Furanoside phosphite-phosphoroamidite: new ligand class for the asymmetric nickel-catalyzed trialkylaluminium addition to aldehydes

We have described the first successful application of bidentate ligands in the asymmetric Ni-catalyzed trialkylaluminium addition to several aldehydes. The ligands are prepared from inexpensive d-(+)-xylose and d-(+)-glucose and have the advantage of carbohydrate and phosphite/phosphoroamidite moieties. After systematic variation of the position of the phosphoroamidite group at either C5 or C-3, the configuration of C-3 and the substituents in the biaryl phosphite/phosphoroamidite moieties, enantioselectivities up to 84% and high yields were obtained in the Ni-catalyzed trialkylaluminium addition to several aldehydes.     

A simple method for fabrication of sole composition nickel hexacyanoferrate modified electrode and its application

Nickel hexacyanoferrate film modified gold electrode was prepared by a simple chemical deposition procedure from a fresh prepared solution containing ferricyanide, Ni²⁺, and sodium nitrate. The resultant films have solo composition and are significantly stable as compared to the electrochemically deposited NiHCF films. For different concentrations of Na⁺ in the solution, the formal potential values of NiHCF shift according to the Nernstian behavior with a slope of 48 mV in the range of 10⁻⁴ to 1.0 M. The NiHCF film was also used for the electrocatalytic oxidation of ascorbic acid. The anodic peak current observed in cyclic voltammetry increased with the ascorbic acid concentration. At a fixed potential under hydrodynamic conditions, the calibration plot was linear over the ascorbic acid concentration range 0.1-12 mM.     

Nanocrystalline Ni0.6Zn0.4Fe2O4: A novel semiconducting material for ethanol detection

The structure and crystal phase of the nanocrystalline powders of Ni_1−xZn_xFe₂O₄ (0 ≤ x ≤ 0.5) mixed ferrite, synthesized by ethylene glycol mediated citrate sol-gel method, were characterized by X-ray diffraction and microstructure by transmission electron microscopy. Further studies by Fourier transform infrared spectroscopy were also conducted. Moreover, DC electrical properties of the prepared nanoparticles were studied by DC conductivity measurements. The response of prepared Ni_1−xZn_xFe₂O₄ mixed ferrites to different reducing gases (ethanol, hydrogen sulfide, ammonia, hydrogen and liquefied petroleum gas) was investigated. In particular, Ni_0.6Zn_0.4Fe₂O₄ composition exhibited high response to 100 ppm ethanol gas at 300 °C. Incorporation of palladium further improved the response, selectivity and response time of Ni_0.6Zn_0.4Fe₂O₄ to ethanol gas with the blue shift in the operating temperature by 25 °C.     

Synthesis and characterization of nickel catalysts supported on different carbon materials

Nickel catalysts supported on various carbon materials such as multiwall carbon nanotubes, shortened length carbon nanotubes, graphite and amorphous carbon were synthesized, characterized and tested in cyclohexene hydrogenation reaction. We have found that carbon nanotube supports are superior to graphite and amorphous carbon both in terms of catalytic activity and stability.     

Synthesis and Structure of a Hybrid Metal Phthalate Compound and Its Magnetic Property

The hybrid transition metal – alkali metal compound, [Ni(H₂O)₆·(μ‐H₂O)₂·K₂(phth)₄(H₂O)], (phth = phthalate) ( 1 ), was synthesized from nickel(II) nitrate, KOH and potassium hydrogen phthalate, and was isolated by crystallization. Single‐crystal X‐ray analysis revealed that 1 belongs to the monoclinic system, space group P2₁/c with a = 10.455(2) Å, b = 6.8670(14) Å, c = 29.704(6) Å, γ = 98.14(3)°, R₁ = 0.0585, wR₂ = 0.1503. In the title compound, [K₂(phth)₄]²⁺ units are bonded to water‐bridged Ni chains forming 2D lamellar‐like compounds.     

Synthesis, Electrochemical Characteristics of [Ni(phen)(H2O)4]SO4⋅2H2O and Its Interaction Mechanism with DNA

A polypyridyl nickel complex of [Ni(phen)(H₂O)₄]SO₄?2H₂O (phen = 1,10-phenanthroline) was synthesized and characterized by X-ray diffraction and IR spectroscopy. The results indicated that the central nickel ion is in a distorted octahedral geometry coordinated by two nitrogen atoms from 1,10-phenanthroline and four water molecules. The crystal data for this complex are: a=8.8797(18) Å, b=18.468(4) Å, c=22.081(4) Å, α=90°, β=90°, γ=90°, R ₁=0.0533, and wR ₂=0.2095. Electrochemical experiments showed that the complex could be reoxidized at a gold electrode under the precondition of electrolysis stripping. According to the results of cyclic voltammetry and coulometry, an electrochemical reaction mechanism was proposed. The DNA binding properties of the complex were further investigated by electronic absorption spectrophotometry and electrochemistry. The binding constant and the binding mode between the two species were estimated based on the spectroscopic and electrochemical results.     

Metal-to-Oxide Charge Transfer Observed by a Kelvin Probe Force Microscope

The charge transfer from a nanometer-sized transition metal particle to a catalyst support is thought to affect reactions over the metal surface. We propose the application of Kelvin probe force microscope, which is an extension of the atomic force microscope, to observe the charge transfer particle-by-particle. Our recent results on Na adatoms, Cl adatoms, Pt adatoms and particles, and Ni particles evaporated on TiO₂(110) are reviewed.     

Cavity Ring Down Laser Absorption Spectroscopy of Nil

The absorption spectrum of NiI between 445 and 510 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring down laser absorption spectroscopy. Two new transitions namely,[21.3]^2△5/2-X^2△5/2 and [21.9]^2Ⅱ3/2-X^2△5/2 systems were identified and studied. Spectra of both ^58NiI and ^60NiI isotopic molecules were observed. Equilibrium molecular constants for both electronic states are reported and the equilibrium bond length for the [21.3]^2△5/2 state and the[21.9]^2Ⅱ3/2 state was respectively determined to be 2.431 and 2.481 A.     

Synthesis, spectroscopic and electrochemical properties of manganese, nickel and iron octakis-(2-diethylaminoethanethiol)-phthalocyanine

The syntheses, spectroscopic and electrochemical properties of manganese (3), nickel (4) and iron (5) phthalocyanine complexes, octa-substituted at the peripheral positions with diethlyaminoethanethiol substituent, are reported. The electrochemistry of these complexes and the corresponding cobalt complex (6) are reported. Complex 3 showed two reversible reduction couples attributed to the Mn^IIIPc⁻²/Mn^IIPc⁻² (E_½ = −0.12 V versus Ag|AgCl) and Mn^IIPc⁻²/Mn^IIPc⁻³ (E_½ = −0.82 V versus Ag|AgCl) species. Two ring-based reduction couples were also observed for complex 4. Two reduction couples, assigned to the Fe^IIPc⁻²/Fe^IPc⁻² (E_½ = −0.35 V versus Ag|AgCl) and Fe^IPc⁻²/Fe^IPc⁻³ (E_½ = −0.96 V versus Ag|AgCl) species, and an oxidation couple, attributed to Fe^IIIPc⁻²/Fe^IIPc⁻² (E_½ = 0.26 V versus Ag|AgCl) species, were observed. For complex 6, two reductions and one oxidation were also observed with the potential range of 1.2 to −1.8 V versus Ag|AgCl Spectroelectrochemical studies were used to confirm some of the assigned processes.     

Coordination chemistry of 5,6,7-trimethyl-[1,2,4]triazolo[1,5-a]pyrimidine with first-row transition-metal salts: Synthesis, spectroscopy and single-crystal structures, with counter-anion dependence of the structures

A variety of new coordination compounds with transition-metal salts and the ligand trimethyl[1,2,4]triazolo[1,5-a]pyrimidine (abbreviated as tmtp) is described, together with several of their 3D crystal structures and spectroscopic and magnetic properties. The compounds were selected based on the coordination ability of the counterion, halide, nitrate, sulfate, thiocyanate and perchlorate. The formed coordination compounds and their coordination numbers were found to be strongly dependent on both the cation and the used counter-anion. The several compounds studied have the following structural formulae: [CuCl₂(tmtp)₂], [CuBr₂(tmtp)₂], [ZnBr₂(tmtp)₂], [Cu(NO₃)₂(tmtp)₂], [CuSO₄(tmtp)₂]₂(H₂O)(MeOH), [Cu(H₂O)(NCS)₂(tmtp)₂], [Zn(NCS)₂(tmtp)₂], [Cd(NCS)₂(tmtp)₂] and [M(H₂O)₂(tmtp)₄](BF₄)₂, in which M = Co, Ni, Zn.The new coordination compounds have been further characterized by NMR, (far-)IR and LF spectra, as well as by C, H, N element analyses, and EPR spectra for the Cu(II) compounds. The coordination around the metal varies from 4 (Zn, Cu), via 5 (Cu) to 6 (for Co, Cu and Cd). The anions usually complete the coordination sphere; only the Co and Zn compounds with the tetrafluoridoborate anions have no coordinated anions, but water ligands complete the octahedral coordination sphere. In the 5-coordinated [Cu(H₂O)(NCS)₂(tmtp)₂] water completes the square pyramid geometry.