Horacio López-Sandoval

Synthesis, structure and biological activities of cobalt(II) and zinc(II) coordination compounds with 2-benzimidazole derivatives

In this work we present the synthesis, structural and spectroscopic characterisation of a series of cobalt(II) and zinc(II) coordination compounds with benzimidazole (bz) and its 2-benzimidazole derivatives: 2-aminobenzimidazole (2ab), albendazole (abz) and tris(2-benzimidazolylmethyl)amine (ntb). The compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Micrococcus luteus, Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli and Proteus vulgaris. Their cytotoxic activity was also evaluated using human cancer lines, HeLa, HCT-15 and SKLU-1. The halide tetrahedral compounds [Co(bz)2Br2] 3, [Zn(2ab)2Cl2].0.5H2O 11, [Co(abz)Cl2(H2O)].3H2O 14, [Co(abz)Br2(H2O)] 15, [Zn(abz)Cl2(H2O)].3H2O 17 and [Zn(abz)Br2(H2O)].H2O 18 displayed similar minimal inhibition concentration (MIC) values against Micrococcus luteus and Escherichia coli, comparable to those of amoxicillin and chloramphenicol. Additionally, 11 showed a wide range of activity towards Gram(+) and Gram(-) microorganisms. The tetradentate ntb and its trigonal bipyramidal cobalt(II) and zinc(II) compounds were active, regardless of the anion present in the complex. Compound [Co(abz)Cl2(H2O)].3H2O 14 showed promising activity in HeLa cells, while [Co(ntb)Br]Br.H2O 21 inhibited Hela and HCT-15 cell lines.

Cytotoxic activity, X-ray crystal structures and spectroscopic characterization of cobalt(II), copper(II) and zinc(II) coordination compounds with 2-substituted benzimidazoles

Herein we present the synthesis, structural and spectroscopic characterization of coordination compounds of cobalt(II), copper(II) and zinc(II) with 2-methylbenzimidazole (2mbz), 2-phenylbenzimidazole (2phbz), 2-chlorobenzimidazole (2cbz), 2-benzimidazolecarbamate (2cmbz) and 2-guanidinobenzimidazole (2gbz). Their cytotoxic activity was evaluated using human cancer cell lines, PC3 (prostate), MCF-7 (breast), HCT-15 (colon), HeLa (cervic-uterine), SKLU-1 (lung) and U373 (glioblastoma), showing that the zinc(II) and copper(II) compounds [Zn(2mbz)(2)Cl(2)].0.5H(2)O, [Zn(2cmbz)(2)Cl(2)].EtOH, [Cu(2cmbz)Br(2)].0.7H(2)O and [Cu(2gbz)Br(2)] had significant cytotoxic activity. The isostructural cobalt(II) complexes showed not significant activity. The cytotoxic activity is related to the presence of halides in the coordination sphere of the metal ion. Recuperation experiments with HeLa cells, showed that the cells recuperated after removing the copper(II) compounds and, on the contrary, the cells treated with the zinc(II) compounds did not. These results indicate that the mode of action of the coordination compounds is different.

Coordination chemistry of a bis(benzimidazole) disulfide: eleven membered chelate ring in cobalt(II), zinc(II) and cadmium(II) halide compounds; oxidative disulfide cleavage when coordinated to nickel(II)

Herein we report the synthesis, structural and spectroscopic characterization of coordination compounds with bis[2-(1H-benzimidazol-2-yl)phenyl]disulfide [bis-(2phSbz)] (1) and cobalt(II), zinc(II) and cadmium(II) halides (2-7). Their X-ray diffraction analyses showed that the metal ions present similar distorted tetrahedral structures, with the disulfide ligand coordinated through the imidazolic nitrogen atoms, forming a twisted eleven membered chelate ring. Structures of nickel(II) compounds 8 and 9, showed that the disulfide bond in the ligand was cleaved forming six membered chelates. In 8, the two ligands are sulfides, however in 9 one of them was oxidized to a sulfone. In both compounds the nickel(II) has a distorted square planar geometry and the sulfur atoms are in cis positions. The oxidation reaction of bis-(2phSbz) was performed in KMnO4/NaOH, giving the 2-(1H,3H-benzimidazolium-2-yl)-benzene sulfonate (10). The solid state structure of compounds 2-5 and 7-10 was determined by X-ray diffraction analyses.

Synthesis, crystal structure and magnetic properties of the triangulo-tricopper(II) complex [Cu3(cpse)3(H2O)3]·8.5H2O

The trinuclear copper(II) complex [Cu3(cpse)3(H2O)3]·8.5H2O has been obtained from mononuclear [Cu(Hcpse)2]·H2O {H2cpse = N-[2-hydroxy-1(S)-methyl-2(S)-phenylethyl]-N-methylglycine, threo isomer} and crystallographically characterised. The structure of the compound consists of three CuII atoms, each having distorted square-pyramidal geometry, linked by oxo-bridges to form an equilateral triangular array. The magnetic behaviour corresponds to an antiferromagnetically coupled triangular system, with J = −114.2 cm−1. The EPR spectra at different temperatures have been determined. The analogue [Cu(Hceph)2]·H2O (H2ceph = N-[2-hydroxy-1(S)-methyl-2(R)-phenylethyl]-N-methylglycine), prepared from the erythro isomer, was obtained and characterised by X-ray crystallography.

Química Inorgánica Medicinal: vanadio, platino, oro

Este articulo pretende presentar una perspectiva medicinal de la quimica inorganica basada en vanadio, platino y oro, sus aplicaciones como agentes terapeuticos para el tratamiento de variadas enfermedades y la relevancia de su quimica de coordinacion. Van a tratarse los compuestos de vanadio como sustitutos de la insulina para tratar la Diabetes II; los compuestos de coordinacion del cis-platino, que estan siendo utilizados como agentes terapeuticos para diferentes tipos de cancer y los compuestos de oro que estan siendo efectivos para tartar la artritis reumatoide.

Lone pair···π interactions on the stabilization of intra and intermolecular arrangements of coordination compounds with 2-methyl imidazole and benzimidazole derivatives

Abstract Spectroscopic and single crystal X-ray diffraction studies of coordination compounds of CoII, NiII, ZnII, and PdII with phenylsulfonyl imidazole and benzimidazole derivatives (2-mfsiz, 2-mfsbz) were performed. The relevance of non-covalent interactions on the stabilization of intra and intermolecular arrangements in the ligands and their coordination compounds was investigated. The imidazole 2-mfsiz ligand presents two enantiomeric conformers, where the ethylphenylsulfone moiety stabilizes intermolecular lone pair···π (S–O···π(phe)) and H···π contacts, while its tetrahedral coordination compounds, [M(2-mfsiz)2X2] (M2+ = Co, Ni, Zn; X = Cl, Br) showed intramolecular lone pair···π interactions (S–O···π(iz)). On the other hand, compounds [Cu2(2-mfsiz)2(µ2-AcO)4] and trans-[Pd(2-mfsiz)2Cl2] do not present lone pair···π interactions due to the metal ion geometry (square base pyramidal or square planar), which leads to formation of π(iz)···π(phe) interactions. For the benzimidazole ligand 2-mfsbz, an intramolecular, H(phe)···π(bz) contact was observed, remaining in its tetrahedral and octahedral coordination compounds, [M(2-mfsbz)2X2] (M2+ = Co, Zn; X = Cl, Br, NO3). This interaction limits the free rotation of the ethylphenylsulfone moiety for stabilization of an intermolecular lone pair···π interaction (S–O···π(iz)). The dimeric [Zn2(2-mfsiz)2(µ2-AcO)4] compound has a π(bz)···π(phe) contact. Theoretical calculations confirmed the non-covalent interactions in the ligands and their coordination compounds. Graphical Abstract

Transition metal coordination compounds of an antiobesity serotoninergic ligand: spectroscopic characterization and adipogenesis activity

Coordination compounds of cobalt(II), nickel(II), copper(II) and zinc(II) with L-5-hydroxytryptophan (L-5-HTP) were synthesized and characterized by elemental analysis, IR and UV–Vis-NIR spectroscopy, mass spectrometry and thermogravimetric analysis. The X-ray structure of the pure enantiomer ligand (L-5-HTP) was obtained. The ligand coordinates to the metal ions in an unidentate mode, where the donor atom is the oxygen from the carboxylic group. The intramolecular H-bond, N1H···O2, observed in the X-ray crystal structure of the free L-5-HTP, remains as a stabilization factor in all of the coordination compounds. Two types of geometries were adopted by the metal centers: tetrahedral and octahedral. In vitro antiadipogenic studies of the coordination compounds showed that the tetrahedral cobalt(II) and copper(II) complexes presented potential antiobesity properties.

Stereochemistry of optically active nickel(II) and cobalt(II) coordination compounds derived from N-acetyl aminoalcohols

Herein, we report the stereoselective synthesis and stereochemical analysis of nickel(II) and cobalt(II) coordination compounds derived from N-acetyl-(−)-ephedrine 1(−) and N-acetyl-(+)-ephedrine 1(+), N-acetyl-(+)-pseudoephedrine 2(+) and N-acetyl-(−)-phenylephrine 3(−). Two ligands are coordinated to the metal ion in a tridentate mode giving place to optically active coordination compounds ML2, in a fac octahedral geometry. In all cases, the coordination to the metal ion occurs through the nitrogen atom, the OH group and the deprotonated carboxylic group, forming two five-membered rings. The coordination compounds are characterized in the solid state by UV-Vis-NIR reflectance spectra, IR, X-ray crystallography and magnetic susceptibility measurements. The metal becomes a stereogenic center and, for each ligand, coordination to the metal ion produces two new stereogenic nitrogen and oxygen. Different modes of ligand bonding are present, the fac all-trans, which originates from the fact that the two new stereogenic atoms in each ligand present opposite configurations (mirror effect), as a consequence the bonded ligands are diasteromeric and the complexes have C1 symmetry. The second bonding mode is the fac–cis, which results in the new stereogenic centers acquiring the same configuration; the two bonded ligands are stereochemically identical, producing a complex with C2 symmetry. The use of enantiomeric ligands 1(−) and 1(+) produces separately and stereoselectively the corresponding enantiomeric metallic complexes which are crystallized pure, whereas the use of a racemate of compound 1 produces a different isomer where the metal has a different configuration. Complexes prepared with N-acetyl-ephedrines are diasteromers of those obtained from N-acetyl-pseudoephedrine. The phenylephrine complexes show that the acquired N-configuration is independent of the substitution of the nitrogen vicinal carbon atom and depends only of the cis or trans ligand coordination mode. Analysis of the conformation of the aminoalcohol rings shows that, in all compounds, the phenyl groups are in the equatorial position determining the conformation of the chelates.