Syntheses,Structures, and Properties of Two Zn(II)/Ag(I) Complexes Assembled from Tetracarboxylic Acids and N-Donor Ligands

Two new complexes {[Zn(H₂L)(Bpp)] · H₂O} _n (I) and {[Ag(H₃L)(Bpp)] · 0.25H₂O} _n (II) (H₄L = 5-(2,3-dicarboxy phenoxy) isophthalic acid, Bpp = 1,3-bis(4-pyridyl)propane) were prepared and characterized by single crystal X-ray diffraction (XRD) (CCDC nos. 1578523 (I), 1578529 (II)), element analysis and powder XRD. Compound I showed a one-dimensional chain structure, in which the zinc(II) ion is fourcoordinated with a tetrahedral geometry. Compound II is a 1D chain structure with the H₃L– suspension arms. Complexes I and II are further extended into three-dimensional supramolecular framework via hydrogen bonds and π–π interactions. The solid state luminescent properties of compounds I and II have been investigated.     

Three metal complexes based on tetrazolyl ligands: Hydrothermal syntheses,crystal structures,and fluorescence properties

Three new complexes based on 1-tetrazole-4-imidazole-benzene (Tibz), namely, [Cd(Tibz)₂(H₂O)₂] _n (I), [Mn(Tibz)₂(H₂O)₄] · 2H₂O (II) and [Co(Tibz)₂(H₂O)₄] · 2H₂O (III) have been synthesized through hydrothermal method and structurally characterized by element analyses, IR spectroscopy and single-crystal X-ray diffraction analyses (CIF files CCDC nos. 1443867 (I), 1443868 (II), 1443869 (III)). Single-crystal X-ray diffraction reveals that complex I is a 1D double-chain architecture, II and III are both mononuclear complexes. The results of single-crystal X-ray diffraction analyses indicate that the hydrogen bond and π··· π stacking exist in the complexes, which make great contribution to the stabilities of complexes I–III. The fluorescent properties of these complexes have also been studied in the solid state at room temperature.     

Supramolecular homobimetallic <Emphasis Type="Italic">bis</Emphasis>-diorganotin(IV) complexes of ditopic oxygen nitrogen donor ligand: synthesis,spectroscopic characterization,crystal structure and biological screening

Six new homobimetallic bis-diorganotin(IV) complexes: [Me₂Sn]₂L (1), [Et₂Sn]₂L (2), [n-Bu₂Sn]₂L (3), [Ph₂Sn]₂L (4), [Oct₂Sn]₂L (5) and [n-BuClSn]₂L (6) (H ₄ L=N¹′, N⁶′-bis(2-hydroxybenzylidene)adipodihydrazide) have been synthesized and structurally characterized by means of elemental analysis, mass spectroscopy, FT-IR, NMR (¹H, ¹³C{¹H}, ¹¹⁹Sn) and single-crystal X-ray diffraction. Spectroscopic studies indicate coordination of the ligand to the diorganotin(IV) moieties via iminolic oxygen, nitrogen and phenolic oxygen atoms generating pentacoordinated tin centers. Single-crystal X-ray analysis of (1) revealed homobimetallic nature of complex with dimethyltin moieties oriented in trans-conformation. The ligand is non-planar with each Sn atom in a distorted square pyramidal coordination geometry. Packing diagrams suggest the essential role of C–H^…N and C–H^…O interactions in generating supramolecular assembly. The ligand and complexes were screened for in vitro antimicrobial activity and cytotoxicity. Compound (4) exhibits highest cytotoxicity.     

Four supramolecular transition metal(II) complexes based on triazole-benzoic acid derivatives: crystal structure,Hirshfeld surface analysis,and spectroscopic and thermal properties

Four new complexes [M(3-tba)₂(H₂O)₄] (1–3) and [Co(4-tba)₂(H₂O)₄] (4) {M = Zn (1), Ni (2), Co (3), 3-Htba = 3-(1H-1,2,4-triazol-1-yl)benzoic acid, 4-Htba = 4-(1H-1,2,4-triazol-1-yl)benzoic acid} have been synthesized under solvothermal conditions and structurally characterized by single crystal X-ray diffraction. Complexes 1–4 are also determined by elemental analysis, X-ray powder diffraction, IR and electronic spectroscopy. Single crystal X-ray diffraction reveals that complexes 1–3 are isostructural and they crystallize in the orthorhombic space group of Pbca, while complex 4 belongs to triclinic system with Pī space group. Based on different intermolecular hydrogen bonding and π···π stacking interactions, complexes 1–4 further assembled into 3D supramolecular frameworks. Hirshfeld surface analysis was used to further study the intermolecular interactions of the complexes. The thermogravimetric analyses (TGA) reveal that these complexes possess good thermal stability, and the differential scanning calorimetry (DSC) analyses show intense exothermic phenomena in the decomposition processes of triazole groups. Besides, the photoluminescence property of complex 1 in the solid state is also determined.     

Cobalt(III) complexes with biguanide derivatives: Synthesis,structures, and antiviral activity

Three Co(III) complexes with biguanide derivatives [Co(NH₂C(=NH)NHC(=NH)NR¹R²)₃]Cl₃ (R¹R² = Me₂ (I), Et₂ (II), and H^sBu (III)) were obtained and characterized by elemental analysis, IR spectroscopy, and electronic absorption spectroscopy. Structure III was confirmed by X-ray diffraction (CIF file CCDC no. 1401783). Complexes I–III and [M(SC(NH₂)₂)₄]Cl₂ (M = Pd, Pt, and [Co(En)₃]Cl₃) were tested for in vitro antiviral activity against the A/California/07/09 (H1N1pdm09) influenza virus. The best results were achieved with complex III and both thiourea complexes.     

New complexes of Ni(II) and Cu(II) with tridentate ONO Schiff base ligand: synthesis,crystal structures,electrochemical and theoretical investigation

In this research, we prepared a new series of the Cu(II) (1) and Ni(II) (2) metal complexes of a tridentate Schiff base ligand, (E)-2-(5-bromo-2-hydroxybenzylideneamino) phenol (H₂L). These complexes were characterized by elemental analysis, FT-IR, UV–Vis, and ¹H-NMR spectroscopy. The crystal structures of (1) and (2) were determined by X-ray diffraction studies. The single crystal X-ray diffraction analyses revealed that copper(II) cation is five-coordinated and the coordination polyhedron is a slightly distorted square pyramid. Nickel(II), on the other hand, is four-coordinated, and has a regular, square planar geometry. Further discussed were the electrochemical reduction of these complexes. We also analyzed the nature of the metal–ligand bond in the complexes through NBO and EDA analysis. Besides, vibrational sample magnetometer (VSM) revealed complex (1) was ferromagnetic.     

Syntheses,structures and catalytic activities of molybdenum carbonyl complexes based on pyridine-imine ligands

Thermal treatment of pyridine imines [C₅H₄N-2-C(H)=N-C₆H₄-R] [R = H (1), CH₃ (2), OMe (3), CF₃ (4), Cl (5), Br (6)] with Mo(CO)₆ in refluxing toluene provided six novel mononuclear molybdenum carbonyl complexes of the type [(η²-2-C₅H₄N)CH=N(C₆H₄-4-R)]Mo(CO)₄ [R = H (7); CH₃ (8); OMe (9); CF₃ (10); Cl (11); Br (12)]. All of these complexes were separated by chromatography and fully characterized by elemental analysis, IR, and NMR spectroscopy. The crystal structures of complexes 7, 8 and 10 were determined by X-ray crystal diffraction analysis. In addition, the catalytic performance of these complexes was also tested, and it was found that these complexes had obvious catalytic activity on Friedel–Crafts reactions of aromatic compounds with a variety of acylation reagents.     

Synthesis,characterization, crystal structures,and antibacterial activity of oxidovanadium(V) complexes with mixed ligands

Two new oxidovanadium(V) complexes, [VO(L)(Ehp)] (I) and [VO(L)(Aha)] (II), where L is the dianionic form of 4-bromo-N'-(4-oxopentan-2-ylidene)benzohydrazide (H₂L), Ehp is the monoanionic form of 2-ethyl-3-hydroxy-4H-pyran-4-one (HEhp), and Aha is the monoanionic form of acetohydroxamic acid (HAha), were prepared and characterized by elemental analysis, infrared and electronic spectra, and ¹H NMR spectra. Structures of the complexes were further confirmed by single crystal X-ray diffraction (CIF files CCDC nos. 1477847 (I), 1477850 (II)). H2L coordinates to the V atom through the two enolic O atoms and the imino N atom. The ligands Ehp and Aha coordinate to the V atoms through bidentate OO donor set. The V atoms of the complexes are in octahedral coordination, with the oxo group furnished the octahedral geometry. The complexes show effective antibacterial activity against Bacillus subtilis.     

Mono- and dinuclear vanadium complexes with the pentadentate schiff base 2,6-diacetylpyridine bis(nicotinylhydrazone): Synthesis and structures

A reaction between VOSO₄, 2,6-diacetylpyridine, and nicotinohydrazide in a molar ratio of 1: 1: 2 afforded two complexes differing in both color and crystal shape as well as in chemical composition and molecular structure. The compositions and structures of the vanadium complexes were determined by IR spectroscopy and X-ray diffraction (CIF files CCDC_nos. 1411235 (I) and 1411236 (II)). These complexes can be formulated as [V ₂ ^II (H₂L)₂](NO₃)₄ ? H₂O (I) and [V^IV(=O)(H₂L)(SO₄)] ? 5H₂O (II), where H₂L is 2,6-diacetylpyridine bis(nicotinylhydrazone). Complex I consists of centrosymmetric dinuclear complex cations [V₂(H₂L)₂]⁴⁺, NO ₃ ^- anions, and crystal water molecules in a ratio of 1: 4: 1; complex II is built from molecular V(IV) complexes and crystal water molecules in a ratio of 1: 5. The coordination polyhedron of the metal atom in I is a tetragonal pyramid made up of the electron-donating atoms N₃O₂ of two ligands H₂L. The coordination polyhedron of the metal atom in II is a pentagonal bipyramid made up of the electron-donating atoms N₃O₂ of one neutral five-coordinate ligand H₂L and two O atoms coming from the oxo ligand and the SO ₄ ^2- anion coordinated in a monodentate fashion.     

Two new palladium and platinum complexes with a bidentate pyrazole-based ligand: crystal structure,fluorescence and Hirshfeld surface analysis

Two new precious metal coordination complexes [Pd(HL)₂] (1) and [PtL₂] (2) (where H₂L is 1-(carboxymethyl)-1H-pyrazole-3-carboxylic acid) were synthesized by one-pot in situ hydrolysis. The complexes are assembled into a 3D structure by hydrogen bonding interactions and intermolecular contacts. The structures have been established by single-crystal X-ray diffraction, and characterized by FT-IR and liquid state fluorescent spectroscopy. Hirshfeld surface analysis reveals that the O···H contacts outnumber the other contacts in both structures (49.4 % of the total interactions for 1 and 41.6 % for 2).     

Tuning the regioselectivity of (benzimidazolylmethyl)amine palladium(II) complexes in the methoxycarbonylation of hexenes and octenes

Reactions of N-(1H-benzoimidazol-2-ylmethyl-2-methoxy)aniline (L1) and N-(1H-benzoimidazol-2-ylmethyl-2-bromo)aniline (L2) with p-TsOH, Pd(AOc)₂ and two equivalents of PPh₃ or PCy₃ produced the corresponding palladium complexes, [Pd(L1)(OTs)(PPh₃)] (1), [Pd(L2)(OTs)(PPh₃)] (2) and [Pd(L1)(OTs)(PCy₃)] (3), respectively, in good yields. The new palladium complexes 1–3 and the previously reported complexes [Pd(L1)ClMe] (4) and [Pd(L2)ClMe] (5) gave active catalysts in the methoxycarbonylation of terminal and internal olefins to produce branched and linear esters. The effects of complex structure, nature of phosphine derivative, acid promoter and alkene substrate on the catalytic activities and selectivity have been studied and are herein reported.     

Influence of methyl group position in bipyridine ligand on structure and luminescence of related zinc(II) nitrate complexes

Three new zinc(II) complexes of [Zn(6-mbipy)(η²-NO₃)₂] (1), [Zn(6,6′-dmbipy)(η²-NO₃)₂] (2) and [Zn(5,5′-dmbipy)(η²–NO₃)(H₂O)₂](NO₃).H₂O (3) were prepared from the reaction of 6-methyl-2,2′-bipyridine (6-mbipy), 6,6′-dimethyl-2,2′-bipyridine (6,6′-dmbipy) and 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) with Zn(NO₃)₂·4H₂O in methanol, respectively. These three complexes were thoroughly characterized by elemental analysis, thermal gravimetric analysis, differential thermal analysis, infrared, UV–Vis, ¹H NMR and ¹³C{¹H} NMR spectroscopy, and their structures have all been determined by the single-crystal X-ray diffraction. The luminescence spectra of the title complexes show that the intensity of their emission bands is stronger than the bands for the free ligands.     

Supramolecular assembly of three Ag(I) coordination polymers derived from flexible N-containing ligands and polycarboxylates: synthesis,structures, and catalytic properties

Three Ag(I) coordination polymers [Ag(L1)]·(H₃bptc)·H₂O (1), [Ag₂(L2)(oba)]·H₂O (2), and [Ag₂(L2)₂]·(H₂bptc) (3) [L1 = 1,4-bis(3,5-dimethylpyrazole)butane, L2 = 1,4-bis(2-methylbenzimidazole)butane, H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, H₂oba = 4,4′-oxybis(benzoic acid)] constructed from N-containing ligands with different flexibilities and organic carboxylates as co-ligands have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. All three complexes display 1D chain structures, which are further extended into 2D supramolecular networks via non-classical C–H···O hydrogen bonding interactions. The fluorescence and catalytic properties of the complexes 1–3 have been investigated in detail. Complexes 2 and 3 reveal promising catalytic activities for the degradation of methyl orange in a Fenton-like process.     

Two new cadmium(II) coordination polymers with bis(benzimidazole) ligands

Two new cadmium(II) coordination polymers, {[Cd(L1)(tbta)]·H₂O} _n (1) and [Cd(L2)(tbta)] _n (2) (L1 = 1,4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₂tbta = tetrabromoterephthalic acid and L2 = 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene) are obtained under hydrothermal conditions and structurally characterized by single crystal X-ray diffraction methods, IR spectroscopy, TGA and elemental analysis. The L1 and L2 ligands differ by subtle variation of substituents at semi-rigid bis(benzimidazole) bakcbones. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6⁶ topology. Complex 2 displays a 2D {4⁴.6²} sql/Shubnikov tetragonal plane network. Complexes 1 and 2 possess high thermal stabilities and promising fluorescence behavior in the solid state.     

Copper complexes of pyridyl–tetrazole ligands with pendant amide and hydrazide arms: synthesis,characterization, DNA-binding and antioxidant properties

Pyridyl–tetrazole ligands 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetamide (L1), 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetamide (L2), 2-(5-(pyridin-2-yl)-1H-tetrazol-1-yl)acetohydrazide (L3) and 2-(5-(pyridin-2-yl)-2H-tetrazol-2-yl)acetohydrazide (L4) have been prepared and coordinated with CuCl₂·2H₂O to furnish the corresponding complexes [Cu(L1) ₂ ]–[Cu(L4) ₂ ]. EPR spectra of the complexes are characteristic of square planar geometries, with nuclear hyperfine spin 3/2. DNA-binding studies using UV–Vis absorption spectroscopy, viscosity and thermal denature studies revealed that all of these complexes are avid binders of calf thymus DNA. The antioxidant properties of the free ligands and the Cu(II) complexes were investigated using the p-nitrosodimethyl aniline hydroxyl radical scavenging method, and [Cu(L4) ₂ ] was found to show the highest activity.     

Synthesis and crystal structure of (1<Emphasis Type="Italic">H</Emphasis>-Benzo[<Emphasis Type="Italic">d</Emphasis>]imidazol-2-yl)(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)methanone (L). complex formation of copper(II) and cobalt(II) chlorides with L

(1H-Benzo[d]imidazol-2-yl)(3,3-dimethyl-3,4-dihydroisoquinolin-1-yl)methanone (L) and its complexes with copper and cobalt chlorides [CuLCl₂] (I) and [CoLCl₂] (II) are synthesized and studied by IR spectroscopy. The structure of molecule L is determined by X-ray diffraction analysis. Molecule L crystallizes as a cis-trans isomer. The dihydroisoquinoline (A) and benzimidazole (B) fragments lie in the mutually perpendicular planes. The N-C bond lengths of fragment A (double bond N(1)-C(1) 1.278(3) Å, ordinary bond N(1)-C(9) 1.490(3) Å) differ noticeably. The N-C bond lengths in fragment B range from 1.327(4) to 1.389(4) Å. The C=O bond is 1.218(3) Å According to the data of IR spectroscopy and X-ray diffraction analysis, complexes I and II are assumed to have different structures with different coordination modes to the metal atom of molecule L: through the imine atoms N(1) and N(2) of fragments A and B in I and through the N(1) atom of the dihydroisoquinoline fragment and the O atom of the carbonyl group in II.     

Syntheses,crystal structures,and properties of two supramolecules based on methoxyphenyl imidazole dicarboxylates

Two cobalt(II) and cadmium(II) complexes, [Co(H₂DMOPhIDC)₂(H₂O)₂] ? 2H₂O (H₃DMOPhIDC = 2-(3,4-dimethoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid) (I), [Cd(H₂MOPhIDC)₂-(Phen)] ? C₂H₅OH (H₃MOPhIDC = 2-(3-dimethoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid, Phen = 1,10-phenanthroline) (II), have been hydro(solvo)thermally synthesized by employing two kinds of organic ligands, H₃DMOPhIDC or H₃MOPhIDC, respectively. The molecular structures of I and II have been characterized by IR spectra, elemental analyses and single-crystal X-ray diffraction (CIF files CCDC nos. 935845 (I), 935846 (II)). Both complexes show three-dimensional supramolecular structures supported by intermolecular H-bonds. Furthermore, the thermogravimetric and photoluminescent properties of two complexes have been investigated as well.     

Synthesis characterization,crystal structures,and antibacterial activity of 8-hydroxyquinoline-coordinated oxidovanadium(V) complexes with tridentate hydrazone ligands

Two new oxidovanadium(V) complexes, [VO(L¹)(L)] (I) and [VO(L²)(L)] (II), where L¹ and L² are the dianionic form of N'-(2-hydroxy-5-methoxybenzylidene)pivalohydrazide (H₂L¹) and N'-(2-hydroxy-3-methoxybenzylidene)pivalohydrazide (H₂L²), respectively, and L is the monoanionic form of 8-hydroxyquinoline (HL), were prepared and characterized by elemental analysis, infrared and electronic spectra, and ¹H NMR spectra. Structures of the complexes were further confirmed by single crystal X-ray determination (CIF files CCDC nos. 1477854 (I), 1477856 (II)). H₂L¹ and H₂L² coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. 8-Hydroxyquinoline coordinates to the V atoms through bidentate ON donor set. The V atoms of the complexes are in octahedral coordination with the oxo group furnished the octahedral geometry. The complexes show effective antibacterial activity against Bacillus subtilis.     

Ring-opening polymerization of ε-caprolactone catalysed by (pyridyl)benzoazole Zn(II) and Cu(II) complexes

This paper describes the synthesis of (pyridyl)benzoazole Zn(II) and Cu(II) complexes and their applications as catalysts in ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). Reactions of 2-(3-pyridyl)-1H-benzimidazole (L1), 2-(2-pyridyl)-1H-benzothiazole (L2) and 2-(2-pyridyl)-1H-benzimidazole (L3) with Zn(II) and Cu(II) acetates produced the corresponding complexes; [Zn₂(L1)₂(OAc)₄)] (1), [Cu₂(L1)₂(OAc)₄] (2), [Zn(L2)(OAc)₂)] (3), [Zn(L3)(OAc)₂)] (4) and [Cu(L3), (OAc)₂)] (5). Molecular structures of complexes 2 and 5a revealed that while L1 adopts a monodentate binding mode, through the pyridyl nitrogen atom, L3 exhibits a bidentate coordination mode. All the complexes formed active catalysts in the ROP of ε-CL to afford moderate molecular weight polymers. The kinetics of the ROP reactions of ε-CL were pseudo-first-order with respect to monomer and catalysts.     

Three New Cadmium Complexes Based on 3-Nitrophthalic Acid: Syntheses,Crystal Structures and Fluorescent Properties

Three metal–organic coordinate complexes based on 3-nitrophthalic acid (H₂NPA), namely Cd₂(H₂O)(OH)₂(NPA) (1), Cd₂(Im)₄(NPA)₂ (2) and Cd₂(Bim)₄(H₂O)(NPA)₂ (3) (Im = imidazole, Bim = benzimidazole), have been obtained by hydrothermal method and characterized by X-ray single crystal structure determination. Structural analysis reveals that complex 1 exhibits 2D layers constructed by polyhedral aggregates. Complex 2 exhibits a dinuclear cadmium structural unit and assembles by hydrogen bonds into a 2D supramolecular architecture. Complex 3 is assembled by NPA^2? into layers of a (3,4)-connected dinodal net topology of (4·5₂)(4·5₃·7₂). The fluorescent properties of complexes 1–3 have been investigated.