Thermodynamics of sorption of platinum on superparamagnetic nanoparticles functionalized with mercapto groups

Journal of Thermal Analysis and Calorimetry - The adsorption of Pt(IV) by iron oxide (Fe3O4) superparamagnetic nanoparticles (SPION) functionalized with 3-mercaptopropionic acid (3-MPA) is...     

L3C3P3: Tricarbontriphosphide Tricyclic Radicals and Cations Stabilized by Cyclic (alkyl)(amino)carbenes

Alkynes usually oligomerize to give rings with a conjugated π‐electron system. In contrast, phosphaalkynes, R?C≡P, frequently give compounds with polycyclic structures, which are thermodynamically more stable than the corresponding π‐conjugated isomers. The syntheses of the first C₃P₃ tricyclic compounds are reported with either radical or cationic ground states stabilized by cyclic (alkyl)(amino)carbenes (CAACs). These compounds may be considered as examples of tricarbontriphosphide coordinated by carbenes and are likely formed via trimerization of the corresponding mono‐radicals CAAC‐CP^.. The mechanism for the formation of these tricarbontriphosphide radicals has been rationalized by a combination of experiments and DFT calculations.     

On a result of Birkhoff

The research of the first two authors was supported by the NSERC of Canada.     

Rationale for kinetic heterogeneity of ultrafast light-induced electron transfer from Ru(II) complex sensitizers to nanocrystalline TiO2

Because of their successful use in dye-sensitized solar cells, Ru(II) polypyridyl complex dyes adsorbed on nanocrystalline TiO2 films have been regarded as model systems for the experimental study of the ultrafast dynamics of interfacial light-induced electron transfer. Most studies have reported charge injection kinetics from Ru(dcbpyH2)2(NCS)2 (N3) to take place with a fast (sub-100 fs) phase, followed by a slower (0.7-100 ps) multiexponential component. This complex, multiphasic behavior observed for the electron injection process has prevented the development of a satisfying kinetic model and has led to often contradicting conclusions. Here, we show that the observed kinetic heterogeneity can result from the aggregation of sensitizer molecules on the surface. Carefully controlled deposition of Ru(II) complex dye molecules onto nanocrystalline titania consistently yields a monophasic injection dynamics with a time constant shorter than 20 fs. The latter figure suggests the process is beyond the scope of vibration-mediated electron transfer kinetic models and might be controlled by the electron dephasing in the solid.     

Chemical Constltuents from the Roots of Zizyphus jujuba Mill. var. spinosa (I)

The chemical constituents of the roots of Zizyphus jujuba Mill. var. spinosa were investigated with a combination of Sephadex LH-20 column, centrifugal partition chromatography and RP-18 low pressure liquid chromatography. We isolated seven flavonoids-quercetin ( 1 ), (+)-dihydroquercetin ( 2 ), (+)-dihydrokaempferol ( 7 ), quercetin-3-0-β-glucoside ( 8 ), 2-hydroxynaringenin ( 11 ), rutin ( 12 ), and quercetin 3-0-(2^G-β-D-xylopyranosylrutinoside) ( 13 ); four catechins-(-)-gallocatechin ( 3 ), (-)-epigallocatechin ( 4 ), (-)-catechin ( 5 ), and (-)-epicatechin ( 6 ); and two phenolic carboxylic acids-p-hydroxybenzoic acid ( 9 ) and protocatechuic acid ( 10 ) from the water soluble fraction of the ethanolic extract NMR date of 13 were assigned by 2D NMR techniques.     

Das cyclische Thioarsenat(III) (PPh4)2As2S6

The Cyclic Thioarsenate(III) (PPh₄)₂As₂S₆ The reaction of Na₃AsS₄ with tetraphenylphosphonium chloride in ethanol or dimethylformamide proceeds with an intramolecular redox reaction, yielding (PPh₄)₂As₂S₆. According to its X-ray crystal structure analysis (4071 reflections, R = 0.070) the anion consists of a six-membered ring of two As and four S atoms in the chair conformation. The As atoms occupy the ring positions 1 and 3, and each of them has an additional terminal S atom.     

The rapid separation of trace metals from neutron-activated saline matrices by chelation on a poly-5-vinyl-8-hydroxyquinoline column

Instrumental neutron activation analysis of biological and environmental samples suffers from interferences caused by high salt concentrations. Poly-5-vinyl-8-hydroxy-quinoline coated on controlled pore diameter glass beads is suggested as a chelating column for the rapid removal of aluminum, vanadium, copper and manganese from neutron-activated sea-water samples. Separation from bulk elements is satisfactory at flow rates of 20 ml min⁻¹. With addition of carriers and with chemical yield determinations, relative standard deviations of 2–10% can be achieved for spike concentrations of 0.1 μg Mn ml⁻¹, 0.3 μg V ml⁻¹, 20 μg Al ml⁻¹ and 1.0 μg Cu ml⁻¹.     

Toward a realistic description of NO(x) storage in BaO: the aspect of BaCO3

NO(x) storage over hexagonal BaCO3(110) is investigated using first-principles calculations. Special focus is put on the importance of surface decarbonation. Upon decarbonation, supported BaO quasi-molecules are formed and a small drive toward (BaO)n cluster formation is predicted. Introduction of NO2 makes the decarbonation energetically relevant, while forming NO2-BaO-NO2 units, on the decarbonated surface. With this configuration, it is possible to replace all surface carbonates with nitrites and nitrates, forming a BaCO3 supported BaNO3NO2 overlayer. Thermodynamic considerations are employed to elaborate on the thermal stability of the formed NO(x) overlayers.     

Optisch aktive O-silyl-β-dicarbonylverbindungen : I.Darstellung und struktur

The reaction of optically active methylphenyl-α-naphthylchlorosilane with acetylacetone, ethyl acetoacetate, diethyl malonate, ethyl butyroacetate, ethyl benzo-acetate, and benzoylacetone in the presence of sodium or triethylamine leads to the formation of optically active O-silyl-β-dicarbonyl compounds(I)–(VI) with inversion of configuration. The compounds (I)–(VI) are obtained as cis-trans mixtures, the cis-trans-ratio depending on the preparative conditions. At room temperature, the cis-isomer of (I) exhibits rapid intramolecular silyl group migration from one O-atom to the other with retention of configuration. The trans-isomers of (I)–(VI) are also able to exchange silyl groups, but by intermolecular transfer and obviously with inversion of configuration. On standing for a longer time or on heating to ca. 190° a cis-trans-rearrangement, which leads to racemisation, can be observed for all compounds.