EPR study of NO radicals encased in modified open C60 fullerenes

Using pulsed electron paramagnetic resonance (EPR) techniques, the low-temperature magnetic properties of the NO radical being confined in two different modified open C60-derived cages are determined. It is found that the smallest principal g value g3, being assigned to the axis of the radical, deviates strongly from the free electron value. This behaviour results from partial compensation of the spin and orbital contributions to the g3 value. The measured g3 values in the range of 0.7 yield information about the deviation of the locking potential for the encaged NO from axial symmetry. The estimated 17 meV asymmetry is quite small compared to the situation found for the same radical in polycrystalline or amorphous matrices ranging from 300 to 500 meV. The analysis of the temperature dependence of spin relaxation times resulted in an activation temperature of about 3 K, assigned to temperature-activated motion of the NO within the modified open C60-derived cages with coupled rotational and translational degrees of freedom in a complicated three-dimensional locking potential

Activation Process of [NiFe] Hydrogenase Elucidated by High-Resolution X-Ray Analyses: Conversion of the Ready to the Unready State

SummaryHydrogenases catalyze oxidoreduction of molecular hydrogen and have potential applications for utilizing dihydrogen as an energy source. [NiFe] hydrogenase has two different oxidized states, Ni-A (unready, exhibits a lag phase in reductive activation) and Ni-B (ready). We have succeeded in converting Ni-B to Ni-A with the use of Na2S and O2 and determining the high-resolution crystal structures of both states. Ni-B possesses a monatomic nonprotein bridging ligand at the Ni-Fe active site, whereas Ni-A has a diatomic species. The terminal atom of the bridging species of Ni-A occupies a similar position as C of the exogenous CO in the CO complex (inhibited state). The common features of the enzyme structures at the unready (Ni-A) and inhibited (CO complex) states are proposed. These findings provide useful information on the design of new systems of biomimetic dihydrogen production and fuel cell devices

Rational syntheses of helical π-conjugated oligopyrrins with a bipyrrole linkage: geometry control of bis-copper(II) coordination

Rational syntheses of long-chain helical π-conjugated oligopyrrins and their bis-copper complexes afford systematically modulated optical and magnetic properties.</p

BC[+]+Ar⇔BC+Ar[+]系における状態を選別した電荷移動反応の研究 : BCとしてH[2], O[2], NOを用いた時の比較

京都大学0048新制・論文博士理学博士乙第5331号論理博第870号新制||理||473(附属図書館)UT51-59-H111(主査)教授 志田 忠正, 教授 波多野 博行, 教授 廣田 襄学位規則第5条第2項該当Kyoto UniversityDFA

Coherent Raman spectroscopy of nuclear quadrupole resonance of La around Pr^<3+> in LaF_3

Coherent Raman spectroscopy was applied for an optical-rf double-resonance study of a LaF_3 crystal doped with Pr^. The coherent nuclear spin Raman scattering was detected as a function of the applied rf frequency. Exciting the resonance condition of the ^3H_4→^3P_0 transition of Pr^ (20 925 cm^), only the La nuclei surrounding the Pr^ ion were observed through their nuclear quadrupole resonance ~NQR!. The double resonance between the optical transition of the ion and the NQR transition of its neighboring nucleus is theoretically described by analyzing the magnetic dipolar interaction that is affected by the optical excitation. Under a certain restriction, which the present system fulfills, the intensity of the Raman heterodyne signal can be described by an analytical function of the internuclear vector and the orientation of the electric-field gradient ~EFG! at the Pr and La nuclei. Five different neighboring La nuclei were observed. They are different from the bulk La in both magnitude and orientation of the EFG. In addition, it was found that the laser frequency jitter affects the relative signal intensity of the different La NQR transitions through the optical pumping of the La spin levels.[S0163-1829(98)03145-2

Direct C-H bond activation of ethers and successive C-C bond formation with benzene by a bifunctional palladium-titania photocatalyst

Palladium-loaded titanium oxide was found to work as a bifunctional photocatalyst for functionalization of benzene with ether upon photoirradiation, without using any special reagents. The metal-loaded TiO2 photocatalyst activated a C–H bond of ethers and the heterogeneous Pd metal nanoparticle catalyst promoted the successive C–C bond formation between benzene and the radical species. In this reaction, benzene reacted very selectively with the α-carbon of various ethers at least in the initial stage of the reaction. Kinetic and ESR studies revealed a detailed mechanism for the reaction

High-spin polycationic states of an alternate meta-para-linked oligoarylamine incorporating two macrocycles.

High-spin alignment for dicationic, tricationic, tetracationic and hexacationic species of a meta-para-linked oligoarylamine was accomplished by incorporating cyclophane skeletons into the oligomer backbone

An N-substituted aza[14]metacyclophane tetracation: a spin-quintet tetraradical with four para-phenylenediamine-based semi-quinone moieties.

Includes Supplementary Information.A fully dianisylaminophenylated aza[1(4)]metacyclophane has been synthesized that exhibits four reversible two-electron oxidation processes, and its dicationic and tetracationic species have been found to be in spin-triplet and spin-quintet states

A compact planar low-energy-gap molecule with a donor-acceptor-donor nature based on a bimetal dithiolene complex.

Accepted 04 Sep 2015We present the first report of a compact, planar and low-energy-gap molecule based on a π-conjugated bimetal system comprising a tetrathiooxalate (tto) skeleton. The observed low HOMO-LUMO energy gap (1.19 eV) is attributed to its donor-acceptor-donor (D-A-D) nature because the skeleton acts as an electron acceptor as well as a tiny and noninnocent bridging moiety