No abstract

The catalytic enantioselective reaction of diphenylmethylidene-protected α-aminoacetonitriles with imines has been developed. Good yields and diastereo- and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts. The reaction of α-aminonitriles with di-tert-butyl azodicarboxylate afforded chiral α,α-diaminonitriles in high yields with high enantioselectivities.

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Gold nanospheres were dispersed in gelatin sections (10–100 µm thickness) and their laser desorption/ionization (LDI) efficiencies of gold ions (Au+, Au2+, Au3+) under pulsed-laser irradiation were examined. The mass signal intensities were linear to the surface densities ranging from 6 × 104 to 6 × 106 particles/mm2. When the thickness of the sections was thinner than or equal to 50 µm, the LDI efficiency of gold nanospheres was independent of the thickness. Thus, the mass intensity was dependent on the surface densities of gold nanospheres in the gelatin sections. It was also found that the LDI efficiencies were affected by the concentration of gelatin solutions. Based on the high reproducibility of mass signals obtained from gelatin sections, the LDI efficiencies of star-shaped gold nanoparticles (gold nanostars) were also evaluated. It was found that the nanostars showed higher LDI efficiencies than gold nanospheres, but the enhancement was not more than 25%.

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The catalytic enantioselective reaction of diphenylmethylidene-protected a-aminoacetonitriles with imines has been developed. Good yields and diastereo-and enantioselectivities were observed for the reaction of various imines using chiral bis(imidazoline)/Pd catalysts.The reaction of a-aminonitriles with di-tert-butyl azodicarboxylate afforded chiral a,adiaminonitriles in high yields with high enantioselectivities.

Silver or palladium shelled gold nanoparticles were fused into alloy nanoparticles by pulsed-laser irradiation. The alloy nanoparticles could carry antibodies on their surfaces without affecting their immune functionalities and interact selectively with antigens on a blotting membrane. Silver or palladium ions desorbed from the alloy nanoparticles as reporter ions upon the UV laser irradiation in a mass spectrometer.

Desorption and ionization of gold anions and cations from gold nanorods and nanospheres were investigated using a matrix-assisted laser desorption/ionization mass spectrometry instrument. The signal intensities of the gold anions from nanorods with a volume of 4.8 × 10 3 nm 3 were about 28 times larger than the signal intensities of gold anions from nanospheres of similar volume. Gold cations did not show a remarkable difference depending on the nanoparticles' shapes. The unique desorption behavior of gold anions suggests their potential as reporter ions in mass spectrometry.