced by an Extended Bis(triazole) Ligand

The introduction of an extended bridging bis(triazole) ligand, that is, 4,4′‐bis(1,2,4‐triazol‐1‐ ylmethyl)biphenyl (BBPTZ), into the hydrothermal reaction system containing transition metal ions and Keggin‐type polyoxometalates (POMs) led to the isolation of three new organic–inorganic hybrid entangled coordination networks, [Cu^I₂Cu^II(BBPTZ)₆][SiW₁₂O₄₀]?12 H₂O ( 1 ), [Ni(BBPTZ)₂(H₂O)][H₂SiW₁₂O₄₀]?11 H₂O ( 2 ), and [Ni₂(BBPTZ)₄(H₂O)₂][SiW₁₂O₄₀]?3 H₂O ( 3 ). All three compounds were characterized by elemental analysis, IR spectroscopy, TG analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compound 1 contains a 2‐D POM‐based metal–organic layer entangled with 1‐D ladder‐like metal–organic chains. The adjacent 2‐D networks are parallel to each other, further stacking into a 3‐D supramolecular framework with 1‐D channels. Compound 2 exhibits a 1‐D cantilever‐type loop‐containing chain. The Keggin‐type POMs act as the cantilever groups, leading to the adjacent catilever‐type chains interwaving together to form a 3‐D supramolecular open framework with two types of channels. Compound 3 possesses a 3‐D open framework based on 2‐D metal–organic undulated layer and Keggin‐type POM clusters. Three sets of such frameworks further interpenetrate with each other to form an interesting three‐fold interpenetrating framework. The photocatalytic activities of compounds 1–3 for the decomposition of methylene blue (MB) under UV light have been investigated.     

Novel Hybrids Constructed from Keggin-Polyoxometalate and Mixed Copper Complex

Abstract  Two new Keggin-polyoxometalate hybrids, {[Cu₂(4,4′-bpy)₂][PW₁₀^VIW₂^VO₄₀]}[Cu₂(obpy)₂]₄ · 2 H₂O (1) and {[Cu₄(2,2′-bpy)₄(4,4′-bpy)₃][SiW₁₂O₄₀]} · 2H₂O (2) (4,4′-/2,2′-bpy = 4,4′-/2,2′-bipyridyl, Hobpy = 6-hydroxy-2,2′-bipyridyl), were hydrothermally synthesized and structurally characterized. Gillard type hydration of 2,2′-bipy is observed during the synthesis of 1, resulting in a new obpy ligand in situ. X-ray structural analyses show that 1 consists of 1D hybrid chain {[Cu₂(4,4′-bpy)₂][PW₁₀^VIW₂^VO₄₀]}_∞ and [Cu₂(obpy)₂] dimer, whereas 2 possesses 1D hybrid structure based on Keggin-type [SiW₁₂O₄₀]⁴⁻ anions and tetra-nuclear copper complexes [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺. Both compounds present interesting supramolecular architectures based on π–π stacking and hydrogen bonds. Graphical Abstract  Compounds {[Cu₂(4,4′-bpy)₂][PW₁₂O₄₀]}[Cu₂(obpy)₂]₄ · 2H₂O (1) and [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃][SiW₁₂O₄₀] · 2H₂O (2) were hydrothermally synthesized. 1 features that the [Cu₂(obpy)₂] dimers based on in situ generated obpy ligands are stumped between the layers where 1D hybrid chain {[Cu₂(4,4′-bpy)₂][PW₁₂O₄₀]}_∞ locates, while 2 exhibits 1D chain-like structure based on anions [SiW₁₂O₄₀]⁴⁻ and tetra-copper complexes [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺.      

Influence of metal ions on the structures of Keggin polyoxometalate-based solids: Hydrothermal syntheses, crystal structures and magnetic properties

Three new Keggin polyoxometalate (POM)-based compounds linked to 3d metal complexes have been synthesized under hydrothermal conditions: [Cu(phen)₂]₂{[Cu(phen)]₂ [SiMo₁₂O₄₀(VO)₂]} (1), {[Zn(phen)₂]₂[GeMo₁₂O₄₀(VO)₂]}{[Zn(phen)₂(H₂O)]₂ [GeMo₁₂O₄₀(VO)₂]}·3H₂O (2) and {[Co(phen)₂]₂[PMo₁₂O₄₀(VO)₂]}{[Co(phen)₂(OH)]₂ [PMo₁₂O₄₀(VO)₂]}·2.5H₂O (3) (phen=1,10-phenanthroline). These three compounds present, as building blocks, the bicapped Keggin anions [XMo₁₂O₄₀(VO)₂] (X=Si, Ge and P). Compound 1 consists of a bicapped Keggin anion [SiMo₁₂O₄₀(VO)₂]²⁻ linked to two [Cu(phen)]⁺ complexes with two [Cu(phen)₂]⁺ countercations. Compound 2 contains two bicapped Keggin anions [GeMo₁₂O₄₀(VO)₂]⁴⁻, one linked to two [Zn(phen)₂(H₂O)]²⁺ cations and the other one linked to two [Zn(phen)₂]²⁺ cations. Compound 3 is a two-dimensional POM-based square network formed by bicapped Keggin anions [PMo₁₂O₄₀(VO)₂]⁴⁻ connected by [Co(phen)₂]²⁺ cations. Discrete bicapped Keggin anions [PMo₁₂O₄₀(VO)₂] linked to two [Co(phen)₂(OH)]⁺ cations are located between the layers. The magnetic properties show the presence of antiferromagnetic interactions among the reduced Mo(V) atoms (in the three compounds) plus a paramagnetic contribution from the V(IV) atoms (in 1 and 2). Compound 3 shows, in addition, an antiferromagnetic interaction between the Co(II) and the V(IV) ions directly linked through an oxygen bridge. The low-temperature ESR spectra of compound 3 confirm the presence of the reduced Mo(V) ions and the antiferromagnetic coupling between the Co(II) and the V(IV) ions.