Synthesis,Crystal Structure,and Photocatalytic Properties of a Zinc(II) Coordination Polymer Based on 3‐Hydroxy‐2‐pyridinecarboxylic Acid

The zinc(II) compound, [Zn₃(HL)₆]_n ( 1 ) (H₂L = 3‐hydroxypyridine‐2‐carboxylic acid) was synthesized by a solvothermal reaction of Zn(NO₃)₂ · 6H₂O and 3‐hydroxypyridine‐2‐carboxylic acid as raw materials. The structure of complex 1 was determined by single‐crystal X‐ray diffraction analysis and further characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, as well as powder X‐ray diffraction. X‐ray structure analysis demonstrates that the complex crystallizes in the monoclinic system, space group P2₁/n. There are three zinc ions in the asymmetric unit, which are either five‐coordinate or six‐coordinate. The asymmetric units are further bridged by the carboxylate of the organic ligands, featuring a 2D framework. The solid state diffuse‐reflectance UV/Vis spectra reveals that complex 1 has semiconducting nature with the energy bandgap (E_g) estimated to be 3.11 eV. The photocatalytic properties of complex 1 in degradation of organic dyes were further investigated. Results showed that the complex could degrade 54 % of the dye methylene blue solution within 120 min under UV irradiation light and reused for five times without the decline of the photocatalytic activity.     

Synthesis,crystal structure,and photophysical properties of a double open cubane-like Cd(II) complex based on 2-substituted-8-hydroxyquinoline

A 2-substituted-8-hydroxyquinoline (E)-2-[2-(3-thienyl)ethenyl]-8-quinolinol (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a tetranuclear complex [Cd₄L₆Br₂]·6DMF (1) was fabricated by assembly of Cd(II) with HL. X-ray structural analysis shows that 1 exhibits a double open cubane-like core structure, which is bridged by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 1 features a 3-D porous solid constructed by aromatic stacking interactions, C–H···π interactions and C–H···O hydrogen bonds. The assembly of cadmium salts and HL in solution was investigated by UV–vis and photoluminescence. We also studied the thermal stability and photophysical properties (fluorescent emission, lifetime, and quantum yield) of 1. The results show that 1 emits yellow luminescence in the solid state.     

Interactions of hexamethyltetrabutyl-substituted biladiene-a,c with cobalt(II) and zinc(II) acetates

The thermodynamics of the reaction of 1,3,7,13,17,19-hexamethyl-2,8,12,18-tetrabutylbiladiene-a,c (H₂L) with cobalt(II) and zinc(II) acetates in dimethylformamide (298.15 K) was studied by spectrophotometric and calorimetric titration. It was found that H2L and Zn(II) form a mononuclear complex ZnL, and in the case of Co(II), a binuclear biligand complex Co₂L₂ is formed. Thermodynamic characteristics of the formation of Co(II) and Zn(II) complexes with biladiene-a,c in DMF at 298.15 K were determined.     

Synthesis,characterization, and crystal structures of cobalt(II), copper(II), and zinc(II) complexes of a bidentate iminophenol

A bidentate iminophenol (HL = 2-((4-methoxyphenylimino)methyl)-4,6-di-tert-butylphenol derived from condensation of 4-methoxyaniline and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) was mixed with divalent metal salts to form the corresponding mononuclear metal complexes [M^II(L)₂] (M = Co (1), Cu (2), and Zn (3)). The complexes are characterized by different spectroscopic and analytical tools. X-ray crystal structures of the complexes revealed homoleptic mononuclear complexes with MN₂O₂ coordination. The cobalt(II) (1) and zinc(II) (3) complexes display a pseudo-tetrahedral coordination geometry, whereas the copper(II) complex (2) exhibits a distorted square-planar coordination. The zinc(II) complex (3) emits at 460 nm with a twofold enhancement of emission with respect to the free iminophenol.     

Tetrazolate bridged dinuclear photo-luminescent zinc(II) Schiff base complex prepared via 1,3-dipolar cycloaddition at ambient condition

A bis(μ-NN′-tetrazolate)-bridged centrosymmetric dinuclear zinc(II) Schiff base complex, [Zn₂(L)₂(PZTZ)₂] (HL is a tridentate Schiff base, 2-(2-(dimethylamino)ethyliminomethyl)-6-ethoxyphenol and HPZTZ is 2-pyrazinyltetrazole), has been synthesized via [3 + 2] cycloaddition of 2-cyanopyrazine and sodium azide in the presence of zinc(II) acetate dihydrate and HL. The structure of the complex is confirmed by single-crystal X-ray diffraction analysis. The complex shows fluorescence.     

Structure of Methanol Solvated Iodozinc(II) Complexes in Solution

The structures of the solvated zinc ion and the solvated zinc–iodide complexes in methanol solution have been determined by EXAFS. The zinc ion is six-coordinated in an octahedral fashion with a mean Zn–O bond distance of 2.071(4) Å. According to the stability constants of the zinc–iodide system in methanol solution the first complex, ZnI⁺, is suppressed, which may indicate that a coordination change takes place at this step. On the other hand, the second complex, ZnI₂, predominates at excess of iodide. The methanol solvated ZnI₂ complex has a tetrahedral structure with mean Zn–I and Zn–O bond distances of 2.55(1) and 1.99(1) Å, respectively. The mean Zn–I bond distance in a solution containing a maximal content of ZnI⁺, ca. 12%, strongly indicates that the first complex also has a tetrahedral structure.     

Formation of Zinc(II) and Cadmium(II) Complexes with Pyridine Oxime Ligands in Aqueous Solution

Complex formation equilibria involving pyridine-2-carboxaldehyde oxime (1), 1-(2-pyridinyl)ethanone oxime (2) and 6-methylpyridine-2-carboxaldehyde oxime (3), HL, with zinc(II) and cadmium(II) ions were studied in aqueous 0.1 M NaCl solution at 25° C by potentiometric titrations with a glass electrode. Experimental data were analysed with the least-squares computer program SUPERQUAD to determine the complexes formed and their stability constants. With Ligands 1 and 2 the sets of complexes for Zn(II) and Cd(II) are essentially the same, mono- and dinuclear oxime complexes and their deprotonated/hydrolysed products H_pM_q(HL)^2q+p _r. Owing to the steric requirements of the 6-methyl group, sets of complexes formed with 3 are distinctly different. For zinc(II), only dinuclear oximato species H_pZn₂(HL)^4q+p ₂ ( p = ? 2, ? 3, ? 4) are found, while for the larger cadmium(II) ion mononuclear oximato species CdL⁺ and CdL₂ are detected in addition to the dinuclear complex H_pCd₂(HL)^4q+p ₂ ( p = ? 3).     

A zinc(II) amidine complex: tandem synthesis,structure, and self assembly

A five-coordinate zinc(II) amidine complex, [Zn(DEP)(N₃)₂] (DEP = N′-(2-(diethylamino)ethyl)picolinamidine), has been synthesized with 2-cyanopyridine and sodium azide in the presence of zinc(II) acetate dihydrate. The structure of the complex is confirmed by single-crystal X-ray diffraction analysis. The complex crystallizes in triclinic space group P-1 with cell dimensions a = 7.486(5) Å, b = 7.678(5) Å, c = 14.480(5) Å, α?=?96.697(5)°, β = 90.282(5)°, and γ?=?95.716(5)°. The hydrogen bonding interactions in the complex lead to the formation of a 2-D supramolecular network. The complex shows fluorescence with lifetime ~4 ns.     

Structure and photophysical properties of a dimeric Zn(II) complex based on 8-hydroxyquinoline group containing 2,6-dichlorobenzene unit

A novel 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a dimeric complex (ZnL₂)₂ (1) was fabricated by self-assembly of Zn(II) ions with ligand HL. X-ray structural analysis shows that 1 exhibits a binuclear core, which is bridged by two 8-hydroxyquinoline rings. The supramolecular structure of 1 features a lamellar solid constructed by aromatic stacking interactions, Cl?Cl interactions and nonclassical C–H?Cl hydrogen bonds derived from 2,6-dichlorophenyl group of the ligand HL. The aggregation behavior of zinc salts and HL in solutions was investigated with a variety of techniques, including ¹H NMR, UV–vis, and photoluminescence (PL). In addition, we also studied the photophysical properties of compound 1 by UV–vis and PL. The experimental results show that the complex 1 emits yellow luminescence in the solid state.     

[(bmpyr)2{Zn(OC6H3(NO2)2)4}]: Influence of an Ionic Liquid on Liquid/Liquid Extraction of Metal Ions in a Biphasic System

The compound [(bmpyr)₂{Zn(OR)₄}] (OR = 2,4‐dinitriphenolate) has been prepared from Zn(NO₃)₂·6H₂O and sodium 2,4‐dinitrophenolate in a biphasic aqueous ionic liquid (Butyl‐methyl‐pyrrolidinium trifluoromethylsulfonate [bmpyr][OTf]) system. The presence of the anionic zinc complex in [bmpyr][OTf] is made possible by the exchange of the ionic liquid anions into the aqueous phase for the zinc complex. [(bmpyr)₂{Zn(OR)₄}] was characterized in solution by ¹³C‐ and ¹H‐NMR spectroscopy and in the solid state by crystal structure determination. The zinc complex represents the first type of a zinc complex with more than two phenolate ligands.     

Synthesis,characterization and crystal structures of copper(II), zinc(II) and vanadium(V) complexes,derived from 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide,with antibacterial activity

Three copper(II), zinc(II), and vanadium(V) complexes, [CuL(HL)]ClO₄ (1), [ZnL₂] (2) and [VO₂L] (3), where L is the anionic form of 3-methyl-N′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL), were prepared and characterized by IR, UV–vis and single-crystal X-ray determination. X-ray analysis indicates that the complexes are mononuclear species, with the Cu and Zn ions in 1 and 2 in octahedral coordination, and with the V ion in 3 in trigonal bipyramidal coordination. The hydrazone compound and the three complexes were evaluated for antibacterial activities. The copper complex has effective activities.     

Synthesis, Structure and Biological Activity of Zn（Ⅱ） Complex with Tris（benzimidazol-2-yl-methyl）amine Ligand

A new Zn(II) mononuclear complex with tris(benzimidazol‐2‐yl‐methyl)amine (NTB) was synthesized with stoichiometry of [Zn(NTB)NO₃]NO₃ · DIPY · DMF (DIPY : 4,4′‐dipyridyl). The complex was characterized by elemental analysis, UV and IR spectra. The crystal structure was determined by using X‐ray diffraction analysis. The crystal structure indicates that four N atoms and one O atom coordinate to zinc ion to construct a distorted trigonal‐dipyramid configuration. Three nonprotonated N atoms from imidazole groups are in the equatorial plane, one alkylamino N atom and one O atom from NO₃^?_‐ in the axial directions. The biological activity assay shows that this complex presents certain biological activity by means of pyrogallol autoxidation and it can be called a model compound of superoxide dismutase (SOD).     

A Brønsted‐Ligand‐Based Iron Complex as a Molecular Switch with Five Accessible States

A mononuclear Fe^II complex, prepared with a Brønsted diacid ligand, H₂L (H₂L=2‐[5‐phenyl‐1H‐pyrazole‐3‐yl] 6‐benzimidazole pyridine), shows switchable physical properties and was isolated in five different electronic states. The spin crossover (SCO) complex, [Fe^II(H₂L)₂](BF₄)₂ ( 1_A ), exhibits abrupt spin transition at T_1/2=258 K, and treatment with base yields a deprotonated analogue [Fe^II(HL)₂] ( 1_B ), which shows gradual SCO above 350 K. A range of Fe^III analogues were also characterized. [Fe^III(HL)(H₂L)](BF₄)Cl ( 1_C ) has an S=5/2 spin state, while the deprotonated complexes [Fe^III(L)(HL)], ( 1_D ), and (TEA)[Fe^III(L)₂], ( 1_E ) exist in the low‐spin S=1/2 state. The electronic properties of the five complexes were fully characterized and we demonstrate in situ switching between multiple states in both solution and the solid‐state. The versatility of this simple mononuclear system illustrates how proton donor/acceptor ligands can vastly increase the range of accessible states in switchable molecular devices.     

Zinc–Organic Battery with a Wide Operation‐Temperature Window from −70 to 150 °C

Aqueous zinc (Zn) batteries have been considered as promising candidates for grid‐scale energy storage. However, their cycle stability is generally limited by the structure collapse of cathode materials and dendrite formation coupled with undesired hydrogen evolution on the Zn anode. Herein we propose a zinc–organic battery with a phenanthrenequinone macrocyclic trimer (PQ‐MCT) cathode, a zinc‐foil anode, and a non‐aqueous electrolyte of a N,N‐dimethylformamide (DMF) solution containing Zn²⁺. The non‐aqueous nature of the system and the formation of a Zn²⁺–DMF complex can efficiently eliminate undesired hydrogen evolution and dendrite growth on the Zn anode, respectively. Furthermore, the organic cathode can store Zn²⁺ ions through a reversible coordination reaction with fast kinetics. Therefore, this battery can be cycled 20 000 times with negligible capacity fading. Surprisingly, this battery can even be operated in a wide temperature range from ?70 to 150 °C.     

Zinc–Organic Battery with a Wide Operation-Temperature Window from −70 to 150 °C

Aqueous zinc (Zn) batteries have been considered as promising candidates for grid-scale energy storage. However, their cycle stability is generally limited by the structure collapse of cathode materials and dendrite formation coupled with undesired hydrogen evolution on the Zn anode. Herein we propose a zinc–organic battery with a phenanthrenequinone macrocyclic trimer (PQ-MCT) cathode, a zinc-foil anode, and a non-aqueous electrolyte of a N,N-dimethylformamide (DMF) solution containing Zn²⁺. The non-aqueous nature of the system and the formation of a Zn²⁺–DMF complex can efficiently eliminate undesired hydrogen evolution and dendrite growth on the Zn anode, respectively. Furthermore, the organic cathode can store Zn²⁺ ions through a reversible coordination reaction with fast kinetics. Therefore, this battery can be cycled 20 000 times with negligible capacity fading. Surprisingly, this battery can even be operated in a wide temperature range from −70 to 150 °C.     

Synthesis and characterization of zinc(II) and cobalt(III) Schiff base complexes

Two mononuclear complexes with the Schiff base ligand 2-((2-(dimethylamino)ethylimino)methyl)phenol (HL), namely ZnL₂ and CoL₂(N₃), have been synthesized and characterized using single-crystal X-ray diffraction and spectroscopy (IR, ¹H NMR, UV–Vis, MS and EA). Both complexes are mononuclear. The coordination geometry in the Zn(II) complex is distorted square-pyramidal with a weak Zn···N interaction. The Co(III) complex is distorted octahedral, and the neutral molecule unit [Co^IIIL₂(N₃)] is connected by C–H···N hydrogen bonds to form a one-dimensional infinite chain. The luminescence of the zinc compound has been investigated. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Prevention and mechanism effect of Zn(II) coordination complex on oral implant restoration

In this study, by reaction of Zn(NO₃)₂·6H₂O with HL ligand under a slow evaporation reaction condition, a novel mononuclear Zn(II) complex [Zn(L)₂]·C₂H₅OH (1) with tetrahedral coordination geometry has been created by employment of an adamantan-type Schiff-base ligand 2-(adamantan-1-ylimino)methyl-4-methylphenol (HL). Its application values against the recurrent infection after oral implants were evaluated with ELISA assay and real time RT-PCR assay. The Zn(II) complex toxicity was evaluated in this research with CCK-8 assay. The molecular docking simulation confirmed that the adamantane functional group applied a hindrance effect on the connected nitrogen atom and therefore, the oxygen atom on the hydroxyl functional group could form binding interaction with receptor as expected.     

1-D wave-like chain,twofold 2-D layer,and chiral 3-D open framework based on multidentate ligand: structural diversities,thermal properties,and photoluminescence

From 1-D to 3-D zinc coordination polymers based on multifunctional flexible 4-(1,2,4-triazole-methylene)-benzonitrile (tzbt), {[Zn(tzbt)₂(bdc)]·2H₂O}_n (1), [Zn(tzbc)₂]_n (2), and [Zn(bpdc)(H₂O)]_n (3) (bdc = 1,4-benzenedicarboxylic acid, tzbc = 4-(1,2,4-triazole-methylene)-benzoic acid, bpdc = 4,4′-biphenyldicarboxylic acid), were synthesized under hydrothermal conditions. The tzbt was synthesized by N-alkylation and hydrolyzed in situ to produce tzbc (in 2). Single-crystal X-ray diffraction analysis reveals that 1 displays 1-D wave-like chains based on [Zn(bdc)]_n. 2 is a chiral twofold interpenetrating 2-D architecture constructed with “V”-shaped tzbc. 3 is a 3-D chiral compound constructed from achiral H₂bpdc with right-handed helical chains. 1–3 display stable blue-emitting luminescence with emission maxima ranging from 383 to 410 nm, depending on ligand-centered π*→π transitions. The effects of different polarity solvents and temperature on luminescence are discussed. TGA and VT-XPRD reveal that 2 has thermal stability to 360 °C.     

Solution equilibria of zinc(II) and cadmium(II) complexes with 2,2′-bipyridine in N,N-dimethylacetamide at 25°C

Complexation of zinc(II) and cadmium(II) ions with 2,2-bipyridine (bpy) are studied in N,N-dimethylacetamide (DMA) by calorimetry. Formation constants, enthalpies, and entropies of five mononuclear complexes, [Zn(bpy)_n]²⁺ (n=1–3) and [Cd(bpy)_n]²⁺ (n=1,2), are determined, and compared with the corresponding values in an analogous but less bulky solvent, N,N-dimethylformamide (DMF). The zinc complexes are more stable and the formation is more exothermic in DMA than in DMF, whereas the solvent effect on the cadmium complexes are rather small. A largely positive value of the enthalpy of transfer of Zn²⁺ from DMF to DMA shows that the greater stability of the zinc complexes in DMA is due to the weaker solvation of the metal ion, which is caused by the steric hindrance of DMA molecules. The transfer enthalpies become smaller in the order Zn²⁺>[Zn(bpy)]²⁺>[Zn(bpy)₂]²⁺>[Zn(bpy)₃]²⁺ and dictate gradual relaxation of the steric effect in the complexes. On the other hand, the transfer enthalpies of Cd²⁺ and its complexes are all small, indicating that the hindrance is insignificant in the vicinity of this larger cation.     

Synthesis and characterization of a zinc(II) complex of 1,3-bis(1-benzylbenzimidazol-2-yl)-2-oxopropane

A ligand 1,3-bis(1-benzylbenzimidazol-2-yl)-2-oxopropane (Bobb) and the zinc(II) complex, [Zn(Bobb)₂](picrate)₂ · 2DMF, were synthesized and characterized by elemental analyses, electrical conductivities, IR, and UV. The crystal structures of the ligand and the zinc complex have been determined by single crystal X-ray diffraction. The ligand displays a V-shaped configuration and the Zn(II) cation is six-coordinate by four nitrogens and two oxygens from Bobb. The N₄O₂ donor set is a distorted octahedron.