Showing papers on "Platinum published in 1978"
629 citations
TL;DR: In this article, the authors investigated the photodecomposition of acetic acid on anatase powders and showed that the results were mainly methane and CO/sub 2, with small amounts of hydrogen and ethane.
Abstract: The heterogeneous photocatalytic decomposition of acetic acid/acetate mixtures was studied on n-type TiO/sub 2/ powder. The influence of solution composition, reaction temperature, light intensity, and semiconductor properties (crystallographic structure, doping) was investigated. For photodecarboxylation in the absence of molecular oxygen, anatase powders proved to be most efficient with increased reactivity due to doping and/or partial coverage of the powder particles with platinum. The products of the photodecomposition of acetic acid on platinized anatase powder were mainly methane and CO/sub 2/, with small amounts of hydrogen and ethane. Other saturated carboxylic acids (propionic, n-butyric, n-valeric, pivalic, adamantane-1-carboxylic acid) were also photocatalytically decarboxylated to the corresponding alkanes. An interpretation based on the photoelectrochemical properties of n-type TiO/sub 2/, with photooxidation and (dark) reduction reactions occurring on the particles on local cell processes, is proposed.
442 citations
328 citations
TL;DR: In this paper, high-resolution electron energy loss spectroscopy was applied to study the adsorption of benzene (C6H6 and C6D6) on Pt(111) and Ni(111), single crystal surfaces between 140 and 320 K.
261 citations
TL;DR: In this paper, it was shown that the activation energies for the adsorbates increased in the order Au, Pt, Ir, and P, with the differences in adatom size having little effect.
249 citations
TL;DR: Among the platinum complexes tested, oxalato(cis-1,2-diminocyclohexane)platinum had a remarkably high therapeutic index and modification of the nonleaving group as well as that of the leaving group is important in order to find better antitumor platinum complexes.
Abstract: Platinum complexes derived from three isomers of 1,2-diaminocyclohexane have been synthesized and their antitumor activities were evaluated against ascites Sarcoma-180. All the platinum complexes had high antitumor activity. Platinum complexes derived from cis-1,2-diaminocyclohexane were more effective than those derived from trans-l-and trans-d-1,2-diaminocyclohexane. Among the platinum complexes tested, oxalato(cis-1,2-diminocyclohexane)platinum had a remarkably high therapeutic index. Modification of the nonleaving group as well as that of the leaving group is important in order to find better antitumor platinum complexes.
222 citations
TL;DR: In this paper, the activation energies, kinetic orders, and relative activities have been determined for the oxidation of CO by O2 over five supported noble metals, including iridium, rhodium, and palladium.
222 citations
221 citations
TL;DR: Some platinum coordination complexes are active anticancer drugs in animal and man This new class of chemotherapeutics was discovered during the course of investigation of the electric field effect on bacterial growth The platinum electrodes electrolyzed during the experiment, releasing a platinum complex which caused complete cessation of cell division in the bacterial rods with this filamentation assay system, was able to identify the specific chemical as cis-dichlorodiammineplatinum(II), a complex known since 1848 as discussed by the authors.
Abstract: Some platinum coordination complexes are active anticancer drugs in animal and man This new class of chemotherapeutics was discovered during the course of investigation of the electric field effect on bacterial growth The platinum electrodes electrolyzed during the experiment, releasing a platinum complex which caused complete cessation of cell division in the bacterial rods With this filamentation assay system, we were able to identify the specific chemical as cis-dichlorodiammineplatinum(II), a complex known since 1848 The bacterial studies with many such complexes suggested to us the generalizations that charged platinum complexes were bacteriocidal, while the neutral platinum complexes induced filamentation and, in lysogenic bacteria, lysis The neutral complexes have ignificant activity against transplantable, virally induced, and chemically induced cancers in animals They are synergistic with almost every other anticancer drug in current use In man kidney toxicity is the dose limiting
209 citations
TL;DR: In this article, low energy electron diffraction patterns were obtained for Pt(100), Pt(111), and polycrystalline electrodes before and after exposure to aqueous 1 M H 2 SO 4.
207 citations
TL;DR: In this article, a small amount of methanol was also produced over the pyrolysed catalysts of smaller Rh, Pt, and Ir carbonyl clusters on ZnO, MgO, CaO, and BeO.
Abstract: Methanol synthesis by the catalytic hydrogenation of carbon monoxide proceeded under atmospheric pressure and at 150–250 °C over rhodium, platinum and iridium crystallite catalysts, prepared from well-defined Rh, Pt, and Ir carbonyl cluster compounds highly dispersed on ZnO and MgO. The activity and selectivity of methanol formation depended considerably on the kind of metal carbonyl clusters and metal oxides employed as inorganic carriers. The catalysts prepared by the pyrolysis of smaller Rh, Pt, and Ir carbonyl clusters on ZnO, MgO, CaO, and BeO exhibited a higher selectivity of methanol synthesis. A small amount of ethanol was also produced besides methanol in CO–H2 reaction over the pyrolysed catalysts of Rh carbonyl clusters on MgO, CaO, and BeO. Other metal oxides such as SiO2 gel, γ-Al2O3, SnO2, and WO2 were employed for preparation of the dispersed Rh catalysts from carbonyl clusters, which catalysed mainly formation of methane and higher hydrocarbons with negligible selectivity of the oxygenated...
TL;DR: In this paper, an experimental program was conducted to investigate the catalytic activity of platinum black and platinum supported on carbon for electrochemical reduction of oxygen in 99 wt% phosphoric acid at 177°C as a function of platinum surface area.
TL;DR: In this article, the authors determined the kinetic parametes for the oxygen evolution reaction on 50-50 atom percent alloys of Ru, Ir, RuO 2, IrO 2 and IrPt and compared with results obtained using ruthenium, iridium, platinum, and RuO2 /TiO 2 electrodes.
TL;DR: The usefulness of Crewe's Z-contrast technique for the study of small catalyst particles in the scanning transmission electron microscope is investigated and discussed in this article, by forming suitable combinations of the annular dark-field and energy-loss signals, structural details in platinum particles as small as 2 nm can be imaged, and clusters of image size approaching the probe dimensions (0·5 nm), not visible in the bright-field images, may be detected.
Abstract: The usefulness of Crewe's Z-contrast technique for the study of small catalyst particles in the scanning transmission electron microscope is investigated and discussed. By forming suitable combinations of the annular dark-field and energy-loss signals, structural details in platinum particles as small as 2 nm may be imaged, and clusters of image size approaching the probe dimensions (0·5 nm), not visible in the bright-field images, may be detected. In the case of crystalline supports, about 10% of the particles are obscured by strong diffraction contrast in the substrate, although it is found that contrast variations arising from thickness variations in the substrate are suppressed in the energy-loss signal. Particle sizes in the various signals employed are compared.
TL;DR: In this paper, a study of the effects of various heat treatments on the state of dispersion of platinum in alumina-supported catalysts has shown that during heat treatments in hydrogen and air the hydrogen-chemisorption capacity (expressed as the H Pt ratio) of the catalysts decreases.
TL;DR: In this article, the circular dichroism (CD) spectra of a series of DNA · platinum complexes were presented and three types of spectra clearly demonstrate the different platinum binding modes on DNA.
Abstract: The circular dichroism (CD) spectra of a series of DNA · platinum complexes are presented. The following platinum compounds, [Pt(dien)Cl]Cl, cis-Pt(NH3)2Cl2, cis-Pt(en)Cl2, trans-Pt-(NH3)2Cl2, K[Pt(NH3)Cl3] and K2[PtCl4] were complexed with the DNA extracted from bacteria Micrococcus lysodeikticus (72% dG + dC), Escherichia coli (50% dG + dC). Clostridium perfringens (32% dG + dC) and salmon sperm (41% dG + dC). Strong differences were found between the different DNA · Pt complexes. Three types of spectra clearly demonstrate the different platinum binding modes on DNA. In the first type, the platinum compound, i.e. [Pt(dien)Cl]Cl, is fixed to DNA with only one bond (monofunctional complex formation) and no significant change of the CD positive band of DNA is found. The main feature of the second type is a continuous intensity decrease of the positive band as observed for trans-Pt(NH3)2Cl2 (trans-bidentate complex formation). The third type concerns the cis-bidentate platinum fixation obtained with cis-Pt(NH3)2Cl2, cis-Pt(en)Cl2, K[Pt(NH3)Cl3] and K2[PtCl4]. The CD spectra are in this case characterized by an increase in the positive Cotton effect which is dG + dC-dependent up to an rb value around 0.10 (where rb= number of platinum atoms bound per nucleotide), followed by a decrease until DNA saturation with platinum is reached. A linear decrease in the amplitude of the negative band is detected in all the complexes except in the case of the monofunctional DNA · Pt complexes. For the cis-bidentate and trans-bidentate platinum fixation, a continuous bathochromic shift occurs.
TL;DR: In this article, isomerization and hydrogenolysis reactions of neopentane and neohexane were studied in the presence of excess hydrogen at 455 to 625 K in a flow reactor over various Pt/silica and Pt/Y-zeolite catalysts having dPt in the range 1 to 20 nm.
Patent•
19 Oct 1978
TL;DR: In this paper, a compound of platinum having the structure: "STR1" is described, in which X and Y are halogenoid groups which are the same or different and are preferably both chloride but may be other halide or pseudohalide such as cyanate, thiocyanate and azide or other similar groups.
Abstract: This invention relates to a compound of platinum having the structure: ##STR1## in which X and Y are halogenoid groups which are the same or different and are preferably both chloride but may be other halide or pseudohalide such as cyanate, thiocyanate and azide or other similar groups, and A and B are the same or different branched chain aliphatic amine groups co-ordinated to the Pt through their N atoms.
TL;DR: In this paper, surface reactions have been studied in high vacuum on the (100) surface of platinum that was clean or covered with various amounts of sulfur, and three different poisoning mechanisms were identified: (i) when the surface is covered with one S atom per two surface Pt atoms, it is chemically inert, (ii) at lower coverages, the strong chemical bond to sulfur modifies the chemical properties of the platinum surface and weakens its interaction with adsorbates, and when the sulfur coverage is one S per four Pt, a regular sulfur overlayer is established;
TL;DR: In this article, a multilayer surface oxidation of polycrystalline Pt wire is studied for the first time at moderate oxygen pressures using a high precision electrical resistance technique, and the dependence of the oxidation rate on pressure, temperature, and time is investigated.