Three-dimensional Coordination Network Research Articles

Synthesis, magnetic and fluorescence detection properties of four metal-organic frameworks based on imidazole carboxylic acid ligands

Four new metal-organic frameworks (MOFs), namely [M(HL)H2O]n (1–3) [M = Co (1), Ni (2), Cu (3)] and [Cd(HL)]n (4), were successfully structured based on imidazole carboxylic acid ligands [H3L = 5-(((1H-imidazol-2-yl)methyl)amino) isophthalic acid]. X-ray single-crystal diffraction analysis showed that MOFs 1–3 possess the same two-dimensional (2D) planar structure, while MOF 4 exhibited a three-dimensional (3D) coordination network. The magnetic test results showed that MOFs 1–3 have typically antiferromagnetic behavior. The sensing experimental showed that MOF 4 could be considered as a promising bifunctional fluorescent sensor for Cu2+ and Fe3+ ions with excellent selectivity and sensitivity, and the detection limit were 4.11 μM and 4.89 μM, with Ksv values of 1.37 × 104 M−1 and 1.24 × 104 M−1, respectively. The cycling experiment illustrated the good reusability of the material. In addition, the fluorescence quenching mechanism of MOF 4 was further explored in detail.

Solvent control of dimensionality in titanium aryloxide coordination polymers prepared from 4,4′-bis(hydroxyphenyl)sulfide

The crystal and molecular structures of three covalent metal–organic network (CMON) materials synthesized from titanium (IV) isopropoxide and the Bisphenol-A analog 4,4′-bis(hydroxyphenyl)sulfide in three different solvents have been determined. The structures of the one-dimensional chain coordination polymer [trans-Ti(μ-O:O’-OC6H4SC6H4O)2(C5H5N)2]n (1) obtained from pyridine and the two-dimensional sheet coordination polymer {[Ti2(μ-O:O’-OC6H4SC6H4O)2(μ2O:κO’-OC6H4SC6H4O)2(C4H8O)2]∙(C4H8O)y}n (2) from tetrahydrofuran both contain octahedral titanium (IV) coordination geometries, whereas the doubly interpenetrated three-dimensional coordination network [Ti2(μ-O:O’-OC6H4SC6H4O)2(μ2O:κO′-OC6H4SC6H4O)2]n (3) synthesized from benzene contains trigonal bipyramidal titanium (IV). Each material has been characterized by single crystal and powder X-ray diffraction, elemental analysis, and by 1H NMR quench when it contains more than one organic component.

An anionic In(III)-MOF for efficient adsorption of CO2 from CO2/N2 mixture and dye removal

Efficient adsorption of CO2 and dye molecules is crucial for reducing carbon emission and environmental pollution. Metal-Organic Frameworks (MOFs) are considered to be the ideal candidates for gas adsorption material because of their designability. In this work, a new In(III)-MOF (HBU-22) was synthesized by the reaction of a tetracarboxylic acid ligand (H4L, 9,9′-bicarbazole-3,3′,6,6′-tetracarboxylic acid) with In3+ ions, which shows a three-dimensional (3D) coordination network. The saturated adsorption capacity of CO2 and N2 are 21.11 cm3‧g−1 and 0.66 cm3‧g−1 at ambient condition (298 K, 100 kPa). And the higher IAST selectivity of CO2/N2 (v/v, 15:85) reaches 347.37, exceeding that of most MOFs. Furthermore, it can also capture C2H2 with the maximum uptake of 42.80 cm3 g−1. More interestingly, HBU-22 as an anionic framework, which can selectively adsorb Rhodamine B (RhB) within 250 s with the maximum adsorption capacity of 105.04 mg‧g−1. Further studies show that higher gas adsorption capacity is mainly related to the larger Qst of the gas, while its adsorption of Rhodamine B (RhB) is mainly due to ion exchange mechanism.

Cyanido-bridged FeII-NbIV spin-crossover complex with FeII-crosslinking ligands possessing disulfide bonds

A cyanido-bridged FeII-NbIV spin-crossover complex, [FeII(dpds)2]2[NbIV(CN)8]·6H2O (dpds = 4,4′-dipyridyldisulfide), is synthesized with a three-dimensional coordination network. The network has cyanido bridges to connect the FeII and NbIV sites and dpds as an additional ligand to crosslink the FeII sites. [FeII(dpds)2]2[NbIV(CN)8]·6H2O exhibits a gradual and incomplete spin crossover in which 22% of the high-spin FeII sites change to low-spin FeII sites as the temperature decreases. The calculation indicates that the spin transition occurs sparsely, rather than forming low spin site domains.

Crystal structures, gas storage and magnetic properties of lanthanide-organic frameworks built up from dicarboxylates, [Ln2(2,5-pydc)2(2,5-pipdc)(H2O)2]n (Ln = Ce, Pr, Eu) and (H2pip)n[Ln2(2,6-pydc)4(H2O)2]n (Ln = Ce, Pr, Eu, Sm)

We have synthesized various kinds of lanthanide complexes, [Ln2(2,5-pydc)2(2,5-pipdc)(H2O)2]n (Ln = Ce (MOF 1), Pr (MOF 2), Eu (MOF 3); 2,5-pydc = 2,5-pyridinedicarboxylate, 2,5-pipdc = 2,5-piperazinedicarboxylate), and (H2pip)n[Ln2(2,6-pydc)4(H2O)2]n (Ln = Ce (MOF 4), Pr (MOF 5), Eu (MOF 6), Sm (MOF 7); 2,6-pydc = 2,6-pyridinedicarboxylate, H2pip = piperazinediium) under hydrothermal conditions. The X-ray crystallographic analysis shows that [Ln2(2,5-pydc)2(2,5-pipdc)(H2O)2]n forms three-dimensional coordination network, while (H2pip)n[Ln2(2,6-pydc)4(H2O)2]n forms one-dimensional coordination polymer, whose different coordination network structure is controlled by the positional isomer of pyridinedicarboxylate (2,5-pydc, 2,6-pydc). The magnetic properties and gas storage (H2 and CO2) capacities were also investigated, and among the synthesized compounds MOF 7 had the highest gas storage capacities for H2 and CO2. From the analysis of magnetic susceptibility measurements, the Weiss constants for Ce, Pr, and Sm complexes were estimated. In the case of Pr complexes, MOF 2 and MOF 5, the magnetic susceptibility deviates from the Curie-Weiss law below 20 K and 10 K, respectively, which is the precursor phenomenon of antiferromagnetic ordering. In the case of Sm(III) complex, MOF 7, the magnetic susceptibility multiplied by temperature (χT) as a function of temperature between 300 K and 2 K was theoretically analyzed and the spin-orbit coupling constant (λ) and the energy levels of ground multiplet, 6HJ, were determined.

Crystal structure of a three-dimensional neodymium(III) coordination polymer, [Nd2(H2O)6(glutarato)(SO4)2] n.

A three-dimensional coordination polymer, poly[hexa-aqua-(μ4-glutarato)bis(μ3-sulfato)-dineodymium(III)], [Nd2(glutarato)(SO4)2(H2O)6] n (glutarato2- = C5H6O4 2-), 1, consisting of cationic {Nd2(H2O)6(SO4)2} n 2n+ layers linked by bridging glutarate ligands, was synthesized by the microwave-heating technique within few minutes. The crystal structure of 1 consists of two crystallographically independent TPRS-{NdIIIO9} (TPRS is tricapped trigonal-prismatic geometry) units that form an edge-sharing dinuclear cluster inter-connected to neighbouring dimers by the μ3-SO4 2- anions, yielding a cationic two-dimensional {Nd2(H2O)6(SO4)2} n 2n+ sheet. Adjacent cationic layers are then linked via the μ4-glutarato2- ligands into a three-dimensional coordination network. Strong O-H⋯O hydrogen bonds are the predominant inter-action in the crystal structure.

Distinct and Selective Amine- and Anion-Responsive Behaviors of an Electron-Deficient and Anion-Exchangeable Metal-Organic Framework.

Smart materials that respond to chemical stimuli with color or luminescence changes are highly desirable for daily-life and high-tech applications. Here, we report a novel porous metal-organic framework (MOF) that shows multiple, selective, and discriminative responsive properties owing to the combination of different functional ingredients [tripyridinium chromogen, Eu(III) luminophore, cationic framework, and special porous structure]. The MOF contains two interpenetrated three-dimensional cationic coordination networks built of a tetrahedral [Eu4(μ3-OH)4] cluster and a tripyridinium-tricarboxylate zwitterionic linker. It shows reversible and discriminative chromic response to aliphatic amines and aniline through different host-guest interactions between electron-deficient pyridinium and electron-rich amines. The size- and shape-selective response to aliphatic amines is ascribed to the radical formation through host-guest electron transfer, whereas the response to aniline is ascribed to the formation of sandwich-type acceptor-donor-acceptor complexes. The MOF is capable of reversible anion exchange with various anions and shows selective and discriminative ionochromic response to iodide, bromide, and thiocyanate, which is attributed to charge-transfer complexation. The above chromic behaviors are accompanied by efficient quenching of Eu(III) photoluminescence. The MOF represents a multi-stimuli dual-output responsive system. It can be used for discrimination and identification of anions and amines. The potential use in invisible printing, reusable sensory films, and optical switches was demonstrated by the ink and the membrane made of the MOF and organic polymers.

Water-sulfate anion interplay in the evolution of solid state architectures and emission properties of Zn and Cd coordination networks with four azine ligands

Reactions of zinc and cadmium sulfates with 1,2-bis(pyridin-3-ylmethylene)hydrazine (3-bphz), 1,2-bis(pyridin-4-ylmethylene)hydrazine (4-bphz), and two methylated derivatives, 1,2-bis(1-(pyridin-3-yl)ethylidene)hydrazine (3-bpmhz) and 1,2-bis(1-(pyridin-4-yl)ethylidene)hydrazine (4-bpmhz) resulted in eight coordination compounds. For Zn(II) the structural landscape includes binuclear complexes and two-dimensional coordination polymers, [Zn2(3-bphz)(H2O)10](SO4)2.4H2O (1), [Zn2(SO4)2(3-bphz)(H2O)4]n (2), [Zn2(3-bpmhz)3(H2O)8](SO4)2 (3), and {[Zn(SO4)(4-bpmhz)(H2O)2].1.5(H2O)·0.25(4-bpmhz)}n (4). For Cd(II) two- and three-dimensional coordination networks, {[Cd(SO4)(4-bpmhz)(H2O)1.32]·1.2(H2O)}n (5), [Cd(SO4)(3-bpmhz)(H2O)]n (6), {[Cd(SO4)(4-bphz)(H2O)]·(H2O.C2H5OH)}n (7), and [Cd3(SO4)3(3-bphz)3(H2O)2]n (8) are reported. The extension of crystal structures up to two- and three-dimensional coordination networks has been achieved via bidentate bridging neutral azine ligands, and bi- and tridentate bridging sulfate anions that provide the metal-sulfate inorganic scaffolds in the forms of different one- and two-dimensional coordination arrays. The new crystalline solids were studied by X-ray single crystal and powder diffraction, spectroscopic and thermogravimetric analytical methods. The water-sulfate-anion interplay, similarities and dissimilarities in the coordination networks' topologies, the inherent chiralities of coordination networks, an impact of ligands’ methylation on solvent uptake, and the emission events accompanying the thermal stress are demonstrated and discussed.

Syntheses, crystal structures, properties of zinc(II) and cadmium(II) coordination polymers based on a novel asymmetric semi-rigid multicarboxylate ligand

Abstract A series of new metal coordination polymers constructed from a novel asymmetric semi-rigid aromatic carboxylate ligand, namely, {[M2L·5H2O]∙2H2O}n ((M = Zn, and Cd for 1 and 2, respectively), {[Zn2(L)(bipy)(H2O)2]·3H2O}n (3), and {[Zn(HL)(Habpt)(H2O)2]2·5H2O}n (4) (H4L = 4-((3,5-dicarboxyphenyl)carbamoyl)phthalic acid; bipy = 4,4′-bipyridine; abpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole), have been hydrothermally synthesized and characterized by elemental analysis, infrared spectra, and single-crystal X-ray diffraction. Both compounds 1 and 2 present three-dimensional coordination networks. Compound 3 forms a two-dimensional layer structure whereas 4 displays a one-dimensional (1D) chain structure built from both Habpt ligand and HL3− ligand, which further extend into three-dimensional network via hydrogen bonds. The versatile structures of the title polymers indicate that structural diversity may be influenced by various factors, such as the coordination mode of ligands, the nature of metal nodes and the kind of ancillary ligand. Additionally, the photoluminescence of 1–4 were also investigated.

Coordination polymers of Cu(II), Co(II) and Cd(II) based on a tetramethyl-substituted terphenyldicarboxylic acid

Three new 3D-metal–organic frameworks based on 2′,3′,5′,6′-tetramethyl-[1,1′:4′,1′′-terphenyl]-4,4′′-dicarboxylic acid (H2L) and Co, Cu, and Cd nodes have been synthesized. The complexes were characterized by elemental, thermogravimetric analysis, IR spectroscopy, single crystal, powder X-ray diffraction and gas sorption experiments. The crystal structure of [Cu2L2(H2O)2]n (1) corresponds to a two-dimensional coordination polymer, in which the metal nodes are two crystallographically equivalent Cu(II) atoms linked by four μ2-O,O′ carboxylate ligands in a centrosymmetric {Cu2O10} paddle-wheel building block. The structure of compound [CoL(dmso)]n (2) has a 3D metal–organic coordination lattice, in which the metal centers are connected by the linear organic ligand to generate a dense three-dimensional coordination polymer. Also, a three-dimensional coordination network was identified in the case of compound [Cd2L2(dmf)]n (3), whose structure is very similar to that of compound 2. In compound 3, the carboxylate groups of the linear L2− spacers behave as μ2-κ3O, O′:O tridentate bridging ligands. The compounds have a high thermal stability. Polymers 3 and 1 have moderate porosity (specific surface areas of approximately 900 m2/g and 600 m2/g, respectively), while polymer 2 has a dense structure.

Assembly and Adsorption Properties of Seven Supramolecular Compounds with Heteromacrocycle Imidazolium.

Seven supramolecular compounds comprising multivalent imidazolium macrocycles and metal halides, {[MC-IM][Ag2I4]}n (1), {[PC-IM]2[Ag7I11]}n (2), {[ODC-IM][Ag3I7]} (3), {[ODC-IM][Bi2I10]} (4), {[MDC-IM][Bi2I10]} (5), {[PDC-IM][Bi2I10]} (6), and {[MDC-IM][HgI4]} (7), have been synthesized by solvothermal reactions and structurally characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Notably, the three tetravalent imidazolium macrocycles were introduced for the first time and the extended anion structures are featured with three-dimensional coordination networks, one-dimensional chains, or zero-dimensional oligomers. This new study attempts to not only fill the gap in this supramolecular hybrid area that has been neglected but also enrich the type of imidazolium cyclophane. It is important that good efforts were devoted to study the adsorption properties of supramolecular compounds. Compound 5 exhibited great adsorption performance for organic dyes methylene blue, methyl orange, and rhodamine B (RhB) and can be evaluated as a potential candidate for industrial wastewater treatment.

The structures and properties of zinc(II) and cadmium(II) coordination polymers based on semi-rigid phenylenediacetate and 1,4-bis(2-methylimidazol-1-ylmethyl)benzene linkers

A systematic investigation into the reactions of o- and p-phenylenediacetic acid with zinc(II) and cadmium(II) salts in the presence of the semi-rigid 1,4-bis(2-methylimidazol-1-ylmethyl)benzene (pbmeix) co-ligand is reported. Five new coordination polymers – [Zn(μ-opda)(μ-pbmeix)0.5]n1, {[Zn(μ-ppda)(μ-pbmeix)]·H2O}n2, {[Zn(μ-ppda)(μ-pbmeix)]∙0.5pbmeix·H2O}n3, {[Cd(μ-opda)(μ-pbmeix)]·0.5DMF}n4 and [Cd(μ-ppda)(μ-pbmeix)0.5]n5 (o/ppda = 1,2-/1,4-phenylenediacetate) – have been prepared and structurally characterised. Compounds 1 and 5 were found to form three-dimensional coordination networks, 2 forms a two-dimensional structure whereas both 3 and 4 form one-dimensional nanotubular structures. Compounds 1 and 4 are opda complexes in which the dicarboxylate shows a tridentate coordination mode in 1 and a tetradentate coordination mode in 4. Compounds 2, 3 and 5 are ppda complexes in which the dicarboxylate adopts bidentate (2, 3) and hexadentate (5) coordination modes. The structure of 2 contains interpenetrated 2D frameworks and is a polycatenane with ppda linkers from one framework passing through Zn2(μ-pbmeix)2 rings from a neighbouring framework. The thermal stability of complexes 1–4 and luminescence properties of complexes 1 and 4 are also reported.

Syntheses, structures, and properties of three mixed-ligand complexes based on 3,6-bis(imidazole-1-yl)pyridazine

Three new coordination polymers [Co(L)(1,2,4,5-BTC)0.5(H2O)]n (1), {[Ni(L)(1,2-BDC)(H2O)3]·H2O}n (2) and {[Zn3(L)2(1,3,5-BTC)2(H2O)2]·3H2O}n (3) [L = 3,6-bis(imidazole-1-yl)pyridazine, H4BTC = 1,2,4,5-Benzenetetracarboxylic acid, H2BDC = 1,2-Benzenedicarboxylic acid, H3BTC = 1,3,5-Benzenetricarboxylic acid] were synthesized based on a rigid ligand L and different aromatic carboxylic acid ligands under solvothermal conditions. The structures of the complexes 1–3 were determined by single crystal X-ray diffraction and further characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). In addition, UV–vis diffuse-reflectance spectra demonstrate wide band gaps. The structural analysis reveals that complex 1 features a two-dimensional (2D) layer structure with a 6-connected sql topological net. Complex 2 shows a one-dimensional (1D) zigzag chain, while complex 3 displays a three-dimensional (3D) coordination network which exhibits an intriguing (5,5,6)-connected novel topological net with the point symbol of {32·42·53·63}2{32·44·54·63·72}. Moreover, the luminescence property and lifetimes of complex 3 has been measured at room temperature. Furthermore, in the complex-catalyzed homocoupling reaction of 4-substituted aryl iodides, the catalytic activities of complexes 1–3 have also been studied and discussed.

Structural diversity of a series of terpyridyl carboxylate coordination polymers: Luminescent sensor and magnetic properties

Eleven new coordination polymers, [Zn2(ctpy)2(HCOO)2]n·3nH2O (1), [Zn2(ctpy)2(HCOO)2(H2O)2]n·nH2O (2), [Zn2(ctpy)2(H2O)4]n·2n(CH3COO)·nH2O (3), [Zn2(ctpy)2(CH3COO)2]n·nH2O (4), [Zn(ctpy)2]n·nH2O (5), [Zn2(ctpy)2(Hidc)(H2O)2]n(6), [Cd2(ctpy)4]n(7), [Cd2(ctpy)2(Hidc)]n(8), [Co2(ctpy)2(HCOO)2(H2O)2]n·nH2O (9), [Co(ctpy)(DMF)(ox)0.5]n(10), [Co(ctpy)(ox)0.5]n(11) and the closely related compound [Zn(ctpy)(ox)0.5]n·0.5nH2O (12) (Hctpy = 4′-carboxy-4,2′:6′,4′′-terpyridine, H2ox = oxalic acid and H3idc = imidazole-4,5-dicarboxylic acid) have been synthesized by hydro(solvo)thermal reaction of 4′-carboxy-4,2′:6′,4′′-terpyridine with divalent metal salts and characterized by elemental analysis, IR spectra, single crystal X-ray diffraction. Compounds 1 and 4 have similar structure which demonstrate a two-fold interpenetrating 3D framework with a 3-connected utp topological net, which contains the same number of left and right-handed 21 helical chains. Compounds 2 and 9 are isostructural 2D layer with a 3-connected hcb topological net. Similar to 2, compound 3 also displays a 3-connected 2D hcb topological net. Compounds 5 and 10 are a 2D layer with a 4-connected sql topological net. Compound 6 shows a chiral 2D layer based on a 1D left- or right-handed helical chains, which are further extended into an achiral 2D + 2D→3D supramolecular network by hydrogen bonds with alternately arrangement. Compound 7 features an unusual 2-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,5)-connected binodal topological net with the Schläfli symbol of (52·6)(53·63·73·8). Compound 8 shows a 2D→3D supramolecular structure based on (3,4)-connected 2D bilayers with the Schläfli symbol of (44·62). Compound 11 displays an unusual three-dimensional coordination network which exhibits an intriguing (3,8)-connected binodal new topological net with Schläfli symbol (42·62)2(42·623·83). Compound 12 features a two-fold interpenetrating (3,4)-connected 3D framework with the fsc topological net. Compounds 1–12 were obtained under similar reaction conditions. The diverse structures indicate that rational selection of the second ligand, metal salt, counter anion and solvent are good methods to further design metal-organic compounds with new structures and properties. Moreover, their thermal stabilities, photoluminescent and magnetic properties were also investigated. More importantly, compound 12 has been successfully applied in the detection of Fe3+ ion in DMF solutions and nitrobenzene and the possible detecting mechanism was also discussed.

Luminescence, adsorption and topological analysis of a new two-fold interpenetrating 3D Cd(II) coordination polymer based on a tetracarboxylate ligand

A new 3D microporous coordination polymer [Cd(H2BTTB)]n·0.5nH2O (1), (H4BTTB = 4,4′,4″,4‴-benzene-1,2,4,5-tetrayltetrabenzoic acid), was constructed under solvothermal condition and structurally characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXPD) and thermogravimetric analyses (TGA). Single crystal X-ray diffraction indicates that compound 1 displays a two-fold interpenetrating dinodal (4,4)-connected three-dimensional coordination network with the PtS topological net and the point symbol of {42·84}. Furthermore, photoluminescence and adsorption of 1 were investigated.

A 3D Coordination Network Built from CuII4Cl3(H2O)2 Linear Clusters and Tetrapyridyl Tetrahedral Silane Ligands: Reversible Iodine Uptake and Friedel-Crafts Alkylation Reactions.

A novel three-dimensional coordination network 1 in a new 4,5,6-connected topology (4,5,6T115) built from linear CuII4Cl3(H2O)2 clusters and tetrahedral tetrakis(3-pyridyl)vinylsilane ligands is reported. Utilizing a similar tetrahedral ligand, tetrakis(3-pyridyl)ethylsilane, a different framework 2 having CuII2Cl(H2O)2 clusters is obtained in tcs topology. The activated sample of 1 shows an excellent and reversible uptake of I2 in solid as well as in solution phases owing to the presence of uncoordinated chloride ions and electron rich vinylic groups in it. The I2 uptake studies on the anion-exchanged samples, of bromide, iodide, and nitrate ions, show a progressive decrease in the adsorption capacity with the sample containing uncoordinated Cl- ion showing a maximum uptake of 48.5% and the one with the NO3- ions exhibiting the lowest uptake of 24.0%. These observations suggest that the halide counterions interact better with I2 in comparison with nitrate ions and the better I2 uptake in the presence of Cl- ions over the other two halides is due to its smaller size that offers a larger surface area for adsorption. Also, both these compounds were shown to be useful catalysts for the solvent-free syntheses of bis(indolyl)methanes via Friedel-Crafts alkylation reaction.

Zinc(II) and cadmium(II) coordination polymers containing phenylenediacetate and bis(imidazol-1-ylmethyl)benzene linkers: The effect of ligand isomers on the solid state structures

This work presents a systematic investigation of the reactions of o-, m- and p-phenylenediacetic acid with Zn(II)/Cd(II) salts in the presence of different semi-rigid o-, m- and p-bis(imidazol-1-ylmethyl)benzene co-ligands. Fourteen new coordination polymers – {[Zn(μ-opda)(µ-mbix)]·0.5H2O}n (1), {[Zn(μ-mpda)(µ-obix)]·H2O}n (2), {[Zn2(μ-mpda)2(μ-mbix)2]·5H2O}n (3), {[Zn(μ-mpda)(µ-mbix)]·2H2O}n (4), {[Zn(μ-mpda)(µ-pbix)]·0.5H2O}n (5), [Zn(μ-ppda)(μ-obix)]n (6), {[Zn(μ-ppda)(µ-mbix)]·0.5H2O}n (7), {[Zn(μ-ppda)(μ-pbix)]·H2O·DMF}n (8), {[Cd(μ-mpda)(μ-obix)1.5]·H2O}n (9), {[Cd(μ-mpda)(μ-obix)]·H2O}n (10), {[Cd(μ-mpda)(μ-mbix)(H2O)]·H2O}n(11), [Cd(μ3-ppda)(µ-obix)]n (12), [Cd(μ3-ppda)(µ-mbix)]n (13) and [Cd(μ3-ppda)(µ-pbix)]n (14) (o/m/ppda=1,2/1,3-/1,4-phenylenediacetate, o/m/pbix=1,2-/1,3-/1,4-bis(imidazol-1-ylmethyl)benzene) – have been prepared and structurally characterized. Two of the complexes were found to possess one-dimensional (1D) structures, eleven complexes were found to be two-dimensional (2D) coordination networks and one of the complexes was found to be a three-dimensional (3D) coordination network. Of the 1D structures, 3 forms nanotubes, whereas in 8 pairs of pbix ligands bridge the zinc(II) centers to generate Zn2(pbix)2 dimers, which in turn are linked together by pairs of ppda linkers to give chains. Compound 5 contains a 4-fold interpenetrated 3D framework. The structure of 10 contains interpenetrated 2D frameworks, leading to a three-dimensional gross structure. The thermal stabilities and luminescent properties for 1–14 are also reported.

Partial in Situ Reduction of Copper(II) Resulting in One-Pot Formation of 2D Neutral and 3D Cationic Copper(I) Iodide–Pyrazine Coordination Polymers: Structure and Emissive Properties

On the way to copper(I) iodide coordination polymers with specific luminescent properties, the in situ reduction of Cu(II) in the presence of KI and bidentate N-heteroatomic ligand, either pyrazine (pyz) or 4,4'-bipyridine (bpy), resulted in one two-dimensional and two three-dimensional new coordination networks. Starting from Cu(NO3)2·3H2O in the presence of pyz, successive precipitation of known yellow [(CuII)2(pyz)]n, new orange [CuII(pyz)]n, and new dark blue {[CuI(pyz)2]·I5}n polymeric solids was observed. Starting from the same salt in the presence of bpy resulted in the successive precipitation of known yellow [(CuII)2(bpy)]n and new brown {[CuII(NO3)(bpy)2]·I3·(dmf·H2O)}n coordination polymers. By using either Cu(CH3COO)2·H2O or Cu(BF4)2 as starting materials, both known forms, yellow [(CuII)2(bpy)]n and orange [CuII(bpy)]n, precipitated successively. The new solids were characterized by IR spectroscopy and X-ray analysis. [CuII(pyz)]n represents the missing member in the row of two-dimensional coordination networks with general formula [CuIX(pyz)]n (X = Cl, Br, I). Its steady state and time-resolved characterization together with DFT and TDDFT calculations revealed that the emission at room temperature is mainly delayed fluorescence originating from mixed singlet metal-to-ligand charge transfer and halide-to-ligand charge transfer states, while that at 77 K is phosphorescence, associated with the small singlet-triplet energy differences (ΔE = 70 meV).

Three coordination polymers based on 9,10-di(pyridine-4-yl)anthracene ligand: Syntheses, structures and fluorescent properties

Three new mixed-ligand divalent coordination polymers (CPs) {[Zn3(L)(1,4-bdc)3]·2DMF}n (1), {[Zn2(L)(2,6-ndc)2]·3DMF}n (2) and {[Cd2(L)3(2,6-ndc)2]}n (3) [L = 9,10-di(pyridine-4-yl)anthracene, 1,4-H2bdc = 1,4-benzenedicarboxylic acid, 2,6-H2ndc = 2,6-naphthalenedicarboxylic acid] have been prepared and well characterized by elemental analyses, infrared spectroscopy, single-crystal X-ray diffraction techniques, powder X-ray diffraction patterns and thermogravimetric analyses. The crystal structure analyses of coordination polymers (CPs) reveal that all the complexes 1–3 have the three-dimensional (3D) coordination networks. The structure of 1 can be simplified as a sqc3 3D 8-connected framework with the point symbol of (424·64). Particularly, in the presence of the linear 2,6-H2ndc auxiliary ligand, a double-deck interpenetrating pcu 3D network of 2 is assembled by 6-connecting framework with the point symbol of (412·63). Complex 3 exhibits a ttd 3D 5-connected net with a point symbol of (46·64). Further, the solid-state luminescent properties of the complexes 1–3 were measured and studied at room temperature.

New lanthanide biphenyl-4,4′-diacetates − hydrothermal synthesis, spectroscopic, magnetic and thermal investigations

The hydrothermal reaction of lanthanide chlorides and sodium salt of biphenyl-4,4′-diacetic acid (H2bpda) yielded a series of coordination polymers of the general formula Ln2(bpda)3·nH2O (Ln=lanthanide ions(III) except for Pm(III), n=3–7). Single-crystal and powder X-ray diffraction analyses revealed that complexes form three-dimensional coordination networks. Tetradentate biphenyl-4,4′-diacetate ligand coordinates Ln(III) through both bidentate-chelating carboxylate groups. Their thermal behaviours was investigated by the TG-DSC and TG-FTIR methods. The influence of atmosphere of heating on thermal stability of complexes was also examined. Magnetic studies of neodymium and praseodymium complexes showed weakly antiferromagnetic exchange interactions between lanthanide ions.