Systematic exploration of a rutile-type zinc(II)-phosphonocarboxylate open framework: the factors that influence the structure

To systematically explore the assembly mechanism of a rutile-type open framework of {[Zn(3)(pbdc)(2)]·2H(3)O}(n) (3) (H(4)pbdc = 5-phosphonobenzene-1,3-dicarboxylic acid) constructed by 3-connected pbdc ligands and 6-connected Zn(3)(CO(2))(4)(PO(3))(2) secondary building units (Zn(3)-SBUs), three major factors including solvothermal procedures, types of solvents and amines, are taken into consideration. Seven novel structures, namely {[Zn(5)(pbdc)(2)(OH)(2)(H(2)O)(4)]·4H(2)O}(n) (1), {[Zn(3)(pbdc)(2)·H(2)O]·(Htea)·H(3)O·2-5(H(2)O)}(n) (2), {[Zn(3)(pbdc)(2)](H(3)O)(2)(dma)}(n) (4), {[Zn(2)(pbdc)(taea)]·3H(2)O}(n) (5), {[Zn(3)(pbdc)(2)(Hpda)(2)]·2H(2)O}(n) (6), {[Zn(5)(pbdc)(2)(Hpbdc)(2)]·2H(2)pz·9H(2)O}(n) (7), {[Zn(3)(pbdc)(2)]·Hpd·H(3)O·4H(2)O}(n) (8) are obtained. The results indicate that the layered-solvothermal method and the isopropanol solvent play crucial roles in the construction of the special anionic open framework of [Zn(3)(pbdc)(2)](2-). Changing these two factors led molecular assembly away from the rutile-type open framework. However, amines play a variable role in the framework, which means that by using appropriate amines, molecular assembly could generate the open framework of [Zn(3)(pbdc)(2)](2-) with pores decorated by amines. These results suggest a different approach towards decorating pores in anionic frameworks with precise structural information.     

Capture and activation of aerial CO2 by carbamoylation of L-threonine in a Ag(I) supramolecular framework

An ultrasonic reaction of Ag(2)O, 4,4'-bipyridine (bipy) and (2S, 3R)-3-amino-2-hydroxybutanoic acid (L-Thr) gives an unexpected Ag(I) supramolecular framework, {[Ag(3)(bipy)(3)(cahba)]·HCO(3)·10H(2)O}(n) (1), in which the (2S, 3R)-3-(carboxyamino)-2-hydroxybutanoic acid (H(2)cahba) is a carbamate derivative of L-Thr, obtained via in situ transformation of amino group of L-Thr into carbamate by means of CO(2) uptake.     

Distinct structures of coordination polymers incorporating flexible triazole-based ligand: topological diversities, crystal structures and property studies

Six new coordination polymers, namely {[Zn(btec)(0.5)(btmb)]·2H(2)O}(n) (1), {[Co(btec)(0.5)(btmb)(H(2)O)]·3H(2)O}(n) (2), {[Cu(btec)(0.5)(btmb)]·H(2)O}(n) (3), {[Cu(4)(btc)(4)(btmb)(4)]·H(2)O}(n) (4), {[Co(3)(bta)(2)(btmb)(2)]·2H(2)O}(n) (5), [Co(Hbta)(btmb)](n) (6) (H(4)btec = 1,2,4,5-benzenetetracarboxylate, H(3)btc = 1,3,5-benzenetricarboxylate, H(3)bta = 1,2,4-benzenetricarboxylate and btmb = 4,4'-bis(1,2,4-triazol-1-ylmethyl)biphenyl), have been successfully synthesized under hydrothermal conditions. All these complexes were structurally determined by single-crystal X-ray diffraction, elemental analysis, IR, TGA and XRD. Crystal structural analysis reveals that 1 is the first example of an unusual 3D framework with (8(6)) topology containing a 2D molecular fabric structure. Complex 2 exhibits a 3D NbO network with (6(4)·8(2)) topology. In 3, Cu(II) ions are coordinated by anti-conformational btmb ligands to form left- and right-handed double helices, which are further bridged by the 4-connected btec(4-) anions to give a 3D porous network. Complex 4 presents a rare 3D gra network structure with (6(3))(6(9)·8) topology. 5 and 6 were obtained through controllable pH values of solution, 5 features a scarce binodal (3,8)-connected tfz-d framework with the trinuclear Co(II) clusters acting as nodes, whereas 6 has an extended 2D 4(4) grid-like layer and the adjacent 2D layers are interconnected by strong hydrogen bonding interactions into a 3D supramolecular framework. The structural diversities indicate that distinct organic acid ligands, the nature of metal ions and the pH value play crucial roles in modulating the formation of the resulting coordination complexes and the connectivity of the ultimate topological nets. Moreover, magnetic susceptibility measurement of 5 indicates the presence of weak ferromagnetic interactions between the Co(II) ions bridged by carboxylate groups.     

High heat of hydrogen adsorption and guest-responsive magnetic modulation in a 3D porous pillared-layer coordination framework

A bimetallic pillared-layer coordination framework {[Mn(3)(bipy)(3)(H(2)O)(4)][Cr(CN)(6)](2)·2(bipy)·4(H(2)O)}(n) has been constructed using a cyanometallate anion ([Cr(CN)(6)](3-)) and an organic linker (4,4'-bipyridyl) that provides high heat of hydrogen adsorption (～11.5 kJ mol(-1)) and shows guest dependent magnetic modulation.     

Evidence for magnetic anisotropy of [Nb(IV)(CN)8]4- in a pillared-layered Mn2Nb framework showing spin-flop transition

The first example of the [Nb(CN)(8)]-based pillared-layered-type framework system {[Mn(II)(2)(bpdo)(H(2)O)(4)][Nb(IV)(CN)(8)]·6H(2)O}(n) (bpdo = 4,4'-bipyridyl-N,N'-dioxide) has been obtained and characterized structurally and magnetically. The presented results provide the first evidence for substantial magnetic anisotropy of [Nb(IV)(CN)(8)].     

Reversible single crystal to single crystal transformation with anion exchange-induced weak Cu2+···I⁻ interactions and modification of the structures and properties of MOFs

{[Cu(6)(TTTMB)(8)(OH)(4)(H(2)O)(6)]·8(NO(3))·34.5H(2)O}(n) can reversibly transform to {[Cu(6)(TTTMB)(8)I(3)]·9I·26H(2)O}(n) upon a single crystal to single crystal process. The transformation is accompanied by the formation of weak Cu(2+)I(-) interactions and changes in the coordination numbers, as well as modulation in their properties.     

Hydrothermal synthesis, structure, and luminescent properties of selected Zn(II)/Cd(II) coordination polymers constructed from 3,5-bis(x-pyridyl)-1,2,4-triazole (x = 3, 4)

Utilizing 3,5-bis(x-pyridyl)-1,2,4-triazole (x-Hpytz, x = 3; x = 4) as multidentate ligands, six novel coordination polymers with Zn(II) or Cd(II) metal ions were prepared: [Zn(3-pytz)(0.5)(OH)(0.5)Cl](n) (1, 1D ladder), {[Zn(3-Hpytz)(H(2)O)(4)] [Zn(3-Hpytz)(H(2)O)(3)·SO(4)]SO(4)·5H(2)O}(n) (2·5H(2)O, 1D chain), [Cd(3-Hpytz)(SO(4))](n) (3, 3D framework), {[Cd(3-Hyptz)SO(4)·3H(2)O]·2H(2)O}(n) (4·2H(2)O, 1D chain), [Zn(4-pytz)Cl](n) (5, 3D framework) and [Zn(2)(4-pytz)(SO(4))(OH)](n) (6, 3D framework). All compounds were obtained from hydrothermal reactions, with the exception of compound 4 which was obtained by solvent diffusion at room temperature. All compounds were characterized by FTIR, elemental analysis and TGA analysis and their structures were determined by X-ray diffraction. All compounds exhibited substantial thermal stability and showed photofluorescent properties that resulted from ligand π-π* transition.     

A reversible SCSC transformation from a blue metamagnetic framework to a pink antiferromagnetic ordering layer exhibiting concomitant solvatochromic and solvatomagnetic effects

A [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon-based blue framework with a metamagnetic transition from an antiferromagnetic ordering to a weak spontaneous magnetization state, {[Co(3)(CH(3)OH)(μ(3)-OH)(2)(datrz)(sip)]·2.25H(2)O}(n) (1, Hdatrz = 3,5-diamino-1,2,4-triazole, sip(3-) = 3,5-dicarboxybenzenesulfonate), was solvothermally synthesized. 1 exhibits a reversible single-crystal-to-single-crystal transformation by solvent exchange to generate a pink antiferromagnetic ordering coordination layer with a similar [Co(6)(μ(3)-OH)(4)(datrz)(2)](6+) ribbon to 1, {[Co(3)(H(2)O)(3)(μ(3)-OH)(2)(datrz)(sip)]·2.125H(2)O}(n) (2). Such concomitant solvatochromic and solvatomagnetic effects are scarcely observed and are significantly due to the coexistence of differently distorted metal coordination spheres and the cleavage/generation of the weak coordination bond.     

Syntheses, structures and properties of silver-organic frameworks constructed with 1,2,3,4-benzenetetracarboxylic acid

The reactions of 1,2,3,4-benzenetetracarboxylic acid (H(4)mpda) and different silver(I) salts under hydrothermal or solvent evaporation conditions yielded four unusual coordination complexes with interesting frameworks: [Ag(4)(mpda)](n) (1), {[Ag(2.5)(mpda)(bpy)(2)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·(NO(3))(0.5)·(H(2)O)(9)}(n) (2), {[Ag(5)(mpda)(2)(bpy)(4)]·[Ag(bpy)]·[Ag(bpy)(H(2)O)]·[Ag(bpy)(H(2)O)]·(H(2)O)(16)}(n) (3), {[Ag(2)(mpda)(H(2)O)]·[Ag(bpy)]·[Ag(bpy)]}(n) (4) (bpy = 4,4'-bipyridine). Complex 1 displays a novel (3,4,7)-connected {4.6(2)}{4.6(5)}{4(2).6(13).8(5).10} topology, in which the carboxylic groups of the mpda(4-) ligand adopt variable coordination modes. In 1, besides Ag-O coordination bonding, AgAg and Agaromatic intermolecular interactions also make their appearance. In complexes 2-4, rare architectures comprising three or four isolated coordination polymers within the same crystalline structure have been obtained, respectively. In 2 and 3, neighboring layers are linked together through water tapes into a three-dimensional supramolecular architecture, which is also consolidated by π···π stacking, while independent infinite rod-like polymer chains fill the void space between layers. Interestingly, an anionic (H(2)O-NO(3)(-))(n) layer, built from water tapes and nitrate anions as well as consolidated by the mpda(4-) ligands, has been structurally identified in compound 2. A new water tape constructed from alternating tetramers and decamers has been obtained in compound 3. In compound 4, a right-handed helical chain and two rod-like polymeric chains are interconnected through host-guest molecular recognition to generate a three-dimensional chiral supramolecular architecture. Bulk materials for 1 and 4 have second-harmonic generation activity, being approximately 0.6 and 0.4 times that of urea. The IR spectra, thermogravimetric analysis and luminescent properties of all compounds were also investigated.     

Host-guest supramolecular interactions in the coordination compounds of 4,4'-azobis(pyridine) with MnX2 (X = NCS–, NCNCN–, and PF6(–)): structural analyses and theoretical study

Three new Mn(II) coordination compounds {[Mn(NCNCN)(2)(azpy)]·0.5azpy}(n) (1), {[Mn(NCS)(2)(azpy)(CH(3)OH)(2)]·azpy}(n) (2), and [Mn(azpy)(2)(H(2)O)(4)][Mn(azpy)(H(2)O)(5)]·4PF(6)·H(2)O·5.5azpy (3) (where azpy = 4,4'-azobis(pyridine)) have been synthesized by self-assembly of the primary ligands, dicyanamide, thiocyanate, and hexafluorophosphate, respectively, together with azpy as the secondary spacer. All three complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses, and single crystal X-ray crystallography. The structural analyses reveal that complex 1 forms a two-dimensional (2D) grid sheet motif. These sheets assemble to form a microporous framework that incorporates coordination-free azpy by host-guest π···π and C-H···N hydrogen bonding interactions. Complex 2 features azpy bridged one-dimensional (1D) chains of centrosymmetric [Mn(NCS)(2)(CH (3)OH)(2)] units which form a 2D porous sheet via a CH(3)···π supramolecular interaction. A guest azpy molecule is incorporated within the pores by strong H-bonding interactions. Complex 3 affords a 0-D motif with two monomeric Mn(II) units in the asymmetric unit. There exist π···π, anion···π, and strong hydrogen bonding interactions between the azpy, water, and the anions. Density functional theory (DFT) calculations, at the M06/6-31+G* level of theory, are used to characterize a great variety of interactions that explicitly show the importance of host-guest supramolecular interactions for the stabilization of coordination compounds and creation of the fascinating three-dimensional (3D) architecture of the title compounds.     

Self-assembly of unprecedented [8+12] Cu-metallamacrocycle-based 3D metal-organic frameworks

[8+12]-metallamacrocycle-based 3D frameworks {[Cu(4)(pbt)(2)(SO(4))(2)(DMF)(2)(CH(3)OH)]·7H(2)O·DMF}(n) (1) and [12]-macrocycle 3D {[Cu(2)(pbt)(SO(4))(DMSO)(CH(3)OH)(2)]·5H(2)O·CH(3)OH}(n) (2) have been obtained. Both complexes display antiferromagnetic couplings and high catalytic activity in the oxidative coupling reaction of 1-ethynylbenzene and oxazolidin-2-one.     

Highly-connected, porous coordination polymers based on [M4(μ3-OH)2] (M = Co(II) and Ni(II)) clusters: different networks, adsorption and magnetic properties

Two new 3D coordination polymers based on tetranuclear clusters, {[Co(4)(ina)(5)(μ(3)-OH)(2)(H(2)O)(EtOH)]-NO(3)·2EtOH·4H(2)O}(n) (1) (Hina = isonicotinic acid) and {[Ni(4)(ina)(5)(μ(3)-OH)(2)(EtCOO)]·6EtOH·2H(2)O}(n) (2), were obtained by the solvothermal reactions from Hina and different metal salts. The [M(4)(μ(3)-OH)(2)] cores act as 7- and 9-connected nodes and are extended through ina linkers to highly-connected frameworks with vmr net for 1 and bct-9-P2(1)/c net for 2. Both the desolvated frameworks display effective gas sorption capacities of N(2) and H(2) with Langmuir surface areas of 546 and 917 m(2) g(-1) for 1 and 2, respectively. Magnetic studies show spin canting and spin-glass behaviours with T(g) = 6.0 and 15.0 K for 1 and 2, respectively. The intra- and inter-tetramer coupling interactions and cooperative magnetic correlation greatly influence the bulk magnetic behaviours in this system.     

Novel iso-reticular Zn(II) metal-organic frameworks constructed by trinuclear-triangular and paddle-wheel units: synthesis, structure and gas adsorption

Two novel Zn(II) metal-organic frameworks (MOFs) constructed by trinuclear-triangular and paddle-wheel units, namely {[Zn(5)(dmtrz)(3)(IPA)(3)(OH)]·DMF·H(2)O}(n) (MAC-4, Hdmtrz = 3,5-dimethyl-1H-1,2,4-triazole, H(2)IPA = isophthalic acid, DMF = dimethyl formamide) and {[Zn(5)(dmtrz)(3)(OH-IPA)(3)(OH)]·DMF·5H(2)O}(n) (MAC-4-OH, OH-H(2)IPA = 5-hydroxyisophthalic acid), were solvothermally synthesized. Single-crystal analyses reveal that MAC-4-OH is an iso-reticular framework of MAC-4 with channels functionalized by hydroxyl groups. Gas adsorption reveals that MAC-4-OH shows a significant enhancement for CO(2) uptake compared with that of MAC-4 due to the existence of electrostatic attractive interactions, though its surface area is lower than that of MAC-4.     

Crystal structures and magnetism of infinite alternating chains arranged by paddle-wheel dinuclear copper and mononuclear copper units

The crystal structures and magnetic properties of two novel polyclusters {[Cu(3)(tci)(2)(H(2)O)(2)]·12H(2)O}(n) (1) and {[Cu(3)(tci)(2)(H(2)O)(2)]·6H(2)O}(n) (2) (tci = tris(2-carboxyethyl) isocyanurate) are investigated. The X-ray crystallographic analysis reveals that they contain interesting infinite alternating chains of dinuclear paddle-wheel copper and mononuclear copper units arranged in ABBA magnetism exchange mode. Variable-temperature magnetic susceptibility measurements on the two polyclusters show strong antiferromagnetism couplings between copper ions with exchange interactions J = -181.4 cm(-1), zj' = -0.31 cm(-1) for 1, J = -170 cm(-1), zj' = -0.42 cm(-1) for 2. With the aim of studying magneto-structural correlation, we synthesized a three-dimensional polymer [Cu(3)(tci)(2)(py)(4)(H(2)O)(2)](n) (3) based on isolated dinuclear cluster and mononuclear copper units. Fitting the susceptibility data yielded J = -176.1 cm(-1), zj' = -0.084 cm(-1) for 3.     

Synthesis of isoreticular zinc(II)-phosphonocarboxylate frameworks and their application in the Friedel-Crafts benzylation reaction

Three isoreticular zinc(II)-phosphonocarboxylate frameworks, namely {[Zn(3)(pbdc)(2)]·2H(3)O}(n) (ZnPC-2), {[Zn(3)(pbdc)(2)]·Hpd·H(3)O·4H(2)O}(n) (Hpd@ZnPC-2) and {[Co(1.5)Zn(1.5)(pbdc)(2)]·2H(3)O}(n) (CoZnPC-2) (H(4)pbdc=5-phosphonobenzene-1,3-dicarboxylic acid, pd=pyrrolidine), were solvothermally synthesized. ZnPC-2 has a 3D structure based on trinuclear Zn(II) clusters (Zn(3)-SBU) showing 3D interconnected channels. Hpd@ZnPC-2 contains an isoreticular framework of ZnPC-2 with small channels blocked by Hpd molecules. In CoZnPC-2, Zn(II) ions in ZnPC-2 are partially substituted by Co(II) ions. The Friedel-Crafts benzylation reactions were carried out over these isoreticular porous materials. The catalytic results reveal that ZnPC-2 is an excellent heterogeneous Lewis acid catalyst with a high selectivity (>90%) towards less bulky para-oriented products. The catalytic reaction has been proved to occur inside the pore of ZnPC-2, and the immobilized Zn(3)-SBUs are the active sites.     

Zn(II) and Cd(II) coordination polymers assembled by di(1H-imidazol-1-yl)methane and carboxylic acid ligands

Five new Zn(II)/Cd(II) coordination polymers constructed from di(1H-imidazol-1-yl)methane (L) mixed with different auxiliary carboxylic acid ligands formulated as [Zn(L)(H(2)L(1))(2)·(H(2)O)(0.2)](n) (1), {[Zn(L)(L(2))]·H(2)O}(n) (2), {[Cd(2)(L)(2)(L(2))(2)]·2H(2)O}(n) (3), {[Cd(L)(L(3))]·H(2)O}(n) (4) and [Cd(L)(L(4))](n) (5) (H(3)L(1) = 1,3,5-benzenetricarboxylic acid, H(2)L(2) = 4,4'-oxybis(benzoic acid), H(2)L(3) = m-phthalic acid and H(2)L(4) = p-phthalic acid) have been synthesized under hydrothermal conditions and structurally characterized. Four related auxiliary carboxylic acids were chosen to examine the influences on the construction of these coordination frameworks with distinct dimensionality and connectivity. The coordination arrays of 1-5 vary from 1D zigzag chain for 1, 2D (4,4) layer for 2-4, to 2-fold interpenetrated 3D coordination network with the α-Po topology for 5. The thermal and photoluminescence properties of complexes 1-5 in the solid state have also been investigated.     

Temperature-directed structural recurrence in low-symmetric Co(II) complexes and nanocrystals

Low-symmetric complexes {[Co(μ(2)-L)(H(2)O)(2)]·H(2)O}(n) (1) and {[Co(μ(3)-L)(H(2)O)]·0.5H(2)O}(n) (2) and corresponding nanocrystals were obtained, which exhibit structural recurrence behaviour at various temperatures as well as changes of chiral, nonlinear optical and ferroelectric properties.     

Systematic structural control of multichromic platinum(II)-diimine complexes ranging from ionic solid to coordination polymer

Reactions of a Pt(II)-diimine-based metalloligand Na(2)[Pt(CN)(2)(4,4'-dcbpy)] (4,4'-H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) with alkaline-earth metal salts Mg(NO(3))(2)·6H(2)O, CaCl(2), SrCl(2)·6H(2)O, and BaBr(2)·2H(2)O in aqueous solution gave luminescent complexes formulated as [Mg(H(2)O)(5)][Pt(CN)(2)(4,4'-dcbpy)]·4H(2)O (MgPt-4·9H(2)O), {[Ca(H(2)O)(3)][Pt(CN)(2)(4,4'-dcbpy)]·3H(2)O}(∞) (CaPt-4·6H(2)O), {[Sr(H(2)O)(2)][Pt(CN)(2)(4,4'-dcbpy)]·H(2)O}(∞) (SrPt-4·3H(2)O), and {[Ba(H(2)O)(2)][Pt(CN)(2)(4,4'-dcbpy)]·3H(2)O}(∞) (BaPt-4·5H(2)O), respectively. The crystal structures of all MPt-4 complexes were determined by X-ray crystallography. In these structures, the alkaline-earth metal ions are commonly coordinated to the carboxyl groups of the [Pt(CN)(2)(4,4'-dcbpy)](2-) metalloligand. In the case of MgPt-4·9H(2)O, the Mg(II) ion is bound by five water molecules and one oxygen atom of a carboxyl group to form a neutral complex molecule [Mg(H(2)O)(5)][Pt(CN)(2)(4,4'-dcbpy)]. In contrast, the alkaline-earth metal ion and metalloligand form two-dimensional (CaPt-4·6H(2)O) and three-dimensional (SrPt-4·3H(2)O and BaPt-4·5H(2)O) coordination networks, respectively. All fully hydrated complexes exhibited a strong phosphorescence from the triplet π-π* transition state. Luminescence spectroscopy revealed that MgPt-4·9H(2)O exhibited interesting multichromic (i.e., thermo-, mechano-, and vapochromic) luminescence, whereas CaPt-4·6H(2)O showed only thermochromic luminescence. The other two complexes did not exhibit any chromic behaviour. Combination analysis of powder X-ray diffraction, thermogravimetry, and IR spectroscopy suggests that the dimensionality of the coordination network contributes considerably to both the structural flexibility and luminescence properties; that is, the low-dimensional flexible coordination network formed in MPt-4 complexes with smaller alkaline-earth metal ions enables a structural rearrangement induced by thermal and mechanical stimuli and vapour adsorption, resulting in the observed multichromic behaviour.     

Co(II), Mn(II) and Cu(II)-directed coordination polymers with mixed tetrazolate-dicarboxylate heterobridges exhibiting spin-canted, spin-frustrated antiferromagnetism and a slight spin-flop transition

Three new paramagnetic ion-directed coordination frameworks, {[Co(4)(H(2)O)(2)(μ(3)-OH)(2)(atz)(2)(nip)(2)]·3H(2)O}(n) (1), {[Mn(4)(H(2)O)(2)(μ(3)-OH)(2)(atz)(2)(nip)(2)]·H(2)O·MeOH}(n) (2) and {[Cu(2)(H(2)O)(μ(3)-OH)(atz)(nip)]·2H(2)O}(n) (3), were, respectively, obtained by solvo-/hydrothermal reactions of 5-amino-1H-tetrazole (Hatz), 5-nitroisophathalic acid (H(2)nip) with an inorganic Co(II), Mn(II) or Cu(II) salt. The former two complexes are two-dimensional (2D) covalent layers built from butterfly-shaped tetranuclear M(4)(μ(3)-OH)(2) clusters and double atz(-) and nip(2-) linkers. Whereas complex 3 is a 3D framework with scarcely observed corner-sharing Cu(3)(μ(3)-OH) Δ-chains extended by nip(2-) linkages, in which the anionic atz(-) ligand acts as a reinforcement to consolidate the Δ-chain. Magnetically, due to the interplay of the anisotropy of spin carrier and magnetic exchange interactions from the adjacent spin carriers, the complexes exhibit spin-canted antiferromagnetism with a Néel temperature lower than 2.0 K for 1 and an antiferromagnetic ordering with a slight field-induced spin-flop transition for 2. In contrast, complex 3 with a local Kagomé sublattice displays spin-frustrated antiferromagnetic behavior with magnetic ordering at 16.0 K.     

A feasible route to approach 3D POM-based hybrids: utilizing substituted or reduced Keggin anions with high charge density

Five new hybrid compounds based on Keggin polyanions, Ag(+)/Cu(+) ions and 1,3-bis(1,2,4-triazol-1-yl)propane (btp) molecules have been hydrothermally synthesized. In [Ag(5)(btp)(4)(H(2)O)(2)][PCuW(11)O(39)]·2H(2)O (1), [Ag(4.33)Na(0.67)(btp)(4)(H(2)O)(2)][PMnMo(11)O(39)]·H(2)O (2) and [Cu(4)(btp)(4)Na(H(2)O)(2)][PMnMo(11)O(39)]·2H(2)O (3), the neighboring mono-substituted Keggin clusters are alternately connected via sharing oxygen atoms to form an unusual Keggin-based transition-metal monosubstituted chain, in which the Keggin cluster serves as a decadentate ligand and grafts ten metal atoms representing the highest connected number for Keggin cluster and forming a 3D framework. In [Ag(5)(btp)(4)][PW(VI)(10)W(V)(2)O(40)] (4) and [Ag(5)(btp)(4)][PMo(VI)(10)Mo(V)(2)O(40)] (5), two-electron reduced Keggin clusters as hexadentate linkages are inserted in the rhomboid-like tunnels of the Ag-btp framework and connect with the framework via six Ag-O bonds to achieve 3D motifs, which are new and rare examples of heteropoly blue based hybrid compounds. The successful synthesis of the five high-dimensional structures may provide a feasible route for us to approach 3D polyoxometalate-based hybrids by using substituted Keggin anions and heteropoly blues with high charge density. Furthermore, photocatalytic experiments indicate that both 1 and 4 have good activities for photocatalytic degradation of RhB under UV irradiation. The luminescent properties of compounds 1-5 in the solid state were also investigated.