Nitrile anion cyclization with epoxysilanes followed by brook rearrangement/ring opening of cyclopropane nitriles/alkylation

The reaction of delta-silyl-gamma,delta-epoxypentanenitrile derivatives with a base and an alkylating agent affords delta-siloxy-gamma,delta-unsaturated pentanenitrile derivatives via a tandem process that involves the formation of the cyclopropane derivative by epoxy nitrile cyclization followed by Brook rearrangement and an anion-induced cleavage of the cyclopropane ring.     

Gamma-p-toluenesulfonyl-alpha,beta-epoxysilane: a new and practical acrolein beta-anion equivalent

[reaction: see text] Reaction of gamma-p-toluenesulfonyl-alpha,beta-epoxysilane with alkyl halides and aldehydes followed by treatment with n-Bu4NF affords alpha,beta-unsaturated aldehydes via a Brook rearrangement-mediated tandem process under extremely mild conditions.     

Selective and efficient transformation of N-(4-substituted benzoyl)-α-dehydroarylalanine alkyl esters into 4,5-dihydrooxazole derivatives via photoinduced electron transfer

The irradiation of N-(4-substituted benzoyl)-α-dehydroarylalanine alkyl esters (1) in methanol containing triethylamine (TEA) was found to quantitatively give cis- and trans-4,5-dihydrooxazole derivatives (2), which were described as being formed via electron transfer from TEA to the excited-state (E)-1 followed by kinetically-controlled cyclization of the (E)-1-derived anion radical. A product composition analysis showed that the cis-2/trans-2 composition ratio is greatly varied depending on the stereoelectronic properties of the substituents, the polarity of protic solvents and the concentration of TEA.     

DNA cleavage induced by thermal electron transfer from a dimeric NADH analogue to acridinium ions in the presence of oxygen

Acridinium ions, which can intercalate to DNA, act as thermal DNA cleavers in the presence of a dimeric NADH analogue and O2 in an aqueous solution via thermal electron transfer from a dimeric NADH analogue to acridinium ions, followed by the electron-transfer reduction of O2 to O2*- by the resulting NAD radicals.     

Proton-coupled electron-transfer processes in photosystem II probed by highly resolved g-anisotropy of redox-active tyrosine YZ

The oxidation of a redox-active tyrosine residue Y(Z) in photosystem II (PSII) is coupled with proton transfer to a hydrogen-bonded D1-His190 residue. Because of the apparent proximity of Y(Z) to the water-oxidizing complex and its redox activity, it is believed that Y(Z) plays a significant role in water oxidation in PSII. We investigated the g-anisotropy of the tyrosine radical Y(Z)(?) to provide insight into the mechanism of Y(Z)(?) proton-coupled electron transfer in Mn-depleted PSII. The anisotropy was highly resolved by electron paramagnetic resonance spectroscopy at the W-band (94.9 GHz) using PSII single crystals. The g(X)-component along the phenolic C-O bond of Y(Z)(?) was calculated by density functional theory (DFT). It was concluded from the highly resolved g-anisotropy that Y(Z) loses a phenol proton to D1-His190 upon tyrosine oxidation, and D1-His190 redonates the same proton back to Y(Z)(?) upon reduction.     

Direct nanocomposite of crystalline TiO2 particles and mesoporous silica as a molecular selective and highly active photocatalyst

Well-crystallised TiO2 particles (P-25, 20-30 nm in diameter) were directly incorporated into surfactant-templated mesoporous silica particles (pore diameter: 2.7 nm), and the composite material with a high TiO2 content (60 wt%) showed molecular selective and enhanced photocatalysis for decomposition of 4-nonylphenol.     

Hyper-Raman scattering enhanced by anisotropic dimer plasmons on artificial nanostructures

Silver nanodimers with a small gap of a few nanometers aligned on glass substrates were used to enhance hyper-Raman scattering of crystal violet dye molecules. When localized surface plasmon of the dimer array was resonantly excited along the interparticle axis, hyper-Raman intensity was significantly enhanced. Moreover, the spectral appearance was slightly different between the two excitation polarizations, suggesting a possibility of two resonance contributions at one-photon and two-photon energies. Since the plasmonic property of dimer arrays can be controlled by the dimer geometry, the dimer arrays are expected to be well-defined substrates for surface-enhanced hyper-Raman spectroscopy.     

Solubility Switching of Metallophthalocyanines and Their Larger Derivatives upon Encapsulation

Metallophthalocyanines (MPcs) are very useful pigments but scarcely soluble without appropriate functional groups in common solvents. Herein, we report that bent polyaromatic amphiphiles act as excellent solubilizing reagents for nonfunctionalized MPcs and larger MPc derivatives (e.g., CuPc, perhalogenated CuPcs, Cu‐naphthalocyanine, CuPc polymers, and double‐decker MPcs) in neutral water upon encapsulation. The resultant MPc nanocomposites display high stability towards heat and pH change. More importantly, the encapsulated MPcs can be released by simple protocols under mild conditions both into a bulk solvent and onto glass or polymer plates.