Ruthenium-catalyzed transfer oxygenative cyclization of α,ω-diynes: unprecedented [2 + 2 + 1] route to bicyclic furans via ruthenacyclopentatriene

A novel oxygen-atom-transfer process enables the catalytic [2 + 2 + 1] synthesis of bicyclic furans from α,ω-diynes with DMSO. [CpRu(AN)(3)]PF(6) catalyzed the transfer oxygenative cyclization of diynes with aryl terminal groups, while those of diynes with alkyl terminal groups were effectively promoted by the corresponding Cp* complex. A mechanism for bicyclic furan formation via a ruthenacyclopentatriene was proposed on the basis of both experimental and theoretical studies.     

New evaluation of fullerene molecules on Si(111)-(7 × 7) reconstructed structure using non-contact scanning non-linear dielectric microscopy

Fullerene (C₆₀) molecules on an Si(111)-(7 × 7) surface have been investigated using non-contact scanning non-linear dielectric microscopy (NC-SNDM) under an ultra-high vacuum. The topography, the interface between the C₆₀ molecule and Si adatoms, and the internal structure of the C₆₀ molecules were successfully investigated. For ～ 0 ML and ～ 0.4 ML coverage, both phase reversal sites and sites without phase reversal could be observed in the first order phase (θ1) image. On the other hand, for 1 ML coverage, phase reversal could not be identified. These results indicate that charge transfer only occurred from Si adatoms to C₆₀ molecules at three-fold symmetric sites on the Si(111)-(7 × 7) surface, and the electric dipole moment is reflected in the electronic state of the C₆₀ molecules. The internal structure of C₆₀ molecules was clearly observed in topography by the second order amplitude (A₂) feedback signal for 1 ML coverage, reflecting the LDOS originating from the t_1u orbital.     

A primal–dual interior point method for nonlinear semidefinite programming

This paper is concerned with a primal–dual interior point method for solving nonlinear semidefinite programming problems. The method consists of the outer iteration (SDPIP) that finds a KKT point and the inner iteration (SDPLS) that calculates an approximate barrier KKT point. Algorithm SDPLS uses a commutative class of Newton-like directions for the generation of line search directions. By combining the primal barrier penalty function and the primal–dual barrier function, a new primal–dual merit function is proposed. We prove the global convergence property of our method. Finally some numerical experiments are given.     

Length of Longest Cycles in a Graph Whose Relative Length is at Least Two

Let G be a graph. We denote p(G) and c(G) the order of a longest path and the order of a longest cycle of G, respectively. Let κ(G) be the connectivity of G, and let σ ₃(G) be the minimum degree sum of an independent set of three vertices in G. In this paper, we prove that if G is a 2-connected graph with p(G) ? c(G) ≥ 2, then either (i) c(G) ≥ σ ₃(G) ? 3 or (ii) κ(G)?=?2 and p(G) ≥ σ ₃(G) ? 1. This result implies several known results as corollaries and gives a new lower bound of the circumference.     

Cyano-bridged Mn(III)-M(III) single-chain magnets with M(III)=Co(III), Fe(III), Mn(III), and Cr(III)

A series of isostructural cyano-bridged Mn(III)(h.s.)-M(III)(l.s.) alternating chains, [Mn(III)(5-TMAMsalen)M(III)(CN)(6)]?4H(2)O (5-TMAMsalen(2-)=N,N'-ethylenebis(5-trimethylammoniomethylsalicylideneiminate), Mn(III)(h.s.)=high-spin Mn(III), M(III)(l.s.)=low-spin Co(III), Mn-Co; Fe(III), Mn-Fe; Mn(III), Mn-Mn; Cr(III), Mn-Cr) was synthesized by assembling [Mn(III)(5-TMAMsalen)](3+) and [M(III)(CN)(6)](3-). The chains present in the four compounds, which crystallize in the monoclinic space group C2/c, are composed of an [-Mn(III)-NC-M(III)-CN-] repeating motif, for which the -NC-M(III)-CN- motif is provided by the [M(III)(CN)(6)](3-) moiety adopting a trans bridging mode between [Mn(III)(5-TMAMsalen)](3+) cations. The Mn(III) and M(III) ions occupy special crystallographic positions: a C(2) axis and an inversion center, respectively, forming a highly symmetrical chain with only one kind of cyano bridge. The Jahn-Teller axis of the Mn(III)(h.s.) ion is perpendicular to the N(2)O(2) plane formed by the 5-TMAMsalen tetradentate ligand. These Jahn-Teller axes are all perfectly aligned along the unique chain direction without a bending angle, although the chains are corrugated with an Mn-N(axis) -C angle of about 144°. In the crystal structures, the chains are well separated with the nearest inter-chain M???M distance being relatively large at 9?? due to steric hindrance of the bulky trimethylammoniomethyl groups of the 5-TMAMsalen ligand. The magnetic properties of these compounds have been thoroughly studied. Mn-Fe and Mn-Mn display intra-chain ferromagnetic interactions, whereas Mn-Cr is characterized by an antiferromagnetic exchange that induces a ferrimagnetic spin arrangement along the chain. Detailed analyses of both static and dynamic magnetic properties have demonstrated without ambiguity the single-chain magnet (SCM) behavior of these three systems, whereas Mn-Co is merely paramagnetic with S(Mn)=2 and D/k(B)=-5.3?K (D being a zero-field splitting parameter). At low temperatures, the Mn-M compounds with M=Fe, Mn, and Cr display remarkably large M versus H hysteresis loops for applied magnetic fields along the easy magnetic direction that corresponds to the chain direction. The temperature dependence of the associated relaxation time for this series of compounds systematically exhibits a crossover between two Arrhenius laws corresponding to infinite-chain and finite-chain regimes for the SCM behavior. These isostructural hetero-spin SCMs offer a unique series of alternating [-Mn-NC-M-CN-] chains, enabling physicists to test theoretical SCM models between the Ising and Heisenberg limits.     

Tenuipyrone, a novel skeletal polyketide from the entomopathogenic fungus, Isaria tenuipes, cultivated in the presence of epigenetic modifiers

The concomitant addition of the histone deacetylase inhibitor and the DNA methyltransferase inhibitor to the culture medium of an entomopathogenic fungus, Isaria tenuipes, greatly enhanced its secondary metabolite production and led to the isolation of tenuipyrone (1), a novel polyketide with an unprecedented tetracyclic ring system bearing a spiroketal structural component, along with two known C(10)-polyketides, cephalosporolide B (2), which is a plausible biosynthetic precursor of 1, and cephalosporolide F (3).     

Ambipolar behavior of hydrogen-bonded diketopyrrolopyrrole-thiophene co-oligomers formed from their soluble precursors

Organic field-effect transistors with hydrogen-bonded diketopyrrolopyrrole-thiophene co-oligomers were fabricated by a solution-process method with annealing at 200 °C, showing ambipolar charge-carrier transfer with field-effect mobilities up to μ(h) = 6.7 × 10(-3) cm(2) V(-1)s(-1) and μ(e) = 5.6 × 10(-3) cm(2) V(-1) s(-1).     

A theoretical study of the reactivity of Cu2O(111) surfaces: the case of NO dissociation

We compare the electronic properties of Cu(111) and Cu(2)O(111) surfaces in relation to the dissociation of NO using first principles calculations within density functional theory. We note a well-defined three-fold site on both O- and Cu-terminated Cu(2)O surfaces which is verified as the active site for the adsorption and dissociation of NO. The interaction of Cu with O atoms results in the forward shifting of the local density of states and formation of unoccupied states above the Fermi level, compared to the fully occupied d band of pure Cu. These results give valuable insights in the realization of a catalyst without precious metal for the dissociation of NO.     

Stable Sugar‐Chain‐Immobilized Fluorescent Nanoparticles for Probing Lectin and Cells

Sugar chains are important molecules in cellular recognition and signaling, and quantum dots (QDs) are a very powerful tool for in vitro and in vivo imaging. Herein, we report the preparation of stable sugar‐chain‐immobilized fluorescent nanoparticles (SFNPs) and their application to the analysis of sugar‐chain–protein interactions and cellular imaging. SFNPs were easily prepared by mixing CdTe/CdS core/shell QDs with our previously developed sugar‐chain–ligand conjugates. The obtained SFNPs were very stable and could be stored for several months. In the binding analysis, β‐galactose‐ and α‐glucose‐immobilized SFNPs were specifically interacted with Ricinus communis agglutinin I and concanavalin A, respectively, and made into aggregates. The binding interaction was detected visually, fluorescently, or both. In the experiment for cellular imaging, it was found that SFNPs were predominantly taken up by human hepatocyto carcinoma cells (HepG2), suggesting the possible usage of our designed SFNPs for various biochemical analyses of sugar chains.     

Optical band gap of semiconductive type II Si clathrate purified by centrifugation

The optical properties of Si clathrate, which is believed to have potential as a new Si-based material for optical devices, were investigated in this study. Si clathrates with type II structure (Na_xSi₁₃₆) with low Na content (x = 1.3, 2.0) were synthesized by thermal decomposition of NaSi. The synthesized samples were purified by centrifugation using a solution of CH₂Br₂–C₂Cl₄ to remove impurities. Using the obtained high purity samples (Na_1.3Si₁₃₆, 93 wt.%; Na_2.0Si₁₃₆, 90 wt.%), the optical absorption spectra of Na_xSi₁₃₆ were clarified, for the first time, from diffuse reflection measurements. The inclusion of Na in Si₁₃₆ was found to cause free carrier absorption in the infrared region but had little effect on the fundamental absorption edge found in the visible region.