Salen Type Homo-multinuclear Yb3 and Yb4 Complexes and Their NIR Luminescence

Two discrete salen type homo-multinuclear Yb₃ and Yb₄ complexes, namely, [Yb₃L₃(OAc)₃]·3CH₃OH·H₂O (1) and [Yb₄L₂(OAc)₄(μ₃-OH)₂(H₂O)₂](ZnCl₄)·3CH₃OH (2) (H₂L = N,N′-bis(2-oxy-3-methoxybenzylidene)-1,2-phenylenediamine) have been synthesized by reactions of H₂L and different ytterbium salts. X-ray crystallographic analysis reveals that complex 1 exhibits a triple-decker Yb₃ sandwich structure with a ratio of H₂L:Yb = 1:1, while complex 2 exhibits a defect-dicubane Yb₄ core with a ratio of H₂L:Yb = 1:2. The NIR luminescence of complexes 1 and 2 have been investigated and discussed.     

The Inclusion of Organometallic Derivatives of Cyclotriphosphazenes Inside SiO2 Matrix and Their Conversion to Nanostructured Metal-Oxides and Phosphates

Organometallic derivatives of the cyclotriphosphazene N₃P₃[OC₆H₄CH₂CN·TiClCp₂]₆ (1), N₃P₃(O₆H₅)₅[OC₆H₄N·W(CO)₅] (2), N₃P₃[OC₆H₄CH₂CN·Mo(CO)₅]₆ (3), [N₃P₃(O₆H₅)₅(OC₅H₄N·CpRu(PPh₃)₂)][PF₆] (4), [N₃P₃(O₂C₁₂H₈)₂OC₅H₄N·Ag(PPh₃)][OSO₂CF₃] (5), N₃P₃[OC₆H₅]₅ [OC₅H₄N·Cu][PF₆] (6) and N₃P₃[OC₆H₄CH₂CN·CuCl]₆[PF₆]₆ (7),were incorporated inside SiO₂ through the sol–gel method. The metal–organic nanocomposites of the general formula N₃P₃[OC₆H₄CH₂CN·TiClCp₂]₆·nSiO₂ (G ₁ ), N₃P₃[OC₆H₄N·W(CO)₅]·nSiO₂ (G ₂ ), N₃P₃[OC₆H₄CH₂CN·Mo(CO)₅]₆·nSiO₂ (G ₃ ), N₃P₃(O₆H₅)₅OC₅H₄N·CpRu(PPh₃)₂][PF₆]·nSiO₂ (G ₄ ), [N₃P₃(O₂C₁₂H₈)₂OC₅H₄N·Ag(PPh₃)][OSO₂CF₃]·nSiO₂ (G ₅ ), N₃P₃[OC₆H₅]₅[OC₅H₄N·Cu][PF₆]·(SiO₂) _n (G ₆ ), and N₃P₃[OC₆H₄CH₂CN·CuCl]₆[PF₆]₆·(SiO₂) _n (G ₇ ), were characterized by IR spectroscopy; ¹²C, ³¹ P and ²⁹Si MAS NMR measurements as well as UV–Visible diffuse reflectance spectra, indicating the presence of the respective organometallic derivatives of the cyclotriphosphazene incorporated into SiO₂. Pyrolysis of these nanocomposites under air at 800 °C gives rise to nanostructured metal-oxides and metal phosphates incorporated into amorphous SiO₂, with the presence in some cases of complexes phase mixtures. From some precursors, we obtained metal-oxides/phosphates nanoparticles separated from the SiO₂ nanoparticles instead the oxides/phosphates nanoparticles inside the SiO₂ matrix. Additionally and for comparison purposes, we used the compound N₃P₃[NH(CH₂)₃Si(OEt)₃]₆ as gelator. Nanocomposites (G′ ₁ ), (G′ ₂ ) and (G′ ₃ ) exhibited mainly morphological differences while in some cases composition differences when using TEOS as gelator. Some simple metal-containing compounds as (O₃SCF₃)Ag(PPh₃)(HOC₅H₄N), [CuCl₂·NC₅H₄OH] and [CuCl₂·NCCH₂C₆H₄OH]—which are useful models of the most complexes (G ₅ ), (G ₆ ) and (G ₇ ) were also prepared and incorporated in amorphous silica. Their pyrolytic products were compared with those of more complex cyclotriphosphazene analogous. Interestingly, the pyrolysis of the nanocomposite [(O₃SCF₃)Ag(PPh₃)(HOC₅H₄N)][SiO₂] _n affords the firstly-reported materials containing Ag₂O along with SiO₂ nanoparticles.     

Hydrothermal Syntheses and Crystal Structures of Three Zn(II) Coordination Compounds Constructed with 3,5-Pyrazoledicarboxylic Acid

Three novel metal–organic coordination compounds, [Zn(Hdcp)(H₂O)₄]·1.5H₂O (1), [Zn(Hdcp)(H₂O)₂]_∞ (2) and [Zn₃(dcp)₂(H₂O)₅]_∞ (3) with the ligand 3,5-pyrazoledicarboxylic acid were prepared by the hydrothermal method. The complexes were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Compound 1 is a mononuclear molecule that is linked into a 3D supramolecular framework via N–H···O and O–H···O hydrogen bonds. In 2, two types of carboxylic bridges were found between Zn^II ions to form a 1D double-chain. The 1D chains were further construct into a 3D structure by hydrogen bonds. Trinuclear 3 consists of 1D bi-infinite parallelogram chains of [Zn₃(dcp)₂(H₂O)₃] trimers. In the basic trinuclear unit a further bridging mode of the ligand is seen where two dcp^3? ligands chelate three Zn^II ions by utilizing five donors of the dcp^3? ligand. The photoluminescent properties of 1, 2 and 3 were investigated.     

Synthesis and Structural Characterization of Three New Tetraorganodistannoxanes

An efficient method was developed for the preparation of three tetraorganodistannoxane complexes, (C₂H₅)₈Sn₄Cl₂(CH₃O)₂O₂ (1), (CH₃)₈Sn₄(C₃H₄N₃S)₂(CH₃O)₂O₂ (2) and (C₄H₉)₈Sn₄(C₃H₄N₃S)₂(CH₃O)₂O₂ (3). All prepared complexes were characterized by infrared, ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopes and elemental analysis. The molecular structure of a representative complex (1) was determined by single-crystal X-ray diffraction. Results showed that 1 is a tetranuclear, centrosymmetric dimeric, and contains two endo-cyclic five-coordinated tin atoms and two exo-cyclic five-coordinated tin atoms. Compound 1 lies about a center of inversion and the tetranuclear molecule features a three-ring-staircase Sn₄O₄ core. The asymmetric unit of 1 contains two independent Sn(IV) atoms and a 2D infinite rigid chain structure forms via C–H···Cl interactions between tetranuclear units.     

Cu(II) and Zn(II)-Pyridine-2,3-Dicarboxylate Complexes with 2-Methylimidazole: Syntheses, Crystal Structures, Spectroscopic and Thermal Analyses

Two new Cu(II) and Zn(II)-pyridine-2,3-dicarboxylate (pydc) complexes with 2-methylimidazole (2-Meim), [Cu(pydc)(2-Meim)₃]·H₂O (1) and {[Zn(μ-pydc)(H₂O)(2-Meim)]·H₂O}_n (2) have been synthesized and characterized by elemental, spectral (IR and UV–Vis.) and thermal analyses. The molecular structures of mononuclear (1) and polynuclear (2) complexes have been determined by the single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic P ? 1 space group, while compound 2 crystallizes in the monoclinic P2₁/c space group. The pyridine-2,3-dicarboxylate ligand acts in two different coordination modes; namely, bidentate-(N,O) for 1 and μ-tridentate-(N,O,O) for 2, the latter displaying a 1D polynuclear structure. The crystal packing of the complexes exhibit 3D supramolecular frameworks including channels by C–H···π, π···π, and N–H···O interactions. Water molecules occupy the channels by O–H···O hydrogen bonds.     

Metallopolymer Films Exhibiting Three-Color Electrochromism in the UV/Vis and Near-IR Region: Remarkable Utility of Trimetallic Clusters Bearing Thienyl Pendants and Their Mixed-Valent Charge Transfer Transitions

Novel oxo-centered, acetate-bridged trinuclear ruthenium clusters functionalized with two pyridine ligands with thienyl substituents, [Ru₃O(CH₃COO)₆(CO)(L1)₂] (1) and [Ru₃O(CH₃COO)₆(CO)(L2)₂] (2), where L1 = 4-(2-thienyl)pyridine and L2 = 4-(2,2′-bithienyl)pyridine, have been synthesized and characterized. The molecular structure of 2 has been determined by single-crystal X-ray diffraction. One-electron oxidation of 2 with silver(I) cation has led to the isolation of a CO-dissociated product, [Ru₃O(CH₃COO)₆(H₂O)(L2)₂]PF₆ (3·PF ₆ ), and subsequent reaction with 4-dimethylaminopyridine (dmap) gave [Ru₃O(CH₃COO)₆(dmap)(L2)₂]PF₆ (4·PF ₆ ). Linear metallopolymers containing the {Ru₃O(CH₃COO)₆} groups have been deposited onto indium-tin oxide surface via oxidative electropolymerization of 2, 3·PF ₆ , and 4·PF ₆ . These metallopolymer thin films exhibit three-color electrochromism in the UV/Vis and near-IR region associated with the Ru₃ ^II,III,III, Ru₃ ^III,III,III, and Ru₃ ^III,III,IV oxidation states.     

Synthesis, Crystal Structure, Fluorescence and Thermostability of Ni(II), Zn(II), Cd(II) Complexes with Schiff Base 2-Acetylpyridine-d-tryptophan

Three novel transition metal coordination polymers, [Ni(C₁₈H₁₆N₃O₂)₂·2CH₃OH] _n (1), [Zn(C₁₈H₁₆N₃O₂)₂·4CH₃OH] _n (2) and [Cd(C₁₈H₁₆N₃O₂)₂·2CH₃OH] _n (3) (C₁₈H₁₆N₃O₂=2-acetylpyridine-d-tryptophan) were synthesized and characterized by elemental analysis, IR, UV, ¹H NMR and X-ray diffraction single crystal analysis. The analyses of the structures indicate that all three materials crystallize in the tetragonal crystal system, space group P4₁2₁2. They have similar structures; i.e., the Schiff base coordinates in its deprotonated form and behaves as a hexadentate (4N+2O) coordinated ligand to form a distorted octahedron geometry. On the other hand, as a result of the alternate arrangement of chains through N–H···O intermolecular hydrogen bonds interactions, 2-D layers are formed for the three complexes. Furthermore, the luminescent properties and thermal stabilities of the three complexes were investigated.     

Fluorescence Properties Change of Lanthanide Coordination Polymers Dispersed in Mesoporous SBA-15 by Energy Transition Process

Four lanthanide coordination polymers, {[Ln(HPDA)(PDA)(H₂O)₂]·4H₂O} _n (Ln?=?Sm (1), Eu (2), Tb (3)) and {[Sm₃(H₂PDA)₂(HPDA)₂(PDA) (OH)₅(H₂O)₃]·2dta·4H₂O} _n (4) (H₂PDA?=?pyridine-2,6-dicarboxylic acid, dta?=?diethyl amine), have been synthesized under hydrothermal conditions and were characterized by elemental analysis, IR spectrometer, and single-crystal X-ray crystallography. In the complexes 1–3, the 1D chains are assembled into 2D layer by hydrogen bonds formed between the carboxyl groups, and were further assembled into 3D framework by hydrogen bonds and π–π stacking interactions. In complex 4, each Sm³⁺ ion connected to the neighboring Sm³⁺ ion through bridging carboxyl oxygen atoms, and then give rise to a new 2D layered open-framework structure. The 3D supramolecular structure of 4 is constructed through hydrogen-bonding and π–π stacking interactions between adjacent metal–organic polymeric coordination chains. Complexes 1–3 were dispersed in mesoporous materials SBA-15 in DMF solution (denoted as ML-SBA-15, ML?=?1, 2, 3), which were characterized by XRD, IR, and fluorescence spectra. Compared to the complexes 1–3, the photoluminescence efficiency of hybrid material was improved by the energy transition between mesoporous materials and the complexes. The complexes encapsulated in mesoporous materials SBA-15 exhibited stronger luminescence intensity and longer fluorescence lifetime.     

Three New Coordination Polymers Constructed from Mixed Ligands: Syntheses,Luminescence and Magnetism

Three new coordination polymers, namely, {[Cd(H₂bptc)(IP)(H₂O)]·2H₂O} _n (1), {[Mn₂(IP)₂(dstc)]·6H₂O} _n (2) and {[Zn₂(IP)₂(dstc)]·3H₂O} _n (3) (IP = 1H-imidazo[4,5-f][1,10]-phenanthroline, H₄bptc = 3,3′,4,4′-benzophenonetetracarboxylic acid, and H₄dstc = 3,3′,4,4′-diphenylsulfonetetracarboxylic acid) have rationally designed and characterized by single crystal X-ray diffraction. Polymer 1 shows a 1D ribbon-like structure. Although compounds 2 and 3 feature 2D grid networks, the coordinative modes of dstc ligand and the arrangements of IP ligand are very different. Furthermore, the luminescence properties for 1 and 3, as well as the magnetism of 2 are explored in detail.     

Discrete and Polymeric Lead(II) Complexes Containing 4-Methyl-1,2,4-triazole-3-thiol Ligand: X-ray Studies,Spectroscopic Characterization,and Thermal Analyses

[Pb(Hmptrz)₄(NO₃)₂] complex (1) and [Pb(μ-mptrz)₂(H₂O)]_n complex (2) (Hmptrz is 4-methyl-1,2,4-triazole-3-thiol) were prepared from the reaction of 4-methyl-1,2,4-triazole-3-thiol with Pb(NO₃)₂ and Pb(OAc)₂·3H₂O in CH₃OH/H₂O, respectively. Both complexes were characterized by elemental analysis, IR, UV–Vis, ¹H NMR, ¹³C{¹H}NMR, and luminescence spectroscopy and their structures were studied by single-crystal X-ray crystallography. The thermal stabilities of the title complexes were studied by thermogravimetric and differential thermal analyses. Complex 1 is a discrete and complex 2 is a polymer; both structures are without precedent in the literature.     

Two Supramolecular Microporous Metal–Organic Frameworks Templated by Keggin Polyoxometalates

Two new Keggin polyoxometalates (POM)-templated supramolecular metal–organic frameworks (MOF) with micropores, Cu₃(L)₆[H₃(PMo₁₂O₄₀)₂]·6H₂O (1) and Cu₃(L)₆[H₅(SiW₁₂O₄₀)₂]·6H₂O (2) (L?=?1,2-bis(imidazol-1-ylmethyl)ethane), have been prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra and cyclic voltammetry. These two isostructural compounds are constructed by two distinct moieties, a Keggin polyanion and a linear [Cu(L)₂]⁺ subunit. The [Cu(L)₂]⁺ subunits further form a microporous MOF through supramolecular interactions. The Keggin polyanions act as templates inducing the micropores. The electrochemical and electrocatalytic behavior of compounds 1 and 2 bulk-modified carbon paste electrodes (1-, 2-CPE) was studied.     

A Series of Luminescent Lanthanide–Organic Complexes Constructed from In Situ Generated Dithiobenzoic Acid

Two types of lanthanide thiolato-carboxylate complexes, [Type I: [Yb(dtba) (Hdtba)] _n (1), Type II: [Ln(dtba)_1.5(biim)] _n (Ln = Pr (2a), Nd (2b), Sm (2c), Eu (2d), Gd (2e), Tb (2f), Dy (2g), H₂dtba = 2,2′-dithiodibenzoic acid, bimm = diimidazole)] have been obtained by hydrothermal method and characterized by the single-crystal X-ray diffraction, IR, 2D-COS IR, TG and the luminescence analysis. The H₂dtba ligand came from the in situ S–S function reaction of 2-mercaptobenzoic acid (H₂mba) under the hydrothermal condition. Complex 1 is a 2D bamboo-like sqr-topology layered structure, and the 3D (4, 4, 6)-connected supramolecular frameworks is produced by the hydrogen bonds of O–H···O. Complexes of type II (from 2a to 2g) are isostructural and they are assigned to 1D rope-like chains by introducing the chelating ligand of diimidazole. These 1D rope-like chains are further linked by N–H···O hydrogen bonds into a 3D supramolecular framework with CdSO₄-type topology. Photoluminescence studies reveal that complexes 2b, 2c, 2d, 2f, 2g exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.     

Direct Synthesis and Crystal Structure of Dehydrated State in Vapochromic MMX-type Quasi-One-Dimensional Iodide-Bridged Platinum Complexes

The dehydrated vapochromic 1D coordination polymer, (H₃NC₄H₈NH₃)₂[Pt₂(pop)₄I] (1) was synthesized directly from methanol solution. Although vapochromic 1 · 4H ₂ O has been synthesized, dehydrated high-temperature structure has never been determined because of lowering the quality of crystal by dehydration. The crystal structure of 1 was determined by X-ray crystal structure analysis, and we confirmed that it was identical to the dehydrated high-temperature structure of 1 · 4H ₂ O by comparing the powder X-ray diffraction (XRD) patterns. The Pt–I–Pt distance (d(Pt–I–Pt)) of compound 1 · 4H ₂ O was shortened for approximately 1.1 Å by desorption of water to form compound 1, accompanied with phase transition in electronic states. The other crystal including methanol molecule as lattice solvent, 1 · 2MeOH, was also obtained as by-product. The synthesis from various kinds of organic solvent has the great potential to develop the field of vapochromism accompanying phase transition of electronic state.     

Structural Variations in Coordination Polymers of Sodium and Cesium Dicarboxylates

The coordination polymer {[Na₂L(μ-H₂O)(H₂O)₃]·H₂O} _n (1) derived from 2,2′-(phenylmethylidene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H₂ L) has repeat units comprising of hexa-coordinate diaqua-bridged dinuclear sodium complex ions. These units are connected through intervening mononuclear complex parts having penta-coordinated sodium ions. The sodium ions adopt repeated hexameric chair-like arrangement in the polymer. The cesium salt of H₂ L namely [Cs(HL)(μ-H₂O)(H₂O)] _n (2) is a coordination polymer. In this case one acid group of the ligand is deprotonated and 2 form self-assembly by intermolecular hydrogen bonds between the free carboxylic acid groups. The fluoro-substituted ligand 2,2′-(2-fluorophenylmethyledene-bis(3,5-methyl-2-phenyleneoxy)] diacetic acid (H ₂ L _f ) forms disodium salt with a composition [{Na₂L_f(μ-H₂O)(H₂O)₃}·H₂O] _n (3); which is a two dimensional coordination polymer. On the other hand the corresponding cesium salt of H ₂ L _f has a composition [{(H₂O)Cs(μ-H₂O)(μ-L_f)Cs(H₂O)₂}] (4); which is also a 2-D coordination polymer. The cesium ions are six or nine coordinate in the polymer and the coordination polymer possesses unusual Cs···F–C coordination bond.     

Oxidation of Benzene Catalyzed by 2,2′-Bipyridine and 1,10-Phenantroline Cu(II) Complexes

The use of mononuclear Cu(II) 2,2′-bipyridine and 1,10-phenantroline complexes as catalysts in the oxidation of benzene, using hydrogen peroxide and tert-butyl hydroperoxide as oxidant in CH₃CN/H₂O solution is presented. The reactions were carried out at 25 and at 50 °C. The complexes [Cu(bipy)₃]Cl₂ · 6H₂O (1), [Cu(bipy)₂Cl]Cl · 5H₂O (2), [Cu(bipy)Cl₂] (3), [Cu(phen)₃]Cl₂ · 7H₂O (4), [Cu(phen)₂Cl]Cl · 5H₂O (5), [Cu(phen)Cl₂] (6) were able to oxidize benzene into phenol, hydroquinone and p-benzoquinone. Highest conversion (22%) was obtained using [Cu(Phen)Cl₂] (6) as catalyst.     

Uranyl Coordination Polymers Incorporating η5-Cyclopentadienyliron-Functionalized η6-Phthalate Metalloligands: Syntheses,Structures and Photophysical Properties

The reaction of two η⁵-cyclopentadienyliron(II)-functionalized terephthalate and phthalate metalloligands, namely [(η⁵-C₅H₅)Fe^II(η⁶-1,4-HO₂CC₆H₄CO₂H)][(η⁵-C₅H₅)Fe^II(η⁶-1,4-HO₂CC₆H₄CO₂)][PF₆] and [(η⁵-C₅H₅)Fe^II(η⁶-1,2-HO₂CC₆H₄CO₂H)][(η⁵-C₅H₅)Fe^II(η⁶-1,2-HO₂CC₆H₄CO₂)][PF₆]—hereafter [H₂ CpFeTP][HCpFeTP][PF₆] and [H₂ CpFeP][HCpFeP][PF₆], respectively—with [UO₂(NO₃)₂]·6H₂O under hydrothermal conditions yielded four new coordination polymers; (1) [(UO₂)F(HCpFeTP)(PO₄H₂)]·2H₂O, (2) [(UO₂)₂(CpFeTP)₄]·5H₂O, (3) [(UO₂)₂F₃(H₂O)(CpFeP)], and (4) [H₂ CpFeP][UO₂F₃]. The use of metalloligands has proven to be a viable route towards the incorporation of a secondary metal center into uranyl bearing materials. Depending upon the protonation state, the iron sandwich metalloligands may vary from zwitterionic neutral or monoanionic coordinating species as observed in compounds 1–3, or a positively charged species that hydrogen bonds with anionic [UO₂F₃]^? chains as observed in 4. Further, the hydrolysis of the charge balancing PF₆ ^? anion increases the diversity of UO₂ ²⁺ coordinating species by contributing both F^? and PO₄ ^3? anions (1, 3, 4). The luminescent properties of 1–4 were also studied and revealed the absence of uranyl emission, suggestive of a possible energy transfer from the uranyl cation to the iron(II) metal center.     

Two New Zn(II) Coordination Polymers Constructed from Asymmetric Biphenyl-Dicarboxylate and Imidazole-Containing Ligands: Structures and Photoluminescent Properties

Two new coordination polymers, [Zn(2,4′-bpdc) (L₁)_0.5·(H₂O)] _n (1) and {[Zn(3,4′-bpdc) (L₁)]·(H₂O)} _n (2), have been obtained from hydrothermal reactions of zinc (II) nitrate with the ligands 1,4-bis(imidazol-1-yl)benzene (L) and two asymmetric biphenyl-dicarboxylate [biphenyl-2,4′-dicarboxylate (2,4′-bpdc) and biphenyl-3,4′-dicarboxylate (3,4′-bpdc)]. Single-crystal X-ray diffraction analysis the two coordination polymer show different structures due to the different dicarboxylate ligands. Complex 1 features a 3D mab topological net. Complex 2 is unusual case that has 3D frameworks constructed from 2D 4⁴-sql layers by parallel polycatenation. The photoluminescent properties of 1 and 2 have also been investigated.     

Ancillary Ligand-Mediated Syntheses,Structures and Fluorescence of Three Zn/Cd(II) Coordination Polymers Based on Nitrobenzene Dicarboxylate

The Zn/Cd(II)-nbdc carboxylate motifs mediated by various dipyridyl-typed ligands afforded three new coordination compounds, namely, [Zn(nbdc)(bpa)_0.5(H₂O)]·H₂O (1), [Zn₂(nbdc)₂(bpp)₂]·H₂O (2), and [Cd(nbdc)(bpe)_0.5(H₂O)₂] (3) (H₂nbdc = 4-nitrobenzene-1,2-dicarboxylic acid, bpa = 1,2-bi(4-pyridyl)ethane, bpe = 1,2-di(4-pyridyl)ethylene, and bpp = 1,3-bis(4-pyridyl)propane), which were synthesized by hydrothermal reaction and characterized by elemental analysis, IR, thermal analysis (TGA), and fluorescent analysis. The single-crystal X-ray diffractions reveal that three complexes display a diverse range of connectivity topology from 1D to 3D, which is dependent on the type of dipyridyl-typed ligands and metal centers. Complex 1 is the 1D chain featuring Zn-carboxylate binuclears extended further by bpa coligands. Complex 2 is the 2D thick-layer containing double-stranded chains cross-linked further by bpp coligands. Complex 3 is the 3D framework with (6³)(6⁵.8) ins topology featuring Cd-carboxylate chiral layers pillared by bpe coligands. The thermal stabilities and fluorescence properties for complexes 1–3 are investigated.     

Construction of Two New Metal–Organic Frameworks from Pamoic Acid and N-Containing Auxiliary Ligands

Two new metal–organic frameworks; namely, [Cd₂(pam)₂(bpe)_1.5(DMF)₂(H₂O)] _n ·2n(DMF) (1) and [Cd(pam)(bix)] _n (2) (H₂pam = pamoic acid, bpe = 1,2-di(4-pyridyl)ethylene, bix = 4,4′-bis(imidazol-1-ylmethyl)benzene, DMF = N,N′-dimethylformamide), were solvothermally synthesized via varying the auxiliary ligand. Single crystal X-ray diffraction analysis reveals that compound 1 shows a 2D→3D polythreaded motif based on (3,4)-connected 2D sheets, while compound 2 features a 4-connected sql tetragonal plane net, which further extended into a 3D supramolecular framework through intermolecular CH···π interactions. In addition, the luminescent and thermal stabilities properties of these two compounds were investigated.     

Synthesis and Crystal Structures of a Lanthanum(III) 1D Polymer and a Mixed-Ligand Cerium(III) Binuclear Complex Derived from Pyridine-2,6-dicaboxylic Acid

Lanthanum(III) and cerium(III) complexes of pyridine-2,6-dicaboxylic acid (H₂Pydc) have been prepared and their crystal structures were determined by X-ray crystallography. The single crystal analysis reveals that the lanthanum(III) complex, 1 is polymeric consisting of {[La(Pydc)₂(H₂O)₂]·4H₂O} _n units linked through carboxylate oxygen atoms and exhibiting nine coordination number. Intermolecular O–H···O hydrogen bonds produce R ₁ ¹ (6), R ₄ ⁴ (16) and R ₄ ⁴ (20) rings, which lead to three-dimensional polymeric chains. The crystal structure of the cerium(III) complex, 2 [{Ce(Pydc)₃}{Ce(Pydc)(HO–CH₂CH₂–OH)(H₂O)₃}·6H₂O)] shows that the complex is a mixed-ligand binuclear system in which one cerium coordinated to three Pydc molecules, while the other cerium is bound to one Pydc, one oxygen atom of the other Pydc, one ethylene glycol and three water molecules. Each of the two Ce(III) ions is nine coordinated. Intermolecular O–H···O hydrogen bonds produce R ₂ ² (8) and R ₂ ² (20) rings, which lead to three-dimensional polymeric chains. The complexes were further investigated using elemental analysis, FTIR spectroscopy and thermogravimetric analysis.