Synthesis,spectroscopic, and thermal analyses of trinuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with some sulfa derivatives

New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, ¹H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and ¹H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn₂L¹(AcO)₂(H₂O)₆] (1), [Co₂(L¹)₂(H₂O)₈] (2), [Ni₂L¹(AcO)₂(H₂O)₆] (3), [Mn₃L²(AcO)₃(H₂O)₉] (5), [Co₃L²(AcO)₃(H₂O)₉] · 4H₂O (6), [Ni₃L²(AcO)₃(H₂O)₉] · 7H₂O (7), [Mn₃L³(AcO)₃(H₂O)₆] (9), [Co₂(HL³)₂(H₂O)₈] · 4H₂O (10), [Ni₃L³(AcO)₃(H₂O)₉] (11), [Mn₃L⁴(AcO)₃(H₂O)₉] · H₂O (13), [Co₂(HL⁴)₂(H₂O)₈] · 5H₂O (14), and [Ni₃L⁴(AcO)₃(H₂O)₉] (15) while [Zn₂L¹(AcO)₂(H₂O)₂] (4), [Zn₃L²(AcO)₃(H₂O)₃] · 2H₂O (8), [Zn₃L³(AcO)₃(H₂O)₃] · 3H₂O (12), and [Zn₃L⁴(AcO)₃(H₂O)₃] · 2H₂O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]⁺ and fragments supporting the formulation.     

Synthesis,structures, and urease inhibition of nickel(II), zinc(II), and cobalt(II) complexes with similar hydroxy-rich Schiff bases

Four new nickel(II), zinc(II), and cobalt(II) complexes, [Zn(L¹)₂]?·?H₂O (1), [Ni(L¹)₂]?·?H₂O (2), [Ni(L²)₂] (3), and [Co(L³)₂]?·?H₂O (4), derived from hydroxy-rich Schiff bases 2-{[1-(5-chloro-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL¹), 2-{[1-(2-hydroxy-3-methoxyphenyl)methylidene]amino}-2-ethylpropane-1,3-diol (HL²), and 2-{[1-(5-bromo-2-hydroxyphenyl)methylidene]amino}-2-methylpropane-1,3-diol (HL³) have been synthesized and characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray determination. Each metal in the complexes is six-coordinate in a distorted octahedral coordination. The Schiff bases coordinate to the metal atoms through the imino N, phenolate O, and one hydroxyl O. In the crystal structures of HL¹ and the complexes, molecules are linked through intermolecular O–H···O hydrogen bonds, forming 1-D chains. The urease inhibitory activities of the compounds were evaluated and molecular docking study of the compounds with the Helicobacter pylori urease was performed.     

Supramolecular interactions in high molecular weight bisdithiocarbamate adducts of divalent Zn(II), Cd(II), and Hg(II): spectral,VBS, and single crystal X-ray structural studies on MS4N2 chromophores

This article describes supramolecular interactions induced in a high molecular weight dithiocarbamate, padtc, by its design. Synthesis, spectral studies involving zinc, cadmium and mercury, padtc, and adducts with tmed, such as [Zn(padtc)₂] (1), [Zn(padtc)₂(tmed)]?·?C₆H₅CH_3?·?0.5(H₂O) (2), [Cd(padtc)₂] (3), [Cd(padtc)₂(tmed)]?·?C₆H₅CH₃?·?0.36(H₂O) (4), [Hg(padtc)₂]?·?H₂O (5), [Hg(padtc)₂(2,2′-bipy)]?·?H₂O (6), [Hg(padtc)₂(1,10-phen)]?·?H₂O (7), and [Hg(padtc)₂(oxine)]?·?H₂O (8) (where padtc^??=?N,N′-(iminodiethylene)bisphthalimidedithiocarbamate, 1,10-phen?=?1,10-phenanthroline, tmed?=?tetramethylethylenediamine, 2,2′-bipy?=?2,2′-bipyridine, oxine?=?8-hydroxyquinoline) along with the single crystal X-ray structural analysis of [Zn(padtc)₂(tmed)]?·?C₆H₅CH₃?·?0.5(H₂O) (2) and [Cd(padtc)₂(tmed)]?·?C₆H₅CH₃?·?0.36(H₂O) (4) are reported. All the complexes were characterized by IR, NMR (¹H and ¹³C), and thermogravimetric study. The IR spectra of the complexes show the contribution of the thioureide form to the structures. In ¹³C NMR spectra, the most important thioureide (N¹³CS₂) carbon signals are observed at 210–212?ppm. Single crystal X-ray structural analyses of 2 and 4 show the presence of extensive supramolecular interactions stabilizing the solid-state structure. Both zinc and cadmium are in a distorted octahedral environment with MS₄N₂ chromophores. VBS of Zn and Cd are 1.76 and 1.98, respectively, supporting the correctness of the determined structure and the valence of the central metal ions.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Synthesis,characterization, DNA-binding,and antioxidant activities of four copper(II) complexes containing N-(3-hydroxybenzyl)-amino amide ligands

Four new substituted amino acid ligands, N-(3-hydroxybenzyl)-glycine acid (HL₁), N-(3-hydroxybenzyl)-alanine acid (HL₂), N-(3-hydroxybenzyl)-phenylalanine acid (HL₃), and N-(3-hydroxybenzyl)-leucine acid (HL₄), were synthesized and characterized on the basis of ¹H NMR, IR, ESI-MS, and elemental analyses. The crystal structures of their copper(II) complexes [Cu(L₁)₂]·2H₂O (1), [Cu(L₂)₂(H₂O)] (2), [Cu(L₃)₂(CH₃OH)] (3), and [Cu(L₄)₂(H₂O)]·H₂O (4) were determined by X-ray diffraction analysis. The ligands coordinate with copper(II) through secondary amine and carboxylate in all complexes. In 2, 3, and 4, additional water or methanol coordinates, completing a distorted tetragonal pyramidal coordination geometry around copper. Fluorescence titration spectra, electronic absorption titration spectra, and EB displacement indicate that all the complexes bind to CT-DNA. Intrinsic binding constants of the copper(II) complexes with CT-DNA are 1.32?×?10^6?M^?1, 4.32?×?10^5?M^?1, 5.00?×?10^5?M^?1, and 5.70?×?10^4?M^?1 for 1, 2, 3, and 4, respectively. Antioxidant activities of the compounds have been investigated by spectrophotometric measurements. The results show that the Cu(II) complexes have similar superoxide dismutase activity to that of native Cu, Zn-SOD.     

DNA binding and cleavage activity of reduced amino-acid Schiff base complexes of cobalt(II), copper(II), and cadmium(II)

Three new reduced amino-acid Schiff base complexes, [Co(HL)₂(H₂O)₂] · 4H₂O (1), [Cu(HL)₂(H₂O)₂] · 2H₂O (2), and [Cd(HL)₂(H₂O)₃] · 2H₂O (3), where H₂L is the reduced Schiff-base ligand derived from the condensation of N-(4-hydroxybenzaldehyde) with L-glycine, have been synthesized and characterized by physico-chemical and spectroscopic methods. In these complexes, the two bidentate monoanionic Schiff base ligands coordinate the metal center through the secondary amine N atom and the carboxylate O atom. Water ligands complete a distorted octahedral (1, 2) or a pentagonal bipyramidal coordination geometry (3) around each metal center. The binding interactions of the complexes with CT-DNA have been investigated by UV–visible spectrophotometry and fluorescence quenching methods. The results show that these complexes bind to CT-DNA with an intercalative mode. In addition, DNA cleavage experiments have been also investigated by agarose gel electrophoresis. Complexes 1–3 show oxidative DNA cleavage activity in the presence of H₂O₂/sodium ascorbate and the reactive oxygen species responsible for the DNA cleavage is most likely singlet oxygen. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis,structure, and urease inhibitory activities of Co(III), Mn(II) and Zn(II) complexes with hydrazone derived from protocatechuic acid

[Co^III(L₁)₂·H₂O]NO₃ (1), [Mn^II(L₁)₂·H₂O] (2), and [Zn^II(L₁)₂·H₂O] (3) with a hydrazone derived from protocatechuic acid (HL₁ = C₁₅H₁₃N₃O₃) were designed, synthesized, and characterized by C, H, N elemental analyses, single-crystal X-ray diffraction, and IR spectra, which revealed that the three complexes are similar structures. Docking study has been done. The urease inhibitory activities of the three complexes were tested. Complexes 1 and 3 showed strong inhibitory activity against jack bean urease with IC₅₀ values of 45.9 and 11.64 μM. Complex 2 had no obvious inhibitory activity to urease; the IC₅₀ was > 50 μM.     

Transition metal complexes of 3-acetylpyridine 4 N-(2-pyridyl)thiosemicarbazone (HAPS); structural,spectroscopic, and biological studies

This work examines transition metal ion complexes which have been synthesized from 3-acetylpyridine ⁴ N-(2-pyridyl)thiosemicarbazone (HAPS) (1). [Cu(HAPS)₂Cl₂]?·?H₂O (2), [Hg(HAPS)₂Cl₂] (3), [Ni(HAPS)Cl₂]?·?2H₂O (4), [UO₂(APS)₂]?·?2H₂O (5), [VO(HAPS)₂]SO₄?·?H₂O (6), and [Zn(HAPS)₂Cl₂] (7) were characterized by elemental analysis, spectral (IR, ¹H-NMR, and UV-Vis), magnetic, and molar conductance measurements. The biochemical studies showed that 2 and 3 have powerful and complete degradation on both DNA and protein. Complexes 2, 4, and 7 showed significant antioxidant properties, especially scavenging on superoxide and hydroxyl radicals. The antibacterial screening demonstrated that all studied complexes have maximum and broad range activities against Gram-positive and Gram-negative bacterial strains.     

Synthesis,characterization, and electrochemical study of two new macroacyclic Schiff bases and their copper(II) and zinc(II) complexes

Two new potentially octadentate N₂O₆ Schiff-base ligands 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)phenoxy)phenylimino)methyl)-6-methoxyphenol H₂L¹ and 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)-4-tert-butylphenoxy)phenylimino)methyl)-6-methoxyphenol H₂L² were prepared from the reaction of O-Vaniline with 1,2-bis(2′-aminophenoxy)benzene or 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene, respectively. Reactions of H₂L¹ and H₂L² with copper(II) and zinc(II) salts in methanol in the presence of N(Et)₃ gave neutral [CuL¹]?·?0.5CH₂Cl₂, [CuL²], [ZnL¹]?·?0.5CH₂Cl₂, and [ZnL²] complexes. The complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, ESI–MS spectra, molar conductance (Λ_m), UV-Vis spectra and, in the case of [ZnL¹]?·?0.5CH₂Cl₂ and [ZnL²], with ¹H- and ¹³C-NMR. The crystal structure of [ZnL¹]?·?0.5CH₂Cl₂ has also been determined showing the metal ion in a highly distorted trigonal bipyramidal geometry. The electrochemical behavior of H₂L² and its Cu(II) complex, [CuL²], was studied and the formation constant of [CuL²] was evaluated using cyclic voltammetry. The logarithm value of formation constant of [CuL²] is 21.9.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Three new coordination complexes of cobalt(III), manganese(II), and copper(II) with N,N,O-donor hydrazone ligands: syntheses and structural characterizations

Three new coordination complexes, 2{[Co(L¹)₂]ClO₄} · 0.5CH₃OH (1), [Mn(L²)₂] (2), and [Cu(HL²)(L²)]ClO₄ · 2H₂O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL¹, 2-acetylpyridine-salicyloylhydrazone, and HL², 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV–Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L¹)₂]⁺ units and 2 consists of a neutral [Mn(L²)₂] molecule while 3 consists of a cationic [Cu(HL²)(L²)]⁺ unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.     

Synthesis and characterization of three ionic pairs of Fe(II) and Co(II) complexes with tridentate salicylideneglycine

Three new transition metal complexes, [Fe^II(H₂O)₆][(C₉H₇NO₃)₂Fe^II] · H₂O (1), H[K(H₂O)₃][(C₉H₇NO₃)₂Co^II] · H₂O (2), and [Co^II(H₂O)₆][(C₉H₇NO₃)₂Co^II] · H₂O (3), with salicylideneglycine have been synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectroscopy, and X-ray crystallography. The structure analyses indicate that the tridentate salicylideneglycine binds through aliphatic nitrogen, phenoxy, and carboxylic oxygen in the anion. There are many inter- and intra-molecular hydrogen bonds among lattice water, the anion, and the cation to form a 3-D network. The thermogravimetric analyses and the quantum chemistry calculations of compounds 1, 2, and 3 are also discussed.     

Synthesis,characterization, thermal,and antimicrobial studies of binuclear metal complexes of sulfa-guanidine Schiff bases

A series of metal complexes of Schiff bases derived from condensation of sulfa-guanidine with 1-benzoylacetone (H₂L¹), 2-hydroxybenzophenol (H₂L²), dibenzoylmethane (H₂L³), 5-methylisatine (H₂L⁴), and 1-methylisatine (H₂L⁵) have been synthesized. The complexes are characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, UV–Vis, ¹H NMR, and ESR spectra, as well as thermogravimetric analysis. The low molar conductance values indicate the complexes are nonelectrolytes. IR and ¹H NMR spectra show that H₂L¹–H₂L⁵ are coordinated to metal ions by two bidentate centers. Mn(II), Co(II), Ni(II), and Cu(II) complexes display paramagnetic behavior, whereas the Zn(II)-complex was diamagnetic. All studies confirm the formation of an octahedral geometry for [Cu₂L¹(AcO)₂(H₂O)₆] · 3H₂O (1), [Mn₂L⁴(AcO)₂(H₂O)₆] · 2H₂O (6), [Ni₂L⁴(AcO)₂(H₂O)₆] · 2H₂O (8), a tetrahedral geometry for [Cu₂L²(AcO)₂(H₂O)₂] (2), [Cu₂(L⁴)₂] (4), [Co₂(L⁴)₂] · 2H₂O (7) and [ZnHL⁴(AcO)(H₂O)] · 2H₂O (9) and a trigonal bipyramid geometry for [Cu₂L³(AcO)₂(H₂O)₄] (3) and [Cu₂HL⁵(AcO)₃(H₂O)₃] · H₂O (5). H₂L⁴ was most effective on Gram negative, Gram positive bacteria, and fungi (diameters inhibition zone ranged between 10.5–27.5 mm) after 24 and 48 h, respectively. Complex 8 showed moderate antimicrobial activity. Its minimum inhibitory concentration (MIC) against Escherichia coli, Bacillus subtilis, Candida albicans and Aspargllus flavas was 20 mg L^–1. The compound proved to be of moderate toxicity and its LD₅₀ was 20 mg L^–1.     

Self-assembly of copper(II) complexes with substituted aroylhydrazones and monodentate N-heterocycles: synthesis,structure and properties

Two ternary copper(II) complexes [Cu(L¹)(py)] (1) and [Cu(L²)(Himdz]?·?CH₃OH (2) with substituted aroylhydrazones, 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H₂L¹) and 5-bromo-salicylaldehyde-p-methyl-benzoylhydrazone (H₂L²), pyridine (py) and imidazole (Himdz), have been synthesized. Their crystal structures and spectroscopic properties have been studied. In each complex, the metal is in a square-planar N₂O₂ coordination formed by the phenolate-O, the imine-N and the deprotonated amide-O atoms of L^2?, and the sp²?N atom of the neutral heterocycle. In the solid state, 1 exists as a centrosymmetric dimer due to very weak apical coordination of the metal bound phenolate-O. Complex 2 has no such apical coordination and exists as a monomer. Self-assembly via C–H?···?O, N–H?···?O and O–H?···?N interaction leads to a one-dimensional chain arrangement; other non-covalent interactions such as C–H?···?π and π?···?π are not involved.     

Synthesis,spectroscopic properties,and antimicrobial activity of some new 5-phenylazo-6-aminouracil-vanadyl complexes

Six complexes, [VO(L¹-H)₂]?·?5H₂O (1), [VO(OH)(L^2,3?H)(H₂O)]?·?H₂O (2,3), [VO(OH)(L^4,5?H)(H₂O)]?·?H₂O (4,5), [VO(OH)(L⁶?H)(H₂O)]?·?H₂O (6), were prepared by reacting different derivatives of 5-phenylazo-6-aminouracil ligands with VOSO₄?·?5H₂O. The infrared and ¹H NMR spectra of the complexes have been assigned. Thermogravimetric analyses (TG, DTG) were also carried out. The data agree quite well with the proposed structures and show that the complexes were finally decomposed to the corresponding divanadium pentoxide. The ligands and their vanadyl complexes were screened for antimicrobial activities by the agar-well diffusion technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values for 1–4 and 6 were calculated at 30°C for 24–48?h. The activity data show that the complexes are more potent antimicrobials than the parent ligands.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Coordination compounds of cobalt(II), nickel(II), and copper(II) with 4-(3-hydroxyphenyl)-1,2,4-triazole: Synthesis and study

New Co(II), Ni(II), and Cu(II) complexes with 4-(3-hydroxyphenyl)-1,2,4-triazole (L) with the compositions [Co₃L₆(H₂O)₅(C₂H₅OH)](NO₃)₆ · 2H₂O · C₂H₅OH (I), [Ni₃L₆(H₂O)₆](NO₃)₆ · 2H₂O (II), and [M₃L₆(H₂O)₆](ClO₄)₆ · nH₂O (M = Co2⁺, n = 2 (III); Ni²⁺, n = 2 (IV); Cu²⁺, n = 0 (V)) are synthesized. The complexes are studied by X-ray structure analysis, X-ray diffraction analysis, UV and IR spectroscopy, and the statistical magnetic susceptibility method. All compounds have the linear trinuclear structure. Ligand L is coordinated to the metal ions by the N(1) and N(2) atoms of the heterocycle according to the bidentate bridging mode. In all compounds the coordination polyhedron of the metal atom is a distorted octahedron. The molecular and crystal structures of compound I, [Co₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IIIa), and [Ni₃L₆(H₂O)₆](ClO₄)₆ · 8C₂H₅OH (IVa) are determined.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Synthesis, Spectroscopic and Electrochemical Investigations of Two vic-Dioximes and Their Mononuclear Ni（Ⅱ）, Cu（Ⅱ） and Co（Ⅱ） Metal Complexes Containing Morpholine Group

Two vic-dioxime ligands （LxH2） containing morpholine group have been synthesized from 4-[2-（dimethylaminoethyl）] morpholine with anti-phenylchloroglyoxime or anti-monochloroglyoxime in absolute THF at -15 ℃. Reaction of two vic-dioxime ligands with MCl2·nH2O （M： Ni, Cu or Co and n=2 or 6） salts in 1 ： 2 molar ratio afforded metal complexes of type [M（LxH）2] or [M（LxH）2·2H2O]. All of metal complexes are non-electrolytes as shown by their molar conductivities （Am） in DMF （dimethyl formamide） at 10^-3 mol·L^-1. Structures of the ligands and metal complexes have been solved by elemental analyses, FT-IR, UV-Vis, ^1H NMR and ^13C NMR, magnetic susceptibility measurements, molar conductivity measurements. Furthermore, redox properties of the metal complexes were investigated by cyclic voltammetry.     

Synthesis,crystal structures,and fluorescence properties of (RS)-2-methylglutarato Zn(II), Cd(II) complexes

Reactions of fresh M(OH)₂ (M = Zn²⁺, Cd²⁺) precipitate and (RS)-2-methylglutaric acid (H₂MGL), 2,2′-bipyridine (bipy), or 1,10-phenanthroline (phen) in aqueous solution at 50°C afforded four new metal–organic complexes [Zn₂(bipy)₂(H₂O)₂(MGL)₂] (1), [Zn₂(phen)₂(H₂O)(MGL)₂] (2), [Cd(bipy)(H₂O)(MGL)] · 3H₂O (3), and [Cd(phen)(H₂O)(MGL)] · 2H₂O (4), which were characterized by single crystal X-ray diffraction, IR spectra, TG/DTA analysis as well as fluorescence spectra. In 1, the [Zn(bipy)(H₂O)]²⁺ moieties are linked by R- and S-2-methylglutarate anions to build up the centrosymmetric dinuclear [Zn₂(bipy)₂(H₂O)₂(MGL)₂] molecules. In 2, the 1-D ribbon-like chains [Zn₂(phen)₂(H₂O)(MGL)₂] _n can be visualized as from centrosymmetric dinuclear [Zn₂(phen)₂(H₂O)₂(MGL)₂] units sharing common aqua ligands. Both 3 and 4 exhibit 1-D chains resulting from [Cd(bipy)(H₂O)]²⁺ and [Cd(phen)(H₂O)]²⁺, respectively, bridged alternately by R- and S-2-methylglutarate anions in bis-chelating fashion. The intermolecular and interchain π···π stacking interactions form supramolecular assemblies in 1 and 1-D chains in 2–4 into 2-D layers. The hydrogen bonded lattice H₂O molecules are sandwiched between 2-D layers in 3 and 4. Fluorescence spectra of 1–4 exhibit LLCT π → π* transitions.