A series of metal-organic frameworks based on 9,10-bis(imidazol-1-ylmethyl)anthracene and structurally related aromatic dicarboxylates: Syntheses, structures, and photoluminescence

A series of new metal-organic frameworks (MOFs) based on 9,10-bis(imidazol-1-ylmethyl)anthracene and four structurally related aromatic dicarboxylates, namely, [Cd(L)(o-bdc)]·1.25H₂O (1), [Cd(L)(pydc)] (2), [Zn(L)(pydc)] (3), [Cd₃(L)₂(m-bdc)₃] (4) and [Cd(L)(p-bdc)]·2H₂O (5) (L = 9,10-bis(imidazol-1-ylmethyl)anthracene, o-H₂bdc = 1,2-benzenedicarboxylic acid, H₂pydc = 2,3-pyridinedicarboxylic acid, m-H₂bdc = 1,3-benzenedicarboxylic acid, p-H₂bdc = 1,4-benzenedicarboxylic acid) have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses, and further characterized by infrared spectra (IR), elemental analyses and powder X-ray diffraction (PXRD). Compound 1 displays a two-dimensional (2D) layer structure, which is stabilized by intramolecular hydrogen-bonding interactions. Compounds 2 and 3 are isostructural and show 2D layer structures, which are further extended by intermolecular C-H···O hydrogen-bonding interactions to form 3D supramolecular frameworks. Compound 4 has a 2D layer structure with trinuclear units [Cd₃(u₃-O)₂]⁶⁺. Compound 5 is a 3D three-fold interpenetrating framework with a Schläfli symbol (6⁶·8). The structural differences of these compounds indicate that the anions play important roles in the resulting structures of the MOFs. The luminescent properties were also investigated for compounds 1-5.     

Syntheses, structures and photoelectronic properties of a series of tri- and tetra-nuclear metal complexes based on a 36-membered tetraphenol macrocyclic ligand

In this article, tetranuclear Zn^II coordination complexes [Zn₄L(μ₂-OH)₂]·2(NO₃)·6(CH₃OH)·H₂O (1) and [Zn₄L(μ₂-OH)₂(H₂O)₂]·(p-bdc)·2(CH₃OH)·3H₂O (2), dinuclear Zn^II complex [Zn₄L(NH₂-bdc)₂]·2(CH₃OH)·3H₂O (3), and trinuclear Cd^II complexes [Cd₃L(m-bdc)]·6.5H₂O (4) and [Cd₃L(NH₂-bdc)]·5.5H₂O (5), based on a tetraphenol 36-membered macrocycle (L) having four ethylenediamine and four 2,6-diformyl-4-methylphenol functionalities, have been synthesized at room temperature (p-bdc = 1,4-benzenedicarboxylate, NH₂-bdc = 5-aminoisophthalate and m-bdc = 1,3-benzenedicarboxylate). In 1 and 2, four Zn^II centers are bridged by phenoxide and hydroxy atoms of the L ligands to form tetranuclear Zn^II complexes. The inorganic and organic anions in 1 and 2 do not coordinate to Zn^II centers, but act as counter anions. In 3, two Zn^II centers are bridged by two phenoxide O atoms to form a Zn^II cluster (Zn₂O₂N₄). Moreover, two (Zn₂O₂N₄) clusters within the ring of the L ligand are further bridged by two NH₂-bdc anions in a monodentate fashion. Compound 4 possesses the trinuclear Cd^II clusters (Cd₃N₈O₈), which has a similar structure to compound 5. The trinuclear Cd^II clusters are bridged by the dicarboxylate anions to yield an infinite coordination polymers chain. The photoelectric transfer properties of complexes 1, 2 and 4 were investigated by surface photovoltage spectroscopy (SPS) and the field-induced surface photovoltage spectra (FISPS) techniques. The results reveal that the complexes exhibit positive surface photovoltage (SPV) responses in the range of 300-600 nm, possessing the p-type semiconductor characteristics. So far, the surface photovoltage properties of the macrocycle complexes based on tetraphenol macrocyclic ligands were investigated for the first time. Moreover, elemental analyses, IR spectra, and luminescent properties of these compounds were also studied.     

Salen-type nickel(II), palladium(II) and copper(II) complexes having chiral and racemic camphoric diamine components

Chiral and racemic Salen-type Schiff-base ligands (H₂L¹, H₂L² and H₂L³), condensed between D-(+)- and D,L-camphoric diamine (also known as (1R,3S)-1,2,2-trimethylcyclopentane-1,3-diamine) and 2-hydroxybenzaldehyde or 3,5-dibromo-2-hydroxybenzaldehyde with a 1:2 molar ratio, have been synthesized and characterized. A series of new nickel(II), palladium(II) and copper(II) complexes of these chiral and racemic ligands exhibiting different coordination number (4, 5 and 6) have been characterized with the formulae [NiL¹]·CH₃OH (3), [NiL¹]·H₂O (4), [NiL²] (5), [PdL²] (6), [Cu₂(L²)₂(H₂O)] (7) and [NiL³(DMF)(H₂O)] (8). Different solvent molecules in 3 and 4 (methanol and water molecules) as well as different apical ligands in 7 and 8 (water and DMF molecules) are involved in different O–H···O hydrogen bonding interactions to further stabilize the structures. UV–Vis (UV–Vis), circular dichroism (CD) spectra and thermogravimetric (TG) analyses for the metal complexes have also been carried out.     

Various coordination architectures constructed from N-[(carboxyphenyl)-sulfonyl]glycine: Structural variation via ligand isomerism effects and metal-directed assembly

Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H₃L₁) and N-[(3-carboxyphenyl)-sulfonyl]glycine (H₃L₂), a series of new coordination polymers, [Mn(phen)(H₂O)₄][HL₁] (1), [Co₃(L₁)₂(bipy)₃(H₂O)₆]_n·8nH₂O (2), [Cu₄(L₁)₂(OH)₂(bipy)₄]_n·12nH₂O (3), [Na(H₂L₁)(H₂O)]_n (4), [Mn₂(HL₂)₂(dpe)₃(H₂O)₂]_n·ndpe (5), (phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene), varying from 0D to 3D, have been synthesized and structurally characterized. Compound 1 has a [Mn(phen)(H₂O)₄]²⁺ cation and a HL₁²⁻ anion. Compound 2 features a new 1D triple chain, based on octahedral cobalt atoms bridged by bipy molecules and terminally coordinated by two H₃L₁ ligands. Compound 3 has a 2D layered structure, constructed from new alternating chains where H₃L₁, hydroxyl and water molecules simultaneously act as bridging ligands. Compound 4 possesses a bilayer structure in which two adjacent layers are pillared by H₃L₁ ligands into a 2D bilayer network. Compound 5 is a unique 3D coordination polymer in which each Mn center binds two trans-located dpe molecules. The thermal stability as well as magnetic properties of 5 was also studied. This work and our previous work indicate that the positional isomer of the anionic N-[(carboxyphenyl)-sulfonyl]glycine is important in the construction of these network structures, which are also significantly regulated by the metal centers.     

Chains,helices, sheets and unusual 3D nets: Diverse structures of the flexible,ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazolyl)ethane

The flexible ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazol-1-yl)ethane (L^4Et) displays remarkable versatility in the complexes that it forms with transition metals with products ranging from 1D chains to interpenetrating 3D networks. The L^4Et ligand itself crystallises in the space group P2₁, adopting a helical twist, although it is found in a variety of other conformations in its complexes. Coordination polymers containing the L^4Et ligand vary from almost straight, parallel 1D chains of [Ag₂(L^4Et)₂(ClO₄)₂(DMF)]·DMF (1), through interdigitating helical complexes containing tetrahedral Zn(II), [Zn(NCS)₂(L^4Et)]·DMF·H₂O (2) to 2D sheets of [Cu(L^4Et)₂(H₂O)₂](PF₆)₂·xH₂O (3) and the three-fold interpenetrating 3D network of [Co(L^4Et)₂(NCS)₂] (4). The 3D network adopts an unusual 3D 4-connected dmp (6⁵.8) topology. Dimensionality can be limited by the use of chelating co-ligands, demonstrated by the formation of the dinuclear complex [{Cu(py-2,6-CO₂)(H₂O)}₂(L^4Et)] (5).     

Infinite chains constructed from flexible bis(benzimidazole)-based ligands

Two neutral ligands, L¹ · 2H₂O and L² · H₂O, and seven complexes, [Cu(pmb)₂(L¹)] (1), [Cu(pmb)₂(L²)] (2), [Cu(Ac)₂(L²)] · 4H₂O (3), [Cu(4-aba)₂(L²)] (4), [Ag(4-ts)(L¹)(H₂O)] (5), [Ag₂(epes)₂(L¹)] · 2H₂O (6), [Ag(1,5-nds)_0.5(L²)] · 0.5C₂H₅OH · H₂O (7) [where L¹ = 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole); L² = 1,1′-(1,4-butanediyl)bis(2-ethylbenzimidazole), pmb = p-methoxybenzoate anion; Ac = acetate anion; 4-aba = 4-aminobenzoate anion; 4-ts = p-toluenesulfonate anion; epes = N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonate) anion; 1,5-nds = 1,5-naphthalenedisulfonate anion], have been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The L¹ and L² ligands in compounds 1–7 act as bridging ligands, linking metal ions into chain structures. The chains in compounds 3, 4 and 6 interlace with each other by hydrogen bonds to generate 3D supramolecular structures. In compound 5, π–π interactions between adjacent L¹ ligands hold the chains to a supramolecular layer. In compound 7, the sulfonate anions act as counterions in the framework. The thermal stabilities of 3, 6 and 7, and the luminescent properties for 5–7 in the solid states are also discussed.     

Structural diversity in Cu(II), Cd(II) and Hg(II) coordination complexes with the rigid N,N′-bis(2/3-aryl)-1,4-benzenedicarboxamide ligand

The syntheses and structures of a series of metal complexes, namely Cu₂Cl₄(L¹)(DMSO)₂·2DMSO (L¹ = N,N′-bis(2-pyridinyl)-1,4-benzenedicarboxamide), 1; {[Cu(L²)_1.5(DMF)₂][ClO₄]₂·3DMF}_∞ (L² = N,N′-bis(3-pyridinyl)-1,4-benzenedicarboxamide), 2; {[Cd(NO₃)₂(L³)]·2DMF}_∞ (L³ = N,N′-bis-(2-pyrimidinyl)-1,4-benzenedicarboxamide), 3; {[HgBr₂(L³)]·H₂O}_∞, 4, and {[Na(L³)₂][Hg₂X₅]·2DMF}_∞ (X = Br, 5; I, 6) are reported. All the complexes have been characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complex 1 is dinuclear and the molecules are interlinked through S?S interactions. In 2, the Cu(II) ions are linked through the L² ligands to form 1-D ladder-like chains with 60-membered metallocycles, whereas complexes 3 and 4 form 1-D zigzag chains. In complexes 5 and 6, the Na(I) ions are linked by the L³ ligands to form 2-D layer structures in which the [Hg₂X₅]⁻ anions are in the cavities. The L² ligand acts only as a bridging ligand, while L¹ and L³ show both chelating and bridging bonding modes. The L¹ ligand in 1 adopts a trans-anti conformation and the L² ligand in 2 adopts both the cis-syn and trans-anti conformations, whereas the L³ ligands in 3–6 adopt the trans conformation.     

1D coordination polymers of silver(I) and copper(II) based on bis(N-heterocyclic carbene) ligands: Synthesis and structural studies

The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L¹H₂·I₂) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L²H₂·I₂), and their silver(I) and copper(II) coordination polymers, [L¹AgI]_n (1) and [L²Cu₂I₄]_n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L¹) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L²) and coplanar quadrilateral Cu₂I₂ units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds.     

Syntheses,topological networks and properties of four complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand

Reactions of metal acetates with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) and co-ligands gave rise to four new complexes, namely [Zn₂(3-abpt)(beta)(DMF) (H₂O)₂]_n·nH₂O (1), [Zn(3-abpt)(ip)]_n·3nH₂O (2), [Zn(3-abpt)(ip)(H₂O)₂]_n·2nH₂O (3), and [Cu₂(3-abpt)₂(C₆H₅COO)₄(H₂O)₂]_n·2nH₂O (4) (ip = isophthalate, beta = 1,2,4,5-benzenetetracarboxylate). Compound 1 is a 3D coordination polymer with uncommon 3,4-connected (6².8)₂(6².8².10²) network. Compounds 2–4 are all 1D coordination polymers, which exhibit diversity structures. Compound 2 is a tubular-like chain, 3 is a ring-like network, and 4 is a zigzag chain. Their thermal stabilities and the photoluminescence of 1 have also been investigated.     

Synthesis, crystal structure and photoluminescent properties of four lanthanide 5-nitroisophthalate coordination polymers

Four new lanthanide coordination polymers, [Y(Hnip)(nip)(H₂O)]·H₂O (1), [Ln(Hnip)(nip)(H₂O)₂]·2H₂O [Ln=Eu(2), Tb(3)] and [Y(nip)₂]·(H₂4,4′-bpy)_0.5 (4) [5-nip=5-nitroisophthalate, 4,4′-bpy=4,4′-bipyridine], have been hydrothermally synthesized and structurally characterized. Compound 1 features novel lanthanide-carboxylate groups chains composed of three samehanded helical strands intersecting each other through hinged lanthanide atoms, and these chains are cross-linked by phenylene moieties of carboxylate ligands into a 2D layer structure. Compounds 2 and 3 are isomorphous, and contain 1D catenanelike Ln-O-C-O-Ln chains, which are interconnected by phenylene moieties into 2D layer structures. Compound 4, however, displays a 3D architecture sustained by strong hydrogen bonding interactions between the protonated 4,4′-bpy and the carboxyl oxygen atom from [Y₂(nip)₄]²⁻ with 2D layer structure, and 4,4′-bpy as the guest molecules exist in bilayer channel. The studies for the thermal stabilities of the four compounds show that compound 4 is more stable than other compounds. Compound 2 emits characteristic red luminescence of Eu³⁺ ions at room temperature, and its luminescent lifetime and quantum efficiency has been determined.     

Diversity of coordination architecture of silver(Ι) complexes with different 2-aminopyrimidyl derivatives: Effect of counter anions and ligands

Five new silver(Ι) complexes of the formula [Ag(L₁)(CF₃SO₃)(H₂O)]_n (1), [Ag₄(L₁)₄(CF₃CO₂)₄]_n (2), [Ag₂(L₁)₄(ClO₄)₂] (3), [Ag(L₂)(ClO₄)]_n (4), and [Ag(L₃)(ClO₄)]_n (5) have been synthesized by reactions of varied silver(Ι) salts with the corresponding 2-aminopyrimidyl ligands (namely, 2-amino-4,6-dimethylpyrimidine (L₁), 2-amino-4-methoxy-6-methylprimidine (L₂), and 2-amino-4,6-dimethoxyprimidine (L₃)). The influences of counter anions and ligands on the structure of the complexes are discussed. Two complexes, 1 with one-dimensional (1D) zigzag chain and 2 with 1D ladder network are obtained by using the same ligand L₁ but different silver(Ι) salts. On the other hand, using the same silver(Ι) perchlorate but different ligands under the same synthetic conditions, complexes 3–5 are isolated, respectively. In the case of 3, two metal atoms and four L₁ ligands form dimeric [Ag₂(L₁)₄] unit further connected by intermolecular hydrogen bonds and π–π interactions to form an infinite 2D layer structure. Complex 4 displays a two-dimensional (2D) grid network. Complex 5 has a 1D zigzag chain but different from that of 1. An extended 3D framework arises from N–H···O intermolecular hydrogen bonds and Ag···O weak interaction. The results reveal that the nature of the counter anions and organic ligands all has great impact on the structure of the complexes. In addition, the hydrogen-bonding interactions and π–π stacking also play important roles in the formation of supramolecular architectures, for instance, to link low-dimensional entities to high-dimensional frameworks. The luminescence properties of the synthesized silver complexes were investigated in the solid state at room temperature.     

A series of Cd(II) complexes with π-π stacking and hydrogen bonding interactions: Structural diversities by varying the ligands

Seven new Cd(II) complexes consisting of different phenanthroline derivatives and organic acid ligands, formulated as [Cd(PIP)₂(dnba)₂] (1), [Cd(PIP)(ox)]·H₂O (2), [Cd(PIP)(1,4-bdc)(H₂O)]·4H₂O (3), [Cd(3-PIP)₂(H₂O)₂]·4H₂O (4), [Cd₂(3-PIP)₄(4,4′-bpdc)(H₂O)₂]·5H₂O (5), [Cd(3-PIP)(nip)(H₂O)]·H₂O (6), [Cd₂(TIP)₄(4,4′-bpdc)(H₂O)₂]·3H₂O (7) (PIP=2-phenylimidazo[4,5-f]1,10-phenanthroline, 3-PIP=2-(3-pyridyl)imidazo[4,5-f]1,10-phenanthroline, TIP=2-(2-thienyl)imidazo[4,5-f]1,10-phenanthroline, Hdnba=3,5-dinitrobenzoic acid, H₂ox=oxalic acid, 1,4-H₂bdc=benzene-1,4-dicarboxylic acid, 4,4′-H₂bpdc=biphenyl-4,4′-dicarboxylic acid, H₂nip=5-nitroisophthalic acid) have been synthesized under hydrothermal conditions. Complexes 1 and 4 possess mononuclear structures; complexes 5 and 7 are isostructural and have dinuclear structures; complexes 2 and 3 feature 1D chain structures; complex 6 contains 1D double chain, which are further extended to a 3D supramolecular structure by π-π stacking and hydrogen bonding interactions. The N-donor ligands with extended π-system and organic acid ligands play a crucial role in the formation of the final supramolecular frameworks. Moreover, thermal properties and fluorescence of 1-7 are also investigated.     

Auxiliary aromatic-acid effect on the structures of a series of Zn coordination polymers: Syntheses, crystal structures, and photoluminescence properties

Five novel Zn^II-(pyridyl)imidazole derivative coordination polymers, [Zn(L)₂] (1), [Zn₂(μ₃-OH)L(m-BDC)] (2), [Zn₂(μ₃-OH)L(p-BDC)]·H₂O (3), [Zn₂L(BTC)(H₂O)]·2.5H₂O (4) and [Zn_3.5(μ₃-OH)L₂(BTEC)(H₂O)]·H₂O (5) (L=4-((2-(pyridine-2-yl)-1H-imidazol-1-yl)methyl)benzoic acid, p-H₂BDC=1,4-benzenedicarboxylic acid, m-H₂BDC=1,3-benzenedicarboxylic acid, H₃BTC=1,3,5-benzenetricarboxylic acid, H₄BTEC=1,2,4,5-benzenetetracarboxylic acid), were successfully synthesized under hydrothermal conditions through varying auxiliary aromatic-acid ligands and structurally characterized by X-ray crystallography. Compound 1 exhibits a 1D chain linked via double L bridges. Compound 2 features a well-known pcu topology with bent dicarboxylate ligand (m-H₂BDC) as an auxiliary ligand, while 3 displays a bcu network with linear dicarboxylate ligand (p-H₂BDC) as an auxiliary ligand. The structure of compound 4 is a novel 3D (3,5)-connected network with (4·6²)(4·6⁴·8²·10·12²) topology. It is interesting that compound 5 shows an intricate (3,4,8)-connected framework with (4·6²)(4²·6³·8)(4²·6⁴)(4²·6¹⁸·7·8⁶·10) topology. In addition, their infrared spectra (IR), X-ray powder diffraction (XPRD) and photoluminescent properties were also investigated in detail.     

1D Mn–Fe heterometallic coordination polymer built by an approach of metalloligand

1D heterometallic coordination polymer of [(Fe^II(L)₂)(Mn^III(salen))(ClO₄) · 2CH₃CN · CH₃OH] (1 · 2CH₃CN · CH₃OH) has been built through a metalloligand approach (L = hydrotris (1,2,4-triazolyl)borate). Ferrous [Fe^II(L)₂] moiety can be easily incorporated into further extended networks by the facile reduction of ferric antiprismatic [Fe^III(L)₂]⁺ metalloligand due to the reducing ability of borate ligands during the reaction. And more, hydroquinone facilitates the reduction. Therefore, we present single crystal X-ray structure analysis of 1 · 2CH₃CN · CH₃OH along with X-ray absorption spectroscopy to confirm the reduction of iron centres.     

Dinuclear double-helical cobalt complexes with two-armed terdentate ligands: Synthesis,structure and physical properties

Three ligands with flexible bis-terdentate coordination sites, di(2-pyridylcarbaldehyde)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L¹), di(2-acetylpyridyl)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L²) and di(2-pyridylketone)-6,6′-dicarboxylic acid hydrazone-2,2′-bipyridine (H₂L³) have been easily prepared. Dinuclear double-stranded helicates Co₂(L¹)₂(ClO₄)₂(C₂H₅OH)₂(H₂O)₂ (1), Co₂(HL²)(L²)(ClO₄)₃(C₂H₅OH)₂(H₂O)₂ (2) and Co₂(HL³)(L³)(ClO₄)₃(H₂O)₄ (3) based on the ligands, H₂L^1–3, respectively, have been obtained via self-assembly, their structures were determined by FT-IR, Elemental Analysis, ESI-MS and X-ray diffraction method.     

Four divalent transition metal carboxyarylphosphonate compounds: Hydrothermal synthesis, structural chemistry and generalized 2D FTIR correlation spectroscopy studies

Four divalent transition metal carboxyarylphosphonates, [Ni(4,4′-bipy)H₂L¹(HL¹)₂(H₂O)₂]·2H₂O 1, [Ni₂(4,4′-bipy)(L²)(OH)(H₂O)₂]·3H₂O 2, Mn(phen)₂(H₂L¹)₂3 and Mn(phen)(HL²) 4 (H₃L¹=p-H₂O₃PCH₂-C₆H₄-COOH, H₃L²=m-H₂O₃PCH₂-C₆H₄-COOH, 4,4′-bipy=4,4′-bipyridine, phen=1,10-phenanthroline) were synthesized under hydrothermal conditions. 1 features 1D linear chains built from Ni(II) ions bridging 4,4′-bipy. In 2, neighboring Ni₄ cluster units are connected by pairs of H₃L² ligands to form 1D double-crankshaft chains, which are interconnected by pairs of 4,4′-bipy into 2D sheets. 3 exhibits 2D supramolecular layers via the R₂²(8) ringed hydrogen bonding units. 4 has 1D ladderlike chains, in which the 4-membered rings are cross-linked by the organic moieties of the H₃L² ligands. Additionally, 2D FTIR correlation analysis is applied with thermal and magnetic perturbation to clarify the structural changes of functional groups from H₃L¹ and H₃L² ligands in the compounds more efficiently.     

New anion-templated 3D heterobimetallic open frameworks based on lanthanide-carboxylate layers and copper pillars

A series of new three-dimensional (3D) lanthanide-transition metal (4f-3d) heterobimetallic open frameworks, [Ln₂(1,2-bdc)₂(H₂O)₂ Cu(inic)₂](ClO₄) (Ln=Eu (1), Tb (2), Nd (3) and Sm (4); 1,2-bdc=1,2-benzenedicarboxylate; Hinic=isonicotinic acid) have been hydrothermally synthesized and characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction analysis. Compounds 1-4 are isostructural. They possess a new anion-templated 3D heterobimetallic open framework, which is observed for the first time in the {Ln/TM/bdc/inic} (TM=transition metal) system. Compounds 1 and 2 exhibit the characteristic fluorescent properties of Eu(III) and Tb(III), respectively.     

Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI2(DME)(triglyme), cis-BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8

The reaction between BaI₂ · 2H₂O and NaHFIP [HFIP = OCH(CF₃)₂] in a 1:1 stoichiometry gave the heterometallic compound NaBaI₂(HFIP)(H₂O)(THF)_0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI₂(DME)₃ (2), trans-BaI₂(DME)(triglyme) (3) and cis-BaI₂(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI₂ · 2H₂O and NaTFA (TFA = O₂CCF₃) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)₂]I₂ · C₇H₈ (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and ¹H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.     

Palladium and half sandwich ruthenium(II) complexes of selenated and tellurated benzotriazoles: Synthesis, structural aspects and catalytic applications

1-(Phenylselenomethyl)-1H-benzotriazole (L¹) and 1-(4-methoxyphenyltelluromethyl)-1H-benzotriazole (L²) have been synthesized by reacting 1-(chloromethyl)-1H-benzotriazole with in situ generated nucleophiles PhSe⁻ and ArTe⁻, respectively. The complexes of L¹ and L² with Pd(II) and Ru(II)(η⁶-p-cymene) have been synthesized. Proton, carbon-13, Se-77 and/or Te-125 NMR spectra authenticate both the ligands and their complexes. The single crystal structures of L¹, L² and [RuCl(η⁶-p-cymene)(L)][PF₆] (L = L¹: 3, L = L²: 4) have been solved. The Ru-Se and Ru-Te bond lengths have been found 2.4801(11) and 2.6183(10) Å, respectively. The palladium complexes, [PdCl₂(L)] (L = L¹: 1, L = L²: 2) have been explored for Heck and Suzuki-Miyaura C-C coupling reactions. The TON values are upto 95,000. The Ru-complexes have been found promising for catalytic oxidation of alcohols (TON ∼ 7.8-9.4 × 10⁴). The complexes of telluroether ligands are as efficient catalysts as those of selenoether ones and in fact better for catalytic oxidation.     

Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L¹)₂]_n (1), [CuL¹N₃]_n (2), [Cu(L²)₂·0.5C₂H₅OH·H₂O]_n (3) and [Co(L²)₂]_n (4) (here, HL¹=1H-imidazole-1-yl-acetic acid, HL²=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4⁴-sql topologies, while another 2D complex 1 has a (4³)₂(4⁶)-kgd topology. And 2 is a 3D complex composed dinuclear μ_1,1-bridging azido Cu^II entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied.