Jesús Castro

Electrochemical synthesis of nickel(II) complexes of tosylamides: crystal structures of [(4-methylphenyl)sulfonyl]-imino-1H-pyridine], 2,2′-bipyridine bis{[(4-methylphenyl) sulfonyl]-2-pyridyl-amide}nickel(II) and 1,10-phenanthroline bis{[(4-methylphenyl) sulfonyl]-2-pyridyl-amide}nickel(II)

The complex [NiL2] has been synthesised by the electrochemical oxidation of nickel in an acetonitrile solution of [(4-methylphenyl)sulfonyl]-imino-1H-pyridine (HL). When the oxidation was carried out in the presence of neutral ligands L′ (pyridine, 2,2′-bipyridine or 1,10-phenanthroline) the complexes [NiL2py2], [NiL2bipy] and [NiL2phen] were obtained. The crystal structures of [(4-methylphenyl)sulfonyl]-imino-1H-pyridine, 2,2′-bipyridine bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}nickel(II) and 1,10-phenanthroline bis{[(4-methylphenyl) sulfonyl]-2-pyridyl-amide}nickel(II) were determined by X-ray diffraction methods. In the monomeric complexes, the nickel atom is in a distorted octahedral environment defined by the amide and pyridyl nitrogen atoms of the two ligands and the two bipyridine or phenanthroline nitrogen atoms. The vibrational and electronic spectra of the complexes are discussed and are shown to agree with the structures.

Different coordinative behaviour of methyl-substituted 2-pyridylsulfonamide derivatives as ligands in zinc complexes

Abstract Neutral zinc complexes [ZnL2L′] of a series of methyl-substituted N-2-pyridylsulfonamide ligands (HL) and 1,10-phenanthroline or 2,2′-bipyridine (L′) have been synthesised by electrochemical oxidation of anodic zinc metal in an acetonitrile solution of the ligand and the coligand. The compounds obtained have been characterised by microanalysis, IR and 1H NMR spectroscopy, LSI mass spectrometry studies and some of the mixed complexes by single-crystal X-ray diffraction. The crystal structures show different octahedral environments around the metal (N6 or N4O2) depending on the position of the substituent on the pyridine ring.

ELECTROCHEMICAL SYNTHESIS OF MANGANESE(II) COMPLEXES OF PYRIMIDINE-2-THIONES: THE CRYSTAL STRUCTURES OF BIS-4,6-DIMETHYLPYRIMIDYL-2-2'-DISULPHIDE AND 1,10-PHENANTHROLINE-BIS(4,6-DIMETHYLPYRIMIDINE-2-THIOLATO)MANGANESE(II)

Abstract The electrochemical oxidation of anodic manganese in an acetonitrile solution of pyrimidine-2-thione (pymtH) or 4,6-dimethylpyrimidine-2-thione (4,6-Me 2 pymtH) and nitrogen donor bidentate ligands such as 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy), yielded mixed complexes [Mn(pymt) 2 phen], [Mn(4,6-Me 2 pymt) 2 phen] and [Mn(4,6-Me 2 pymt) 2 bipy]. The crystal structures of bis-4,6-dimethylpyrimidyl-2,2′-disulphide and 1,10-phenanthroline-bis-(4,6-dimethylpyrimidine-2-thiolato)manganese(II) have been determined by X-ray diffraction. In the manganese complex the metal has a distorted octahedral trans -MnS 2 N 4 geometry with one nitrogen atom of each pyrimidine ligand uncoordinated.

Syntheses, characterizations, crystal structures, and biological activities of two new mixed ligand Ni(II) and Cu(II) Schiff base complexes

Two mixed-ligand complexes, [Cu(L)(2imi)] (1) and [Ni(L)(2imi)]·MeOH (2) [L = 2-(((5-chloro-2-oxyphenyl)imino)methyl)phenolato) and 2imi = 2-methyl imidazole], have been prepared by the reaction of appropriate metal salts with H2L and 2-methyl imidazole. Their structures were characterized by microanalysis, FT-IR, UV–vis, molar conductivity, and 1H NMR for [Ni(L)(2imi)]·MeOH. The structures were determined using single crystal X-ray diffraction. Each four-coordinate metal center, Cu(II) in 1 and Ni(II) in 2, is surrounded by donors of Schiff base (L2−) and N of 2-methyl imidazole in square planar geometries. α-Amylase activities of these compounds have also been investigated. The experimental data showed that α-amylase was inhibited by Ni(II) complex while the Cu(II) complex causes a 1.3-fold decrease in Km value. Antimicrobial results show that these compounds, especially the Cu(II) complex, have potential for antibacterial activity against Gram negative and Gram positive bacteria and antifungal activity against Aspergillus fumigatus.

Synthesis, characterization, crystal structure, DNA and BSA binding, molecular docking and in vitro anticancer activities of a mononuclear dioxido-uranium(VI) complex derived from a tridentate ONO aroylhydrazone.

A mononuclear dioxido-uranium(IV) complex [UO2(L)(DMSO)2], was prepared from the reaction of (2-hydroxy-3-methoxybenzylidene)benzohydrazide [HL] with UO2(OAc)2·2H2O in DMSO. The obtained complex was fully characterized. Single crystal X-ray diffraction analysis of [UO2(L)(DMSO)2] revealed that U(VI) ion has been coordinated by ONO donor atoms of the dianionic ligand (L(2-)), oxo groups and two DMSO molecules in a pentagonal bipyramid geometry. In addition, interactions of the complex with salmon sperm DNA and bovine serum albumin (BSA) were thoroughly investigated using UV-vis absorption, voltammetry and molecular docking methods. The experimental studies showed an intercalative mode of interaction between the complex and DNA. Experiments on BSA interaction indicated a change in the polarity of the environment surrounded the complex as a result of the interaction between BSA and [UO2(L)(DMSO)2]. Finally, MTT assays indicated that the U(VI) complex had excellent cytotoxicity against human carcinoma cell lines of MCF-7, HPG-2, and HT-29, with IC50 values of 8.4, 10.6 and 10.0μM, respectively.

Synthesis of nickel(II), copper(II), zinc(II), and cadmium(II) complexes of 2-[(2-mercaptophenyl)iminomethyl] pyrrole and 2-[(2-mercaptoethyl)-iminomethyl]pyrrole by the electrochemical cleavage of a disulphide bond: the crystal structure of bis{2-[(pyrrol-2-yl)methyleneamino]thiophenolato-S,N}zinc(II)

The electrochemical oxidation of anodic metal (nickel, copper, zinc, or cadmium) in acetonitrile solutions of the Schiff bases derived from 2-pyrrolecarbaldehyde and bis(2-aminophenyl)disulphide (H2L2) or cysteamine (H2L2′) gives compounds [ML], [ML′] or [Zn(HL)2]. The crystal structure of bis{2-[(pyrrol-2-yl)methyleneamino]thiophenolato}zinc(II) is orthorhombic, space group Pbca with a= 13.764(3), b= 17.819(1), c= 16.593(2)A, and Z= 8. The zinc atom has ZnS2N2 distorted tetrahedral stereochemistry and the pyrrolic nitrogen atoms are not co-ordinated.

Direct electrochemical synthesis of cobalt(II) complexes of tosylamides: crystal structures of [CoL2py2], [CoL2DMF2], [CoL2bipy] and [CoL2phen], L=[(4-methylphenyl)sulfonyl]-2-pyridylamide

Abstract Several complexes with tosylamides were synthesised by the electrochemical oxidation of cobalt in an acetonitrile solution of [(4-methylphenyl)sulfonyl]-imino-1H-pyridine (HL) and the appropriate neutral coligand: L′ (pyridine, 2,2′-bipyridine, 1,10-phenanthroline or N,N-dimethylformamide). The structures of bis-(N,N-dimethylformamide)bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II), bis-(pyridine)bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II), 2,2′-bipyridine bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II) and 1,10-phenanthroline bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cobalt(II) were determined by X-ray diffraction methods. In these monomeric complexes, the cobalt atom is in a distorted octahedral environment. The vibrational and electronic spectra of the complexes are discussed and are shown to agree with the structures.

Synthesis, spectral characterization, structural studies, molecular docking and antimicrobial evaluation of new dioxidouranium(VI) complexes incorporating tetradentate N2O2 Schiff base ligands

Two new uranyl(VI) Schiff base complexes [UO2(L1)(DMSO)] (1), where L1 = N,N′-di(5-bromosalicylidene)-1,2-cyclohexyldiaminate ligand and [UO2(L2)(MeOH)] (2), where L2 = N,N′-di(5-bromosalicylidene)-o-phenylenediaminate ligand, were synthesized and characterized by elemental analysis, 1H NMR, FTIR, UV-vis, fluorescence spectroscopy and molar conductivity measurements. The structure of the H2L1 free ligand and both complexes (1) and (2) were also determined by single crystal X-ray diffraction. According to the results obtained, the title complexes have a distorted pentagonal bipyramidal geometry where positions around the U(VI) centre are occupied by the ONNO donors of the deprotonated dibasic Schiff base ligands (L1 for 1 and L2 for (2)), two oxido groups and the oxygen of coordinated solvent. The antimicrobial activity of ligands and complexes was also screened against Gram positive bacteria Staphylococcus aureus PTCC 1112, Micrococcus luteus PTCC 1110, Bacillus cereus PTCC 1015, Enterococcus faecalis; Gram negative bacteria Pseudomonas aeruginosa PTCC 1214, Escherichia coli PTCC1330, Pseudomonas sp., Klebsiella pneumoniae; and fungus strain (Candida albicans). The molecular docking of GlcN-6-P synthase with the synthesized compounds was also performed. According to the results, complex 2 displayed minimum binding energy and can be considered as a good antimicrobial agent.

Cadmium(II) complexes with [(4-methylphenyl)sulfonyl]-2-pyridyl-amine: crystal structures of bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II); aquo-bis(pyridine) bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II) and 1,10-phenanthroline bis{[(4-methylphenyl)sulfonyl]-2-pyridyl-amide}cadmium(II)

Abstract Electrochemical oxidation of cadmium in a solution of [(4-methylphenyl)sulfonyl]-2-pyridyl-amine (HL) in acetonitrile/dichloromethane afforded the compound [CdL2]. When pyridine (py), 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) was added to the electrolytic phase, [CdL2py2(H2O)], [CdL2bipy] and [CdL2phen] were obtained. The crystal structures of [CdL2] (1), [CdL2py2(H2O)] (2) and [CdL2phen] (3) have been determined by X-ray diffraction techniques. The complex [CdL2] is best described in terms of a linear polymer with the metal atom in a [CdN4O2] distorted octahedral environment. The [CdL2py2(H2O)] and [CdL2phen] complexes are monomeric, with the cadmium atoms in [CdN6O] distorted pentagonal bipyramid and [CdN6] trigonal prismatic environments, respectively.

Electrochemical Synthesis and Characterization of Zinc(II) Complexes with [(4-Methylphenyl)Sulfonyl]-1H-Amido-2-Phenyl-2-Oxazolines†

A series of [(4-methylphenyl)sulfonyl]-1H-amido-2-phenyl-2-oxazoline ligands, HTs-ROz, has been synthesized by the reaction of substituted 2-(2-aminophenyl)oxazolines and p-toluensulfonyl chloride. The electrochemical oxidation of a sacrificial zinc anode in an acetonitrile solution of the corresponding ligand gave compounds of general formula [Zn(Ts-ROz)2]. All complexes have been characterized by microanalysis, IR and 1H NMR spectroscopy and single-crystal X-ray diffraction. In all cases, the metal atom is coordinated by the nitrogen atoms of two monoanionic ligands. spectros-Elektrochemische Synthese und Charakterisierung von Zink(II)-Komplexen mit [(4-Methylphenyl)sulfonyl]-1H-amido-2-phenyl-2-oxazolinen complexes; Crystal structure Eine Serie von [(4-Methylphenyl)sulfonyl]-1H-amido-2-phenyl-2-oxazolin-Liganden HTs-ROz wurden durch Reaktion von substituierten 2-(2-Aminophenyl)oxazolinen mit p-Toluolsulfonylchlorid synthetisiert. Die elektrochemische Oxidation von Opfer-Zink-Anoden in Acetonitrillosungen der entsprechenden Liganden fuhrt zu Verbindungen der Formel [Zn(Ts-ROz)2]. Alle Komplexe wurden durch Mikroanalysen, IR- und 1H-NMR-Spektren und durch Einkristall-Strukturanalysen charakterisiert. In allen Fallen sind die Metallatome durch die N-Atome zweier monoanionischer Liganden koordiniert.