Fragment molecular orbital study of the electronic excitations in the photosynthetic reaction center of Blastochloris viridis

All electron calculations were performed on the photosynthetic reaction center of Blastochloris viridis, using the fragment molecular orbital (FMO) method. The protein complex of 20,581 atoms and 77,754 electrons was divided into 1398 fragments, and the two‐body expansion of FMO/6‐31G* was applied to calculate the ground state. The excited electronic states of the embedded electron transfer system were separately calculated by the configuration interaction singles approach with the multilayer FMO method. Despite the structural symmetry of the system, asymmetric excitation energies were observed, especially on the bacteriopheophytin molecules. The asymmetry was attributed to electrostatic interaction with the surrounding proteins, in which the cytoplasmic side plays a major role. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

Structural features of humic acid of the coastal sediment in Ariake Sea tidelands: use of humic acid as an environmental indicator for river basins and coastal regions.

The structural features of humic acid (HA) at the sediment surface of the tideland at the Hayatsuegawa-river mouth at the Ariake Sea were investigated for the utilization of HA toward an environmental indicator of the features of the river basin and coastal region. 1H NMR analysis revealed a high-content hydrocarbon residue with a similar type of terrigenous HA. Direct and methylation-pyrolysis-GC analysis suggested the incorporation of long-chain carboxylate in HA in the tidelands. The incorporation of branched-chain carboxylate residues in HA is the result of the microbial decomposition of detritus; these residues could be one of the characteristic structural features of HA in this area, which is rich in biodiversity and microbial activity. Because the structural features of coastal zone HA appear to reveal the characteristics and activities of the biological environment, these findings suggest the possibility of becoming an indicator of the detailed analysis of the structural features of coastal zone HA.     

On Central Elements in the Universal Enveloping Algebras of the Orthogonal Lie Algebras

We present an analogy of the famous formula that the square of the Pfaffian is equal to the determinant for an alternating matrix for the case where the entries are the generators of the orthogonal Lie algebras. This identity clarifies the relation between the two sets of central elements in the enveloping algebra of the orthogonal Lie algebras. We employ systematically the exterior calculus for the proof.     

Multi-Wavelength Mueller Matrix Polarimeter

The retardation of two quarter-wave plates designed for a particular wavelength decreases or increases in accordance with the wavelength of input light beam. Compensating the shifted retardation at each measurement wavelength allows us to get Mueller matrices of samples at different wavelengths without exchanging the plates. Initial orientation errors of two plates and an analyzer, which remain constant through all wavelengths, are also taken into consideration. The availability and accuracy of this polarimeter is assessed by measurement of a quarter-wave plate designed for 632.8 nm wavelength. The results show that this system is very attractive to measure optical properties and dispersion in samples.     

Total synthesis of (+)-eupomatilone 2 via asymmetric [2,3]-Wittig rearrangement of highly oxygenated biphenylmethyl ethers

We have achieved the total synthesis of (±)- and (+)-eupomatilone 2 isolated from the Australian shrub Eupomatia bennettii. The key reaction was an asymmetric [2,3]-Wittig rearrangement employing a bis(oxazoline) chiral ligand. Although the highly oxygenated biphenylmethyl ether exhibited considerably lowered enantioselectivity as compared with the non-substituted biphenylmethyl ether, the selectivity was improved to 89% ee by using n-BuLi and ether as the base and the co-solvent, respectively.     

Rhodium-catalyzed oxidative 1:1, 1:2, and 1:4 coupling reactions of phenylazoles with internal alkynes through the regioselective cleavages of multiple C-H bonds

The direct oxidative coupling of phenylazoles with internal alkynes proceeds efficiently in the presence of a rhodium catalyst and a copper oxidant accompanied by double or quadruple C-H bond cleavages. Thus, as a representative example, 4,5-diphenylpyrazolo[1,5-a]quinoline, 1-(1,2,3,4-tetraphenylnaphthalen-5-yl)pyrazole, and 1-(1,2,3,4,5,6,7,8-octaphenylanthracen-9-yl)pyrazole can be obtained selectively through the coupling of 1-phenylpyrazole and diphenylacetylene in 1:1, 1:2, and 1:4 manners, respectively. The reactions preferentially take place at the electron-deficient sites on the aromatic substrates. A comparison of reactivities of variously substituted and deuterated substrates sheds light on the mechanism of C-H bond cleavage steps. The reaction pathway is highly dependent on reaction conditions employed, especially on the nature of solvent. The influence of solvation of a key rhodacycle intermediate has been investigated computationally. In addition, some of the condensed aromatic products have been found to exhibit intense fluorescence in the solid state.     

Asymmetric [2,3]‐Wittig Rearrangement of Oxygenated Allyl Benzyl Ethers in the Presence of a Chiral di‐tBu‐bis(oxazoline) Ligand: A Novel Synthetic Approach to THF Lignans

We have accomplished highly enantioselective [2,3]‐Wittig rearrangements of functionalized allyl benzyl ethers in the presence of a chiral di‐tBu‐bis(oxazoline) ligand. In various oxygenated benzylic ethers, the reactions proceeded with excellent diastereo‐ and enantioselectivities, although the presence of a methoxy substituent at the ortho‐position on the benzyl group drastically decreased the enantioselectivity. Conversely, o‐ethyl and o‐phenyl substituents had no significant effect on the selectivity. We found that the C2‐substituent of the allylic moiety played an important role in producing high enantioselectivity. Highly enantioselective [2,3]‐Wittig rearrangement in the presence of catalytic amounts of the chiral ligands is also described.     

Electrochemical Detection of Free Chlorine Using Ni Metal Nanoparticles Combined with Multilayered Graphene Nanoshells

An electrochemical detection of free chlorine using carbon‐metal (C?M) composite powder, with a nickel‐metal nanoparticle combined with a multilayered graphene nanoshell (Ni metal@multilayered graphene) as the main component, synthesized from CH₄ via multimode microwave‐assisted catalytic decomposition, was studied. Morphological analysis of the C?M composite powder was performed by TEM–EDX and Raman spectroscopy. The C?M composite powder was packed in a porous microelectrode (PME), and its electrochemical activity with respect to free chlorine was evaluated using a potential sweep method. The C?M composite powder exhibited a sufficient activity against free chlorine. A current based on the reduction of free chlorine was observed in the potential < around+0.3 V vs. Ag/AgCl. A linear relationship was observed between the current and the concentration.