A novel 3D Cd-coordination framework with helical units in a mixed flexible ligand system: Encapsulating right-handed helical water chains

In flexible co-ligand system, the P-handed [Cd(bpb)]_n and the M-handed [Cd(pda)]_n helical chains interweave mutually into a novel 3D coordination framework with diamondoid skeleton, namely, {[Cd(1,4-pda)(bpb)(H₂O)]·H₂O}_n (1) [bpb = 1,4-bi(4-pyridyl)butane , 1,4-H₂pda = 1,4-phenylenediacetic acid ]. Interestingly, 1D hydrophilic tunnel of 1 acts as a template for the formation of the P-handed 1D helical water chains, displaying molecular recognition and chirality transfer. The photoluminescent property and thermal stability of 1 were also discussed.     

Ditopic, flexible hydrazone-based building blocks with pendant 2,2′:6′,2′′-terpyridine metal-binding domains

The synthesis and characterization of three new bis(2,2′:6′,2′-terpyridine) (tpy) ligands containing different hydrazone spacers between the metal-binding domains are described. Treatment of 1,4-benzenedicarbaldehyde bis(2,2′:6′,2′′-terpyridin-4′-ylhydrazone) (1) with [(tpy)RuCl₃] in the presence of N-ethylmorpholine results in the formation of [(tpy)Ru(μ-1)Ru(tpy)]⁴⁺. Single crystal X-ray diffraction data for [(tpy)Ru(μ-1)Ru(tpy)][PF₆]₄·8MeCN confirm the ability of the hydrazone-based ligand to bridge two ruthenium(II) centres, providing proof-of-principle for the application of this class of flexible ligand in the design of coordination polymers.     

Solvothermal synthesis of 1D and 2D cobalt(II) and nickel(II) coordination polymers with 2,5-dihydroxy-p-benzenediacetic acid

1D cobalt(II) and nickel(II) coordination polymers {[Co(dba)(H₂O)₄] · H₂O}_n (1) and {[Ni(dba)(H₂O)₄] · H₂O}_n (2) (H₂dba = 2,5-dihydroxy-p-benzenediacetic acid) were synthesized under low temperature solvothermal condition. When 4,4′-bipyridine (bpy) was introduced to the synthetic systems of 1 and 2, respectively, two novel 2D coordination polymers {[Co(dba)(bpy)] · 0.5H₂O}_n (3) and [Ni(dba)(bpy)(H₂O)₂]_n (4) with different structures were obtained. All of the compounds were characterized by elemental analysis, FT-IR, UV–Vis spectra and single crystal X-ray diffraction.     

Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

Novel Hg and Mn supramolecular complexes with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiolate involving in situ ligand formation

Reaction of potassium N′-(pyridine-4-carbonyl)-hydrazinecarbodithioate ([K⁺(H₂L)⁻]) with Hg^II or Mn^II inorganic salt in the presence of 1,10-phenanthroline (phen) or 4,4′-bipyridine (bipy), yields complexes [Hg(pyt)₂(phen)] (1) and {[Mn(pyt)₂(H₂O)₂]·(bipy)·(H₂O)₂}_n (2), in which the pyt ligand (Hpyt = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol) is obtained by in situ ligand formation from the acyclic precursor [K⁺(H₂L)⁻]. Single crystal X-ray diffraction suggests that the pyt anionic ligands in 1 and 2 behave as thiolate and thione isomers, respectively, and display S- and μ-N_pyridyl, N_oxadiazole-binding fashions. Complex 1 shows a 1-D fishbone-like supramolecular array via strong aromatic stacking interactions between the discrete mononuclear coordination motifs, whereas 2 has a 2-D layered host coordination framework with the inclusion of bipy and water guests in the cavities.     

tert-butylaluminium complex of 2,2-di(hydroxymethyl)biphenyl: intra-molecular hydrogen bonding

The reaction of 2,2^′-di(hydroxymethyl)biphenyl with (t-Bu)₃Al leads to the formation of the bimetallic compound [(t-Bu)₄Al₂(HOCH₂C₁₂H₈CH₂O)₂] (1) with two hydroxyl groups. The compound 1 has been characterized by ¹H and ¹³C NMR spectroscopy, cryoscopic molecular weight measurements and elemental analysis and molecular structure has been confirmed by X-ray crystallography. The 18 membered cycle (Al₂O₄C₁₂) of 1 adopts a configuration with endocyclic oxygen atoms that allow for the intra-molecular hydrogen bonding formation.     

A novel infinite 1D covalent chain of end-to-end thiocyanato bridged heptacoordinated cadmium(II)Schiff base: π…π interaction and weak C–H…S hydrogen bonded supramolecule

A new Schiff base, N,N′-(bis(pyridin-2-yl)formylidene)ethane-1,2-diamine (bpfd) is prepared and used to synthesize a novel end-to-end thiocyanato bridged infinite 1D polymeric heptacoordinated cadmium(II) chain [Cd(bpfd)(μ_1,3-NCS)(NCS)]_n (1) which forms a 3D supramolecule through weak C–H…S hydrogen bonding and π…π interaction.     

Rapid synthesis of a novel cadmium imidazole-4,5-dicarboxylate metal–organic framework under microwave-assisted solvothermal condition

A novel three-dimensional (3D) coordination polymer, [Cd(μ₃-HIDC)(bbi)_0.5]_n (1) (H₃IDC = 4,5-imidazoledicarboxylic acid, bbi = 1,1’-(1,4-butanediyl)bis(imidazole)), has been synthesized under microwave heating solvothermal conditions and characterized by elemental analysis, IR, TG, and single crystal X-ray diffraction. The crystal structure reveal that compound 1 consists of 2D brickwall-like networks of [Cd(μ₃-HIDC)]_n, which are further linked through μ₂-bbi to generate a 3D structure. Compound 1 is stable up to 330 °C and displays strong blue fluorescent emission at room temperature. This work demonstrates that microwave-assisted solvothermal synthesis method is an efficient and fast way to prepare metal coordination polymers.     

A new binuclear potassium (І) complex with a novel 1D infinite water chain containing (H2O)12 clusters

A novel 1D infinite water chain made of (H₂O)₁₂ clusters containing two different chair water hexamers is found in the binuclear coordination compound, [K₂(L)₂(phen)₄]·6H₂O (1) (where L = 2,2′-azanediyldibenzoic dianion, phen = 1,10′-phenanthroline), which has been synthesized and structurally characterized by single-crystal X-ray diffraction. The fluorescence spectrum and thermogravimetric analysis (TGA) of the title complex 1 have been also discussed.     

An unexpected sulfinate–sulfonate mixed coordination polymer of copper(II)

By reaction of copper nitrate trihydrate and 2,2′-dipyridyldisulfide in both aerobic and anaerobic conditions, the mixed [{Cu(2-pySO₂)₂}_n]–[{Cu(2-pySO₃)₂}_n] coordination polymer of copper(II) (1) has been synthesized. The X-ray diffraction analysis indicates that complex 1 exhibits an infinite one-dimensional polymeric chain consisting of [Cu(C₅H₄N)₂] building units connected by SO₂/SO₃ groups. The atom which has been labelled O3 is only present in 60% of the molecules. Complex 1 exhibits a very weak ferrogmagnetic spin coupling (zJ = +0.40 cm⁻¹).     

Preparation, crystal structure and properties of two novel metal-organic frameworks assembled from pyridine-3,5-dicarboxylic acid N-oxide

Two novel coordination polymers, [Cu(PDCO) · (H₂O)]_n (1) and [Cd(PDCO)(bipy) · (H₂O) · 5H₂O]_n (2), (H₂PDCO = pyridine-3,5-dicarboxylic acid N-oxide, bipy = 4,4′-bipyridine), have been synthesized under hydrothermal conditions, and their structures were determined by single-crystal X-ray diffraction studies. Polymer 1 features a three-dimensional (3D) network with nonequivalent nodes of (6³)₂(6⁹ · 8⁵ · 10) topology. Polymer 2 exhibits one-dimensional (1D) double-stranded chains. The magnetic character of 1 as well as the gas adsorption and luminescent properties of 2 have been investigated.     

Two novel d frameworks based on a new V-shaped ligand 2,4′-dipyridylamine and a flexible dicarboxylate ligand

Via hydrothermal synthesis, the self-assembly of d¹⁰ metal, 2,4′-dipyridylamine (L) and 1,3-adamantanediacetic acid (H₂ADA) generated two unprecedented coordination polymers [Zn(ADA)(L)]_n (1) and [Cd(ADA)(L)₂]_n (2). Complex 1 possesses a novel 1D looped-chain topology structure decorated with arms. Complex 2 shows an extended threaded framework involving 2D coordination layers of square (4⁴) topology with dangling ligands, which gives the novel (2D → 3D) polythreaded array. To the best of our knowledge, complex 2 is the first example with four dangling arms coordinated in the axial sites of dinuclear nodes. In addition, both of the complexes show strong photoluminescence at room temperature, and may be good candidates for potential luminescence materials.     

Synthesis, crystal structure and magnetic properties of a new three-dimensional porous framework: [Gd2(BDA)3(DMF)2(H2O)4] · 2DMF

The open framework compound of [Gd₂(BDA)₃(DMF)₂(H₂O)₄] · 2DMF (1), prepared by heating GdCl₃ with 2,2′-bipyridyl-4,4′-dicarboxylatic acid (BDA) in mixed solvent, is constructed from BDA linking up polymeric [GdO₅(DMF)(H₂O)₂]_n tethers. The 1D channels are filled with coordinated and uncoordinated DMF molecules hydrogen bonding to terminal aqua ligands. The study of the temperature dependent magnetic susceptibilities revealed that there are ferromagnetic interactions between intra-chain Gd^III atoms and weak antiferromagnetic interactions between inter-chain Gd^III atoms.     

Terminal ligand effect on the structure variation of Copper(II) complexes

Two copper(II)–poly(pyrazolyl)methane complexes [Cu₂(bpm)₄(ta)](ClO₄) ₂ · 2H₂O 1 and {[Cu₂(tpm)₂(ta)₂] · H₂O}_n 2 (bpm = bis(3,5-dimethylpyrazolyl)methane, tpm = tris(pyrazolyl)methane, H₂ta = terephthalic acid) were synthesized and characterized by elemental analysis, FT-IR and UV–vis spectra. 1 is a binuclear complex, while 2 exhibits as a 1D zigzag coordination polymer.     

Two 2D metal–organic frameworks based on 2,2′-bibenzimidazole ligand with (6,3) net topology

Two 2D metal–organic frameworks (MOFs), {[Zn₄(Hbbim)₄(bbim)₂] 2H₂O}_n (1) and [Cd₂(Hbbim)₂(bbim)]_n (2) (H₂bbim = 2,2′-bibenzimidazole) were obtained by solvothermal reaction and characterized by single crystal X-ray diffraction analysis. Different metal ions, Cd(II)/Zn(II), adopt very different coordination geometries though two title compounds both have a 2D honeycomb network with (6,3) topology. The frameworks of compounds 1 and 2 are stable below 360 °C and 475 °C, respectively. Solid-state luminescent spectroscopy of compound 2 exhibits an emission peak at 407 nm.     

Four Flexible Bis(Thiabendazole)-Based Cd(II) Coordination Polymers with Various Aromatic Carboxylates: Syntheses,Structures and Properties

Four Cd(II) coordination polymers (CPs) including [Cd(btbb)_0.5(L1)] _n (1), [Cd(btbb)(L2)·(H₂O)_1.5] _n (2), [Cd(btbb)(L3)] _n (3), and [Cd(btbb)(HL4)] _n (4) (btbb?=?1,4-bis(thiabendazole)butane, H₂L1?=?5-hydroxyisophthalic acid, H₂L2?=?4,4′-biphenyldicarboxylic acid, H₂L3?=?tetrabromoterephthalic acid, H₃L4?=?5-nitro-1,2,3-benzenetricarboxylic acid) were prepared under hydrothermal conditions based on flexible bis(thiabendazole) ligand and different co-carboxylates. Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, X-ray powder diffraction, and thermogravimetric analyses. CP 1 exhibits a 3D 2-nodal (3,4)-connected framework with the 3,4T10 topology. CP 2 and 3 feature typical hcb layer structure, and 3 is further combined into a 3D supramolecular architecture through C–H?O hydrogen bonds. CP 4 possesses an infinite chain and further extended into 2D supramolecular network by O–H?O hydrogen-bonding interactions. The effects of the aromatic polycarboxylate co-ligands on the CPs framework have been discussed and the catalytic activities of CPs 1–4 for degradation of methyl orange in Fenton-like process are also investigated.     

Solvothermal synthesis of a novel mixed valence Cu(I)/Cu(II) complex containing sulphate, malate and 4,4-bipyridine, [CuCu2(mal)(SO4)(bpy)2 · H2O]n. Unique binding mode of the malate anion

The reaction of CuSO₄ · 5H₂O with 4,4^′-bipyridine and malic acid at 140 °C under solvothermal conditions afforded a mixed valence three-dimensional coordination polymer [Cu^ICu^II₂(mal)(SO₄)(bpy)₂ · H₂O]_n, (1). The building unit consists of a Cu²⁺-dimer in which copper centers are bridged by malate and sulphate anions. SO₄²⁻ anion further connects dimeric unit with the Cu¹⁺ center. Building units are linked by 4,4^′-bipyridine ligands to form double chains, that are interconnected into 3D network through additional sulphate bridge.     

A New 2D Cd(II) Grid-like Structure Based on Hetero-Chiral Helical Chains: Synthesis, Crystal Structure, Thermal and Luminescent Properties

A new 2D Cd(II) coordination polymer, [Cd(BBI)₄Cl₂] _n (BBI = 1,1′-(1,4-butanediyl)bis (imidazole)) (1), was synthesized under hydrothermal conditions, and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction crystallography. For complex 1, each Cd(II) ion crystallizes in a [CdN₄Cl₂] six-coordinated slightly distorted octahedral geometry, coordinating to four BBI ligands by Cd–N bonds, completed by two terminal Cl⁻ anions. The characteristic of 2D grid-like layers, from the central Cd(II) ions as knots and BBI ligands as spacers, is the hetero-chiral helical chains of left- and right-hand helixes. Two kinds of π interactions assemble 2D layers into 3D supramolecular architecture in an ···ABC··· packing arrangement. The fluorescent properties were studied in the solid state for its luminescent applications.     

Syntheses, structures, and photoluminescence of two Cd(II) coordination polymers constructed from analogue (pyridyl)imidazole derivative and polycarboxylate acid

Two novel Cd(II) coordination frameworks based on a semirigid asymmetric ligand L and aromatic multi-carboxylate ligands, {[Cd₂L(btc)(H₂O)₂]·5H₂O}_n (1) and [Cd₂L₂(bdc)]_n (2) (L = (4-((2-(pyridine-2-yl)-1H-imidazol-1-yl)methyl)benzoic acid, H₃btc = 1,3,5-benzenetricarboxylic acid, H₂bdc = 1,3-benzenedicarboxylic acid), have been hydrothermally synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Due to various coordination modes and conformations of the semirigid asymmetric ligand, and carboxylate containing co-ligands, therefore, the two complexes exhibit structural and dimensional diversity. Complex 1 exhibits a novel 2D (3, 5)-connected network structure with (3·5²)(3²·5³·6⁴·7) topology. Complex 2 exhibits a novel 3D CdSO₄ topology, which is formed from different dinuclear cadmium units. In addition, the photoluminescence properties of the free ligand L, and complexes 1 and 2 were studied in the solid state at room temperature.     

Bimetallic nickel complexes of trimethyl phenyl linked salicylaldimine ligands: Synthesis, structure and their ethylene polymerization behaviors

Bimetallic salicylaldimine-nickel complexes, 2,4,6-Me₃-1,3-{[NCH–(3′-R-5′-Y-2′-O–C₆H₃)-κ²-N,O]Ni(Ph) (PPh₃)}₂ [R = tert-Bu, Y = Me, 1b; R = Ph, Y = H, 2b] were prepared and their catalytic behaviors of ethylene polymerization were investigated. The bimetallic complex 2b shows higher activities (2.9 × 10⁵ g PE mol⁻¹ Ni h⁻¹) for ethylene polymerization and affords polymer with high molecular weight (M_w = 1.41 × 10⁵) and broad molecular weight distribution (M_w/M_n = 6.1) than its mononuclear matrix, {[(2,6-Me₂C₆H₃)–NCH–(3′-Ph-2′-O–C₆H₃)-κ²-N,O]Ni(Ph)(PPh₃)} (3) (Activity = 5.5 × 10⁴ g PE mol⁻¹ Ni h⁻¹; M_w = 1.86 × 10⁴; M_w/M_n = 2.8).