Synthesis and structural characterization of mixed carbene-carboxylate complexes of palladium(II)

Mixed carbene-carboxylate complexes of Palladium(II) have been prepared by reacting {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) diiodide (1) [Angew. Chem. 107 (1995) 2602; Angew. Chem. Int. Ed. Engl. 34 (1995) 2371; J. Organomet. Chem. 557 (1998) 93] with AgO₂CR, where R=CF₃, CF₂CF₃ and CF₂CF₂CF₃. In this manner, {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(trifluo-roacetate) (2), {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(pentafluoropropionate) (3) and {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(heptafluorobutyrate) (4) were obtained. All three complexes were fully characterized by ¹H-, ¹³C- and ¹⁹F NMR spectroscopy as well as ESI mass spectrometry. X-ray crystal structure analyses of complexes 3 and 4 reveal mononuclear species with a square planar metal center coordinated by a cis-chelating dicarbene and two monodentate carboxylate ligands. The results show that the introduction of a cis-chelating N,N-heterocyclic carbene ligand stabilizes the palladium-carboxylate moiety effectively.     

Intermethod comparisons of active sampling procedures and analysis of aldehydes at environmental levels

Within the framework of a European interlaboratory exercise, the Vito facility for the generation of controlled atmospheres was used to test the suitability of four sampling techniques for priority aldehydes namely formaldehyde, acrolein, acetaldehyde, and glutaraldehyde at the ranges of 0.5 to 150 microg x m(-3). The samplers are DNPH-containing impingers, DNPH-impregnated cartridges and filters, and 2-HMP coated XAD-2 tubes. The three first DNPH samplers are to be analyzed by HPLC and the latter by GC-MS for the oxazolidine derivatives. The intermethod comparison comprises two to five sets of experiments depending on the compounds of interest. The aim of the exercise was also to assess the chemical interferences caused by ozone, nitrogen dioxide, and ammonia when using different techniques for sampling and analysis. The active DNPH method (with minor modifications such as shorter sampling time, immediate elution after sampling, and/or eventually wetting of samplers) delivered results within the 30% overall relative uncertainty for formaldehyde, acetaldehyde, and acrolein at the upper microg x m(-3) levels. However, the results suggest that the current DNPH methods for aldehydes do not comply with the 30% minimum performance criteria at the sub microg x m(-3) level. Sampling of aldehydes in the presence of ozone and NO2 interferences by using a "scrubber" cartridge appears to be beneficial to the quality of results.     

Crystal structure ofcis-[Ru(bpy)2{PPh2(o-tol)}Cl][ClO4]·1.5(CH2Cl2), a structure containing both ordered and disordered dichloromethane molecules of crystallization

The complexcis-[Ru(bpy)₂ {PPh₂(o-tol)}Cl][ClO₄] crystallizes from dichloromethane as the sesqui-dichloromethane solvate. The complex crystallizes in the monoclinic space group P2₁/n with Z=4. The structure was refined toR=5.50% for those 2552 independent reflections with |F ₀|>6(|F ₀|) The octahedral Ru(II) cation is associated with the following bond lengths: Ru-PPh₂(o-tol)=2.360(3)Å. Ru–Cl=2.433(2)Å and Ru–N(bpy)=2.041(8)–2.095(8)Å. Both the perchlorate anion and the dichloromethane molecules of solvation exhibit large amplitudes of vibration. One dichloromethane molecule lies in a general position, the other lies about an inversion center and suffers from disorder.     

Preparation and characterization of indium doped tin oxide (ITO) via a non-aqueous sol-gel

ABSTRACT

Tin-doped indium oxide (ITO) nanoparticles (NPs) were conceived as promising materials using as noncarbon support for Pt NPs on the cathode side of Proton Exchange Membrane Fuel Cells (PEMFC). In this paper, ITO nanoparticles have been synthesized via a nonaqueous sol-gel process using indium acetylacetonate and tin bis(acetylacetonate)dichloride in oleyamine as starting materials. The ITO exhibits solid solution phase, relatively porous, good crystallinity with a uniform size of 15–20 nm, resulting in a high specific surface area and excellent conductivity. The effects of reaction temperature, calcination temperature on the specific surface area as well as the conductivity of ITO nanoparticles were studied in this paper. We found that the ITO nanoparticles synthesized at 235°C and calcination temperature at 500°C for 3 hours shows the excellent conductivity of 1.242 S/cm, was significantly ～8-fold higher than that of commercial ITO produced by Sigma-Aldrich (0.15 S/cm). The results of this research suggested that the ITO synthesized by non-aqueous sol-gel process exhibits relatively good properties as well as can apply this process to prepare the others nanomaterial support based on In₂O₃-materials by doping different oxide into indium oxide.     

On the symmetry of the Goldie and CS conditions for prime rings

It is shown that: (a) If is a prime right Goldie right CS ring with right uniform dimension at least 2, then is left Goldie, left CS; (b) A semiprime ring is right Goldie left CS iff is left Goldie, right CS.

     

Total annual effective dose and health risk due to intake of natural radionuclides of some vegetables cultivated in suburban Ho Chi Minh City,Vietnam

Journal of Radioanalytical and Nuclear Chemistry - In this work, activity concentration of 40K, 226Ra, 232Th, gross alpha and gross beta and annual effective dose due to ingestion of natural...     

Synthesis,reactivity, and optoelectronic properties of poly(3‐alkenylthiophene) diblock copolymers

Poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) and poly(3‐hexylthiophene)‐b‐poly(3‐undecenylthiophene) diblock copolymers have been synthesized by McCullough method. X‐ray diffraction analysis of the diblock copolymers displayed all the reflection peaks specific to regioregular poly(3‐hexylthiophene), indicating that the presence of poly(3‐alkenylthiophene) block does not affect the packing of the polymer in the solid state. The synthesized diblock copolymers were subjected to hydroboration/oxidation and hydrosilation to demonstrate the reactivity of the alkenyl substituents. Furthermore, poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) was used as a chain transfer agent for the ruthenium‐catalyzed ring‐opening metathesis polymerization of cyclooctene to generate a polycyclooctene graft copolymer, which was hydrogenated to give poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene‐g‐polyethylene). The opto‐electronic properties and the morphology of the synthesized polymers have been investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

NMR Solution Structure of the Duplex Formed by Self‐Pairing of α‐L‐Arabinopyranosyl‐(4′2′)‐(CGAATTCG)

The solution structure of the duplex formed by α‐L ‐arabinopyranosyl‐(4′→2′)‐(CGAATTCG) was studied by NMR. The resonances of all H‐, P‐ and most C‐atoms could be assigned. Dihedral angles and distance estimates derived from coupling constants and NOESY spectra were used as restraints in a simulated annealing calculation, which generated a well‐defined bundle of structures for the six innermost nucleotide pairs. The essential features of the resulting structures are an antiparallel, Watson Crick‐paired duplex with a strong backbone inclination of ca. −50° and, therefore, predominant interstrand base stacking. The very similar inclination and rise parameters of arabinopyranosyl‐(4′→2′)‐oligonucleotides and p‐RNA explain why these two pentapyranosyl isomers are able to cross‐pair.