Selective formation of a stable micro-peroxo ferric heme-Cu(II) complex from the corresponding micro-oxo Fe(III)-Cu(II) species with hydrogen peroxide

An oxo-bridged ferric heme-copper(II) complex, obtained by thermal transformation of the corresponding peroxo-bridged complex, was reacted with an equimolar amount of H2O2 to regenerate the micro-peroxo complex by a ligand exchange from oxo to peroxo, without the formation of a ferryl-oxo species or heme degradation as are observed in general ferric heme-H2O2 reactions.     

Terabit all-optical logic based on ultrafast two-dimensional transmission gating

Terabit all-optical complementary logic is proposed using two successive time slots to represent a unique logical status. An organic molecular thin film is used as an array of optically controlled optical switches. By utilizing the planar structure of the film and its ultrafast optical response, proof-of-principle fully optical NOT and AND logic operations were demonstrated with 400-fs interval pulses.     

Structure elucidation of EI-1941-1 and -2, novel interleukin-1β converting enzyme inhibitors produced by Farrowia sp. E-1941

EI-1941-1 (1a) and EI-1941-2 (2a) accompanied by EI-1941-3 (3) have been isolated from culture broth of Farrowia sp. E-1941 as the inhibitors of interleukin-1β converting enzyme. The structures of 1a, 2a, and 3 were elucidated by the analysis of NMR and MS data, and finally the absolute stereochemistries of 1a and 2a were confirmed by optical rotation data, or X-ray crystallographic analysis of p-bromobenzoate, 2b, respectively.     

Reconfigurable Photonic Crystal Reversibly Exhibiting Single and Double Structural Colors

Unlike absorption-based colors of dyes and pigments, reflection-based colors of photonic crystals, so called “structural colors”, are responsive to external stimuli, but can remain unfaded for over ten million years, and therefore regarded as a next-generation coloring mechanism. However, it is a challenge to rationally design the spectra of structural colors, where one structure gives only one reflection peak defined by Bragg's law, unlike those of absorption-based colors. Here, we report a reconfigurable photonic crystal that exhibits single-peak and double-peak structural colors. This photonic crystal is composed of a colloidal nanosheet in water, which spontaneously adopts a layered structure with single periodicity (407 nm). After a temperature-gradient treatment, the photonic crystal segregates into two regions with shrunken (385 nm) and expanded (448 nm) periodicities, and thus exhibits double reflection peaks that are blue- and red-shifted from the original one, respectively. Notably, the transition between the single-peak and double-peak states is reversible.     

Synthesis and characterization of mononuclear ruthenium(III) pyridylamine complexes and mechanistic insights into their catalytic alkane functionalization with m-chloroperbenzoic acid

A series of mononuclear RuIII complexes [RuCl2(L)]+, where L is tris(2-pyridylmethyl)amine (TPA) or one of four TPA derivatives as tetradentate ligand, were prepared and characterized by spectroscopic methods, X-ray crystallography, and electrochemical measurements. The geometry of a RuIII complex having a non-threefold-symmetric TPA ligand bearing one dimethylnicotinamide moiety was determined to show that the nicotine moiety resides trans to a pyridine group, but not to the chlorido ligand. The substituents of the TPA ligands were shown to regulate the redox potential of the ruthenium center, as indicated by a linear Hammett plot in the range of 200 mV for RuIII/RuIV couples with a relatively large rho value (+0.150). These complexes act as effective catalysts for alkane functionalization in acetonitrile with m-chloroperbenzoic acid (mCPBA) as terminal oxidant at room temperature. They exhibited fairly good reactivity for oxidation of cyclohexane (C--H bond energy 94 kcal mol(-1)), and the reactivity can be altered significantly by the electronic effects of substituents on TPA ligands in terms of initial rates and turnover numbers. Catalytic oxygenation of cyclohexane by a RuIII complex with 16O-mCPBA in the presence of H2 18O gave 18O-labeled cyclohexanol with 100% inclusion of the 18O atom from the water molecule. Resonance Raman spectra under catalytic conditions without the substrate indicate formation of a RuIV==O intermediate with lower bonding energy. Kinetic isotope effects (KIEs) in the oxidation of cyclohexane suggest that hydrogen abstraction is the rate-determining step and the KIE values depend on the substituents of the TPA ligands. Thus, the reaction mechanism of catalytic cyclohexane oxygenation depends on the electronic effects of the ligands.