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Coherent spin transport in a protein containing the [4Fe-4S] cluster were calculated by using NEGF-DFT based on the Landauer model. The results of the spin transmission pathway revealed spin flow via Fe-S clusters. [Display omitted] • Spin transport in an Fe-S protein based on the Landauer formula. • Difference of tunneling characteristics due to oxidized and reduced states. • Spin transmission pathway via Fe-S clusters. Spin transport in a molecule was recently examined to discuss the chiral-induced spin selectivity (CISS) effect. This effect has been particularly reported in metalloproteins because the presence of transition metals improves spin polarization in a helical peptide structure. Among metalloproteins, iron-sulfur proteins have ubiquitous redox properties in photosynthesis and respiration. Iron can enhance spin polarization. In this study, the coherent spin transport in an Fe-S protein was investigated using first-principles calculations based on the Landauer formula. Proteins containing the [4Fe-4S] cluster were used for the calculations. The results of the spin transmission pathway revealed spin flow via Fe-S clusters. [ABSTRACT FROM AUTHOR]

The electronic transport properties of diamantanes as a model of diamondoids (nanodiamonds) were studied by first-principles calculations. For this purpose, diamantane with thiol group was sandwiched between gold electrodes. Additionally, the effect of substitution of equatorial tertiary carbons on conductance was examined in detail. The conductance of boron- and phosphorus-substituted diamantanes was nearly the same as that of non-substituted diamantane, whereas the conductance of nitrogen-doped diamantane was higher. This is due to the fact that the nitrogen-substitution increases the transmittance at the Fermi level by the overlap of nitrogen 2p and sulfur 3s orbitals. Furthermore, the heteroatom-substituted diamantanes exhibited current rectification to a certain degree. [ABSTRACT FROM AUTHOR]

The band structures of metallocene-based polymers in which the nearest metalloecenes were directly linked by a C-C bond have been determined by employing the tight-binding crystal orbital (CO) method. In particular, we determined the band structures of metallocene-based alternate copolymers whose metal sequences in a unit cell were Fe-Co, Fe-Fe-Co-Co, Fe-Ni, Ru-Co and Os-Co. The band structures of alternate copolymers of Fe-Co and Fe-Ni possessed a partially occupied (PO) band whose crystal orbitals were extremely localized at the 3d orbitals of cobalt or nickel atom. Alternate copolymers of Ru-Co and Os-Co had the same tendency as that of band structure of Fe-Co. Therefore, it was clear that the band structures of the metallocene-based alternate copolymers were considered to be a superposition of the polymetallocenylenes. Furthermore, we examined the effect of inserting the bridging part of boron-, phosphorus-, and sulfur bridges between the nearest ferrocenes upon the band structures of ferrocene-based polymers. The electronic structure of the boron-bridged polymer was similar to that of the silicon-bridged polymer whose band structure was determined in our previous study. On the other hand, the phosphorus- and sulfur-bridged polymers yielded two degenerated HO bands whose COs were localized at P or S 2p orbitals. [ABSTRACT FROM AUTHOR]

Photofunctional polymethylphenylsilane (PMPS) and toluene dispersed silica nano-particles (13 nm average diameter) were used for the preparation of organic-inorganic hybrid thin films. The surface of silica nano-particles were modified with phenyl and methyl groups. The thin films were prepared by spin-coating the toluene solution of PMPS and silica nano-particles on quartz and silicon substrates, respectively. The UV spectra of polysilane/phenyl modified silica nano-particle hybrid thin films indicated a red-shift of absorption peak related to the Si-Si bond in PMPS. This interesting phenomenon was caused by the longer σ-conjugation due to the stretched Si-Si bond, which was resulted from the π-π interaction of phenyl groups between PMPS and surface of silica nano-particles. Furthermore, after UV irradiation and heat treatment of the hybrid thin films containing small amount of PMPS, the cross-linked nano porous silica thin films with a low refractive index were obtained. [ABSTRACT FROM AUTHOR]

• Coherent electron transport in a DNA molecule. • DNA conformational transition. • A change in the magnetoresistance ratio. A DNA molecule formed by a cytosine-guanine sequence ((CG) n) exhibits a conformational transition from the B-form to the Z-form by varying the ionic environment. This study reports coherent spin transport in a molecule of double strand 5′-(CG) n -3′ (n = 2, 3, 4) under a magnetic proximity effect from ferromagnetic nickel electrodes. The calculation was performed by using a Landauer-Büttiker formula based on a non-equilibrium Green's function with density functional theory. The conformational transition led to about a 10 times change in conductance, which is similar to the experimental results. In addition, the absolute value of the tunnel magnetoresistance ratio had a tendency to decrease with the conformational transition. The calculation result suggests that not only a change in conductance but also a change in the magnetoresistance ratio can be used to monitor the conformation of a DNA molecule sensitively. [ABSTRACT FROM AUTHOR]

This article presents a synthesis of a block copolymer of poly(methylphenylsilane) (PMPS) and 2-(methylthio)ethyl methacrylate (MTEM), P(MPS-co-MTEM), by photopolymerization using PMPS as a macro-photoinitiator and prepared a bilayer structure of P(MPS-co-MTEM) in which the copolymer is adsorbed to the gold layer. Polysilanes have been known as functional polymers with numerous electronic and optical properties such as photo-conductivity, electro- or photo-luminescence, due to the configuration of silicon-silicon main chain which is confirmed by conspicuous absorption band in the ultra-violet region. Organic-inorganic hybrid materials have also been known as promising materials for practical applications to electronic or optical devices. In order to improve some functionalities of polysilanes, polysilane-inorganic hybrid thin films were prepared in which polysilane segments are embedded in inorganic matrix such as silica, titania and zirconia. It was suggested that some chemical bonds or interactions between the organic and inorganic components are necessary to prepare homogenous organic-inorganic hybrids. Previously, chemical bonds between polysilane-acrylic or -methacrylic block copolymers and inorganic components via sol-gel reaction are used for preparation of homogeneous polysilane-silica or -titania hybrid thin films.