Nickel Catalyzed Copolymerization of Ethylene and Alkyl Acrylates.

Ni(II) complexes bearing an o-bis(aryl)phosphinophenolate ligand were synthesized as catalysts for copolymerization of ethylene and alkyl acrylates. When the P-bound aryl group was 2,6-dimethoxyphenyl group, one of the oxygen atoms in the methoxy groups coordinated to the nickel center on its apical position. This complex was a highly active catalyst without any activators to give highly linear and high molecular weight copolymers. The structures of the copolymers were determined by 1H and 13C NMR to clarify that the alkyl acrylate comonomers were incorporated in the main chain and that the structures of the copolymers were significantly influenced by the structure of the aryl group in the ligand.

Micro-flow synthesis and structural analysis of sterically crowded diimine ligands with five aryl rings.

Sterically crowded diimine ligands with five aryl rings were prepared in one step in good yields using a micro-flow technique. X-ray crystallographic analysis revealed the detailed structure of the bulky ligands. The nickel complexes prepared from the ligands exerted high polymerization activity in the ethylene homopolymerization and copolymerization of ethylene with polar monomers.

Nickel-Catalyzed Propylene/Polar Monomer Copolymerization.

Nickel complexes bearing bidentate alkylphophine-phenolate ligands were synthesized and applied to the polymerization of propylene and the copolymerization of propylene and polar monomers. Therein, the use of bulky alkyl substituents on the phosphorus atom was crucial for the formation of highly regioregular polypropylenes. Theoretical calculations suggested that the 1,2-insertion of propylene is favored over the 2,1-insertion in these nickel-catalyzed (co)polymerization reactions. The substituent at the ortho position relative to the oxido group greatly influences the polymerization activity, the molecular weight, and stereoregularity of the polypropylenes. This method delivers moderately isotactic ([mm] ≤ 68%) crystalline polypropylenes. The present system represents the first example for a nickel-catalyzed regiocontrolled copolymerization of propylene and polar monomers such as but-3-en-1-ol, but-3-en-1-yl acetate, and tert-butyl allylcarbamate.

High frequency of beta-propeller protein-associated neurodegeneration (BPAN) among patients with intellectual disability and young-onset parkinsonism.

Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous disorder, characterized by the accumulation of iron in regions such as the basal ganglia. We enrolled 28 patients with childhood intellectual disability and young-onset parkinsonism (≤40 years at onset) and 4 patients with infantile neuroaxonal dystrophy. All had been clinically diagnosed, and the prevalence of genetic mutations linked to NBIA (PANK2 [exons 1-7], PLA2G6 [exons 2-17], C19orf12 [exons 1-3], WDR45 [exons 2-11], COASY [exons 1-9], FA2H [exons 1-7], and RAB39B [exons 1, 2]) was evaluated. We detected 7 female patients (25.0%, 7 of 28) with de novo heterozygote WDR45 mutations, which are known to be pathogenic for beta-propeller protein-associated neurodegeneration. All 7 patients had common clinical features. Pathogenic mutations in other NBIA genes were not found. We also screened 98 patients with early-onset parkinsonism without intellectual disability and 110 normal controls of Japanese origin for WDR45 mutations. None had WDR45 mutations. Our data suggest a high frequency of beta-propeller protein-associated neurodegeneration mutations in the Japanese population.

Stable spectral dip formation and multicolour changes of plasmonic gold nanoparticles on TiO2.

Spectral dip formation at arbitrary wavelengths and the corresponding multicolour changes were achieved by using plasmonic Au nanoparticles on TiO(2), based on plasmon-induced charge separation and a coordination effect of iodide ions. The dips were stable in air under white light, in marked contrast to the case of conventional Ag nanoparticles.

Plasmon-induced oxidation of gold nanoparticles on TiO2 in the presence of ligands.

The mechanism of plasmon-induced charge separation of gold nanoparticles (Au NPs) on TiO2 was investigated with the help of anionic ligands. Au NPs are oxidized in the presence of KX (X = SCN, Br or Cl), chiefly via direct oxidation to [AuX4](-). The reactivity of Au NPs depends on the solution pH, the type of anion ligands and the excitation wavelength, suggesting that the photopotential of Au NPs during plasmon-induced charge separation depends on both the flatband potential of TiO2 and the energy of irradiated photons. The results indicate that the reactivity and efficiency of the plasmon-induced charge separation and accompanying reactions can be tuned and optimized by changing those factors.