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Platinum
Terms modified by Platinum Selected AbstractsDinuclear Iridium(III) Complexes Linked by a Bis(,-diketonato) Bridging Ligand: Energy Convergence versus Aggregation-Induced EmissionEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2010Chang Hwan Shin Abstract Novel iridium(III)/iridium(III) and iridium(III)/platinum(II) dinuclear complexes, [{Ir(ppyFF)2}2(,2 - L)] (4) and [{Ir(ppyFF)2}(,2 - L){Pt(ppy)}] (5) [ppyFF = 2-(2,4-difluorophenyl)pyridine, ppy = 2-phenylpyridine, L = 1,3-bis(3-phenyl-3-oxopropanoyl)benzene], linked by an L bridging ligand were prepared, and their photophysical properties were investigated in solution and in the solid state. The photophysical properties of mononuclear iridium(III) and platinum(II) complexes, [Ir(ppyFF)2(dbm)] (1) and [Pt(ppy)(dbm)] (2) bearing a dibenzoylmethane (dbm) ligand were also compared. Whereas the UV/Vis absorption spectra of 4 and 5 show independent light absorption at each metal-centered moiety, the photoluminescence spectra of 4 and 5 display almost identical features, but very weak emissions in solution at both room temperature and 77 K. The weak emission in solution is found to mainly originate from a 3LX state of the L bridging ligand, which reflects the occurrence of efficient energy convergence from the triplet states of the Pt(ppy) and Ir(ppyFF) moieties to the 3LX state of L. By contrast, intense orange-red emission, that is, aggregation-induced emission, is produced in the solid state of 4 and 5. Inspection of the crystal-packing structures of 5 reveals that strong intermolecular ,,, interactions between the adjacent pyridine rings of ppyFF ligands in the Ir-centered moieties are responsible for the emissive metal-to-ligand,ligand charge-transfer [3M(LL)CT] state of the solid-state dinuclear systems. The electrochemical properties of 4 and 5 further indicate that the first two reductions occur at the dbm moieties of the L bridging ligand linked to each metal center, which is consistent with the fact that the lowest-energy excited state of the L bridging ligand dominates the excited-state properties of 4 and 5 in solution. [source] PALLADIUM, PLATINUM: Road to Recovery?AFRICA RESEARCH BULLETIN: ECONOMIC, FINANCIAL AND TECHNICAL SERIES, Issue 12 2010Article first published online: 9 FEB 2010 No abstract is available for this article. [source] Effect of Platinum and Ruthenium Incorporation on Voltammetric Behavior of Nitrogen Doped Diamond-Like Carbon Thin FilmsELECTROANALYSIS, Issue 23 2009W. Khun Abstract Nitrogen doped diamond-like carbon thin films with or without platinum and ruthenium incorporation (N-DLC or PtRuN-DLC) were deposited on highly conductive p-Si substrates by DC magnetron sputtering to study the effect of Pt and Ru doping on the voltammetric performance of the N-DLC films. The potential windows of these film electrodes were measured in different electrolytic solutions, such as H2SO4, HCl and KCl. The cyclic voltammograms obtained from the N-DLC film electrodes in these solutions showed wide potential windows while the introduction of Pt and Ru into the film electrodes apparently narrowed down the potential windows due to their catalytic activities. [source] Determination of Platinum with Thiosemicarbazide by Catalytic Adsorptive Stripping Voltammetry (AdSV)ELECTROANALYSIS, Issue 4 2005Sylwester Huszal Abstract This work describes a very sensitive and selective voltammetric procedure for the determination of platinum. Instead of commonly used hydrazine, thiosemicarbazide as a component of supporting electrolyte was applied. The method is based on adsorption of platinum-thiosemicarbazone complex, formed in situ in voltammetric cell from thiosemicarbazide and formaldehyde, coupled with a hydrogen catalytic reaction at a hanging mercury drop electrode. The linear relation between platinum concentration and height of analytical signal was observed up to 1.5×10,9,mol,L,1 with the detection limit calculated as 1.5×10,13,mol,L,1 (3,s of the blank) after 50,s of accumulation time. The effect of various interferences from other ions was studied. Described method was applied for platinum determination in hydroponically cultivated plants after microwave decomposition. [source] Therapy-related leukemia following chemoradiotherapy for esophageal cancerEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 4 2010Naoya Mimura Abstract Chemoradiotherapy has improved the outcome of patients with esophageal cancer. Although a sufficiently long-time survival has resulted in the increase of several treatment-related late toxicities, little is still known about the incidence of secondary malignancies. In our hospital, 348 patients with esophageal cancer received chemotherapy consisting of nedaplatin and 5-fluorouracil and concurrent irradiation. Median and average follow-up durations were 8 and 21 months (1,92), respectively. Four patients developed leukemia after 19,48 months of follow-up. Two patients were diagnosed with overt leukemia from myelodysplastic syndrome presenting a complex karyotype, including the deletion of chromosome 5 or 7. Notably, one patient showed an additional chromosomal abnormality with t(9;22)(q34;q11). Other patients developed acute myeloid leukemia with t(9;22)(q34;q11) and Burkitt leukemia with t(8;14)(q24;q32). All patients eventually succumbed to leukemia. Platinum and fluorouracil have shown relatively lower risks for secondary malignancies in comparison with alkylating agents and topoisomerase II inhibitors. Especially, nedaplatin has never been described to introduce secondary neoplasms. Our report supports the idea that the concurrent administration of radiotherapy with these agents affects the risk of leukemia. Interestingly, rare balanced chromosomal abnormalities were observed in the present cases, thus providing new insights into the leukemogenesis of therapy-related leukemia. [source] Platinum(IV) Complexes of 3- and 4-Picolinic Acids Containing Ammine or Isopropylamine Ligands , Synthesis, Characterization, X-ray Structures, and Evaluation of Their Cytotoxic Activity against Cancer Cell Lines,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008María J. Macazaga Abstract The preparation and characterization of the new complexes trans -[PtCl4(NH3)(3-picolinic acid)] (1), trans -[PtCl4{NH2CH(CH3)2}(3-picolinic acid)] (2), trans -[PtCl4(NH3)(4-picolinic acid)] (3), and trans -[PtCl4{NH2CH(CH3)2}(4-picolinic acid)] (4) are described. The main structural feature of these complexes is the presence of ligands capable of multiple hydrogen-bonding interactions. Crystals of 1, 2, 3, and 4 suitable for single-crystal X-ray diffraction were grown, and the molecular structures of these compounds are discussed. In contrast to the inactive parent PtII complexes, the PtIV complexes displayed cytotoxic activity against various cancer cell lines used at the National Cancer Institute (NCI) for in vitro screens. Once more, the isopropylamine derivatives showed the best cytotoxicity values. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] New Heterodimetallic Platinum(II) Complexes Potentially Useful as Molecular SwitchesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2008Sonia Pérez Abstract Four types of platinum(II) complexes of general formulae [Pt(FcCH=NC6H4OH-2)Cl2(L)] [Fc = (,5 -C5H5)Fe(,5 -C5H4), L = dmso (2) or PhCN (3)], [Pt(FcCH=NC6H4O-2)Cl(dmso)] (4), [Pt{(,5 -C5H3CH=NC6H4O-2)Fe(,5 -C5H5)}(L)] [L = dmso (5) or PPh3 (6)] or [Pt{(,5 -C5H3CH=NC6H4OH-2)Fe(,5 -C5H5)}Cl(L)] [L = dmso (7) or PPh3 (8)] have been prepared. These compounds differ in the mode of binding of the ligand: (N) (in 2 and 3), (N,O), (in 4), [C(sp2, ferrocene),N,O]2, (in 5 and 6) or [C(sp2, ferrocene),N], (in 7 and 8). NMR, UV/Vis and electrochemical studies of 2 and 4,8 reveal that these products can be grouped in three pairs [(2c, 4b), (5, 7) and (6, 8)], and one of the compounds of each pair can be easily converted into its partner by a H+/OH, chemical input. The results obtained revealed that these transformations, that affect the spectroscopic and electrochemical properties, are reversible and robust. A study of the relevancy of the mode of binding of compounds 2 and 4,8 upon their potential utility of the new platinum(II) complexes as molecular switches is reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] New Coordination Modes of L -Ascorbic Acid and Dehydro- L -ascorbic Acid as Dianionic Chelating Ligand for PlatinumEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2008Paola Bergamini Abstract A variety of coordination modes of L -ascorbic acid as an anionic bidentate ligand has been exploited to prepare platinum(II) complexes 1,7 that contain phosphanes or R,R -dach (1R,2R -diaminocyclohexane) as neutral ligands in which O2, O3, O5, O6 and C2 act as anionic donating functionalities. An alternative synthetic route to known O2,O3 complexes is proposed, and their solubility in water has been enhanced by introducing PTA (1,3,5-triaza-7-phosphaadamantane) as a neutral ligand. A new coordination mode of ascorbic acid (O2 and O3 protected) as an O5,O6-diolate chelating ligand has been characterised in solution by NMR spectroscopy and in the solid state by X-ray crystallography. The first example of a platinum complex that contains dehydroascorbic acid, 7, has also been prepared and its X-ray crystal structure has been determined. The antiproliferative activity in vitro of complexes 1,7 has been tested, and the best values were obtained for the DHA complex 7, which was found to be more active than cisplatin on both a cisplatin-sensitive and a cisplatin-resistant cell line.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Click Chelators for Platinum-Based Anticancer DrugsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2008Aurélie Maisonial Abstract Triazoles from "click chemistry" are convenient ligands for the formation of platinum complexes bearing combined triazole,amine or triazole,carboxylate moieties. Striking differences in the chelation modes are observed between the two series. One of the triazole,amine platinum complexes exhibits selective cytotoxicity against breast cancer cells lines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis of Polyamines from Ethylenediamine and Their Platinum(II) Complexes, Potential Antitumor AgentsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006Mara Rubia Costa Couri Abstract This work describes the synthesis and characterization of five new amine ligands and also the preparation and characterization of their respective platinum(II) complexes by reaction with K2PtCl4 in water. These ligands were obtained by treatment of different halides or epoxides with ethylenediamine. Cytotoxic activity and cellular accumulation of three complexes were investigated in a human small-cell lung carcinoma cell line and its cisplatin resistant subline. The introduction of a spacer (cycle) between the two platinum atoms leads to a significant decrease in cytotoxic activity. At equitoxic doses, the intracellular platinum concentrations found for compounds 12 and 15 were significantly higher than those found for the reference compounds, cisplatin, carboplatin, or compound 9. This fact suggests that the formation of adducts between compounds 12 and 15 and the putative pharmacological target, DNA, is less favored. If these compounds bind more slowly to DNA, interaction with other intracellular ligands such as sulfur-containing molecules will become relevant and it may be the reason for the elevated intracellular platinum concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Interactions of Cationic Palladium(II)- and Platinum(II)-,3 -Allyl Complexes with Fluoride: Is Asymmetric Allylic Fluorination a Viable Reaction?EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2006Lukas Hintermann Abstract The complex cations [M(,3 -R2All)(PPFPz{3- tBu})]+ (M = PdII, R2All = 1,3-diphenylallyl, 1,3-dicyclohexylallyl, indenyl; M = PtII, R2All = 1,3-diphenylallyl; PPFPz-{3- tBu} = 3- tert -butyl-1-{1-[2-diphenylphosphanyl-ferrocenyl]ethyl}-1H -pyrazole)have been prepared as salts with PF6, or SbF6,. They have been characterized by NMR spectroscopy in solution and by X-ray crystallography in the solid state. Their reactions with sources of nucleophilic and "naked" fluoride have been investigated by multinuclear NMR spectroscopy. The PdII complexes did not undergo any nucleophilic substitution with concomitant release of allyl fluorides. The dicyclohexylallyl fragment was released as a 1,3-diene by elimination, but with other allyl complexes nonspecific decomposition reactions predominated. The complex [Pt(,3 -1,3-Ph2C3H3)(PPFPz{3- tBu})]PF6 underwent an anion exchange with Me4NF to give [Pt(1,3-Ph2C3H3)(PPFPz{3- tBu})]F which existed as a mixture of interconverting allyl isomers in solution at ambient temperature. For the bromide salt, [Pt(,3 -1,3-Ph2C3H3)(PPFPz{3- tBu})]Br, allyl isomerization was slow at ambient temperature. Precursors of Pt0 reacted with bromo-1,3-diphenylprop-2-ene to give [Pt2(,-Br)2(,3 -1,3-Ph2All)2] and precursors of Pd0 underwent oxidative additions with bromo- and fluoro-1,3-diphenyl-2-propene to give 1,3-diphenylallyl complexes of PdII. Therefore, the nucleophilic attack of fluoride on the allyl fragment of PdII complexes is endergonic, and the high energy barrier of this step is difficult to overcome in a catalytic allylic fluorination reaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Novel Bonding Modes between Tetrathiafulvalenes (TTFs) and Transition Metal Centers: ,-Bonding and Covalent TTFSiMe2,MLn Coordination to PlatinumEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2004Mathuresh N. Jayaswal Abstract Two novel strategies for coordinating TTF to transition metal centers have been developed. The reaction of tetrathiafulvalene (TTF) or 3,4-dimethyltetrathiafulvalene (o -Me2TTF) with [Pt(,2 -C2H4)(PPh3)2] leads to the , complexes [Pt(,2 -TTF)(PPh3)2] (1) and [Pt(,2 - o -Me2TTF)(PPh3)2] (2), respectively. An X-ray crystallographic study performed on 2 confirmed, that TTFs act as a , acidic ligand. NMR studies revealed the existence, in solution, of an equilibrium between free and complexed TTF. Dilithiation of o -Me2TTF and subsequent silylation with ClSiMe2H afforded 3,4-dimethyl-3,,4,-(dimethylsilyl)tetrathiafulvalene (3), which has been structurally characterized. 3 reacts by oxidative addition across [Pt(,2 -C2H4)(PPh3)2] to give [Pt{,2 - o -(SiMe2)2TTFMe2}(PPh3)2] (4), in which the TTF ligand is covalently ligated to platinum via SiMe2 bridges. The redox properties of 3 and 4 have been investigated by cyclic voltammetry. Strong cathodic shifts of the two redox processes were observed for 4, implying the TTF core. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Stable Platinum(0) Catalysts for Catalytic Hydrosilylation of Styrene and Synthesis of [Pt(Ar-bian)(,2 -alkene)] ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2003Jeroen W. Sprengers Abstract The use of alkenes and bidentate N-ligands in the platinum(0)-catalyzed hydrosilylation of styrene with triethylsilane has been evaluated. A number of bidentate N-ligands, phen, bpy, dafo, and phenyl-bian, were tested at various reaction temperatures using in situ formed catalysts with [Pt(nbe)3] as a precursor. The main conclusions are: (i) ligands, such as phen, which form stable platinum(0) complexes, give lower catalytic activities compared to the ligands which form less stable complexes; (ii) a small ligand effect is observed with dafo and phenyl-bian compared to [Pt(nbe)3], the precursor complex, displaying the lability of these ligands. The complex [Pt(nbe)3], that only has labile alkene ligands, is an active catalyst at low temperatures. At higher temperatures, the catalyst is no longer stable and a decrease in yield is observed. Several novel complexes have been synthesized: [Pt(m,m -(CF3)2 -C6H3 -bian)(tcne)], [Pt(m,m -(CF3)2 -C6H3 -bian)(ma)], [Pt(p -MeO-C6H4 -bian)(ma)], [Pt(p -MeO-C6H4 -bian)(dmfu)] and [Pt(phenyl-bian)(dmfu)]. Whereas the two [Pt(Ar-bian)(ma)] complexes are intrinsically more active than the two [Pt(Ar-bian)(dmfu)] complexes, the latter are much more stable, i.e. the nature of the alkene in these complexes is an important factor in determining their catalytic behavior. Compared to [Pt(Me-nq)(nbe)2], the two [Pt(Ar-bian)(dmfu)] complexes are much more stable resulting in significantly higher overall yields. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Coordination Modes of 9-Methyladenine in cis -Platinum(II) Complexes with Dimethyl(phenyl)phosphanes as Ancillary Ligands , Synthesis and Characterization of cis -[PtL2(9-MeAd)2](NO3)2, cis -[PtL2{9-MeAd(,H)}]3(NO3)3, and cis -[L2Pt{9-MeAd(,H)}PtL2](NO3)3EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2003Bruno Longato Abstract Treatment of 9-methyladenine (9-MeAd) with cis -[PtL2(NO3)2] (1) (L = PMe2Ph) in a 2:1 molar ratio generated the bis(adduct) cis -[PtL2(9-MeAd)2](NO3)2 (2), which was isolated and fully characterized by multinuclear (1H, 31P, 13C, 195Pt and 15N) NMR analysis, which showed that the two nucleobases are selectively coordinated through the N1 atom. Small amounts of a mono(adduct) cis -[PtL2(S)(9-MeAd)]2+ (3) (S = solvent) and of a diplatinated species cis -[L2Pt(S){9-MeAd(,H)}PtL2]3+ (4) are formed in DMSO solution when 9-MeAd is present in smaller quantities than 1. Complex 3 is platinated at N1, with a solvent molecule representing the fourth ligand around the metal center. Complex 4 contains an adenine molecule deprotonated and platinated at N1,N6,N7, with two cis -L2Pt units bonded to nitrogen atom N1 and to nitrogen atoms N6 and N7, respectively. With increasing relative concentration of the nucleobase, both complexes 3 and 4 progressively convert into the bis(adduct) 2, the only species detectable in solution when the Ad/Pt molar ratio is 2:1. The trinuclear compound cis -[L2Pt{9-MeAd(,H)}]3(NO3)3 (5) (L = PMe2Ph), containing an NH2 -deprotonated nucleobase bridging the metal centers through the N1 and N6 atoms, is quantitatively formed when the dinuclear hydroxo complex cis -[Pt(,-OH)L2]2(NO3)2 (6) reacts with 9-MeAd in CH3CN solution. The isolated complex was fully characterized by multinuclear NMR spectroscopy and mass spectrometry. It appears to be stable in solution in CH3CN and chlorinated solvents, whereas in DMSO it partially converts into a new species, probably the dinuclear analog cis -[PtL2{9-MeAd(,H)}]2(NO3)2, in which the adenine maintains its coordination mode. At equilibrium the trinuclear/dinuclear species molar ratio is 20:1. Through the addition of a stoichiometric amount of nitrate 1 to a DMSO solution of 5 we were able to generate the diplatinated compound 4 in high yield. Complex 4 displays a new coordination mode for the adeninate ion, with N1 bonded to one platinum atom whereas N6 and N7 are chelated to a second one. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Optical Power Limiters: Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off Optimization (Adv. Mater.ADVANCED FUNCTIONAL MATERIALS, Issue 4 20098/2009) The development of symmetric and unsymmetric platinum(II) bis(acetylide)s as highly transparent optical limiters is described by Wong and co-workers on page 531. Their excited state character is governed by electronic structure, which significantly affects their photophysical properties and optical power limiting (OPL) behavior. The sound OPL responses and low OPL thresholds together with their excellent optical transparency render these materials very promising candidates for practical devices for the protection of human eyes and other delicate electro-optic sensors. [source] Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off OptimizationADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Guijiang Zhou Abstract A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type DC,CPt(PBu3)2C,CD (DPtD), AC,CPt(PBu3)2C,CA (APtA) and DC,CPt(PBu3)2C,CA (DPtA) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade-offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532,nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with , electron-accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: DPtD,>,DPtA,>,APtA. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible-light region and exhibit excellent OPL responses with very impressive figure of merit ,ex/,o values (up to 17), which remarkably outweigh those of state-of-the-art reverse saturable absorption dyes such as C60 and metallophthalocyanines with very poor transparencies. Their lower optical-limiting thresholds (0.05,J,cm,2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07,J,cm,2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro-optic sensors. [source] Preparation of Functional Hybrid Glass Material from Platinum (II) Complexes for Broadband Nonlinear Absorption of LightADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Roman Zieba Abstract The synthesis of trans -di(arylalkynyl)diphosphine platinum(II) complexes bearing trialkoxysilane groups is described, as well as the preparation of siloxane-based hybrid materials from organometallic chromophores through a modified sol,gel process. Glass materials prepared from trans -[P(n,Bu)3]2Pt[(C,C,p,C6H4,C,C,p,C6H4,CH2O(CO)NH(CH2)3Si(OC2H5)3]2 generally show spectral transmittance, absorption and luminescence similar to that of solutions reported in the literature. Measurements of optical power limiting for the hybrid glass are carried out, and show broadband nonlinear absorption throughout the whole visible wavelength range with clamping values in the range 0.2,7,µJ at 120,mM chromophore concentration. The sol,gel process using urethane-propyltriethoxysilane-functionalized chromophores as precursors appears to be a valid method for formation of robust silicate materials with grafted diarylethynyl Pt(II) complexes for OPL devices. [source] Ultrathin Te Nanowires: An Excellent Platform for Controlled Synthesis of Ultrathin Platinum and Palladium Nanowires/Nanotubes with Very High Aspect RatioADVANCED MATERIALS, Issue 18 2009Hai-Wei Liang Uniform ultrathin Pt nanotubes, Pt and Pd nanowires with diameters of only several nanometers and a very-high aspect ratio of ,10,000 can be fabricated using ultrathin Te nanowires as both reducing agent and sacrificial template in ethylene glycol. The valences of metal precursors have a crucial effect on the morphology of the nanostructures. [source] Magnus' Green Salt Revisited: Impact of Platinum,Platinum Interactions on Electronic Structure and Carrier Mobilities,ADVANCED MATERIALS, Issue 15 2006E.-G. Kim Magnus' green salt is the prototype of a class of organic,inorganic hybrid semiconducting materials that combine attractive charge-transport properties and processability. By using density-functional-theory methods, the electronic structure of Magnus' green salt is investigated, in particular the nature of the interplatinum interactions (see figure). In conjunction with time-of-flight measurements of the carrier mobilities, key structure,property relationships for these materials are re-established. [source] Effect of Molecular Orientation of Epitaxially Grown Platinum(II) Octaethyl Porphyrin Films on the Performance of Field-Effect Transistors,ADVANCED MATERIALS, Issue 9 2003Y.-Y. Noh The molecular alignment of platinum(II) octaethyl porphyrin (PtOEP) crystals evaporated on KBr (see atomic force microscopy image, Figure) can be readily changed from perpendicular to parallel by changing the substrate temperature. The field-effect mobility of transisitors prepared using epitaxially grown PtOEP films aligned perpendicularly to a substrate is 100 times higher than that of those of parallel alignment. [source] Efficient Platinum(II) Catalyzed Hydroformylation Reaction in Water: Unusual Product Distribution in Micellar MediaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010Marina Gottardo Abstract The hydroformylation of a variety of terminal and internal alkenes is efficiently performed by cationic platinum triflate complexes of the type [P2Pt(H2O)2](OTf)2 under mild conditions in an aqueous micellar medium. The use of surfactants is essential to ensure dissolution of the catalyst and substrate in water with catalysts being positioned on the anionic surface of the micelles. Aldehydes are obtained with linear to branched ratios up to >99:1. With styrene derivatives also the corresponding benzaldehydes are formed. The catalyst can be separated by extraction of the organic products with hexane and recycled for at least four times with only a modest loss of activity and no effect on selectivity. [source] The use of sodium formate for the recovery of precious metals from acidic base metal effluentsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2001Herman G Julsing Abstract Zinc was used for the reduction of the platinum group metals (PGMs) in acidic effluents. Due to the increasing cost of zinc, sodium formate was investigated as an alternative reductant. In a base metal-containing acidic effluent, called diethylenetriamine barren, sodium formate was used to precipitate the PGMs. This effluent was the filtrate obtained after a precipitation procedure had been used to remove rhodium and iridium. It was found that pH 1.5 was the optimum starting pH for sodium formate reduction. The pH increased to approximately 4.5 after the addition of sodium formate. The optimum concentration of sodium formate was found to be 30,g,dm,3 at a temperature of 100,°C where the process time was 6,h. Platinum and palladium were the most effectively reduced PGMs, both exhibiting an average precipitation efficiency of greater than 99%. Difficulty was experienced with the precipitation of iridium (average precipitation efficiency of 76%). The precipitated PGMs readily dissolved in hydrochloric acid (6,M) and sodium chlorate (2%). A reduction in costs resulted from the discontinuation of the use of zinc for reduction purposes. An additional advantage was that zinc was no longer introduced into the PGM refinery circuits. © 2001 Society of Chemical Industry [source] Treatment of Dogs with Oral Melanoma by Hypofractionated Radiation Therapy and Platinum-Based Chemotherapy (1987,1997)JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2003Kim P. Freeman This retrospective study in 39 dogs with incompletely resected oral melanoma examined the efficacy of hypofractionated radiation therapy and platinum-containing chemotherapy. All dogs were completely staged, with the majority of dogs classified as stage I. Dogs received 6 weekly fractions of 6-gray (Gy) megavoltage irradiation with a cobalt-60 unit or a 4-MeV (megaelectron volts) linear accelerator. Dogs received cisplatin (10,30 mg/m2 IV) or carboplatin (90 mg/m2 IV) chemotherapy 60 minutes before radiation delivery. Durations of local control, metastasis-free survival time, and overall survival time were recorded. By the Kaplan-Meier method, 15% of the dogs had local recurrence within a median time of 139 days. Fifty-one percent of the dogs developed metastatic disease within a median time of 311 days (range, 24,2,163 days). Median survival time for all 39 dogs was 363 days. The combined use of chemotherapy and radiation therapy in this protocol provided local control consistent with previous studies. Low-dose chemotherapy was used with the intent of enhancing radiation therapy for the local control of an incompletely excised tumor. Survival times were longer than previously reported for dogs with oral malignant melanoma. Additional studies are required to determine whether these results were due to the effects of chemotherapy on microscopic disease or the enhanced local control provided by chemoradiation therapy. [source] Platinum-based anticancer agents: Innovative design strategies and biological perspectivesMEDICINAL RESEARCH REVIEWS, Issue 5 2003Yee-Ping Ho Abstract The impact of cisplatin on cancer chemotherapy cannot be denied. Over the past 20 years, much effort has been dedicated to discover new platinum-based anticancer agents that are superior to cisplatin or its analogue, carboplatin. Most structural modifications are based on changing one or both of the ligand types coordinated to platinum. Altering the leaving group can influence tissue and intracellular distribution of the drug, whereas the carrier ligand usually determines the structure of adducts formed with DNA. DNA,Pt adducts produced by cisplatin and many of its classical analogues are almost identical, and would explain their similar patterns of tumor sensitivity and susceptibility to resistance. Recently some highly innovative design strategies have emerged, aimed at overcoming platinum resistance and/or to introduce novel mechanisms of antitumor action. Platinum compounds bearing the 1,2-diaminocyclohexane carrier ligand; and those of multinuclear Pt complexes giving rise to radically different DNA,Pt adducts, have resulted in novel anticancer agents capable of circumventing cisplatin resistance. Other strategies have focused on integrating biologically active ligands with platinum moieties intended to selectively localizing the anticancer properties. With the rapid advance in molecular biology, combined with innovation, it is possible new Pt-based anticancer agents will materialize in the near future. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 5, 633,655, 2003 [source] Dispersion-Driven Hydrogen Bonding: Predicted Hydrogen Bond between Water and Platinum(II) Identified by Neutron Diffraction,ANGEWANDTE CHEMIE, Issue 41 2010Dr. Silvia Rizzato Klassisch oder nicht? Die Metallionen quadratisch-planar koordinierter d8 -Komplexe können als Lewis-Säuren oder -Basen mit H2O-Molekülen in axialen Positionen wechselwirken. Ab-initio-Rechnungen zufolge bilden neutrale PtII -Komplexe Wasserstoffbrücken mit H2O, in denen PtII als Lewis-Base auftritt. Solche nichtklassischen OH,,,Pt-Brücken wurden nun in Kristallen von trans -[PtCl2(NH3)(N -Glycin)],H2O mithilfe von Neutronenbeugung identifiziert. [source] Platinum and Palladium Complexes Containing Cationic Ligands as Catalysts for Arene H/D Exchange and Oxidation,ANGEWANDTE CHEMIE, Issue 34 2010Marion Kationische Komplexe aus Palladium(II) oder Platin(II) und Bipyridinliganden mit Pyridiniumsubstituenten sind hoch aktive und beständige Katalysatoren für den H-D-Austausch und die Oxidation der C-H-Bindungen von aromatischen Substraten mit Umsatzzahlen bis 3200 und Umsatzfrequenzen bis 0.1,s,1. [source] ,3 -Vinylborane Complexes of Platinum and Nickel: Borataallyl- and Alkyl/Borataalkene-Like Coordination Modes,ANGEWANDTE CHEMIE, Issue 15 2010Kristopher Feiner Unterschied: Das Vinylboran PhHCCH-B(C6F5)2 reagiert mit nullwertigen Übergangsmetallspezies der Gruppe,10 zu ,3 -Vinylboran-Komplexen. Der Platin-PtBu3 -Komplex zeigt eine ,3 -Borataallyl-artige Koordination, während der Nickel-(Ph3P)2 -Komplex eine Alkyl-/Borataalken-Koordination bevorzugt. [source] Selective Aggregation of a Platinum,Gadolinium Complex Within a Tumor-Cell Nucleus,ANGEWANDTE CHEMIE, Issue 7 2010Ellen Per Anhalter in den Zellkern: Ein in DNA intercalierter Metallkomplex kann die selektive Ansammlung eines intakten Wirkstoffs in den Kernen von humanen Lungenkrebszellen (A549) ermöglichen. Mit einem Platinkomplex gelang es nun, auf diesem Weg Gadolinium in Zellkerne zu schleusen. Die Synchrotron-Röntgenfluoreszenz-Bildgebung diente zum Nachweis des Prozesses (siehe Bilder). [source] Coencapsulation of Arsenic- and Platinum-based Drugs for Targeted Cancer Treatment,ANGEWANDTE CHEMIE, Issue 49 2009Haimei Chen Zwei in einem: Eine neuartige Strategie für den effizienten Doppeleinschluss von Arsen- und Platin-Wirkstoffen in 100,nm große Liposomen (NBs) beruht auf der Bildung von PtII -AsIII -Addukten (siehe Bild). Das zweifach beladene System dient als robuste Plattform für weitere Modifizierungen mit zielgenauen Liganden und bietet einen Ansatz für die Verbesserung von Tumortherapeutika. [source] Helical Bis(N-Confused Porphyrins) with Subunits Fused by Double Orthometalation with Platinum: Adaptability of an Apparently Rigid System,ANGEWANDTE CHEMIE, Issue 46 2009Piotr Starr und doch flexibel: Wegen der Flexibilität der Porphyrinringe gelingen Racemisierung oder chirale Induktion auch noch bei helicalen metallierten N-invertierten Biporphyrinen, obwohl das Bipyrrolfragment starr ist. Die Porphyrine sind peripher doppelt mit Platin(II) orthometalliert, und einige Produkte ihrer oxidativen Addition wurden ebenfalls erhalten (siehe die Strukturen des Iodmethyladdukts: grau und braun C; blau N; orange Pt; violett I). [source] | ||||||||||||||||||||||||||||||||||||||||