María V. Villa

Complexes of Ni(II) and Cu(II) with ofloxacin. Crystal structure of a new Cu(II) ofloxacin complex.

Several coordination compounds formed between Ni(II) or Cu(II) with ofloxacin have been synthesised and characterised. According to elemental chemical analysis and FT-IR spectroscopy data, direct reaction of Ni(II) and Cu(II) salts with ofloxacin leads to formation of precipitates for which mass spectrometry demonstrates their polymeric nature. However, crystalline [Cu(oflo)2(H2O)].2H2O is formed if the reaction is carried out in the presence of ammonia. This complex crystallises in the triclinic system, space group P-1 with a=9.2887(12), b=11.2376(14), c=17.874(2) A, alpha=92.12(3), beta=95.39(3), gamma=91.71(3) degrees and Z=2. The local geometry around the Cu(II) ion is a slightly distorted square base pyramid. Electronic spectra, magnetic susceptibility measurements and EPR spectra of the synthesised complexes indicate a tetragonal environment.

Oxidative DNA damage of mixed copper(II) complexes with sulfonamides and 1,10-phenanthroline: Crystal structure of [Cu(N-quinolin-8-yl-p-toluenesulfonamidate)2(1,10-phenanthroline)]

Mixed coordination compounds of Cu(II) with sulfonamides and 1,10-phenanthroline as ligands have been prepared and characterised. Single crystal structural determination of the complex [Cu(N-quinolin-8-yl-p-toluenesulfonamidate)(2)(phen)] shows Cu(II) ions are located in a highly distorted octahedral environment, probably as a consequence of the Jahn-Teller effect. The FT-IR and electronic paramagnetic resonance (EPR) spectra are also discussed. The mixed complexes prepared undergo an extensive DNA cleavage in the presence of ascorbate and hydrogen peroxide. Two of the complexes have higher nucleolytic efficiency than the bis(o-phenanthroline)copper(II) complex.

Crystal structure of [Cu(N-quinolin-8-yl-p-toluenesulfonamidate)2]: study of its interaction with DNA and hydrogen peroxide

A new copper complex with N-quinolin-8-yl-p-toulenesulfonamide has been prepared and characterised. The compound crystallises in the triclinic system, space group P1, with a=13.457(3), b=15.067(5), c=18.589(3) A; alpha=112.05(2), beta=93.92(2), gamma=108.30(2) degrees and Z=4. The geometry of the Cu(II) ion is distorted square planar. The N-quinolin-8-yl-p-toulenesulfonamidate anion behaves as a bidentate ligand through the N(sulfonamidate)and N(quinoline) atoms. The complex does not cleave DNA in the presence of hydrogen peroxide.

Copper complexes with dithiocarbamates derived from natural occurring amino acids. Crystal and molecular structure of [Cu(en)(EtOH)(H2O)3][Cu(dtc-pro)2]

Abstract Reaction of Cu(II) salts with dithiocarbamates derived from the amino acids asparagine, glutamine, serine, threonine and tyrosine leads to reduction of the metallic cation and formation of Cu(I) complexes, whereas reaction with proline dithiocarbamate takes place without reduction, leading to formation of a Cu(II) coordination compound. Simultaneous reaction of proline dithiocarbamate and ethylenediamine with Cu(II) leads to the formation of the mixed complex [Cu(en)(EtOH)(H2O)3][Cu(dtc-pro)2]. In the anion, the Cu(II) centre possesses a D2h local symmetry, coordinated by two bidentate dithiocarbamate ligands, while the Cu(II) centre is in a distorted octahedral coordination in the cationic unit. The spectroscopic and magnetic properties of the complexes synthesised are also investigated.

Copper complexes with sulfonamides: crystal structure and interaction with pUC18 plasmid and hydrogen peroxide

N-Quinolin-8-yl-benzenesulfonamide (Hqbsa) and N-quinolin-8-yl-naftalenesulfonamide (Hqnsa) have been synthetized and physicochemically characterized, and used as ligands to coordinate copper complexes with ML2 stoichiometry. The structure of the compounds [Cu(qbsa)2]·DMF and [Cu(qnsa)2] has been determined by X-ray diffraction and both of them crystallize in the orthorhombic system. IR and ESR spectra of the complexes are discussed. The cleavage of pUCI8 by the copper complexes do not behave as chemical nucleases in the range of concentrations assayed.

Structural characterisation and nuclease activity of mixed copper(II) complexes with sulfonamides and bipyridil

Mixed copper complexes have been synthetised through reaction of Cu(II) salts with bipyridil and N-quinolin-8-yl-p-toluenesulfonamide (Hqtsa), N-quinolin-8-yl-benzenesulfonamide (Hqbsa) or N-quinolin-8-yl-naftalenesulfonamide (Hqnsa). Single crystal X-ray diffraction structure determination shows that copper cations are five-coordinated, one complex have distorted bipyramidal trigonal geometry and the other have a distorted square-pyramid. The FT IR and EPR spectra are also reported. Electrophoresis results show that the synthetised complexes in the presence of ascorbate and hydrogen peroxide are chemical nucleases.

Synthesis and characterization of sulfonamides containing 8-aminoquinoline and their Ni(II) complexes. Crystalline structures of the ni complexes

Reaction between 8-aminoquinoline and benzenesulfonyl, toluene-4-sulfonyl and naphthalene-2-sulfonyl chlorides in a basic medium leads to the formation of the corresponding sulfonamides. Reaction of these sulfonamides with Ni(II) salts leads to the formation of the corresponding complexes, with a NiL 2 stoichiometry. Determination of the crystalline structure by X-ray diffraction shows an octahedral environment for the Ni(II) ions, sulfonamides acting as bidentate ligands and two solvent molecules completing the octahedral coordination. The spectroscopic and magnetic properties of these compounds are also discussed.

Complexes of molybdenum(V) and molybdenum(IV) with dithiocarbamates derived from α-amino acids. Reaction kinetics in organic solvents

Abstract The reaction between dithiocarbamate derivatives of α-amino acids (glycine, alanine, α-amino-butyric acid, norvaline, valine, norleucine, leucine and isoleucine) and sodium molybdate in acid medium leads to the formation of molybdenum(V) complexes with the general formula [Mo 2 O 3 )dtc a.a.) 4 ]·2H 2 O (a.a = amino acid). The complexes were characterized by elemental analysis, FT-IR and uv-vis spectroscopies and XPS. They are binuclear complexes with a linear oxygen bridge, the dithiocarbamate moiety acting as a bidentate ligand and thus yielding a distorted octahedral coordination for the metal cation. In organic solvents, these compounds undergo a chemical transformation, yielding complexes with the general formula [MoO(dtc a.a.) 2 ], whose synthesis is also described. These complexes were characterized using the same experimental techniques as above. The kinetics of transformation in organic media were studied, proposing a multi-step reaction mechanism, and the rate constants have also been determined.

Dithiocarbamates derivatives from α-amino acids as chelating agents for toxic metal ions

Abstract A study has been carried out in vitro on the chelating properties of several dithiocarbamates derived from α-amino acids (glycine, DL-alanine, DL-valine, DL-leucine, DL-isoleucine, and L-proline) against Pb(II) and Cd(II). The general formulae of the complexes obtained was M(dtc a.a.), where M = Pb(II), Cd(II), and (dtc a.a.) stands for the dithiocarbamate derivative. The infrared spectra show characteristic absorption bands, especially those originated by stretching modes of CN, CS, NH, and COO− moieties, in addition to other vibrations due to the hydrocarbon chains. Electronic spectroscopy has been used to evaluate the association constants of the complexes larger than 109. A slight decomposition of the dithiocarbamate molecules is observed during formation of the complexes, depending both on the nature of the dithiocarbamate and the nature of the cation, being more pronounced for Cd(II) than for Pb(II).

An EXAFS study of Mo(VI) and Mo(V) complexes with proline dithiocarbamate

Abstract The reaction between proline and carbon disulfide in a basic medium yields the corresponding dithiocarbamate (hereafter dtc pro). Reaction of this compound with Na2MoO4 · 2H2O leads to formation of a coordination compound with the formula MoO2(dtc Hpro)2, while reaction with MoCl5 in an inert atmosphere leads to Mo2O4(dtc Hpro)4. Mo K XANES data are consistent with the presence of Mo(VI) in the former compound, while a lower oxidation state of molybdenum in the latter, Mo(V), shifts the absorption edge to lower energies. EXAFS data indicate that, in these complexes, molybdenum ions are in a different coordination environment. In the first it is in a distorted octahedral coordination, and oxygen atoms are in cis positions, with an Mo–O distance of 1.68 A and an Mo–S distance of 2.48 A. However, in the dimer the Mo atoms (Mo–Mo distance 2.55 A) are bridged by two oxygen atoms (Mo–O distance 1.95 A), and the Mo–S distance is 2.43 A. The molybdenum atom in this case is pentacoordinated with a terminal oxygen atom distance Mo–O of 1.66 A. The dithiocarbamate unit behaves in all cases as a bidentate ligand, both sulfur atoms being equivalent. Both complexes are diamagnetic, and FT-IR spectroscopy provides evidence that the carboxylic group is in the acidic form, not being coordinated to the Mo cations. Only charge transfer bands are detected in the UV–Vis spectra. EPR spectra produced evidence of the presence of a small amount of a paramagnetic Mo(V) species, probably Mo(dtc Hpro)3.