Binuclear Units Research Articles

Synthesis, crystal structure, thermal, luminescent property and antibacterial activity of lanthanide ternary complexes with p-chlorobenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

Four novel lanthanide coordination complexes, [La(p-ClBA)3(5,5′-DM-2,2′-bipy)H2O]n (1), [Ln(p-ClBA)3(5,5′-DM-2,2′-bipy)H2O]2 (Ln = Sm 2, Eu 3, Gd 4) were obtained from the reaction between p-chlorobenzoic acid (p-ClHBA), 5,5′-dimethyl-2,2′-bipyridine (5,5′-DM-2,2′-bipy) and lanthanide nitrate under solvothermal conditions. Single crystal X-ray diffraction analysis showed that complex 1 is a 1D chain structure, crystallized in the monoclinic system, space group P2(1)/n, and formed a 2D sheet through the C–H⋯O hydrogen bond interactions. While complexes 2–4 were binuclear unit and crystallizes isomorphically in the triclinic system, space group Pī. The binuclear unit were assembled into 1D supramolecular structures through the O–H⋯O hydrogen bond interactions along the a-axis and formed a 2D supramolecular structures through the π-π stacking interactions along the b-axis. The thermal analysis of four complexes were studied by TG-DSC/FTIR. The solid state photoluminescent properties of complex 3 were investigated at room temperature. Moreover, the antibacterial activities of complexes 1–4 on Candida albicans were studied.

Construction of lanthanide complexes supported by 2,3‐dimethoxybenzoic acid and 5,5’‐dimethy‐2,2’‐bipyridine: crystal structures, thermoanalysis, magnetic and fluorescence properties

A series of novel trivalent lanthanide complexes, [Ln(2,3‐DMOBA)3(5,5′‐DM‐2,2′‐bipy)]2·C2H5OH (Ln = Eu(1), Sm(2), Gd(3), Ho(4) Er(5), Pr(6), Nd(7)) (2,3‐DMOBA = 2,3‐dimethoxybenzoate, 5,5′‐DM‐2,2′‐bipy = 5,5′‐dimethy‐2,2′‐bipyridine), have been successfully synthesized and structurally validated by single crystal diffraction. All complexes discussed herein feature a binuclear structure, and contain only one free ethanol molecule, which is interesting in the lanthanide complexes. The coordination number of center Ln3+ ions is nine, showing a distorted monocapped square anti‐prismatic coordination geometry. Through a pair of alternating identical C‐H···O hydrogen bonding interactions between two 2,3‐DMOBA ligands on the same lanthanum binuclear unit with 5,5′‐DM‐2,2′‐bipy ligands on two neighboring units, the binuclear complexes can form one‐ The thermal analysis of these complexes are investigated by TG‐DSC/FTIR, the result show that the decomposition process of complexes are mainly divided into four stages with the formation of the respective oxides. The visible light emission experiment of complex 1 is carried out, and the characteristic luminescence behavior of intense red light is exhibited. What'more, fluorescence lifetimes as well as the fluorescent quantum yield of complex 1 is calculated. And the magnetic properties of complexes 3–5 are also studied.

Four octamolybdate-based complexes based on flexible bis-imidazole-bis-amide ligands with different lengths: Structure, electrochemical and photocatalytic properties

By adjusting the spacer length of bis-imidazole-bis-amide ligands and solvents, four octamolybdate-based metal-organic complexes (MOCs), [(Co2(L1)2(H2O)3)2(γ-Mo8O28)(MoO3)2]·6H2O (1), [(Ni2(L1)2(H2O)3)2(γ-Mo8O28)(MoO3)2]·6H2O (2), [Co2(L2)2(H2O)4](β-Mo8O26)·4DMA·6H2O (3) and [Ni(L3)0.5(H2O)(β-Mo8O26)0.5]·3H2O (4), (L1 = 1,2-bis(1H-imidazole-4-carboxamido)ethyl, L2 = 1,4-bis(1H-imidazole-4-carboxamido)butyl, L3 = 1,6-bis(1H-imidazole-4-carboxamido)hexyl, DMA = N,N′-dimethylacetamide), have been synthesized. Complexes 1 and 2 were obtained in H2O:EtOH and H2O:MeOH mixed solvents, respectively, which are isostructural 2D supramolecular structures, both containing binuclear metal organic cation rings and [(γ-Mo8O28)(MoO3)2]8− anion. Interestingly, such a [(γ-Mo8O28)(MoO3)2]8− anion is formed in 1 and is very rare in the polymolybdate-based MOCs. By increasing the length of ligands in H2O:DMA mixed solvent system at the presence of Co2+/Ni2+ ion and [Mo7O24]6− polyoxoanion, a 3D supramolecular complex 3 based on [Co2(L2)2(H2O)4]4+ binuclear units and [β-Mo8O26]4− anions was constructed, while complex 4 shows a 2D supramolecular network based on a 1D [Ni2(L3)2(H2O)2(β-Mo8O26)] wave-like chain. The results reveal that the solvents have great effect on the formation of the target MOCs, and the length of ligand plays important role in tuning the diverse architectures of polymolybdate and polymolybdate-based complexes. The electrochemical and photocatalytic properties of the title complexes were studied.

Synthesis, characterization and electroluminescence properties of a new mixed-ligand diorganotin(IV) complex

AbstractA new mixed-ligand diorganotin(IV) complex, [μ-(4-dpe){Me2Sn(cup)2}2] (1), was synthesized by reacting dimethyltin(IV) dichloride with 1,2-di(4-pyridyl)ethylene (4-dpe) and ammonium N-Nitroso-N-phenylhydroxylamine (cup). The prepared complex was fully characterized by PXRD,1H,13C and119Sn NMR, IR, and UV spectra and elemental analysis (CHN). The structural analysis of complex1by X-ray diffraction showed that this compound consists of centrosymmetric binuclear units that crystallize in the monoclinic system with the space group ofP21/c. Thermal behavior of this complex was interrogated by thermogravimetric and differential thermal analysis (TGA and DTA) under air atmosphere. The study of thermal behavior and luminescence properties of prepared diorganotin(IV) complex exhibited that this complex can be used as a emitting layer in the preparation of optical devices. The prepared coordination compound was used in two different concentrations in the manufacture of two light-emitting diodes (OLEDs).

Synthesis, crystal structure and biological properties of two Cu(II) complexes based on 1-(benzotriazole-1-methyl)-1-(2-ethylimidazole)

Two Cu(II) metal complexes, {[Cu(bmem)(CH3OH)(CH3O)](ClO4)}n (1) and {[Cu(bmem)(CH3O)(SCN)](CH3OH)0.75}n (2) based on 1-(benzotriazole-1-methyl) -1-(2-ethylimidazole) (bmem) were synthesized. The X-ray single crystal diffraction analysis reveals that complexes 1 and 2 both display 1D chain structure containing binuclear copper units. Then the ligand and complexes 1 and 2 were examined for hypoglycemic activity against α-amylase and antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and found that two Cu(II) complexes showed more activity than the ligand bmem. Both complexes 1 and 2 have strong inhibitory effects on α-amylase, and the IC50 values of complexes 1 (1.97 mg/mL) and 2 (1.83 mg/mL) are lower than that of acarbose (2.3 mg/mL) and ligand (10.89 mg/mL). The scavenging rates on DPPH radical of complexes 1 (80.46%, 150 μg/mL) and 2 (63.08%, 150 μg/mL) are significantly higher than that of ligand (6.92%, 150 μg/mL). In addition, the fluorescence properties and thermal stability of metal complexes were determined.

Stable Lanthanide-Organic Framework as a Luminescent Probe To Detect Both Histidine and Aspartic Acid in Water.

A three-dimensional metal-organic framework (MOF) {[Eu(L)(H2O)2]·DMF} n (1) (H3L = 2'-nitro-3,4',5-biphenyl tricarboxylic acid) was obtained by hydrothermal methods and was characterized in detail. Compound 1 contains [Eu2] binuclear units, and [Eu2] units are further linked by H3L, forming a three-dimensional structure. Stability tests suggest that compound 1 exhibits high solvent, pH, and thermal stability. Besides, we also explored the influence of pH values in the luminescence emission of 1 which shows that pH has a negligible effect on the luminescence intensity with the range of pH = 3-11. Importantly, luminescent investigations reveal that 1 can selectively detect aspartic acid or histidine among 14 amino acids with good regenerability in water. Meanwhile, the concentration of aspartic acid can be quantitatively determined. We also discuss the mechanism of luminescence quenching and enhancement in detail. Importantly, this Eu-MOF provides a MOF-based luminescence sensor to detect two amino acids for the first time.

Metal-organic frameworks based on magnesium(ii): adsorption and luminescence properties

Two new metal-organic frameworks based on magnesium(ii) ions, [Mg4(bdc)3(dma)6(NO3)2]•DMA (1; bdc is 1,4-benzenedicarboxylate; dma, DMA is N,N-dimethylacetamide) and [Mg3(bpdc)3(nmp)4] (2; bpdc is 4,4´-biphenyldicarboxylate; nmp is N-methylpyrrolidone), were synthesized in DMA or NMP, respectively. According to the single-crystal X-ray diffraction data, compound 1 is built of binuclear carboxylate units {Mg2(O2CR)3}, which were previously not observed in metal-organic frameworks. Compound 2 is based on trinuclear carb oxylate units {Mg3(O2CR)6}. Compound 1 has a layered structure (hcb topology), whereas compound 2 has a distorted three-dimensional cubic structure (pcu topology). The phase purity and chemical identity of the compounds were confirmed by IR spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction. Photoluminescence properties of both compounds are indicative of intraligand charge-transfer transitions of one (for 1) or two (for 2) types. Textural characteristics of an activated sample of 1 were measured by nitrogen and hydrogen adsorption at 77 K and by carbon dioxide adsorption at 195 K.

Crystal structures, thermal decomposition kinetics and thermodynamic properties of lanthanide Ho(III) complex with 2,5-dichlorobenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

The ternary lanthanide Ho(III) complex, [Ho(2,5-DClBA)3(5,5′-DM-2,2′-bipy)]2 (2,5-DClBA=2,5-dichlorobenzoate; 5,5′-DM-2,2′-bipy=5,5′-dimethyl-2,2′-bipyridine) has been successfully synthesized via conventional solution method at room temperature. The complex is characterized by coordination titration analysis, elemental analysis, Infrared spectroscopy and powder X-ray diffraction. In addition, the structure of the complex was characterized by single crystal X-ray diffraction. The results reveal that complex is a binuclear molecular, crystallizing in the triclinic system P ī space group. Each binuclear unit contains two crystallographically independent Ho(III), six 2,5-DClBA and two 5,5′-DM-2,2′-bipy ligands. The binuclear units are assembled into 1D and 2D supramolecular structures by C–H···Cl hydrogen bond and Cl-π interactions. Thermal behavior of the complex was determined by TG-DSC/FTIR techniques. The second thermal decomposition step for complex was calculated by integral iso-conversional nonlinear (NL-INT) method. The value of activation energy E varies slightly with α , indicating that the second decomposition stage of the title complex is single step reaction. Therefore, the improved double equal-double steps method is used to determine the mechanism function of the second thermal decomposition step of the complex. At the same time, the thermodynamic parameters (Δ H ≠ , Δ G ≠ and Δ S ≠ ) and kinetic parameters (activation energy E and the pre-exponential factor A ) of the complex were also calculated. Heat capacity of the complex was measured by a DSC instrument.The experimental molar heat capacity can be fitted to the polynomial equation with the reduced temperature by the means of least square method. Based on the fitted polynomial and thermodynamic equations, the smoothed heat capacity, enthalpy and entropy were calculated.

First transition metal complex containing SMIA− carboxylate ligand: Synthesis, structure and magnetic properties of a new tetranuclear copper complex [Cu4(SMIA)6(phen)4](ClO4)2

The first new carboxylate complex [Cu4(SMIA)6(phen)4](ClO4)2 (1) (SMIA− = Syn-2-Methoxyimino-2-(2-Furyl)-Acetate, phen = phenanthroline) with a rarely puckered-belt tetranuclear skeleton has been synthesized and characterized by EA, FT-IR, UV and X-ray crystallography. Complex 1 is consists of two independent binuclear copper units Cu2(SMIA)3(phen)2 with two different coordination geometric Cu2+ centers bridged by two tridentate carboxylates. The π-π stacking force and CH⋯O hydrogen bonds are involved in the formation of weak intermolecular forces. Studies on the direct-current (dc) and alternating-current (ac) magnetic susceptibilities of 1 demonstrate that the magnetic coupling interactions between Cu2+ centers are overall antiferromagnetic and the compound has the spin glassy behavior. Under the UV light irradiation, the title complex displays high photocatalytic activity for the degradation of methyl orange (MO) and rhodamine B (RB), which is the simulants of organic pollutants in water.

Fluorescence Lifetime Imaging of p-tau Protein in Single Neuron with a Highly Selective Fluorescent Probe.

Hyperphosphorylated tau (p-tau) protein is one of the key markers of Alzheimer's disease (AD). However, a lack of analytical methods for p-tau protein with high selectivity and accuracy is the bottleneck to understand the pathological processes of AD. In the present work, a highly selective fluorescence lifetime imaging microscopic (FLIM) probe (τ-p-tau) was rationally designed and developed for determination of p-tauprotein, in which binuclear zinc units were designed as the recognition groups, and an improved cyanine was synthesized as the dye unit. The FLIM measurement is independent of the concentration of fluorescent probes, irradiation light sources, and measurement environments. Meanwhile, the developed τ-p-tau probe demonstrated strong affinity toward p-tau protein, thus enhancing the selectivity of determination of p-tau protein against Aβ, Aβ fibril, tau, protein kinases, ATP, and so on. The fluorescence lifetime of τ-p-tau probe showed a good linearity with the concentration of p-tau protein from 1.0 to 5.0 μM with a low detection limit of 85.15 ± 0.03 nM. The response time of the present probe for p-tau protein was estimated to be less than 6.2 s. Furthermore, taking the advantages of low toxicity and good biocompatibility, the developed probe was successfully applied to monitor the fluctuation of concentration of p-tau protein by FLIM imaging at single neuron level. It was found that the concentration of p-tau protein inside live neurons obviously changed upon oxidative stress.

Two metal–organic frameworks based on 2,5-thiophenedicarboxylic acid and semi-rigid bis-imidazole ligand: Luminescence, magnetism and electrocatalytic activities

Tuning metal ion from Cd(II) to Co(II) in the presence of 2,5-thiophenedicarboxylic acid (H2tdc) and semi-rigid bis-imidazole ligand 4-bis(1H-imidazol-1-yl-methyl)benzene(bimb), two metal–organic frameworks, [Cd3(bimb)(μ4-tdc)3(DMA)2]·2DMA (1) and [Co2(bimb)(μ2-H2O)(μ3-tdc)2(DMF)2]·H2O (2), have been generated under solvothermal condition. All two frameworks with (412, 63) topology are pillared by bimb ligands, and the difference is that there exist trinuclear cadmium clusters gathered by tdc ligands in the structure of 1, but binuclear cobalt units in 2. Interestingly, with the change of metal ion from Cd(II) to Co(II), compound 1 displays good luminescent property at room temperature, and compound 2 exhibits not only antiferromagnetic interaction, but also electrocatalytic activity toward the oxidation of ascorbic acid.

Synthesis, Structure and In Vitro Anti-gastric Cancer Activity of Two New Mixed-Ligand Cu(II) and Cd(II)-Coordination Polymers

By using a strategy of introducing two organic ligands with different donor groups, two new Cu(II) and Cd(II) coordination polymers (CPs) [Cu3(OH)(pz)3(Hpz)(H2O)(ipa)](H2O)4 (1, Hpz = pyrazol, H2ipa = isophthalic acid) and [Cd(phen)(ndc)](H2O) (2, phen = 1,10-phenanthroline, H2ndc = 1,2-naphthalene dicarboxylic acid) are synthesized and characterized. The molecular structures of the as-prepared CPs were determined by the single crystal X-ray diffraction (SCXRD) studies and their phase purities have been confirmed via the power X-day diffraction analysis (PXRD). The Cu(II)-based complex 1 is composed of trinuclear Cu3(µ3-OH)(pz)3 clusters that extended by the ipa2− ligands into a 1D left-handed helical chain along the c axis. In complex 2, the ndc2− ligands connect with the binuclear Cd2 unit along the c axis to shape a 1D chain-like structure, which is further stacked into a 2D layered network via π–π stacking. The as-prepared two CPs transformed to the nanoscale regime by mechanical grinding to yield nano 1 and nano 2 with excellent water dispersibility, maintaining its crystallinity. In addition, the in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were conducted on the gastric cancer cell line AGS with increasing concentrations of the two nanosized CPs, which reveal their promising anticancer activity.

Production and Characterization of a New Copper(II) Propanoate-Isonicotinamide Adduct Obtained via Slow Evaporation and using Supercritical CO2 as an Antisolvent

A new adduct of isonicotinamide (INA) with copper(II) propanoate [Cu(C3)2] was prepared [Cu2(C3)4(INA)4] using two different methods. This type of compound shows high fungicidal activity. Solvent evaporation from ethanol rendered crystals suitable for single-crystal X-ray diffraction. Furthermore, a new semicontinuous method capable of simultaneous crystallization and micronization of the adduct using supercritical CO2, the supercritical antisolvent technique (SAS), was also assessed. Crystals were characterized using powder X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis coupled with mass spectrometry, scanning electron microscopy, and microelemental analysis. In the adduct, two copper(II) ions are coordinated through two bridging and two chelating carboxylates to the propanoate anions forming approximately a plane. Each metal ion is then coordinated with the pyridine nitrogen of two different INA molecules that behave as monodentate ligands. The amide groups of the INA form H-bonds with other amide and carboxylate groups forming a molecular crystal with a three-dimensional H-bond arrangement of the binuclear units. With the SAS technique, crystals 100-fold smaller than those obtained by slow evaporation were obtained, proving SAS as a suitable method for mixed-ligand complexes preparation with reduced particle size and therefore expected bioavailability enhancement.

Two ultramicroporous metal-organic frameworks assembled from binuclear secondary building units for highly selective CO2/N2 separation.

Two novel metal-organic frameworks [Ni2(μ2-Cl)(BTBA)2·DMF]·Cl·3DMF (JLU-MOF56, BTBA = 3,5-bis(triazol-1-yl)benzoic acid) and [Co2(μ2-Cl)(BTBA)2·DMF]·Cl·3DMF (JLU-MOF57) have been successfully synthesized under solvothermal conditions. Crystallographic analysis indicates that the two compounds with different metal ions are isoreticular and both are constructed from binuclear [M2(μ2-Cl)(COO)2N4] (M = Co, Ni) and a 3-connected hetero-N,O donor ligand. The overall framework possesses a (3,6)-connected dag topology. Furthermore, both of them feature ultramicroporous channels of 3.5 Å× 3.4 Å, which are suitable for adsorbing smaller carbon dioxide (CO2) gas molecules but not larger nitrogen (N2) gas molecules. Therefore, JLU-MOF56 and JLU-MOF57 exhibit good performance for CO2/N2 separation, and are promising materials for gas adsorption and purification.

A bi-nuclear Cu(II)-complex for selective epoxidation of alkenes: Crystal structure, thermal, photoluminescence and cyclic voltammetry

Herein, we report the molecular and supramolecular structure, photoluminescence, redox behavior and product selective catalytic activity of [Cu2(oxalate)(1,10-phen)2Cl2] (where 1,10-phen = 1,10-phenanthroline) synthesized by using hydrophilic oxalate as bridging ligand and the hydrophobic 1,10-phen as the blocker ligand. Structural analysis reveals that this binuclear Cu(II)-complex crystallizes in achiral monoclinic P21/n space group and it has a 3D supramolecular structure. Each Cu-center displays five coordinated distorted square pyramidal geometry. Two such Cu centers are connected by oxalato-bridge to form the bi-nuclear-metal core and two 1,10-phen molecules block the outer periphery of the core and restrains further polymerization. These binuclear metallic units are connected by supramolecular hydrogen bonding and π⋯π interactions to form a 3D supramolecular architecture. The complex is stable up to 230 °C. A reversible redox couple centered at (E1/2) ∼ −27 mV with ΔEp ∼ 206 mV corresponding to the CuII/I couple was detected in the cyclic voltammogram of the complex in acetonitrile. The complex shows emission maxima at 451 and 480 nm upon excitation at 340 nm due to π-π* transition in the aromatic π-rings of 1,10-phenanthroline. Density functional analysis has been performed to explore the molecular structure and character of the orbitals within the complex. Due to the presence of five coordinated Cu-centers, the lewis acidic catalytic activity of the complex has been studied. It exhibits selective oxidation behavior for alkenes in presence of several oxidants. It shows 100% selectivity with 70% conversion for the oxidation of cis-cyclooctene to corresponding epoxide at 50 °C in presence of H2O2 as oxidant in acetonitrile.

Low-dimensional compounds containing cyanido groups. Part XXXV. Structure, spectral, thermal and magnetic properties of a binuclear CuII-biquinoline complex with bridging and terminal dicyanamide ligands.

From the system CuCl2-biq-NaN(CN)2 (biq is 2,2'-biquinoline), the binuclear molecular complex bis(μ-dicyanamido-κ2N1:N5)bis[(2,2'-biquinoline-κ2N,N')(dicyanamido-κN1)copper(II)], [Cu2(C2N3)4(C18H12N2)2] or [Cu2(biq)2(dca)2(μ1,5-dca)2] (1) [dca is dicyanamide, N(CN)2-] was isolated and characterized by crystal structure analysis, and spectral, thermal and magnetic measurements. IR spectroscopy confirmed the presence of the biq and dca ligands in 1. Its solid-state structure consists of discrete centrosymmetric binuclear copper(II) units with double end-to-end dca bridges. Each CuII atom is in a distorted square-pyramidal environment with the equatorial plane formed by two nitrile N atoms from bridging dca groups, one of the two N atoms of the chelate biq molecule and one nitrile N atom from a terminal dca ligand, whereas the second biq N atom occupies the axial position. Thermal decomposition of 1 in an air atmosphere proceeds gradually, with copper(I) cyanide being the final decomposition product. Magnetic measurements revealed the formation of alternating spin chains and a relatively strong exchange interaction within the binuclear units was also confirmed by Broken Symmetry DFT (density functional theory) calculations.

Diverse Lanthanide Coordination Polymers with 3,3'-Dimethylcyclopropane-1,2-dicarboxylate Ligand: Synthesis, Crystal Structure, and Properties.

In an attempt to investigate the influence of many variables on the synthesis of lanthanide coordination polymers (Ln-CPs) assembled from the ligand 3,3-dimethylcyclopropane-1,2-dicarboxylic acid, three different Ln-CPs with formulae [La9(μ4-dcd)12(μ3-O)2(H)]n (1), [Gd4(μ4-dcd)6(H2O)]n (2), and [Gd2(μ3-OH)2(μ3-dcd)(μ2-ac)2(H2O)]n (3) (dcd = 3,3-dimethylcyclopropane-1,2-dicarboxylate, ac = acetate) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, thermal analysis, powder X-ray diffraction, and single X-ray diffraction techniques. 1 represents the first report of the three-dimensional (3D) Ln-CPs based on nonanuclear lanthanide clusters, although it shows extremely low gas uptakes. 2 exhibits one of the previously reported 3D lanthanide wheel cluster-like frameworks. 3 characterizes a novel one-dimensional ladder-like chain [Gd4(OH)4]n decorated with mixed ligand ribbons. Variable-temperature magnetic susceptibility measurement reveals that the shortest Gd···Gd distance in 3 induces the antiferromagnetic interactions between adjacent Gd3+ cations within the hydroxyl-bridged binuclear unit. Remarkably, magnetic investigation for 2 indicates a unique metamagnetic transition from the antiferromagnet to ferromagnet. Furthermore, magnetic studies for 2 also exhibit the presence of significant magnetocaloric effect with a large magnetic entropy change.

An unusual 2, 12-connected 3-D open framework based on {As2Mo6O26}-type polyoxometallate and copper-pyrazole complex

An unusual 3-D organic-inorganic hybrid based on arsenomolybdate, [{CuI(pyr)2}6(As2Mo6O26)]·H2O (1) (pyr = pyrazole) has been synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR, TG, PXRD, UV–vis, and single-crystal X-ray diffraction. In compound 1, basic structural unit {As2Mo6O26} (abbreviated as {As2Mo6}) as dodeca-dentate ligand utilizes all of its terminal oxygen atoms (12) of {Mo6O24} ring to connect with 12 {Cu(pyr)2} linkers at its periphery. Two {Cu(pyr)2} complexes are bonded together to form binuclear complex unit {Cu2(pyr)4} via sharing two u3-O atoms, which can be viewed as bidentate linker to further connect with adjacent two {As2Mo6} clusters. The coordination number and modes of {As2Mo6} cluster and Cu+ ions together result in a 2, 12-connected 3D open-skeleton with a new {26·448·612}{2}6 topology, which represents the highest connection of {As2Mo6}-based inorganic-organic hybrid. Compound 1 exhibits good fluorescent properties in solid state at room temperature and bifunctional electrocatalytic activities for oxidation of ascorbic acid (AA) and reduction of nitrite (NO2−).

A facile route for tuning emission and magnetic properties by controlling lanthanide ions in coordination polymers incorporating mixed aromatic carboxylate ligands

A series of lanthanide coordination polymers, [Ln (Btca) (Pimda)·2H2O]n (Ln = Nd(1), Sm(2), Eu(3), Gd(4), Tb(5), Dy(6)), (HBtca = 1H-benzo[d][1, 2, 3]triazole-5-carboxylic acid and H3Pimda = 2-propyl-1H-imidazole-4,5-dicarboxylic acid) have been obtained through moderate temperature hydrothermal syntheses. Single crystal X-ray analyses reveal the family of polymers exhibit same 1D chains composed by binuclear units, and further being extended into 2D layer connected by H3Pimda. The 2D layers are further interlinked by strong intermolecular hydrogen bonds interactions, resulting in the 3D supramolecular architectures. The solid state of 4 shows ligand based fluorescence, while 1, 2, 3, 5 and 6 exhibit strong/moderate photoluminescence emissions in the NIR/visible regions based on characteristic Ln3+ emission selected. Importantly, by in situ doping different concentrations of Eu3+ and Tb3+ cations, series of Eu3+/Tb3+ binary polymers were fabricated, showing a tunable emission color from green, yellow, orange to red. Moreover, the magnetic studies reveal the presence of very weak ferromagnetic Gd···Gd coupling within the binuclear units of 4. The depopulation of Stark components at low temperature and possible weak anti-ferromagnetic interactions were observed within polymers 2 and 5. Remarkably, ac magnetic susceptibility study reveals the Dy3+ polymer is a candidate for elucidation of slow relaxation of the magnetization in lanthanide carboxylate system.

Two Novel Binuclear Lanthanide Complexes with 2,5‐Dichlorobenzoic Acid and 5,5’‐Dimethyl‐2,2’‐bipyridine: Crystal Structures, Luminescence and Thermal Properties

AbstractTwo novel binuclear lanthanide complexes [Ln(2, 5‐DClBA)3(5,5’‐DM‐2,2’‐bipy)(H2O)]2(5,5’‐DM‐2,2’‐bipy) (Ln=Eu(1), Tb(2)); 2,5‐DClBA=2,5‐dichlorobenzoate; 5,5’‐DM‐2,2’‐bipy=5,5’‐dimethyl‐2,2’‐bipyridine) have been successfully synthesized via conventional solution method and then characterized by single‐crystal X‐ray diffraction and elemental analysis. These two binuclear complexes differ from other reported binuclear complexes, because the free neutral ligands are not common in crystal structure. The complexes are isomorphic, which have the same coordination number of eight with a distorted square antiprismatic molecular geometry. The binuclear units feature hydrogen bonding (O−H⋅⋅⋅N and C−H⋅⋅⋅Cl) and π‐π stacking interactions assemble the adjacent molecular units into 1D, 2D and 3D supramolecular novel structures. It is worth noting that the novel 1D supramolecular structure is formed by the hydrogen bonding interaction between the nitrogen atoms of free 5,5’‐DM‐2,2’‐bipy ligand and the oxygen atom of the coordination water molecule. The thermal decomposition mechanism of the two complexes were studied by TG/DSC‐FTIR techniques. Additionally, the luminescence spectra and lifetime have been studied in detail. The results indicate that Eu3+ ion and Tb3+ ion could be sensitized by ligands and thus emitted intense characteristic red and green luminescence, respectively.