Copper(II) and zinc(II) complexes with 2-benzoylpyridine-methyl hydrazone

2-Benzoylpyridine-methyl hydrazone (HBzMe) has been obtained as well as its copper(II) [Cu(HBzMe)Cl(2)] (1) and zinc(II) [Zn(HBzMe)Cl(2)] (2) complexes. Upon re-crystallization in 1 - 9 DMSO:acetone conversion of I into dimeric [Cu(BzMe)Cl](2) (1a) occurred. The crystal structures of HBzMe, 1, 1a, and 2 were determined. HBzMe adopts the ZE conformation in the solid. In all complexes the hydrazone adopts the E configuration to attach to the metal through the N(py)-N2-O chelating system. In 1 and 2 a neutral hydrazone coordinates to the metal center while in 1a deprotonation occurs with coordination of an anionic ligand. la presents a dimeric structure. having two copper(II) ions per asymmetric unit. Two chlorides are also present in the copper coordination sphere, which act as bridging ligands and connect the copper centers to each other. (C) 2008 Elsevier B.V. All rights reserved.

Vanadium complexes with 2-pyridineformamide thiosemicarbazones: In vitro studies of insulin-like activity

Reaction of VOCl(2) with 2-pyridineformamide thiosemicarbazone (H2Am4DH) and its N(4)-methyl (H2Am4Me), N(4)-ethyl (H2Am4Et) and N(4)-phenyl (H2Am4Ph) derivatives in ethanol gave as products [VO(H2Am4DH) Cl(2)] (1), [VO(H2Am4Me) Cl(2)] center dot 1/2HCl (2), [VO(H2Am4Et) Cl(2)] center dot HCl (3) and [VO(2Am4Ph) Cl] (4). Upon the dissolution of 1-4 in water, oxidation immediately occurs with the formation of [VO(2)(2Am4DH)] (5), [VO(2)(2Am4Me)] (6), [VO(2)(2Am4Et)] (7) and [VO(2)(2Am4Ph)] (8). The crystal and molecular structures of 5 and 6 were determined. Complexes 5-8 inhibited glycerol release in a similar way to that observed with insulin but showed a low enhancing effect on glucose uptake by rat adipocytes. (C) 2008 Elsevier B.V. All rights reserved.

Ruthenium(II) complexes containing N(4)-tolyl-2-acetylpyridine thiosemicarbazones and phosphine ligands: NMR and electrochemical studies of cis-trans isomerization

[Ru(HL)(PPh3)(2)Cl]Cl complexes have been obtained in which HL = N(4)-ortho (complex 1), N(4)-meta (complex 2) and N(4) pctratolyl 2-acetylpyridine thiosemicarbazone (complex 3). NMR and electrochemical studies indicate that both cis and trans isomers exist in solution, and that the cis isomers are converted into the trans isomers with time. Crystal structure determination of (1) reveals that the traps isomer is formed in the solid state. (c) 2007 Elsevier B.V. All rights reserved.

New Pd(II) and Pt(II) complexes with N,S-chelated pyrazolonate ligands: Molecular and supramolecular structure and preliminary study of their in vitro antitumoral activity

New Pd(II) and Pt(II) complexes [ML2] (HL = a substituted 2,5-dihydro-5-oxo-1H-pyrazolone-1-carbothioamide) have been synthesized by reacting K2MCl4 (M = Pd, Pt) or Pd(OAc)(2) with beta-ketoester thiosemicarbazones. The structures of seven of these complexes were determined by X-ray diffraction. Although all exhibit a distorted square-planar coordination with trans- or (in one case) cis-[MN2S2] kernels, their supramolecular arrangements vary widely from isolated molecules to 3D-networks. The in vitro antitumoral assays performed with two HL ligands and their metal complexes showed significant cytostatic activity for the latter, with the most active [ML2] derivative (a palladium complex) being about sixteen times more active than cis-DDP against the cis-platinum-resistant cell line A2780cisR. (c) 2007 Elsevier Inc. All rights reserved.

Dithiocarbazate complexes with the [M(PPh(3))](2+) (M=Pd or Pt) moiety Synthesis, characterization and anti-Tripanosoma cruzi activity

New neutral Pd(II) and Pt(II) complexes of the type [M(L)(PPh(3))] (M Pd or Pt) were prepared in crystalline form in high-yield synthesis with the S-benzyldithiocarbazates and S-4-nitrobenzyldithiocarbazates derivatives from 2-hydroxyacetophenone, H(2)L(1a) and H(2)L(1b), and benzoylacetone, H(2)L(2a) and H(2)L(2b). The new complexes [Pt(L(1a))(PPh(3))] (1), [Pd(L(1a))(PPh(3))] (2), [Pt(L(1b))(PPh(3))] (3), [Pd(L(1b))(PPh(3))] (4), [Pt(L(2a))(PPh(3))] (5), [Pd(L(2a))(PPh(3))] (6), [Pt(L(2b))(PPh(3))] (7) and [Pd(L(2b))(PPh(3))] (8) were characterized on the basis of elemental analysis, conductivity measurements, UV-visible, IR, electrospray ionization mass spectrometry (ESI-MS), NMR ((1)H and (31)P) and by X-ray diffraction studies. The studies showed that differently from what was observed for the H(2)L(1a) and H(2)L(1b) ligands, H(2)L(2a) and H(2)L(2b) assume cyclic forms as 5-hydroxypyrazolinic. Upon coordination, H2L2a and H2L2b suffer ring-opening reaction, coordinating in the same manner as H(2)L(1a) and H(2)L(1b), deprotonated and in O,N,S-tridentate mode to the (MPPh(3))(2+) moiety. All complexes show a quite similar planar fourfold environment around the M(II) center. Furthermore, these complexes exhibited biological activity on extra and intracellular forms of Trypanosoma cruzi in a time- and concentration-dependent manner with IC(50) values ranging from 7.8 to 18.7 mu M, while the ligand H(2)L(2a) presented a trypanocidal activity on trypomastigote form better than the standard drug benznidazole. (C) 2010 Elsevier Inc. All rights reserved.

Antimycobacterial and antitumor activities of Palladium(II) complexes containing isonicotinamide (isn): X-ray structure of trans-[Pd(N(3))(2)(isn)(2)]

Complexes of the type trans-[PdX(2)(isn)(2)] {X = Cl (1), N(3) (2), SCN (3), NCO (4); isn = isonicotinamide} were synthesized and evaluated for in vitro antimycobacterial and antitumor activities. The coordination mode of the isonicotinamide and the pseudohalide ligands was inferred by IR spectroscopy. Single crystal X-ray diffraction determination on 2 showed that coordination geometry around Pd(II) is nearly square planar, with the ligands in a trans configuration. All the compounds demonstrated better in vitro activity against Mycobacterium tuberculosis than isonicotinamide and pyrazinamide. Among the complexes, compound 2 was found to be the most active with MIC of 35.89 mu M. Complexes 1-4 were also screened for their in vitro antitumor activity towards LM3 and LP07 murine cancer cell lines. (C) 2010 Elsevier Masson SAS. All rights reserved.

Catecholase and DNase activities of copper(II) complexes containing phenolate-type ligands

Three new homodinuclear complexes containing substituted phenolate-type ligands based on the N(5)O(2) donor (2-(N,N-Bis(2-pyridylmethyl)aminomethyl)-6-(N`,N`-(2-hydroxybenzyl)(2-pyridylmethyl))aminomethyl)-4-methylphenol (H(2)L-H) were synthesized and characterized by X-ray crystallography. Potentiometric titration studies in 70% (v/v) aqueous ethanol show that all three complexes exhibit a common {Cu(II)(mu-phenoxo)(mu-OH)Cu(II)(OH)} core in solution. Kinetic studies on the oxidation reaction of 3,5-di-tert-butylcatechol revealed that the catalytic activity of the metal complexes increases toward the ligand containing an electron-donating group. In addition, these complexes also carried out DNA cleavage by hydrolytic and oxidative pathways. Copyright (C) 2010 John Wiley & Sons, Ltd.

Spectroscopic investigation of the interactions between emeraldine base polyaniline and Eu(III) ions

The interactions of emeraldine base form of polyaniline (EB-PANI) and Eu(III) ions in 1-methyl-2-pyrrolidinone (NMP) solution and in films have been investigated by UV-vis-NIR, resonance Raman. luminescence and electron paramagnetic resonance (EPR) spectroscopies. These spectroscopic techniques allowed to characterize quinone and semiquinone segments in the polymeric chains. and the oxidation state of europium ions in Eu-PANI samples. For high values of Eu(III)/N molar ratio (24/1) the presence of a weak polaronic absorption band at 980 nm in UV-vis-NIR spectrum and the observation of bands at 1330 and 1378 (nu(center dot)(C-N+)) cm(-1) due to emeraldine salt in the Raman spectrum at 1064 nm indicate a low doping degree. Oxidation of EB-PANI to pernigraniline base (PB-PANI) occurs in diluted solutions. The experimental data showed that the solvent plays an important role on the nature of formed species. The narrow EPR signal at g = 2.006 (line width 8G) confirms the presence of PANI radical cations in Eu-PANI film. The absence of broad signal characteristic of Eu(II) in EPR spectrum suggested that europium ions are primarily at Eu(III) oxidation state. The luminescence spectra of Eu-PANI film presented emission bands at 405 and 418 nm assigned to PANI moieties and bands at 594,615 and 701 nm assigned to (5)D(0) -> (7)F(J) (J = 1, 2 and 4, respectively) transitions of Eu(III). EPR and photoluminescence data confirm that europium ions are mainly in Eu(III) oxidation state in Eu(III)/PANI films. (C) 2008 Elsevier B.V. All rights reserved.

Triangular ruthenium acetate clusters containing the bis(pyridyl)propane ligand and their inclusion chemistry with beta-cyclodextrin

The triruthenium carboxylate cluster [Ru(3)O(OAc)(6)(py)(2)(bpp)](+) (OAc = acetate) containing the bridging 1,3-bis(4-pyridyl)propane (bpp) ligand, and its dimeric species [{Ru(3)O(OAc)(6)(py(2))}(2)(mu-bpp)](2+) were synthesized in order to investigate their inclusion compounds with beta-cyclodextrin (beta-CD). Characterization of the complexes was carried out based on spectroscopic, electrochemical and spectroelectrochemical techniques, while the formation of inclusion complexes was evaluated using (1)H NMR/NOESY spectroscopy. Since bpp is a flexible ligand, a DFT study was carried out in order to characterize its conformational isomers and their possible role in the host-guest chemistry with beta-CD. Instead of observing the formation of inclusion compounds with different stoichiometries, we observed the formation of 1:1 bpp/beta-CD compounds in which the bpp ligand assumes different conformations. The assembly of polymetallic rotaxane species was successfully demonstrated by monitoring the (1)H NMR spectra of the monomeric cluster species in the presence of aquapentacyanoferrate(II) ions and beta-CD.

Synthesis, spectroscopic characterization and X-ray structures of five-coordinate diorganotin(IV) complexes containing 5-hydroxypyrazoline derivatives as ligands

Four new diorganotin(IV) complexes have been prepared from R(2)SnCl(2) (R = Me, Ph) with the ligands 5-hydroxy-3-metyl-5-phenyl-1-(S-benzildithiocarbazate)-pyrazoline (H(2)L(1)) and 5-hydroxy-3-methyl-5-phenyl-1-(2-thiophenecarboxylic)-pyrazoline (H(2)L(2)). The complexes were characterized by elemental analysis, IR. (1)H (13)C, (119)Sn NMR and Mossbauer spectroscopes The complexes [Me(2)SnL(1)], [Ph(2)SnL(1)] and [Me(2)SnL(2)] were also studied by single crystal X-ray diffraction and the results showed that the Sn(IV) central atom of the complexes adopts a distorted trigonal bipyramidal (TBP) geometry with the N atom of the ONX-tridentate (X = O and S) ligand and two organic groups occupying equatorial sites. The C-Sn-C angles for [Me(2)Sn(L(1))] and [Ph(2)Sn(L(1))] were calculated using a correlation between (119)Sn Mossbauer and X-ray crystallographic data based on the point-charge model Theoretical calculations were performed with the B3LYP density functional employing 3-21G(*) and DZVP all electron basis sets showing good agreement with experimental findings General and Sn(IV) specific IR harmonic frequency scale factors for both basis sets were obtained from comparison with selected experimental frequencies (C) 2010 Elsevier B V All rights reserved

Synthesis, Structural Characterization, and Biological Evaluation of Oxorhenium(V) Complexes with a Novel Type of Thiosemicarbazones Derived from N-[N `,N `-Dialkylamino(thiocarbonyl)]benzimidoyl Chlorides

Reactions of N-[N`,N`-diethylamino(thiocarbonyl)]benzimidoyl chloride with 4,4-dialkylthiosemicarbazides give a novel class of thiosemicarbazides/thiosemicarbazones, H(2)L, which causes a remarkable reduction of cell growth in in vitro experiments. These strong antiproliferative effects are also observed for oxorhenium(V) complexes of the general composition [ReOCl(L)], which are formed by reactions of the potentially tridentate ligands with (NBu(4))[ReOCl(4)]. A systematic substitution of the alkyl groups in the thiosemicarbazone building blocks of the ligands do not significantly influence the biological activity of the metal complexes, while the replacement of the chloro ligand by a PPh(3) ligand (by the replacement of the oxo unit by a nitrido ligand) completely terminated the cytotoxicity of the metal complexes.

Oxotechnetium(V) Complexes with a Novel Class of Tridentate Thiosemicarbazide Ligands

A novel tridentate thiosemicarbazide-type ligand class with an SNS donor set, H(2)L(1), was prepared by reactions of N-[N`,N`-dialkylamino(thiocarbonyl)]benzimidoyl chlorides with thiosemicarbazides. H(2)L(1) ligands readily react with (NBu(4))[TcOCl(4)] in MeOH under the formation of red oxotechnetium(V) complexes of composition [TcOCl(L(1))]. The monomeric, five-coordinate compounds are air-stable and bind (L(1))(2-) tridentate in the equatorial coordination sphere. The compounds represent the first examples of oxotechnetium(V) complexes with NS chelate-bonded thiosemicarbazones.

Development of a new analytical approach based on cellulose membrane and chelator for differentiation of labile and inert metal species in aquatic systems

A new procedure was developed in this study, based on a system equipped with a cellulose membrane and a tetraethylenepentamine hexaacetate chelator (MD-TEPHA) for in situ characterization of the lability of metal species in aquatic systems. To this end, the DM-TEPHA system was prepared by adding TEPHA chelator to cellulose bags pre-purified with 1.0 mol L-1 of HCl and NaOH solutions. After the MD-TEPHA system was sealed, it was examined in the laboratory to evaluate the influence of complexation time (0-24 h), pH (3.0, 4.0, 5.0, 6.0 and 7.0), metal ions (Cu, Cd, Fe, Mn and Ni) and concentration of organic matter (15, 30 and 60 mg L-1) on the relative lability of metal species by TEPHA chelator. The results showed that Fe and Cu metals were complexed more slowly by TEPHA chelator in the MD-TEPHA system than were Cd, Ni and Mn in all pH used. It was also found that the pH strongly influences the process of metal complexation by the MD-TEPHA system. At all the pH levels, Cd, Mn and Ni showed greater complexation with TEPHA chelator (recovery of about 95-75%) than did Cu and Fe metals. Time also affects the lability of metal species complexed by aquatic humic substances (AHS); while Cd, Ni and Mn showed a faster kinetics, reaching equilibrium after about 100 min, and Cu and Fe approached equilibrium after 400 min. Increasing the AHS concentration decreases the lability of metal species by shifting the equilibrium to AHS-metal complexes. Our results indicate that the system under study offers an interesting alternative that can be applied to in situ experiments for differentiation of labile and inert metal species in aquatic systems. (c) 2006 Elsevier B.V. All rights reserved.

A broad study of two new promising antimycobacterial drugs: Ag(I) and Au(I) complexes with 2-(2-thienyl)benzothiazole

Synthesis, characterization, DFT simulation and biological assays of two new metal complexes of 2-(2-thienyl)benzothiazole - BTT are reported. The complexes [Ag(BTT)(2)NO3] - AgBTT2 and [Au(BTT)Cl]center dot 1/2H(2)O - AuBTT were obtained by mixing the ligand with silver (I) nitrate or gold(I) chloride in methanolic solution. Characterization of the complexes were based on elemental (C, H, N and S), thermal (TG-DTA) analysis, C-13 and H-1 NMR, FT-IR and UV-Vis spectroscopic measurements, as well as the X-ray structure determination for AgBTT2. Spectroscopic data predicted by DFT calculations were in agreement with the experimental data for both complexes. The ligand BTT was synthesized by the condensation of 2-thiophenecarboxaldehyde and 2-aminothiophenol in a microwave furnace. AgBTT2 has a monomeric structure. Both complexes show a good activity against Mycobacterium tuberculosis. Free BIT shows low antitubercular activity. (C) 2012 Elsevier Ltd. All rights reserved.

Nanoparticles of octakis [3-(3-amino-1,2,4-triazole)propyl] octasilsesquioxane as ligands for Cu(II), Ni(II), Cd(II), Zn(II), and Fe(III) in aqueous solution

Nanoparticles of octakis[3-(3-amino-1,2,4-triazole)propyl]octasilsesquioxane (ATZ-SSQ) were tested as ligands, for transition-metal ions in aqueous solution with a special attention to sorption isotherms, ligand-metal interaction, and determination of metal ions in natural waters. The adsorption potential of the material ATZ-SSQ was compared with related [3(3-amino-1,2,4-triazole)propyl]silica gel (ATZ-SG). The adsorption was performed using a batchwise process and both organofunctionalized surfaces showed the ability to adsorb the metal ions from aqueous solution. The Langmuir model was used to simulate the sorption isotherms. The results suggest that the sorption of these metals on ATZ-SSQ and ATZ-SG occurs mainly by surface complexation. The equilibrium condition is reached at time lower than 3 min for ATZ-SSQ, while for ATZ-SG is only reached at time of 25 min. The maximum metal ion uptake values for ATZ-SSQ were higher than the corresponding values achieved with the ATZ-SG. In order to obtain more information on the ligand-metal interaction of the complexes on the surface of the ATZ-SSQ nanomaterial, ESR study with various degrees of copper loadings was carried out. The ATZ-SSQ was tested for the determination (in flow using a column technique) of the metal ions present in natural waters. (C) 2007 Elsevier B.V. All rights reserved.