Synthesis and thermal behavior of cis- and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene

The cothermolysis of benzoyl(tert-butyl)bis(trimethylsilyl)silane with 2,3-dimethylbutadiene in a sealed tube at 140 °C for 24 h afforded cis- and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-2-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (2 and 3) in a ratio of approximately 1:1 in 66% combined yield. When cis-silacyclohex-4-ene 2 was heated in a sealed tube at 250 °C for 24 h, dyotropic ring contraction took place to give 1-[(tert-butyl)(trimethylsiloxy)(trimethylsilyl)silyl]-3,4-dimethyl-1-phenylcyclopent-3-ene (4), but not trans-2-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-1-(trimethylsilyl)-1-silacyclohex-4-ene (6). The thermolysis of trans-silacyclohex-4-ene 3 under the same conditions, however, afforded two products, 1-silyl-1-phenylcyclopent-3-ene 4 and trans-1-tert-butyl-4,5-dimethyl-2-phenyl-1-(trimethylsiloxy)-2-(trimethylsilyl)-1-silacyclohex-4-ene (5). The theoretical calculations were carried out to characterize the transition states and other local minima, and to evaluate the activation energies for the dyotropic rearrangement of 2 to 4 and 6, and 3 to 4 and 5. The energy barriers between 2 and 4, between 3 and 4, and between 3 and 5 were evaluated to be 188, 191, 192 kJ mol⁻¹, respectively. The energy barrier between 2 and 6, however, was calculated to be 201 kJ mol⁻¹ or higher. These results are consistent with the experimental finding that the thermal isomerization of 2 affords only 4, but 3 produces both 4 and 5.     

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     

Termitomycamides A to E, fatty acid amides isolated from the mushroom Termitomyces titanicus, suppress endoplasmic reticulum stress

Five fatty acid amides, termitomycamides A to E (1 to 5), were isolated from the giant edible mushroom Termitomyces titanicus. The structures of 1-5 were determined by the interpretation of spectral data and/or synthesis. Compounds 2 and 5 showed protective activity against endoplasmic reticulum stress-dependent cell death.     

Structures and electronic transport on silicon surfaces

By utilizing a variety of surface superstructures formed on silicon surfaces and atomic layers grown on them, close correlations between the atomic-scale structures and electrical conduction phenomena at the surfaces have been revealed. State-of-art techniques for analyzing and controlling atomic/electronic structures of surfaces are leading to an understanding of the novel electronic transport properties at surfaces. For example, the electrical conduction through surface-state bands, which are inherent in the surface superstructure, has been confirmed in in-situ measurements. An important phenomenon has also been found, where adatoms donate carriers into the surface-state band, resulting in a remarkable enhancement in electrical conductance. The nucleation of the adatoms diminishes such a doping effect. Furthermore, electrical conduction through atomic layers grown on the surfaces, whose growth structures are sensitive to the substrate surface structures, will be also discussed. In this review, we emphasize that the surface electronic transport properties are closely related to the atomic structures and atomistic dynamics on surfaces. The ultimate two-dimensional electron systems, consisting of the surface-state bands and grown atomic layers, are expected to provide a new stage in surface physics, as well as a precursory stage leading to atomic-scale electronics devices.     

Formation of new base pairs between inosine and 5-methyl-2-thiocytidine derivatives

In this paper, we report DNA and 2'-OMe-RNA probes containing 5-methyl-2-thiocytidine (m(5)s(2)C) residues that can bind selectively and strongly to the corresponding RNA targets containing inosine residues by the significant stacking effect and steric hindrance of the 2-thiocarbonyl group.     

Selective Functionalization of Fullerenes with N,N-Dihalosulfonamides as an N(1) Unit: Versatile Syntheses of Aza[60]fulleroids and Aziridino[60]fullerenes and their Application to Photovoltaic Cells

Highly selective and versatile methods for the synthesis of aza[60]fulleroids and aziridino[60]fullerenes from C(60) have been developed. The reactions utilized N,N-dihalosulfonamides as an N(1) source. The photophysical, electrochemical, and thermal properties of the iminofullerenes were investigated by means of UV/Vis spectroscopy, cyclic voltammetry, and thermogravimetry, respectively. Furthermore, photovoltaic cells based on the synthesized iminofullerenes were fabricated. The power conversion efficiencies (PCEs) of the devices showed moderate values ranging from 1.33 to 2.35?%.     

Analysis of Renal Cell Carcinoma as a First Step for Developing Mass Spectrometry-Based Diagnostics

Immediate diagnosis of human specimen is an essential prerequisites in medical routines. This study aimed to establish a novel cancer diagnostics system based on probe electrospray ionization-mass spectrometry (PESI-MS) combined with statistical data processing. PESI-MS uses a very fine acupuncture needle as a probe for sampling as well as for ionization. To demonstrate the applicability of PESI-MS for cancer diagnosis, we analyzed nine cases of clear cell renal cell carcinoma (ccRCC) by PESI-MS and processed the data by principal components analysis (PCA). Our system successfully delineated the differences in lipid composition between non-cancerous and cancerous regions. In this case, triacylglycerol (TAG) was reproducibly detected in the cancerous tissue of nine different individuals, the result being consistent with well-known profiles of ccRCC. Moreover, this system enabled us to detect the boundaries of cancerous regions based on the expression of TAG. These results strongly suggest that PESI-MS will be applicable to cancer diagnosis, especially when the number of data is augmented.     

Enantioselective trapping of an α-chiral carbanion of acyclic nitrile by a carbon electrophile

An α-chiral nitrile carbanion generated by deprotonation of enantioenriched O-carbamoyl cyanohydrin was trapped in situ with ethyl cyanoformate to give the corresponding ester derivative in 92% yield and 90?:?10 er, providing the first example of trapping of an α-chiral acyclic nitrile carbanion that has been considered to be very configurationally labile.     

Stokes holography

A new technique, referred to as Stokes holography, is proposed and experimentally demonstrated for controlled synthesis of generalized Stokes parameters in 3D space using Stokes fringes. Stokes fringes are polarization fringes which permit to record and reconstruct complete wavefront. Full use of Stokes fringes in a single step is realized by scattering complex field and subsequently reconstructing using spatial averaging of the randomly scattered field. Mathematical formulations are derived and supported by experimental results of 3D object reconstruction in generalized Stokes parameters.