Characterization and crystal structure of cadmium(II) halide complexes with amino acids and their derivatives: VII. Crystal structures of aquadibromo(3-aminopropanoic acid)cadmium(II), dichloro(4-aminobutanoic acid)cadmium(II), diaquabis(aminohexanoic acid)cadmium(II) tetrachlorocadmium(II), and dibromo(azetidine-3-carboxylic acid)cadmium(II)

Seven cadmium complexes: [CdX2(Hapro)(H2O)n] (X: Cl(1), Br(2)), [CdX2(Hgaba)] (X: Cl(3), Br(4)), [Cd(Hahex)2(H2O)2][CdCl4] (5), and [CdX2(Haze-3)](H2O)n (X: Cl(6), Br(7)) have been prepared and investigated by means of IR and FT Raman spectra. The crystal and molecular structures of 2, 3, 5 and 7 were determined by a single-crystal X-ray diffraction method. In complex 2, the cadmium atom is in a distorted octahedral geometry, ligated by two carboxyl oxygen atoms of Hapro, a water molecule, and three bromine atoms; one is terminal and each of the other two is bridging two cadmium atoms to make a polymer. The structure of 3 consists of one-dimensional polymers bridged by two chlorine atoms and a carboxyl group. The carboxyl oxygen atoms of Hgaba coordinate forkedly to two cadmium atoms. The cadmium atom of [Cd(Hahex)2(H2O)2]2+ in complex 5 is in a distorted octahedral geometry, ligated by four carboxyl oxygen atoms of two molecules of Hahex and by two water molecules. [Cd(Hahex)2(H2O)2]2+ exists between two layers which are formed of infinite [CdCl4]2- chains. The carboxyl oxygen atoms of Hahex coordinate to the same cadmium atom. In complex 7, the cadmium atom is ligated by two carboxyl oxygen atoms and four bridging bromine atoms to make a polymer.     

Spontaneous resolution of binary copper(II) complexes with racemic dipeptides: crystal structures of glycyl-L-alpha-amino-n-butyrato copper(II) monohydrate, glycyl-D-valinato copper(II) hemihydrate, and glycyl-L-valinato copper(II) hemihydrate

Copper(II) complexes with glycyl-DL-alpha-amino-n-butyric acid (H2gly-DL-but), glycyl-DL-valine (H2gly-DL-val), glycyl-DL-norleucine (H2gly-DL-norleu), glycyl-DL-threonine (H2gly-DL-thr), glycyl-DL-serine (H2gly-DL-ser), glycyl-DL-phenylalanine (H2gly-DL-phe), and glycyl-L-valine (H2gly-L-val), have been prepared and characterized by IR, powder diffuse reflection, CD and ORD spectra, and magnetic susceptibility measurements, and by single-crystal X-ray diffraction. The crystal structures of the copper complex with H2gly-DL-but, the copper complex with H2gly-DL-val, and [Cu(gly-L-val)]n.0.5nH2O have been determined by a single-crystal X-ray diffraction method. As for the structure of the copper complex with H2gly-DL-but, the configuration around the asymmetric carbon atom is similar to that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-DL-but is [Cu(gly-L-but)]n.nH2O. On the contrary, as for the structure of the copper complex with H2gly-DL-val, the configuration around the asymmetric carbon atom is different from that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-dl-val is [Cu(gly-D-val)]n.0.5nH2O. So during the crystallization of the copper(II) complexes with H2gly-DL-but and H2gly-DL-val, spontaneous resolution has been observed; the four complexes have separated as [Cu(gly-D-but)]n.nH2O, [Cu(gly-L-but)]n.nH2O, [Cu(gly-D-val)]n.0.5nH2O, and [Cu(gly-L-val)]n.0.5nH2O, respectively. [Cu(gly-L-but)]n.nH2O is orthorhombic with the space group P2(1)2(1)2(1). [Cu(gly-D-val)]n.0.5nH2O and [Cu(gly-L-val)]n.0.5nH2O are monoclinic with the space group C2. In these complexes, the copper atom is in a square-pyramidal geometry, ligated by a peptide nitrogen atom, an amino nitrogen atom, a carboxyl oxygen atom, and a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. So these complexes consist of a two-dimensional polymer chain bridged by a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. The axial oxygen atom is located above the basal plane and the side chain of an amino acid is located below it. These polymer chains consist of only one or the other type of optical isomers; no racemic dipeptides are found. Therefore, spontaneous resolution has been observed in the crystallization of copper(II) complexes with H2gly-DL-but and H2gly-DL-val. The crystal structure of [Cu(gly-D-val)]n.0.5nH2O agrees almost completely with that of [Cu(gly-L-val)]n.0.5nH2O, except for the configuration around the asymmetric carbon atom.     

New Ni(II)-sulfonamide complexes: synthesis, structural characterization and antibacterial properties. X-ray diffraction of [Ni(sulfisoxazole)2(H2O)4].2H2O and [Ni(sulfapyridine)2

The synthesis, structural characterization, voltammetric experiments and antibacterial activity of [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O and [Ni(sulfapyridine)(2)] were studied and compared with similar previously reported copper complexes. [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O crystallized in a monoclinic system, space group C2/c where the nickel ion was in a slightly distorted octahedral environment, coordinated with two sulfisoxazole molecules through the heterocyclic nitrogen and four water molecules. [Ni(sulfapyridine)(2)] crystallized in a orthorhombic crystal system, space group Pnab. The nickel ion was in a distorted octahedral environment, coordinated by two aryl amine N from two sulfonamides acting as monodentate ligands and four N atoms (two sulfonamidic N and two heterocyclic N) from two different sulfonamide molecules acting as bidentate ligands. Differential pulse voltammograms were recorded showing irreversible peaks at 1040 and 1070 mV, respectively, attributed to Ni(II)/Ni(III) process. [Ni(sulfisoxazole)(2)(H(2)O)(4)].2H(2)O and [Ni(sulfapyridine)(2)] presented different antibacterial behavior against Staphylococcus aureus and Escherichia coli from the similar copper complexes and they were inactive against Mycobacterium tuberculosis.     

Preparation of platinum(II) complexes with L-serine using KI. X-ray crystal structure, HPLC and 195Pt NMR spectra

The preparation of platinum(II) complexes containing L-serine using K(2)[PtCl(4)] and KI as raw materials was undertaken. The cis-trans isomer ratio of the complexes in the reaction mixture differed significantly depending on whether KI was present or absent in the reaction mixture. One of the two [Pt(L-ser-N,O)(2)] complexes (L-ser=L-serinate anion) prepared using KI crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=8.710(2) A, b=9.773(3) A, c=11.355(3) A, Z=4. The crystal data revealed that this complex has a cis configuration. The other [Pt(L-ser-N,O)(2)] complex also crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=7.0190(9) A, b=7.7445(6) A, c=20.946(2) A, Z=4. The crystal data revealed that this complex has a trans configuration. The 195Pt NMR chemical shifts of trans-[Pt(L-ser-N,O)(2)] and cis-[Pt(L-ser-N,O)(2)] complexes are -1632 and -1832 ppm, respectively. 195Pt NMR and HPLC measurements were conducted to monitor the reactions of the two [Pt(L-ser-N,O)(2)] complexes with HCl. Both 195Pt NMR and HPLC showed that the reactivities of cis- and trans-[Pt(L-ser-N,O)(2)] toward HCl are different: coordinated carboxyl oxygen atoms of trans-[Pt(L-ser-N,O)(2)] were detached faster than those for cis-[Pt(L-ser-N,O)(2)].     

Zinc(II), cadmium(II) and mercury(II) complexes of the vitamin B1 antagonist oxythiamine

The reaction of oxythiamine chloride hydrochloride (HOxTCl x HCl) with ZnCl2, CdCl2 and HgCl2 in ethanol yielded the complexes [ZnCl3(HOxT)], [CdCl3(HOxT)] and [HgCl3(HOxT)]. In water, the reaction with CdCl2 afforded [CdCl2(OxT)], but reaction with ZnCl2 or HgCl2 yielded unidentified products. The four new complexes were characterized by mass spectrometry and IR spectroscopy in the solid state and by 1H, 13C and 15N nuclear magnetic resonance (NMR) spectroscopy in hexadeuterated dimethylsulfoxide (DMSO-d6), and three were also studied by X-ray diffractometry. In [ZnCl3(HOxT)] and [HgCl3(HOxT)] the oxythiamine ligand is bound to the metal via N(1') and adopts the V conformation exhibited by thiamine in biological contexts. The infrared (IR) spectrum of [CdCl3(HOxT)] suggests a similar coordination mode. In [CdCl2(OxT)] each OxT zwitterion coordinates to one Cd(II) ion via its N(1') atom and to another via its N(3') and O atoms, giving rise to a polymeric chain along the x-axis. The coordination number of the metal is made up to six by Cdc...Cl interactions, two of which link the polymeric chains in pairs. This seems to be the first metal complex containing the oxythiamine ligand as a zwitterion, with the N(3')-H/O(4'alpha)-H group deprotonated. Neither HOxTCl nor its zinc(II) complex showed any significant activity in vitro against HeLa cells.     

The interaction of 5-fluoroorotic acid with transition metals: synthesis and characterisation of Ni(II), Cu(II) and Zn(II) complexes

5-Fluoroorotic acid (H(3)FOro) is a potent inhibitor for some metalloproteins such as dihydroorotase and dihydroorotate dehydrogenase and for thymidylate synthase (nonmetalloprotein) in the human malaria parasite Plasmodium falciparum. To study the coordination chemistry of H(3)Foro, the ammonium salt [NH(4)(+)][H(2)FOro(-)].1H(2)O (1) and the first coordination compounds of H(3)FOro with transition metals [Ni(HFOro(2-))(H(2)O)(4)].1H(2)O (2), [Cu(HFOro(2-))(NH(3))(H(2)O)](n) (3) and [Cu(3)(FOro(3-))(2)(NH(3))(6)(H(2)O)(2)] (4) have been synthesised and characterised by single-crystal X-ray diffraction, IR spectroscopy and by thermogravimetry. Three different coordination modes of 5-fluoroorotic acid have been established. In all cases the ligand is chelated to the metal via an amido-nitrogen and a carboxylate-oxygen but for (3), there is also a carboxylate oxygen from another HFOro(2-) ligand resulting in a polymeric structure and for (4), the second amido-nitrogen in the ororotic acid ring coordinates to give a trinuclear complex. The metal coordination polyhedra are octahedral in (2), square-pyramidal in (3) and square-planar and approximately square-pyramidal in (4). An octahedral coordination geometry including a N(1)/O(61)-chelating HFOro(2-) ligand with four aqua ligands is proposed for the Zn complex [Zn(HFOro(2-)) (H(2)O)(4)].0.5H(2)O (5), based on IR and thermogravimetric data. Extensive hydrogen bonded networks and some ring-ring stacking interactions are observed in each of the structures.     

Synthesis and structural characterization of cadmium(II) complexes with 2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine (PyTT)

We have carried out the synthesis of the cadmium coordination compounds [Cd(NO₃)₂(PyTT)(H₂O)] (1) and [CdCl₂{(μ-Cl)₂CdCl(μ-Cl)(μ-PyTT)Cd}₂]_n (2), together with their structural determination by means of X-ray diffraction. The compounds were also characterized through elemental analysis and infrared spectroscopy. The first complex presents a distorted pentagonal bipyramidal geometry with the axial positions occupied by one oxygen atom from a water molecule and a second one from a nitrate ion which acts as a monodentate ligand, whereas the equatorial plane contains three nitrogen atoms from the organic moiety and two oxygen atoms coming from the other nitrate group, which is bidentate. The structure of the second complex consists of parallel sheets linked by van der Waals forces, each one made up of structural units [CdCl₂{(μ-Cl)₂CdCl(μ-Cl)(μ-PyTT)Cd}₂], which possesses two PyTT ligands, 10 bridging chloro ligands and 5 cadmium(II) centres belonging to three environment types: octahedral CdN₂Cl₄, octahedral CdCl₆, on which a centre of symmetry is located, and tetrahedral CdNCl₃, present in a 2:1:2 ratio.     

Syntheses, crystal structures, and oxidative DNA cleavage of some Cu(II) complexes of 5-amino-3-pyridin-2-yl-1,2,4-triazole

Three new monomeric Cu(II) complexes of 5-amino-3-pyridin-2-yl-1,2,4-triazole (Hapt), [Cu(Hapt)(H(2)O)(2)(SO(4))] (1), [Cu(Hapt)(2)(H(2)O)(NO(3))](NO(3)) (2), and [Cu(Hapt)(2)(NCS-N)](NCS).H(2)O (3), have been prepared and characterized by single crystal X-ray diffraction. One distorted [CuN(2)O(2)+O(')] square-pyramidal (1), one distorted [CuN(3)O+N(')+O(')] octahedral (2), and one distorted [CuN(4)+N(')] intermediate between square-pyramidal and trigonal-bipyramidal (3) coordination configuration were found and are suggested to be due to the chelating nature of the ligand, which interacts with Cu(II) through the N4(triazole) and N(pyridine) atoms. Spectral properties of these chelates are in accordance with the X-ray structural data. With ascorbate and H(2)O(2) activation, compound 2 exhibits higher nuclease activity than compound 1. The influence on the DNA cleavage process of different scavengers of reactive oxygen species: dimethyl sulfoxide (DMSO), tert-butyl alcohol, sodium azide, 2,2,6,6-tetramethyl-4-piperidone and superoxide dismutase enzyme (SOD), and of the minor groove binder distamycin, is also studied.     

Synthesis, characterisation and antimicrobial activity of copper(II) and manganese(II) complexes of coumarin-6,7-dioxyacetic acid (cdoaH2) and 4-methylcoumarin-6,7-dioxyacetic acid (4-MecdoaH2): X-ray crystal structures of [Cu(cdoa)(phen)2].8.8H(2)O and [Cu(4-Mecdoa)(phen)2].13H2O (phen=1,10-phenanthroline)

Two novel coumarin-based ligands, coumarin-6,7-dioxyacetic acid (1) (cdoaH(2)) and 4-methylcoumarin-6,7-dioxyacetic acid (2) (4-MecdoaH(2)), were reacted with copper(II) and manganese(II) salts to give [Cu(cdoa)(H(2)O)(2)].1.5H(2)O (3), [Cu(4-Mecdoa)(H(2)O)(2)] (4), [Mn(cdoa)(H(2)O)(2)] (5) and [Mn(4-Mecdoa)(H(2)O)(2)].0.5H(2)O (6). The metal complexes, 3-6, were characterised by elemental analysis, IR and UV-Vis spectroscopy, and magnetic susceptibility measurements and were assigned a polymeric structure. 1 and 2 react with Cu(II) in the presence of excess 1,10-phenanthroline (phen) giving [Cu(cdoa)(phen)(2)].8.8H(2)O (7) and [Cu(4-Mecdoa)(phen)(2)].13H(2)O (8), respectively. The X-ray crystal structures of 7 and 8 confirmed trigonal bipyramidal geometries, with the metals bonded to the four nitrogen atoms of the two chelating phen molecules and to a single carboxylate oxygen of the dicarboxylate ligand. The complexes were screened for their antimicrobial activity against a number of microbial species, including methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Candida albicans. The metal-free ligands 1 and 2 were active against all of the microbes. Complexes 3-6 demonstrated no significant activity whilst the phen adducts 7 and 8 were active against MRSA (MIC(80)=12.1microM), E. coli (MIC(80)=14.9microM) and Patonea agglumerans (MIC(80)=12.6microM). Complex 7 also demonstrated anti-Candida activity (MIC(80)=22microM) comparable to that of the commercially available antifungal agent ketoconazole (MIC(80)=25microM).     

Synthesis and spectral investigation of manganese(II), cadmium(II) and oxovanadium(IV) complexes with 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone): Crystal structure of manganese(II) and cadmium(II) complexes

The chelating behavior of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) (H₂dapa) towards manganese(II), cadmium(II) and oxovanadium(IV) ions has been studied by elemental analyses, conductance measurements, magnetic properties and spectral (IR, ¹H NMR, UV-Vis and EPR) studies. The IR spectral studies suggest the pentadentate nature of the ligand with pyridine nitrogen, two azomethine nitrogens and two carbonyl oxygen atoms as the ligating sites. Six coordinate structure for [VO(H₂dapa)]SO₄ · H₂O and seven coordinate structures for [Mn(H₂dapa)(Cl)(H₂O)]Cl · 2H₂O and [Cd(H₂dapa)Cl₂] · H₂O complexes have been proposed. Pentagonal bipyramidal geometry for [Mn(H₂dapa)(Cl)(H₂O)]Cl · 2H₂O and [Cd(H₂dapa)(Cl₂)] · H₂O complexes was confirmed by single crystal analysis. The X-band EPR spectra of the oxovanadium(IV) and manganese(II) complexes in the polycrystalline state at room (300 K) and also at liquid nitrogen temperature (77 K) were recorded and their salient features are reported.     

Low-temperature (180 K) crystal structures of tetrakis-mu-(niflumato)di(aqua)dicopper(II) N,N-dimethylformamide and N,N-dimethylacetamide solvates, their EPR properties, and anticonvulsant activities of these and other ternary binuclear copper(II)niflumate complexes

Two pseudopolymorphs, solvates, of [Cu(2)(II)(niflumate)(4)(H(2)O)(2)] of unknown structure were obtained following solution of [Cu(2)(II)(niflumate)(4)(H(2)O)(2)] in N,N-dimethylacetamide (DMA) or N,N-dimethylformamide (DMF). Low-temperature crystal structures obtained for these solvates revealed that they were ternary aqua DMA and DMF solvates: [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMA and [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMF. Intermolecular hydrogen bonding interactions account for the formation of these stable DMA and DMF solvates. These pseudopolymorphs contain a centrosymmetric binuclear center with Cu-Cu bond distances ranging from 2.6439(7) to 2.6452(9) A; the coordination sphere of Cu(II) is characterized by one long Cu-O (water) bond length of 2.128(3)-2.135(3) A and four short Cu-O (carboxylate) bonds of 1.949(3)-1.977(3) A. Crystal parameters for the DMA pseudopolymorph: a=10.372(1), b=19.625(2), c=17.967(2) A, beta=97.40(1) degrees , V=3626.8(6) A(3); monoclinic system; space group: P2(1)/a and for the DMF pseudopolymorph: a=10.125(2), b=18.647(3), c=19.616(4) A, alpha=74.38(2)(o), beta=88.18(2)(o), gamma=79.28(2)(o), V=3504(1) A(3); triclinic system; space group: P1. EPR spectra of these solids are identical and show strong antiferromagnetic coupling between the copper atoms, similar to the spectrum obtained for [Cu(2)(II)(niflumate)(4)(DMSO)(2)]. The [Cu(2)(II)(niflumate)(4)(H(2)O)(2)], [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMA, [Cu(2)(II)(niflumate)(4)(H(2)O)(2)].4DMF, [Cu(2)(II)(niflumate)(4)(DMF)(2)], and[Cu(2)(II)(niflumate)(4)(DMSO)(2)] evidenced protection against maximal electroshock-induced seizures and Psychomotor seizures at various times after treatment, consistent with the well known antiinflammatory activities of Cu chelates, but failed to protect against Metrazol-induced seizures while evidencing some Rotorod Toxicity consistent with a mechanism of action involving sedative activity.     

Manganese(II) complex of 6,7-dicycanodipyridoquinoxaline with antitumor activities: synthesis,crystal structure and binding with DNA

A new Mn(II) complex with the planar ligand 6,7-dicycanodipyrido[2,2-D:2',3'-f]quinoxaline (L) [MnL(NO(3))(H(2)O)(3)]NO(3).CH(3)OH (1) has been synthesized and characterized by elemental analysis, IR, TG-DTA and molar conductance. Its crystal structure was determined by X-ray diffraction, crystal data: yellow, triclinic, space group P1;, Z=2, a=7.3743(8) A, b=11.2487(15) A, c=14.1655(15) A, alpha=79.412(2) degrees, beta=83.208(2) degrees, gamma=80.466(2) degrees. The Mn atom was hexa-coordinated to form a distorted octahedral geometry by two nitrogen atoms of L and four oxygen atoms of three H(2)O and NO(3)(-) in the complex. The binding mode of the complex with calf thymus DNA has also been investigated with spectrophotometric methods, viscosity and thermal denaturation measurements. The experimental results indicate that the complex intercalated into DNA base pairs via the ligand L. The intrinsic binding constant K(b) values for 1 (5.00 x 10(5) M(-1)) and L (1.65 x 10(5) M(-1)) were determined by absorption titration and calculated with the model of McGhee and Von Hippel. Biological tests against four different cell lines (HL-60, KB, Hela and BGC-823) in vitro showed that the complex had significant antitumor properties since the 50% inhibition concentrations (IC(50)) of the complex were within a microM range similar to those of antitumor drug 5-fluorouracil.     

Model complexes with naturally occurring ligands (salicylglycine and imidazol) and the biometals copper and cobalt

Two new complexes [Cu(Imz)(4)Cl(2)][Cu(Imz)(4)Cl] (2)(2-OH-Hip)(2) (1) and [Co(2-OH-Hip)(Imz)(3)].H(2)O (2) (with Imz=Imidazol and 2-OH-Hip=2-hydroxyhippuric acid) were prepared and characterized. The molecular structures and the solution and solid state behavior of the complexes were investigated. Complex 1 crystallizes in the monoclinic space group P2(1)/c with a=16.880(1), b=8.046(1), c=24.683(1) A, beta=107.88(1) degrees, and Z=2, while complex 2 crystallizes in the orthorhombic space group Pbca with a=11.712(2), b=15.741(4), c=22.254(4) A, and Z=8. The [Cu(Imz)(4)Cl(2)][Cu(Imz)(4)Cl](2)(2-OH-Hip)(2) solid consists in two distinct monomeric Cu(II) complexes: one of them is neutral octahedral [Cu(Imz)(4)Cl(2)] and the other, charged square basis pyramida [Cu(Imz)(4)Cl](+). The 2-hydroxyhippuric acid, which here acts as a counter ion, is deprotonated at its carboxylic group. Cobalt(III) ion in [Co(2-OH-Hip)(Imz)(3)].H(2)O is at the center of an octahedral environment, coordinated to three Imidazol ligands and to a triply deprotonated 2-hydroxyhippuric acid molecule acting as a tridentate ligand. Aqueous solution equilibrium of the quaternary system Cu(2+)/2-OH-Hip/Imz/H(+) was studied by potentiometric titrations.     

Model investigations for vanadium-protein interactions: vanadium(III) compounds with dipeptides and their oxovanadium(IV) analogues

The reaction of VCl(3) with 1,10-phenanthroline and a series of dipeptides (H(2)dip), having aliphatic as well as aromatic side chains, in methyl alcohol and in the presence of triethylamine affords vanadium(III) compounds of the general formula [V(III)(dip)(MeOH)(phen)]Cl. Aerial oxidation/hydrolysis of the vanadium(III) species gives their oxovanadium(IV) analogues of the general formula [V(IV)O(dip)(phen)]. X-ray crystallographic characterization of the [V(IV)O(dip)(phen)] compounds (where dip(2-)=Gly- L-Ala, Gly- L-Val and Gly- L-Phe) revealed that the vanadium atom possesses a severely distorted octahedral coordination and is ligated to a tridentate dip(2-) ligand at the N(amine) atom, the deprotonated N(peptide) atom and one of the O(carboxylate) atoms, as well as an oxo group and two phenanthroline nitrogen atoms. Circular dichroism characterization of the V(III)/V(IV)O(2+)-dipeptide compounds revealed a strong signal for the V(IV)O(2+) species in the visible range of the spectrum, with a characteristic pattern which may be exploited to identify the N(am), N(pep) and O(car) ligation of a peptide or a protein to V(IV)O(2+) center, and a weak Cotton effect of opposite sign to their vanadium(III) analogues. The visible spectra of the V(III)-dipeptide compounds revealed two d-d bands with high intensity, thus indicating that the covalency of the metal-donor atoms is significant, i.e. the vanadium d orbitals are significantly mixed with the ligand orbitals, and this is confirmed by the low values of their Racah B parameters. The high-intensity band of the V(IV)O(2+)-dipeptide compounds at approximately 460 nm implies also a strong covalency of the metal with the equatorial donor atoms and this was supported by the EPR spectra of these compounds. Moreover, the V(III)/V(IV)O(2+)-dipeptide complexes were characterized by EPR and IR spectroscopies as well as conductivity and magnetic susceptibility measurements.     

Synthesis, characterization and properties of chromium(III) complex [Cr(SA)(en)2]Cl.2H2O

The reaction of chromium(III) chloride, salicylic acid (SA) and ethylenediamine (en) led to the formation of chromium complex [Cr(SA)(en)(2)]Clx2H(2)O(1). The crystal structure belongs to monoclinic system with the space group P2(1), R(1)=0.0358. In this compound, Cr(III) atom is six-coordinated in octahedral coordination geometry by one phenolic hydroxyl oxygen, one carboxylate oxygen from the salicylic acid and four nitrogen atoms from two ethylenediamine molecules, respectively. The transfer manners of Cr(III) from the title compound to the low-molecular-mass chelator, ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA) and the iron-binding protein apoovotransferrin (apoOTf) were followed by a combination of UV-visible (UV-Vis) and fluorescence spectra in 0.01M Hepes at pH 7.4. The results show that Cr(III) can be transferred from the complex to apoovotransferrin with the retention of the salicylate acted as a synergistic anion.     

Low-temperature (180 K) crystal structure,electron paramagnetic resonance spectroscopy,and propitious anticonvulsant activities of CuII2(aspirinate)4(DMF)2 and other CuII2(aspirinate)4 chelates

The purpose of this research was to characterize by X-ray crystallography the ternary dimethylformamide (DMF) Cu(II) complex of acetylsalicylic acid (aspirin), in an effort to compare the structure-activity relationships for the anticonvulsant activity of this and other Cu(II)aspirinate chelates. The ternary DMF Cu(II) complex of aspirin was synthesized and crystals grown from a DMF solution were characterized by single crystal X-ray diffraction. This crystalline material was analyzed for anticonvulsant activity in the Maximal Electroshock (MES) Grand Mal and subcutaneous Metrazol (scMET) Petit Mal models of seizure used to detect anticonvulsant activity. The ternary DMF complex was found to be a monomolecular binuclear complex, tetrakis-mu-(acetylsalicylato)bis(dimethylformamido)dicopper(II) [Cu(II)(2)(aspirinate)(4)(DMF)(2)] with the following parameters: monoclinic, space group P2(1)/n, a=12.259 (1), b=10.228 (1), c=16.987 (1) A, beta=92.07 (1) degrees; V=2128.5 (3) A(3); Z=2. The structure was determined at 180 K from 2903 unique reflections (I>1sigma(I)) to the final values of R=0.030 and wR=0.033 using F. This binuclear complex contains four acetylsalicylate bridging ligands which are related to each other in a two by two symmetry center. The four nearest O atoms around each Cu atom form a closely square planar arrangement with the square pyramidal coordination completed by the dimethylformamide oxygen atom occupying an apical position at a distance of 2.154 (1) A. Each Cu atom is displaced towards the DMF ligand by 0.187 A from the plane of the four O atoms. Electron paramagnetic resonance (EPR) spectra of [Cu(II)(2)(aspirinate)(4)(DMF)(2)] crystals show a strong antiferromagnetic coupling of the copper atoms, similar to that observed with other binuclear copper(II)salicylate compounds. Studies used to detect anticonvulsant activity revealed that [Cu(II)(2)(aspirinate)(4)(DMF)(2)] was an effective anticonvulsant in the MES model of seizure but ineffective against scMET-induced seizures. The monomolecular ternary binuclear [Cu(II)(2)(aspirinate)(4)(DMF)(2)] complex is more effective in inhibiting MES-induced seizures than other binuclear or mononuclear Cu(II) chelates of aspirin including: binuclear polymeric [Cu(II)(2)(aspirinate)(4)], [Cu(II)(2)(aspirinate)(4)(H(2)O)], which is anticipated to be less polymeric, and monomolecular ternary [Cu(II)(2)(aspirinate)(4)(DMSO)(2)] and [Cu(II)(aspirinate)(2)(Pyr)(2)]. These and other chelates appear to be more effective in the scMET model of seizure than [Cu(II)(2)(aspirinate)(4)(DMF)(2)]. These structure-activity relationships support the potential efficacy of Cu chelates of aspirin in treating epilepsies.     

Preparation of platinum(IV) complexes with dipeptide and diimine. X-ray crystal structure and 195Pt NMR spectra

We prepared platinum(IV) complexes containing dipeptide and diimine or diamine, the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complex, where -N,N,O means dipeptide coordinated as a tridentate chelate, dipeptide=glycylglycine (NH(2)CH(2)CON(-)CH(2)COO(-), digly, where two protons of dipeptide are detached when the dipeptide coordinates to metal ion as a tridentate chelate), glycyl-L-alanine (NH(2)CH(2)CON(-)CHCH(3)COO(-), gly-L-ala), L-alanylglycine (NH(2)CH CH(3)CON(-)CH(2)COO(-), L-alagly), or L-alanyl-L-alanine (NH(2)CHCH(3)CON(-)CHCH(3)COO(-), dil-ala), and diimine or diamine=bipyridine (bpy), ethylenediamine (en), N-methylethylenediamine (N-Me-en), or N,N'-dimethylethylenediamine (N,N'-diMe-en). In the complexes containing gly-L-ala or dil-ala, two separate peaks of the (195)Pt NMR spectra of the [PtCl(dipeptide-N,N,O)(diimine or diamine)]Cl complexes appeared in, but in the complexes containing digly or L-alagly, one peak which contained two overlapped signals appeared. One of the two complexes containing gly-L-ala and bpy, [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3), crystallized and was analyzed. This complex has the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions of a=9.7906(3)A, b=11.1847(2)A, c=16.6796(2)A, Z=4. The crystal data revealed that this [PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex has the near- (Cl, CH(3)) configuration of two possible isomers. Based on elemental analysis, the other complex must have the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) configuration. The (195)Pt NMR chemical shifts of the near- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex and the far- (Cl, CH(3))-[PtCl(gly-L-ala-N,N,O)(bpy)]NO(3) complex are 0 ppm and -19 ppm, respectively (0 ppm for the Na(2)[PtCl(6)] signal). The additive property of the (195)Pt NMR chemical shift is discussed. The (195)Pt NMR chemical shifts of [PtCl(dipeptide-N,N,O)(bpy)]Cl appeared at a higher field when the H attached to the dipeptide carbon atom was replaced with a methyl group. On the other hand, the (195)Pt NMR chemicals shifts of [PtCl(dipeptide-N,N,O)(diamine)] appeared at a lower field when the H attached to the diamine nitrogen atom was replaced with a methyl group, in the order of [PtCl(digly-N,N,O)(en)]Cl, [PtCl(digly-N,N,O)(N-Me-en)]Cl, and [PtCl(digly-N,N,O)(N,N'-diMe-en)]Cl.     

Unusual dimeric Zn(II)-cytosine complexes: new models of the interaction of Zn(II) with DNA and RNA

Synthesis and crystal structure of two Zn(II) dimer complexes with 1-methylcytosine (1-MeC) are reported. In complex [Zn(2)Cl(4)(mu-1-MeC-O2,N3)(2)] (1), two 1-MeC ligands are bridging two ZnCl(2) moieties. In [Zn(2)(1-MeC-N3)(4)(mu-SO(4))(2)].2H(2)O (2), the sulfates act as bridging ligands and 1-MeC are linked via N3 to Zn(II) as terminal ligands. Both complexes represent the first examples of Zn(II)-pyrimidine dimers. The potential biological significance of 1 and 2 is discussed.     

Strong protective action of Copper(II) N-substituted sulfonamide complexes against reactive oxygen species

Copper(II) complexes of N-benzothiazolsulfonamides, [Cu(N-2-(5,6-dimethylbenzothiazole)toluenesulfonamidate)(2)(dmso)(2)] (1), [Cu(N-2-(6-chlorobenzothiazole)benzenesulfonamidate)(2)(dmso)(2)] (2) and [Cu(N-2-(6-chlorobenzothiazole)toluenesulfonamidate)(2)(dmso)(2)] (3) with interesting protective properties against superoxide radicals have been prepared. The compounds have been characterized by X-ray diffraction and their chemical properties have been studied by spectroscopic methods. The crystal structure of 1 shows that the copper(II) is surrounded by two benzothiazole N atoms from the sulfonamide ligands and two O atoms from the dimethylsulfoxide molecules in a square planar arrangement. The coordination polyhedron around copper(II) in 2 and 3 is distorted square pyramidal being the metal ion linked to benzothiazole N and sulfonamidate O atoms of the ligand and to two dimethylsulfoxide O atoms. The three complexes have a strong protective action over Delta sod1 mutant of Saccharomyces cerevisiae against reactive oxygen radicals derived from respiration and against those generated by hydrogen peroxide and menadione.     

Synthesis, structure and antimicrobial activity of manganese(II) and cobalt(II) complexes of the polyether ionophore antibiotic Sodium Monensin A

Mononuclear neutral manganese(II) and cobalt(II) complexes with the antibiotic Sodium Monensin A (Mon-Na, 1b) were synthesized and characterized. The crystal structures of M(Mon-Na)2Cl2.H2O (M=Mn, 2; M=Co, 3) were determined by X-ray crystallography. The complexes crystallize in monoclinic space group C2 with a tetrahedrally coordinated transition metal attached to oxygen atoms of deprotonated carboxyl groups of two Sodium Monensin molecules and two chloride ions. The sodium ion remains in the cavity of the ligand and cannot be replaced by Mn(II) or Co(II). The complexes were additionally characterized by different spectroscopic techniques (UV-Visible, EPR, FAB-MS). A preferable octahedral environment around the transition metal centers is observed in polar solvents while the complexes retain their tetrahedral structure in non-polar media. The antimicrobial activity of 1b, 2 and 3 was tested against Gram(+) and Gram(-) bacteria.