Bridging Carboxylate Research Articles

Novel manganese(ii) and cobalt(ii) 2D polymers containing alternating chains with mixed azide and carboxylate bridges: crystal structure and magnetic properties

Two new Mn(ii) and Co(ii) complexes based on AABAA alternating chains with mixed azide and carboxylate bridges were synthesized, structurally and magnetically studied.

Magneto-structural versatility of copper(II)-3-phenylpropionate coordination polymers with N-donor coligands.

A novel series of copper(II) coordination polymers [Cu2(O2CC8H9)4(pyz)]n (1), [Cu2(O2CC8H9)4(dps)]n (2), {[Cu(O2CC8H9)2(dps)(H2O)]·H2O}n (3), {[NaCu(O2CC8H9)2(bpm)(NO3)]·H2O}n (4), and [Cu4(O2CC8H9)6(OH)2(bpp)2]n (5) [O2CC8H9− = 3-phenylpropionate anion, pyz = pyrazine, dps = di(4-pyridyl)sulfide, bpm = 2,2′-bipyrimidine, and bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and magneto-structurally investigated. Compounds 1 and 2 belong to a large group of copper(II) carboxylates where bis-monodentate pyz (1) and dps (2) ligands connect the paddle-wheel [CuII2(μ-O2CC8H9)4] units leading to alternating copper(II) chains. The structure of 3 consists of uniform chains of trans-[CuII(O2CC8H9)2] units linked by the bis-monodentate dps ligand. Compound 4 consists of heterobimetallic chains where [NaI2CuII2(μ-O2CC8H9)4(NO3)2] units are doubly bridged by bis-bidentate bpm ligands. Compound 5 is also a chain compound whose structure is made up by tetranuclear [CuII4(μ3-OH)2(μ-O2CC8H9)4(O2CC8H9)2] units which are doubly bridged by bis-monodentate bpp ligands. The magnetic properties were investigated in the temperature range 1.8–300 K. Strong antiferromagnetic interactions across the quadruple syn–syn carboxylate are observed in 1 and 2 [J = −378 (1) and −348 cm−1 (2)] whereas a weak ferromagnetic coupling through the double out-of-plane oxo(carboxylate) bridge occurs in 4 [J = +2.66 cm−1], the spin Hamiltonian being defined as H = −JS1·S2 with S1 = S2 = SCu = 1/2. A quasi Curie law is observed for 3 (θ = −0.36 cm−1), the bis-monodentate dps ligand being a very poor mediator of magnetic interactions. The analysis of the magnetic properties of 5 is quite complex because of the presence of two crystallographically independent tetracopper(II) units with single-μ-hydroxo, di-μ-hydroxo, μ3-hydroxo and single-μ-hydroxo plus double syn,syn carboxylate bridges in each one. The nature and values of the magnetic couplings for 5 obtained by fitting (intermediate, strong and weak antiferromagnetic interactions for the three former exchange pathways respectively, and intermediate ferromagnetic interactions for the latter one) were substantiated by DFT type calculations.

A novel coordination polymer based on Co(ii) hexanuclear clusters with azide and carboxylate bridges: structure, magnetism and its application as a Li-ion battery anode.

A novel Co(ii) coordination polymer, [Co(H2O)6][Co6(bpybdc)2(N3)10(H2O)4]·8H2O (bpybdc2- = 1,1'-bis(3,5-dicarboxylatophenyl)-4,4'-bipyridinium), has been synthesized from a rigid zwitterionic tetracarboxylate ligand and azide. In this compound, hexacobalt clusters with mixed μ-1,1-azide, μ3-1,1,1-azide and μ-1,3-carboxylate bridges are linked into chains by μ-1,3-azide bridges, and the chains are interlinked into 2-fold interpenetrated three-dimensional frameworks through the organic ligand and hydrogen bonds mediated by hexaaquacobalt(ii) complex ions. Magnetic analysis suggested that intracluster ferromagnetic and intercluster antiferromagnetic interactions work together to give overall antiferromagnetic ground states for the azide and carboxylate bridged chain. When applied as an anode for lithium-ion batteries, the coordination polymer changes into an amorphous phase and exhibits a relatively high reversible capacity of 510 mA h g-1 with stable cycling behavior and rate performance.

Carboxylate Coordination Assisted Aggregation for Quasi‐Tetrahedral and Partial‐Dicubane [Cu4] Coordination Clusters

AbstractThe reaction of three copper(II) carboxylate (R = Me, Ph and H in RCO2−) salts in MeOH with H3L resulted three [Cu4] aggregates: [Cu4(μ4‐O)(μ‐H2L)2(μ1,3‐O2CCH3)4] (1), [Cu4(μ4‐O)(μ‐H2L)2(μ1,3‐O2CPh)(PhCO2)3]⋅H2O (2⋅H2O), and [Cu4(μ3‐OH)2(μ‐H2L)2(μ1,1‐HCO2)2(HCO2)2]⋅2H2O (3⋅2H2O). Three different carboxylate groups showing varying coordination modes were responsible for the self‐aggregation of two ligand bound [Cu2(H2L)]3+ units. The [Cu4O] and [Cu4(OH)2] cores were generated from water‐derived oxido and hydroxido nucleating groups to provide quasi‐tetrahedral and partial‐dicubane topologies. In complexes 1 and 2⋅2H2O the μ1,3 bridging mode of the carboxylate bridges were responsible for the entrapment of μ4‐O unit, whereas μ1,1 bridge by formato groups resulted in trapping of two μ3‐OH units in complex 3⋅2H2O. Complex 3⋅2H2O is the first reported example of a μ1,1‐formato bridged [Cu4] aggregate. Long range van der Waals forces, in presence of hydrogen bonding interactions, also play significant role in the [Cu4] aggregation process. These have been analyzed by DFT calculations and Hirshfeld surface analysis.

Non-heme μ-Oxo- and bis(μ-carboxylato)-bridged diiron(iii) complexes of a 3N ligand as catalysts for alkane hydroxylation: stereoelectronic factors of carboxylate bridges determine the catalytic efficiency.

A series of non-heme (μ-oxo)bis(μ-dicarboxylato)-bridged diiron(iii) complexes, [Fe2(O)(OOCH)2(L)2](2+)1, [Fe2(O)(OAc)2(L)2](2+)2, [Fe2(O)(Me3AcO)2(L)2](2+)3, [Fe2(O)(OBz)2(L)2](2+)4, [Fe2(O)(Ph2AcO)2(L)2](2+)5 and [Fe2(O)(Ph3AcO)3(L)2](2+)6, where L = N,N-dimethyl-N'-(pyrid-2-ylmethyl)ethylenediamine, OAc(-) = acetate, Me3AcO(-) = trimethylacetate, OBz(-) = benzoate, Ph2AcO(-) = diphenylacetate and Ph3AcO(-) = triphenylacetate, have been isolated and characterized using elemental analysis and spectral and electrochemical techniques. They have been studied as catalysts for the selective oxidation of alkanes using m-chloroperbenzoic acid (m-CPBA) as the oxidant. Complexes 2, 3, and 4 possess a distorted bioctahedral geometry in which each iron atom is coordinated to an oxygen atom of the μ-oxo bridge, two oxygen atoms of the μ-carboxylate bridge and three nitrogen atoms of the 3N ligand. In an acetonitrile/dichloromethane solvent mixture all the complexes display a d-d band characteristic of the triply bridged diiron(iii) core, revealing that they retain their identity in solution. Upon replacing electron-donating substituents on the bridging carboxylates by electron-withdrawing ones the E1/2 value of the one-electron Fe(III)Fe(III)→ Fe(III)Fe(II) reduction becomes less negative. On adding one equivalent of Et3N to a mixture of one equivalent of the complex and an excess of m-CPBA in the acetonitrile/dichloromethane solvent mixture an intense absorption band (λmax, 680-720 nm) appears, which corresponds to the formation of a mixture of complex species. All the complexes act as efficient catalysts for the hydroxylation of cyclohexane with 380-500 total turnover numbers and good alcohol selectivity (A/K, 6.0-10.1). Adamantane is selectively oxidized to 1-adamantanol and 2-adamantanol (3°/2°, 12.9-17.1) along with a small amount of 2-adamantanone (total TON, 381-476), and interestingly, the sterically demanding trimethylacetate bridge around the diiron(iii) centre leads to high 3°/2° bond selectivity; on the other hand, the sterically demanding triphenylacetate bridge gives a lower 3°/2° bond selectivity. A remarkable linear correlation between the pKa of the bridging carboxylate and TON for both cyclohexane and adamantane oxidation is observed, illustrating the highest catalytic activity for 3 with strongly electron-releasing trimethylacetate bridges.

A new family of 1D, 2D and 3D frameworks aggregated from Ni5, Ni4 and Ni7 building units: synthesis, structure, and magnetism.

Three new Ni(ii)-clusters based on a Y-shaped ligand (biphenyl-3,4',5-tricarboxylate, H3BPT), [Ni5(HBPT)4(OH)2(H2O)12]n (), [Ni4(BPT)2(OH)2(H2O)6]n·4nH2O (), and [Ni7(BPT)2(1,4-bib)2(OH)6(HCO2)2]n·3nH2O () (1,4-bib = 1,4-bi(1H-imidazol-1-yl)benzene), have been synthesized under solvothermal conditions. They were studied by infrared spectroscopy (IR), single crystal X-ray diffraction, thermogravimetric analysis (TGA), and magnetochemistry. The complexes contain low nuclear Ni-clusters as building units (BUs). Structurally, in , the cluster BUs of [Ni5(μ3-OH)2](8+) can be viewed as two reverse triangles sharing a common vertex, which are connected by the partially deprotonated μ2-η(1):η(1)-HBPT(2-) forming 1D chains. The BUs of [Ni4(μ3-OH)2](6+) clusters in can be considered as two reverse triangles sharing a common edge and extended by deprotonated μ6-η(1):η(1):η(1):η(1):η(2)-BPT(3-) constructing a 2D framework. The 3D framework of complex consists of a [Ni7(μ3-OH)4(R-COO)7(HCO2)3] cluster BUs with fully deprotonated μ5-η(1):η(1):η(1):η(1):η(1):η(1)-BPT(3-) and 1,4-bib ligands. In addition, TGA reveals that the complexes are stable in the range of 293-548 K. Magnetostructural analyses indicate ferromagnetic coupling of J1 = 1.85(3) and J2 = 2.25(4) cm(-1) in and J = 5.76(6) cm(-1) in , whereas magnetic parameters J1 = -2.64(3), J2 = -23.22(19) and J3 = 12.02(5) cm(-1) indicate an alternating magnetic chain (AF/F) in .

Ir(III)-Catalyzed Synthesis of Isoquinoline N-Oxides from Aryloxime and α-Diazocarbonyl Compounds.

An efficient Ir(III)-catalyzed C-H activation and annulations of aryloxime with α-diazocarbonyl compounds has been developed for the synthesis of substituted isoquinoline N-oxides. The reaction proceeds under mild atmospheric conditions, without any external oxidants and releases N2 and H2O as the byproducts. In addition, synthetic applications of the N-oxide products have been established by performing further functionalization. An interesting dimeric iridacyclic complex allied through a bis-silver carboxylate bridge has been isolated that efficiently catalyzed the reaction.

One pot synthesis, structure and magnetic property of a pseudo-interpenetrated 2D copper framework based on coordinated 1,1′-biphenyl-3,3′,5,5′-tetracarboxylate and synthon

A mixture of 1,1′-biphenyl-3,3′,5,5′-tetracarboxylate acid (abbreviated as H4bpta), 4,4′-bipyridine (abbreviated as 4,4′-bipy), and CuCl2·2H2O generates co-crystallization supramolecular solids [Cu2(cis-H2bpta)2(4,4′-bipy)2]n·nH4bpta·2nH2O (I) under hydrothermal condition and form of partly deprotonated cis-H2bpta2− firstly emerges in this work. Crystallographically, a 1:1 co-crystal is formed by co-crystallization of [Cu2(cis-H2bpta)2(4,4′-bipy)2] and H4bpta in self-assembled process. Structurally, the compound (I) exhibits two-dimensional (2D) double-layered nets with a pseudo-interpenetrated skeleton, one layer is characteristic of metal-organic moiety linked via cis-H2bpta2− and 4,4′-bipy spaces, and the other formed by O–H···O H-bonds presented in neutral H4bpta ligands. Interestingly, its mechanically interlocked structure is formed by hydrogen bonds, which results in an interesting interweaving framework with a new (3,4,5)-connected topological structure. Magnetic couplings between adjacent Cu(II) centers are mediated through double syn-syn carboxylate bridges. Magnetic susceptibility measurement indicates that (I) exhibits a dinuclear Cu(II) behavior with antiferromagnetic coupling (J = −35.69(1) cm−1).

Magnetic and Photochromic Properties of a Manganese(II) Metal-Zwitterionic Coordination Polymer.

The solvothermal reaction of Mn(ClO4)2, NaN3, and a rigid viologen-tethered tetracarboxylic acid (1,1'-bis(3,5-dicarboxyphenyl)-4,4'-bipyridinium chloride, [H4L]Cl2) led to a coordination polymer of formula [Mn4(L)(N3)6(H2O)2]n. X-ray analysis revealed a 3D coordination structure. The Mn(II) ions are connected by mixed azide and carboxylate bridges to give 2D layers, which are pillared by the viologen tether of the zwitterionic ligand. Magnetic analyses suggested that the compound features antiferromagnetism and field-induced metamagnetism. The compound also shows photochromic and photomagnetic properties. The long-range magnetic ordering is owed to the spin-canting structure of the Mn(II)-azide-carboxylate layer; the photochromism involves the formation of viologen radicals via photoinduced electron transfer, and the photomagnetism is related to the interactions between the metal ion and the photogenerated radicals. The study demonstrates a strategy for the design of new multifunctional materials with photoresponsive properties.

Probing the Influence of N‐Donor Capping Ligands on Supramolecular Assembly in Molecular Uranyl Materials

AbstractThe syntheses and crystal structures of six new compounds containing the UO22+ cation, 3,5‐dichlorobenzoic acid, and a chelating N‐donor [2,2′‐bipyridine (bipy), 1,10‐phenanthroline (phen), 4,7‐dimethyl‐1,10‐phenanthroline (dimethylphen), 2,2′:6′,2″‐terpyridine (terpy), 4′‐chloro‐2,2′:6′,2″‐terpyridine (Cl–terpy), or 2,4,6‐tris(2‐pyridyl)‐s‐triazine (TPTZ)] are reported. Single‐crystal X‐ray diffraction analysis of these materials enabled the exploration of the structural relationship between the benzoic acids and the chelating N‐donor as well as providing a platform to evaluate the effects of ligand choice on uranyl hydrolysis and subsequent oligomerization. At an unadjusted pH (ca. 3), a mix of uranyl monomers and dimers are observed, dimer formation resulting from both bridging carboxylate linkers and hydroxo bridges. Assembly by halogen‐ and hydrogen‐bonding interactions as well as π–π interactions was observed depending on the experimental conditions utilized. Further, spectroscopic characterization (both vibrational and luminescence) of complexes 1, 4, and 5 to explore the effects of the electron‐donating ability of the capping ligand on the corresponding uranyl luminescence and vibrational spectra suggests that there is a relationship between the observed bathochromic shifts and the electron‐donating ability of the capping ligands.

ChemInform Abstract: Discrete Metal‐Carboxylate Self‐Assembled Cages: Design, Synthesis and Applications

AbstractReview: 134 refs.

Stereoselective Synthesis of 1,3-Diaminotruxillic Acid Derivatives: An Advantageous Combination of C-H-ortho-Palladation and On-Flow [2+2]-Photocycloaddition in Microreactors.

The stereoselective synthesis of ε-isomers of dimethyl esters of 1,3-diaminotruxillic acid in three steps is reported. The first step is the ortho-palladation of (Z)-2-aryl-4-aryliden-5(4H)-oxazolones 1 to give dinuclear complexes 2 with bridging carboxylates. The reaction occurs through regioselective activation of the ortho-CH bond of the 4-arylidene ring in carboxylic acids. The second step is the [2+2]-photocycloaddition of the CC exocyclic bonds of the oxazolone skeleton in 2 to afford the corresponding dinuclear ortho-palladated cyclobutanes 3. This key step was performed very efficiently by using LED light sources with different wavelengths (465, 525 or 625 nm) in flow microreactors. The final step involved the depalladation of 3 by hydrogenation in methanol to afford the ε-1,3-diaminotruxillic acid derivatives as single isomers.

Synthesis and Crystal Structure of Binuclear and Pentanuclear Nickel(II) Complexes Containing 4-(salicylaldiminato)antipyrine Schiff base

The new title binuclear Ni (II) compound  (1) and the novel pentanuclear Ni (II) cluster {[  } (2) are formed from the reaction of an asymmetric Schiff base ligand L (L = 4-(salicylaldiminato)antipyrine) with Ni .4  in the former or Ni(ClO4)2.6H2O in presence of malonate in the later.  Complex (1) consists of ( ]+ cation) and one uncoordinated tetraphenylborate anion.  The cation adopts a distorted octahedral arrangement around each metal center.  In the binuclear unit both Ni(II) ions are linked through two phenolate (µ2-O) oxygen atoms of L, and two oxygen atoms of a bridging carboxylate group. Each Ni (II) coordinates to four oxygen atoms at the basal plane, two oxygen atoms from two bridging phenolate groups, one from pyrazolone ring and the last of an aqua molecule, and at the axial positions to a bridging carboxylate-O atom and an azomethine nitrogen atom.  In the pentanuclear cluster (2) consisting of [ ]+2 cation and two tetraphenylborate anions, the core of the cation is assembled by four [Ni( )] units, linked to the central Ni-ion by two bridging water molecules. The resulting coordination sphere for the external symmetry related nickel ions is a pseudo octahedron.  The central Ni-atom unusually adopts dodecahedron geometry through its coordination to eight bridging water molecules. In complex (1) each Ni-atom is coordinated to one tridentate L ligand and in complex (2) each [Ni ( )] unit is coordinated to two bidentate L ligands.  Inter-and intramolecular hydrogen bonds are present in both crystal structures.

Crystal structures of two erbium(III) complexes with 4-amino-benzoic acid and 4-chloro-3-nitro-benzoic acid.

The crystal structures of two erbium(III) complexes with 4-amino-benzoic acid (4-ABAH), namely bis-(μ2-4-amino-benzoato-κ(2) O:O')bis-[bis(4-amino-benzoato-κ(2) O,O')di-aqua-erbium(III)] dihydrate, [Er2(C7H6NO2)6(H2O)4]·2H2O, (I), and 4-chloro-3-nitro-benzoic acid (CLNBAH), namely poly[hexa-kis-(μ2-4-chloro-3-nitro-benzoato-κ(2) O:O')bis-(dimethyl sulfoxide-κO)dierbium(III)], [Er2(C7H3ClNO4)6(C2H6OS)2] n , (II), have been determined. In the structure of solvatomorphic compound (I), the symmetry-related irregular ErO8 coordination polyhedra in the discrete centrosymmetric dinuclear complex comprise two monodentate water mol-ecules and six carboxyl-ate O-atom donors, four from two bidentate carboxyl-ate O,O'-chelate groups and two from the bis-monodentate O:O'-bridging group of the third 4-ABA anion. The Er-O bond-length range is 2.232 (3)-2.478 (3) Å and the Er⋯Er separation in the dinuclear complex unit is 4.7527 (4) Å. One of the coordinating water mol-ecules is involved in an intra-unit O-H⋯O hydrogen-bonding association with an inversion-related carboxyl-ate O-atom acceptor. In contrast, the anhydrous compound (II) is polymeric, based on centrosymmetric dinuclear repeat units comprising ErO7 coordination polyhedra which involve four O-atom donors from two bidentate O:O'-bridging carboxyl-ate groups, one O-atom donor from the monodentate dimethyl sulfoxide ligand and two O-atom donors from the third bridging CLNBA anion. The latter provides the inter-unit link in the one-dimensional coordination polymer extending along [100]. The Er-O bond-length range in (II) is 2.239 (6)-2.348 (6) Å and the Er⋯Er separation within the dinuclear unit is 4.4620 (6) Å. In the crystal of (I), extensive inter-dimer O-H⋯O and N-H⋯O hydrogen-bonding inter-actions involving both the coordinating water mol-ecules and the solvent water mol-ecules, as well as the amine groups of the 4-ABA anions, give an overall three-dimensional network structure. Within this structure are also weak π-π ring inter-actions between two of the coordinating ligands [ring-centroid separations = 3.676 (3) and 3.711 (2) Å]. With (II), only weak intra-polymer C-H⋯O, C-H⋯Cl and C-H⋯S inter-actions are present.

Single-Crystal to Single-Crystal Linker Substitution, Linker Place Exchange, and Transmetalation Reactions in Interpenetrated Pillared-Bilayer Zinc(II) Metal-Organic Frameworks.

A twofold interpenetrated pillared-bilayer framework, {[Zn3 (L)2 (L2 )(DMF)]⋅(18DMF)(6H2 O)}n (1), has been synthesized from the ligands tris(4'-carboxybiphenyl)amine (H3 L) and 1,2-bis(4-pyridyl)ethylene (L2 ). The structure contains [Zn3 (COO)6 ] secondary building units (SBUs), in which three Zn(II) ions are almost linear with carboxylate bridging. This framework undergoes reversible pillar linker substitution reactions at the terminal Zn(II) centers with three different dipyridyl linkers of different lengths to afford three daughter frameworks, 2-4. Frameworks 2-4 are interconvertible through reversible linker substitution reactions. Also, competitive linker-exchange experiments show preferential incorporation of linker L3 in the parent framework 1. The larger linker L5 does not undergo such substitution reactions and framework 5, which contains this linker, can be synthesized solvothermally as a twofold interpenetrated structure. Interestingly, when framework 5 is dipped in a solution of L3 in DMF, linker substitution takes place as before, but linker L5 now moves and diagonally binds two Zn(II) centers to afford 6 as a nonpenetrated single framework. This linker place exchange reaction is unprecedented. All of these reactions take place in a single-crystal to single-crystal (SC-SC) manner, and have been observed directly through X-ray crystallography. In addition, each 3D framework undergoes complete copper(II) transmetalation.

Two different one-dimensional Cd(II) halide coordination polymers constructed through bridging carboxylate ligands.

Two cadmium halide complexes, catena-poly[[chloridocadmium(II)]-di-μ-chlorido-[chloridocadmium(II)]-bis[μ2-4-(dimethylamino)pyridin-1-ium-1-acetate]-κ(3)O:O,O';κ(3)O,O':O], [CdCl2(C9H12N2O2)]n, (I), and catena-poly[1-cyanomethyl-1,4-diazoniabicyclo[2.2.2]octane [[dichloridocadmium(II)]-μ-oxalato-κ(4)O(1),O(2):O(1'),O(2')] monohydrate], {(C8H15N3)[CdCl2(C2O4)]·H2O}n, (II), were synthesized in aqueous solution. In (I), the Cd(II) cation is octahedrally coordinated by three O atoms from two carboxylate groups and by one terminal and two bridging chloride ligands. Neighbouring Cd(II) cations are linked together by chloride anions and bridging O atoms to form a one-dimensional zigzag chain. Hydrogen-bond interactions are involved in the formation of the two-dimensional network. In (II), each Cd(II) cation is octahedrally coordinated by four O atoms from two oxalic acid ligands and two terminal Cl(-) ligands. Neighbouring Cd(II) cations are linked together by oxalate groups to form a one-dimensional anionic chain, and the water molecules and organic cations are connected to this one-dimensional zigzag chain through hydrogen-bond interactions.

Crystal structure of di-μ-isobutyrato-κ(4) O:O'-bis-[cis-di-chlorido-(dimethyl sulfoxide-κS)rhenium(III)

The title compound, [Re2(C3H7COO)2Cl4{(CH3)2SO}2], comprises binuclear complex mol-ecules [Re-Re = 2.24502 (13) Å] involving cis-oriented double carboxyl-ate bridges, four equatorial chloride ions and two weakly bonded O atoms from dimethyl sulfoxide ligands in the axial positions at the Re(III) atoms. In the crystal, mol-ecules are linked into corrugated layers parallel to (101) by very weak C-H⋯Cl and C-H⋯O hydrogen-bonding inter-actions. C-H⋯Cl hydrogen bonding provides the links between layers to consolidate a three-dimensional framework.

Crystal structures of the potassium and rubidium salts of (3,5-di-chloro-phen-oxy)acetic acid: two isotypic coordination polymers.

The two-dimensional coordination polymeric structures of the hydrated potassium and rubidium salts of (3,5-di-chloro-phen-oxy)acetic acid (3,5-D), namely, poly[μ-aqua-bis-[μ3-2-(3,5-di-chloro-phen-oxy)acetato]-dipotassium], [K2(C8H5Cl2O3)2(H2O)] n , and poly[μ-aqua-bis-[μ3-2-(3,5-di-chloro-phen-oxy)acetato]-dirubidium], [Rb2(C8H5Cl2O3)2(H2O)] n , respectively, have been determined and are described. The two compounds are isotypic and the polymeric structure is based on centrosymmetric dinuclear bridged complex units. The irregular six-coordination about the alkali cations comprises a bridging water mol-ecule lying on a twofold rotation axis, the phen-oxy O-atom donor and a triple bridging carboxyl-ate O atom of the oxo-acetate side chain of the 3,5-D ligand, and the second carb-oxy-ate O-atom donor also bridging. The K-O and Rb-O bond-length ranges are 2.7238 (15)-2.9459 (14) and 2.832 (2)-3.050 (2) Å, respectively, and the K⋯K and Rb⋯Rb separations in the dinuclear units are 4.0214 (7) and 4.1289 (6) Å, respectively. Within the layers which lie parallel to (100), the coordinating water mol-ecule forms an O-H⋯O hydrogen bond to the single bridging carboxyl-ate O atom.

Facile carboxylate ligand variation of heterotrimetallic 12-metallacrown-4 complexes

Single crystal X-ray structures are presented for three 12-metallacrown-4 complexes, ErIIINa(L)4[11-MCMnIII(N)shi-4], where L is trimethylacetate (OTMA), benzoate (OBen), or salicylate (OSal), MC is metallacrown, and shi3− is salicylhydroximate: ErIIINa(OTMA)4[12-MCMnIII(N)shi-4](H2O)3.73(DMF)0.27·7.45DMF·1.47H2O, 1, ErIIINa(OBen)4[12-MCMnIII(N)shi-3](H2O)4·4DMF·0.87H2O, 2, and ErIIINa(OSal)4[12-MCMnIII(N)shi-4](H2O)3.54(DMF)0.73·4DMF·0.24H2O, 3, where DMF is N,N-dimethylformamide. Compounds 1–3 demonstrate the facile ligand variation of a self-assembled supramolecular coordination complex containing three different metal types. In all three structures, the monoanion carboxylate ligands serve as bridges between the central ErIII ion and the ring MnIII ions. The structures of 1–3 are all domed towards the side of the central Na+ ion, and the 12-MC-4 frameworks of 1–3 are very similar regardless of the monoanion carboxylate bridge, as the metallacrown cavity radii of 1–3 are 0.55Å, 0.54Å, and 0.55Å, respectively. In addition, the cross cavity measurements indicate that the metallacrown frameworks are not significantly altered by the presence of different monoanion carboxylate ligands as the MnIII–MnIII cross cavity distances for 1–3 are 6.52Å, 6.51Å, and 6.49Å, respectively, and the oxime oxygen–oxime oxygen cross cavity distances for 1–3 are 3.71Å, 3.68Å, and 3.69Å, respectively. The conservation of the 12-MC-4 framework among the different structures will be important when assessing the physical and chemical properties of this class of molecules.

Novel binuclear μ-oxo diruthenium complexes combined with ibuprofen and ketoprofen: Interaction with relevant target biomolecules and anti-allergic potential

This work presents the synthesis and characterization of two novel binuclear ruthenium compounds of general formula [Ru2O(carb)2(py)6](PF6)2, where py=pyridine and carb are the non-steroidal anti-inflammatory drugs ibuprofen (1) and ketoprofen (2). Both complexes were characterized by ESI-MS/MS spectrometry. The fragmentation patterns, which confirm the proposed structures, are presented. Besides that, compounds 1 and 2 present the charge transfer transitions within 325–330nm; and the intra-core transitions around 585nm, which is the typical spectra profile for [Ru2O] analogues. This suggests the carboxylate bridge has little influence in their electronic structure. The effects of the diruthenium complexes on Ig-E mediated mast cell activation were evaluated by measuring the enzyme β-hexosaminidase released by mast cells stimulated by antigen. The inhibitory potential of the ketoprofen complex against mast cell stimulation suggests its promising application as a therapeutic agent for treating or preventing IgE-mediated allergic diseases. In addition, in vitro metabolism assays had shown that the ibuprofen complex is metabolized by the cytochrome P450 enzymes.