- Synthesis of NNNN tetradentate macrocyclic ligand and its Pd(II), Pt(II), Ru(III), and Ir(III) complexes: Spectroscopic, Thermal, and antimicrobial studies
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Pd(II), Pt(II), Ru(III), and Ir(III) complexes of general stoichiometry [PdL]Cl2, [PtL]Cl2, [Ru(L)Cl2]Cl, and [Ir(L)Cl2]Cl, with tetradentate macrocyclic ligand, derived from 2,6-diaminopyridine with 3-methyl 2,4-pentanedione has been synthesized. The ligand was characterized on the basis of elemental analyses, IR, mass, and 1H NMR and 13C NMR spectral studies. All the complexes were characterized by elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, mass, electronic spectral techniques, and thermal studies. The value of magnetic moments indicates that all the complexes are diamagnetic except Ru(III) complex, which shows magnetic moments corresponding its one unpaired electron. The macrocyclic ligand and all its metal complexes were tested in vitro against some plant pathogenic fungi and bacteria to assess their biocidal properties. Copyright Taylor & Francis Group, LLC.
- Rani, Soni,Kumar, Sumit,Chandra, Sulekh
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- New metal complexes of N3 tridentate ligand: Synthesis, spectral studies and biological activity
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New tridentate ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2phenyl-2,3-dihydro-1H-pyrazol-4-ylazo}-phenol L was synthesized from the reaction of 1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine and 3.4-amino phenol. A complexes of these ligand [Ni(II)(L)(H2O)2Cl]Cl, [pt(IV)(L)Cl3]Cl and [M(II)(L)Cl]Cl (M = Pd (II), Zn (II), Cd (II) and Hg (II) were synthesized. The complexes were characterized by spectroscopic methods and magnetic moment measurements, elemental analysis, metal content, Chloride containing and conductance. These studies revealed octahedral geometries for the Ni (II), pt (IV) complexes, square planar for Pd (II) complex and tetrahedral for the Zn (II), Cd(II) and Hg (II) complexes. The study of complexes formation via molar ratio and job method in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M:L) as (1:1). The thermodynamic parameters, such as ΔE?, ΔH?, ΔS?ΔG?and K are calculated from the TGA curve using Coats-Redfern method. Hyper Chem-8 program has been used to predict structural geometries of compounds in gas phase. The synthesized ligand and its metal complexes were screened for their biological activity against bacterial species, two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and Pseudomonas aeruginosa).
- Al-Hamdani, Abbas Ali Salih,Al Zoubi, Wail
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- Kinetics and mechanism of the inner-sphere reduction of hexachloroplatinate(IV) by dithionite in acetate buffer
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The kinetics of reduction of hexachloroplatinate( IV) by dithionite have been examined spectrophotometrically in sodium acetate-acetic acid buffer medium in the temperature range 288-303 K. The reaction is first order in both platinum(IV) species and dith
- Pal, Biswajit,Gupta, Kalyan K. Sen
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- The permanent electric dipole moment of PtO, PtS, PtN, and PtC
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The permanent electric dipole moments of the ground, and the low-lying excited electronic states of platinum monocarbide, PtC, platinum monoxide, PtO, and platinum monosulfide, PtS, were measured using a molecular beam optical Stark spectroscopic scheme.The determined values were (in Debye): PtO(X 3Σ-) 2.77(2); PtO(A 1Σ+) 1.15(4); PtS 1.78(2); PtS 0.54(6); PtC(X 1Σ+) 0.99(5); and PtC(A 1Π) 2.454(3).These results, along with the previous results for PtN(X 2Π1/2) 1.977(9); PtN(d 4Π1/2) 1.05(9) , are used as basis for a discussion of the nature of the electronic states.
- Steimle, T. C.,Jung, K. Y.,Li, B.-Z.
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- Influence of C-H/X (X = S, Cl, N, Pt/Pd) Interactions on the Molecular and Crystal Structures of Pt(II) and Pd(II) Complexes with Thiomorpholine-4-carbonitrile: Crystallographic, Thermal, and DFT Study
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Pt(II) and Pd(II) complexes (1 and 2, respectively) with thiomorpholine-4-carbonitrile (TM-CN), an N-substituted thiomorpholine derivative, were synthesized from tetrachlorido precursors in water. Structural analysis has shown that 1 represents the first monomeric metal complex with this ligand type with an axial M-S bond with respect to the TM-CN ring chair conformation, while in 2 a typical equatorial M-S bond position with respect to the ring chair conformation was observed. A detailed DFT investigation revealed that axial conformers are more stable for molecular forms of both metals, while intermolecular interactions in the crystals stabilize the axial conformer for Pt(II) and the equatorial conformer for Pd(II). The magnitude of this stabilization in the case of 2 is large enough to change the most stable axial conformer in the molecular form to the equatorial conformer in the crystal. Further investigation of the strength of individual intermolecular interactions revealed significant differences of some interactions between the two structures. The likely cause of the difference in the crystal structures of experimentally obtained complexes is the fact that 1 and 2 exhibit different dominant interactions: C-H/M and C-H/S are more dominant in 1 and C-H/Cl interactions are more dominant in 2. In addition, DFT calculations have shown that while the axial position of the Pt-S bond with respect to the ring chair conformation results in a significantly shorter C-H/Pt interaction distance than that in the hypothetical equatorial conformer, there is very little difference in C-H/Pd interaction distances in conformers with axial and equatorial positions of Pd-S bond with respect to the ring chair conformation.
- Blagojevi?, Vladimir,Chylewska, Agnieszka,Donnard, Morgan,Filipovi?, Nenad,Gulea, Mihaela,Janji?, Goran,Makowski, Mariusz,Risti?, Predrag,Rodi?, Marko,Todorovi?, Tamara,Vuli?, Predrag
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- Study of Photoreduction of PtCl62- on CdS
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The photoinduced reduction of PtCl62- on CdS was investigated by means of XPS, DTA, and TEM.The experimental results indicate that the photoreduced product of PtCl62- on CdS is PtS in acidic solution and Pt(OH)2 in basic solution.PtS
- Li, Qinglin,Chen, Zhengshi,Zheng, Xinhua,Jin, Zhensheng
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- The color, photophysical and electrochemical properties of azo-imine ligands and their copper(II) and platinium(II) complexes
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Five novel imine based organic ligands (HL1-HL5) and their Cu2+ and Pt2+ metal complexes have obtained and characterized by the micro-analyses, 1H(13C)NMR, Uv–Vis absorption, emission-excit
- Onur, Sultan,Güng?r, Seyit Ali,Tümer, Ferhan,Tümer, Mehmet
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- New Ni(II), Pd(II) and Pt(II) complexes coordinated to azo pyrazolone ligand with a potent anti-tumor activity: Synthesis, characterization, DFT and DNA cleavage studies
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The absolute necessity to fight some class of tumor is perceived as serious health concerns, so the discovery and development of effective anticancer agents are urgently needed. (E)-4-((2-hydroxyphenyl)diazenyl)-3-phenyl-1H-pyrazol-5(4H)-one, HL, and its Ni(II), Pd(II) and Pt(II) complexes were synthesized and the biological activity was evaluated for antitumor, antioxidant and antimicrobial activity as well as DNA cleavage. Their structures were assigned depending on the elemental analysis, conductivity, magnetic moment, spectral measurements (IR, 1HNMR, mass and UV–Vis) and thermal analysis. 3D molecular modeling using DFT method confirmed that the geometrical structures agree well with the suggested experimental ones. The antitumor activity was evaluated against four different cell lines using MTT assay. The ligand HL showed a potent cytotoxic activity compared to 5-fluorouracil as a reference drug. For metal complexes, the order of activity was: Pd(II)?>?Ni(II)?>?Pt(II). A remarkable antioxidant activity for the ligand HL was recorded. It was higher than that of the metal complexes. Results of antimicrobial experiments revealed that all compounds were moderate to highly active against selected bacterial strains but inactive as antifungal except Pd(II) which showed a moderate antifungal activity. Gel electrophoresis showed insignificant nucleases activity for the ligand or its metal complexes even in the presence of H2O2 providing protection of DNA from damage. The antitumor activity of our compounds may be not due to DNA cleavage but may be referred to a mechanism similar to that of 5-fluorouracil which interfere with DNA replication. The present work suggests the use of this ligand in the design and development of new anticancer drugs.
- Bakr, Eman A.,Al-Hefnawy, Gad B.,Awad, Mohamed K.,Abd-Elatty, Hossam H.,Youssef, Mohamed S.
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- Quantitative determination of the catalytic activity of bulk metal oxides for formic acid oxidation
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The dissociative chemisorption of formic acid to surface formate species on metal oxide catalysts was studied. Comparison of the number of active surface sites for bulk metal oxides yielded similar adsorption surface site densities for the majority of samples studied, ~ 5-6 μmole HCOOads/sq m. Kinetic studies of formic acid oxidation made possible the determination of the apparent activation energies for the various metal oxide catalysts for formic acid oxidation. The turnover frequencies (TOF) values for the various metal oxide catalysts studied varied over 11 orders of magnitude. A strong inverse relationship was observed between the TOF values and the decomposition temperatures of the surface formate intermediates, indicating that the thermal stability of the surface formate intermediate is the only significant kinetic factor. Thus, dissociative adsorption of the formic acid molecule is not kinetically significant for kinetic activity during formic acid oxidation over the metal oxide catalysts. The surfaces of the metal oxide catalysts studied were also oxidized, analogous to in situ Raman observation made with V2O5 and MoO3 during methanol oxidation, since methanol and formic acid both lose two hydrogen atoms during oxidation to H2CO and CO2, respectively.
- Wachs,Fein
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- Metal complexes of chalcone analogue: Synthesis, characterization, DNA binding, molecular docking and antimicrobial evaluation
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A novel chalcone, namely 5-(4-(dimethylamino)phenyl)-1-(thiophen-2-yl)penta-2,4-dien-1-one, DMATP, and its complexes with nickel(II), vanadium(III), palladium(II) and platinum(II) metal ions were synthesized and characterized using a set of chemical and spectroscopic tools including elemental analysis, electrical conductance, magnetic susceptibility and spectral techniques. The interactions of the synthesized chalcone and its metal complexes with DNA were studied using steady-state absorption and emission techniques as well as viscosity and electrochemical measurements. The obtained results confirm DNA intercalation. Additionally, theoretical studies were performed for all the investigated compounds using DFT/B3LYP calculations. The optimized geometries are found to be in good agreement with the suggested experimental structures. The bond lengths, bond angles, chemical reactivity, energy components, binding energy and dipole moment were evaluated. Also, theoretical infrared intensities and thermodynamic parameters for all compounds were calculated. Molecular docking calculations show that the Ni(II) complex exhibits the highest DNA binding activity, which agrees well with the experimental results. Finally, the compounds were screened for antimicrobial activity using several microorganisms.
- Atlam, Faten M.,El-Nahass, Marwa N.,Bakr, Eman A.,Fayed, Tarek A.
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- Synthesis, spectral, thermal and antibacterial studies of schiff base complexes derived from tyrosine and benzaldehyde
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In order to develop more potent and novel antibacterial agents, a Schiff base derived from tyrosine and benzaldehyde was prepared along with its Cu(II), Pd(II) and Pt(II) complexes. Formation and purity of the ligand L-1 was determined by1H NMR and elemental analysis along with other analytical techniques like FTIR, UV-Vis spectroscopies, XRD and TGA/DSC analysis. The chemical structures of the prepared Schiff base-metal complexes were suggested depending upon the results obtained from FTIR, UV-Visible spectroscopy, XRD,1H NMR, CHN and TGA/DSC analyses. Analytical data revealed that the Schiff base ligand L-1, can coordinate in the bidentate manner with the metal ions via N and O atoms resulting in the formation of Cu(II), Pd(II) and Pt(II) complexes with 1:2 stoichiometry. Thermal analysis results explained the general decomposition pattern of the prepared compounds and the presence of water molecule in the prepared ligand and its complexes. The crystalline nature of the compounds was confirmed by the powder XRD analysis except for the platinum complex, which was amorphous. The in vitro antibacterial activity of the uncomplexed ligand L-1 and its complexes (Cu(II), Pd(II) and Pt(II)) was also evaluated against gram positive bacterium, Bacillus subtilis and gram negative bacterium, Pseudomonas aeruginosa by the well-diffusion method. Antibacterial activity of the prepared Schiff base ligand L-1 and its complexes was determined in terms of inhibition zones.
- Anjum, Rukhsana,Khan, Irfan Ullah,Khan, Bushra,Javed, Muhammad
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- Structures of polynuclear complexes of palladium(ii) and platinum(ii) formed by slow hydrolysis in acidic aqueous solution
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The aqua ions of palladium(ii) and platinum(ii) undergo extremely slow hydrolysis in strongly acidic aqueous solution, resulting in polynuclear complexes. The size and structures of these species have been determined by EXAFS and small angle X-ray scattering, SAXS. For palladium(ii), the EXAFS data show that the Pd-O and Pd?Pd distances are identical to those of crystalline palladium(ii) oxide, but the intensities of the Pd?Pd distances in the Fourier transform at 3.04 and 3.42 ? are significantly lower compared to those of crystalline PdO. Furthermore, no Pd?Pd distances beyond 4 ? are observed. These observations strongly indicate that the polynuclear palladium(ii) complexes are oxido- and hydroxido-bridged species with the same core structure as solid palladium(ii) oxide. Based on the number of Pd?Pd distances, as derived from the EXAFS data, their size can be estimated to be approximately two unit cells, or ca. 1.0 nm3. For platinum(ii), EXAFS data of the polynuclear species formed in the slow hydrolysis process show Pt-O and Pt?Pt distances identical to those of amorphous platinum(ii) oxide, precipitating from the solution studied. The Pt?Pt distances are somewhat different from those reported for crystalline platinum(ii) oxide. The polynuclear platinum(ii) complexes have a similar structure to the palladium ones, but they are somewhat larger, with an estimated diameter of 1.5-3.0 nm. It has not been possible to precipitate any of these species by ultracentrifugation. They are detectable by SAXS, indicating diameters between 0.7 and 2 nm, in excellent agreement with the EXAFS observations. The number of oxido- relative to hydroxido bridges will increase with increasing size of the complex. The charge of the complexes will remain about the same, +4, at growth, with approximate formulas [Pd10O 4(OH)8(H2O)12]4+ and [Pt14O8(OH)8(H2O)12] 4+ for complexes with a size of 2 and 3 unit cells of the corresponding solid metal oxide, respectively. Their high ionic charge in acidic aqueous solution will result in a stabilizing hydration shell. The Royal Society of Chemistry 2013.
- Torapava, Natallia,Elding, Lars I.,M?ndar, Hugo,Roosalu, Kaspar,Persson, Ingmar
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p. 7755 - 7760
(2013/07/28)
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- N6-benzyladenosine derivatives as novel n-donor ligands of platinum(ii) dichlorido complexes
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The platinum(II) complexes trans-[PtCl2(Ln)2]·xSolv 1-13 (Solv = H2O or CH3OH), involving N6-benzyladenosine-based N-donor ligands, were synthesized; Ln stands for N6-(2-methoxybenzyl)adenosine (L1, involved in complex 1), N6-(4-methoxybenzyl) adenosine (L2, 2), N6-(2-chlorobenzyl)adenosine (L3, 3), N6-(4-chlorobenzyl)- adenosine (L4, 4), N6-(2-hydroxybenzyl)adenosine (L5, 5), N6-(3-hydroxybenzyl)- adenosine (L6, 6), N6-(2-hydroxy-3-methoxybenzyl) adenosine (L7, 7), N6-(4-fluorobenzyl) adenosine (L8, 8), N6-(4-methylbenzyl) adenosine (L9, 9), 2-chloro-N6-(3-hydroxybenzyl) adenosine (L10, 10), 2-chloro-N6-(4-hydroxybenzyl)adenosine (L11, 11), 2-chloro- N6-(2-hydroxy-3- methoxybenzyl)adenosine (L12, 12) and 2-chloro-N6-(2-hydroxy-5- methylbenzyl)adenosine (L13, 13). The compounds were characterized by elemental analysis, mass spectrometry, IR and multinuclear (1H-, 13C-, 195Pt- and 15N-) and two-dimensional NMR spectroscopy, which proved the N7-coordination mode of the appropriate N6-benzyladenosine derivative and trans-geometry of the title complexes. The complexes 1-13 were found to be non-toxic in vitro against two selected human cancer cell lines (HOS and MCF7; with IC50 > 50.0 μM). However, they were found (by ESI-MS study) to be able to interact with the physiological levels of the sulfur-containing biogenic biomolecule L-methionine by a relatively simple 1:1 exchange mechanism (one Ln molecule was replaced by one L-methionine molecule), thus forming a mixed-nitrogen/sulfur-ligand dichlorido-platinum(II) coordination species.
- Starha, Pavel,Popa, Igor,Travnicek, Zdenek,Vanco, Jan
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supporting information
p. 6990 - 7003
(2013/07/26)
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- Synthesis, spectroscopic, and thermal properties of some azomethine complexes of Cu(II), Ni(II), and Pt(II)
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Four polydentate azomehines and their monoand binuclear Pt(II), Cu(II), and Ni(II) complexes were synthesized and characterized. The resulting complexes were characterized by FTIR, magnetic measurements, elemental analysis, conductivity measurements, and thermal analysis. Electronic spectra and magnetic susceptibility measurements sustain the proposed distorted squareplanar structures for the copper complexes. The electronic spectra display the characteristic pattern of square-planar stereochemistryfor the other complexes. The thermal analyses have evidenced the therma l intervals of stability and also the thermodynamic effects that accompany them. Azomethine complexes have a similar thermal behavior for the selected metal ions. The decomposition processes as water elimination, chloride anion removal as well as degradation of the organic ligands were observed.
- Turkyilmaz, Murat,Onder, Alper,Baran, Yakup
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p. 991 - 998
(2012/10/08)
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- Preparation of a Pt/SiO2 catalyst: II. Temperature-programmed decomposition of the adsorbed platinum tetrammine hydroxide complex under flowing hydrogen, oxygen, and argon
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The temperature-programmed decomposition of platinum tetrammine hydroxide mixed with or exchanged on silica in a flow of neutral, oxidizing, or reducing gas is studied using mass-spectrometric analysis of the effluent. A unified interpretation mechanism is proposed whatever the nature of the gas. It involves (≡SiO)2Pt(NH3)y with y ≈ 2 as the intermediate species. This species anchors the particles defined at the drying step. Anchoring takes place at 100-150°C whatever the gas. The subsequent decomposition of this species leads either to Pt(0) (reducing gas), mobile PtO (oxidizing gas), or a mixture of both (neutral gas). The dispersion of the platinum particles ranges between 70 and 80% for metal loading up to 5% when the decomposition is performed under the reducing gas up to 500°C. In the neutral gas, the dispersion ranges from 42 to 72% and depends on the final temperature and on metal loading. In an oxidizing gas, the dispersion can be about 65% provided that the final temperature does not exceed 250°C. Subsequent reduction at a higher temperature reproduces the decomposition under the reducing gas. When the final temperature is raised above 250°C in the oxidizing gas, the dispersion decreases and falls to 20% at 500°C. It is proved that PtO is responsible for low dispersions. Conversely, under reducing conditions, the size of the particles obtained upon drying is kept unchanged. The proposed mechanism explains why a neutral gas gives intermediate results that depend on pressure and metal loading. In the case of high metal loading, decomposition under the reducing gas leads too small particles grouped together, although dispersion remains within 70-80%.
- Goguet,Schweich,Candy
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p. 280 - 290
(2008/10/09)
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- Precious metal-molecular oxygen complexes: Neon matrix infrared spectra and density functional calculations for M(O2), M(O2)2 (M = Pd, Pt, Ag, Au)
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Laser-ablated palladium, platinum, silver, and gold atoms react with molecular oxygen in excess neon during condensation at 4 K. Reaction products, M-(η2-OO), M-(η2-OO)2 (M = Pd, Pt), PtO, PtO2, AuO2,
- Wang, Xuefeng,Andrews, Lester
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p. 5812 - 5822
(2007/10/03)
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