2,2′-Bipyridyl formation from 2-arylpyridines through bimetallic diyttrium intermediate

An alkylyttrium complex supported by an N,N′-bis(2,6-diisopropylphenyl)ethylenediamido ligand, (ArNCH₂CH₂NAr)Y(CH₂SiMe₃)(THF)₂ (1, Ar = 2,6-ⁱPr₂C₆H₃), activated an ortho-phenyl C–H bond of 2-phenylpyridine (2a) to form a (2-pyridylphenyl)yttrium complex (3a) containing a five-membered metallacycle. Subsequently, a unique C(sp²)–C(sp²) coupling of 2-phenylpyridine proceeded through a bimetallic yttrium intermediate, derived from an intramolecular shift of the yttrium center to an ortho-position of the pyridine ring in 3a, to yield a bimetallic yttrium complex (4a) bridged by two-electron reduced 6,6′-diphenyl-2,2′-bipyridyl. Aryl substituents at the ortho-position of the pyridine ring were key in order to destabilize the μ,κ²-(C,N)-pyridyldiyttrium intermediate prior to the C(sp²)–C(sp²) bond formation.     

Femtosecond laser-induced stimulation of a single neuron in a neuronal network

We demonstrated the stimulation of neurons at a single-cell level in cultured neuronal network by a focused femtosecond laser. When the femtosecond laser was focused on a neuron loaded with a fluorescent calcium indicator, the fluorescence intensity immediately increased at the laser spot, suggesting that intracellular Ca²⁺ increases in the neuronal cell due to the femtosecond laser irradiation. The probability of Ca²⁺ elevation at the laser spot depended on the average laser power, irradiation time, and position of the focal point along the optical axis, indicating that the femtosecond laser activates neurons because of multiphoton absorption. Moreover, after laser irradiation of a single neuron cultured on multielectrode arrays, the evoked electrical activity of the neurons was demonstrated by electrophysiological systems, which concluded that the focused femtosecond laser could achieve stimulating a single neuron in a neuronal network with high spatial and temporal resolution.     

SOLVENT EFFECTS ON TRIPLET-STATE BACTERIOCHLOROPHYLL a AS DETECTED BY TRANSIENT RAMAN SPECTROSCOPY AND THE ENVIRONMENT OF BACTERIOCHLOROPHYLL a IN THE LIGHT-HARVESTING COMPLEX OF Rhodobacter sphaeroides R26

The frequency of BChl that was bound to the light-harvesting complex (LHC) of Rhodobacter sphaeroides R26 was found to be 1598 cm^-1, a result which suggests that a pair of BChl molecules form a dimer in the LHC in the T₁ state.     

Heterogeneous photocatalytic synthesis of ammonia from water and nitrogen

Photocatalytic synthesis of ammonia from water and nitrogen was performed. Binary wafered catalysts prepared with semiconductor powder (TiO₂, SrTiO₃, CdS or GaP) and platinum black, where the copolymer of ethylene and vinylalcohol was used as a binder, were found to be more effective to yield ammonia than the semiconductor powders alone.     

Rapid adsorption and entrapment of benzoic acid molecules onto mesoporous silica (FSM-16)

Changes in the molecular state of benzoic acid (BA) in the presence of folded sheet mesoporous material (FSM-16), which has uniformly sized cylindrical mesopores and a large surface area, were assessed with several analyses. When BA was blended with FSM-16 for 5 min (BA content=30%), the X-ray diffraction peaks of BA crystals disappeared, suggesting an amorphous state. Fluorescence analysis of the mixture showed a new fluorescence emission peak for BA at 386 nm after mixing with FSM-16. Fluorescence lifetime analysis of the BA component in the mixture at 386 nm showed a longer lifetime in comparison with that of BA crystals. The solid-state (13)C CP/MAS and PST/MAS NMR spectra of the mixture with FSM-16 showed a significantly different spectral pattern from the mixture with nonporous glass, whose NMR spectra were identical to those of BA crystals. These results indicate that BA molecules disperse quickly into the hexagonal channels of FSM-16 by a simple blending procedure and adsorbed BA molecules had clearly different physicochemical properties to BA crystals.     

Second hyperpolarizabilities (gamma) of bisimidazole and bistriazole benzenes: diradical character, charged state, and spin state dependences

The second hyperpolarizabilities of bisimidazole- and bistriazole-benzene compounds have been calculated at different levels of approximation to unravel the effects of diradical character as well as of charge and spin multiplicity. The largest second hyperpolarizabilities are associated with intermediate diradical character, provided positive charging does not compensate for this effect. For the neutral diradical bisimidazole compound, the singlet diradical species possesses a second hyperpolarizability two to three times larger than the corresponding triplet, demonstrating the possibility of spin state control of the third-order NLO responses for diradical species.     

Beta-NMR measurement of 58Cu in Si

The β-NMR study of short-lived nucleus ⁵⁸Cu (I ^π ?=?1^?+?, T _1/2?=?3.2 s) in Si has been performed. Spin polarization of ⁵⁸Cu induced by the charge exchange reaction of ⁵⁸Ni was observed in Si at 15 K. The ⁵⁸Cu magnetic moment $|\upmu[^{58}\mbox{Cu}]| = (0.46 \pm 0.03)\upmu_{\rm N}$ deduced from the β-NMR spectrum is consistent with the previous results on the laser spectroscopy. The present result shows that the ⁵⁸Cu nucleus is promising as a new nuclear probe for the microscopic study of Cu impurities in Si.     

Development of rotating magnetic field system for the β-NMR method

A rotating magnetic field system has been developed to determine the sign of magnetic (μ) and quadrupole (Q) moments by means of the β-ray-detected nuclear magnetic resonance (β-NMR) method. The rotating magnetic field is obtained using two crossed Helmholtz-like coils at right angles. The phase angles of the alternating currents for the two coils are shifted by 90°. Thus the resulting magnetic field is circularly polarized. By the adjustment of the phase-angle difference, a right- or left-circularly polarized magnetic field is produced. Productions of right- or left-rotating magnetic fields including a linear component were confirmed using pickup-coils.     

Strangeness Nuclear Physics at J-PARC

After the big earthquake in the east part of Japan on March 11, 2011, the beams in the hadron experimental hall at J-PARC have been successfully recovered in February, 2012. The experimental program using pion beams is now on-going with the primary proton beam power of ~5 kW. Before a long summer shutdown scheduled in 2013, several experiments in strangeness nuclear physics are going to take data. In this period, we anticipate the beam power would exceed 10 kW and the experiments to use K ^? beams will start. The experimental program is explained briefly.     

Poly(p‐benzamide) having isopropyl‐substituted chiral tri(ethylene glycol) side Chain: Synthesis and helical conformation

Isopropyl‐substituted tri(ethylene glycol) is used as a chiral side chain of N‐substituted poly(p‐benzamide) in order to increase the difference of stability between the right‐ and left‐handed helical structures of the polymer. The target polymer is synthesized by the chain‐growth condensation polymerization of the corresponding monomer with an initiator using lithium 1,1,1,3,3,3‐hexamethyldisilazide as a base. A circular dichroism (CD) study of the polymer reveals that the CD signal is due to an excess of a thermodynamically controlled right‐handed helical structure of the polymer, and that the replacement of the methyl group with a bulkier isopropyl group at the side chain of poly(p‐benzamide) increases the abundance of right‐handed helical structure in chloroform. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1623–1628