Solid-state fluorescence of squarylium dyes

An N-butyl indolenine squarylium dye could include toluene and p-xylene and exhibited the solid-state fluorescence in near-infrared region (F_max=761 nm) in crystalline form due to inhibition of π/π-interactions between the fluorophores.     

A thin and compact compound-eye imaging system incorporated with an image restoration considering color shift, brightness variation, and defocus

A compact system of the thin observation module by bound optics (TOMBO) imager based on compound-eye imaging has been constructed to demonstrate its advantages over single-eye imaging systems such as thinner hardware. To reconstruct a high-resolution image from low resolution images captured by the compound-eye optics, we propose an image restoration scheme based on the iterative back-projection algorithm with depth map estimated from the disparities on the captured image. The scheme includes suppression of unit-by-unit color shift caused by the offset microlenses and the color filters on the commercial image sensors and deblurring of defocus by geometrical optics using the depth map. In the experiment, three-dimensional objects were captured by the TOMBO imager and reconstructed with the scheme. After the processing, the power spectrum of the captured image was improved by up to 19 dB, and the power spectrum of the effect of the color shift was reduced by 7 dB.     

Sugar nanowires based on cyclodextrin prepared by single particle nanofabrication technique

The direct formation of nanowires consisting of cyclodextrins by single particle nanofabrication technique (SPNT) is investigated in the present paper. Substittuted cyclodextrin (CD) derivatives and their composite with poly(4-bromostyrene) caused efficient cross-linking reaction upon irradiation, and gave nanostructures by SPNT. Successful visualization of the nanostructures by atomic force microscopy suggested drastic increase in the surface area of the materials based on CDs, leading to considerable increase in the selective adsorption efficiency of the molecules fit to the size of the hydrophobic holes of CDs.     

Synthesis of secondary α-perfluoroalkyl- and tertiary α,α-bis(perfluoroalkyl)-N-methylprolinols and their catalytic activities in the acyl transfer reaction

Various chiral α-perfluoroalkyl-N-methylprolinols were prepared and their organocatalytic activities in an acyl transfer reaction of 4-nitrophenyl 2-methoxyacetate with methanol-d₄ in chloroform-d were examined. As a result, α-trifluoromethyl-N-methylprolinol was a more effective acyl transfer catalyst than not only secondary α-perfluorobutyl- and n-butyl-N-methylprolinols but also tertiary α,α-bis(perfluorobutyl)-N-methylprolinol.     

Dialkyl- and diaryl-platinum(II) complexes with secondary phosphines: Preparation,structure and thermal reaction giving the metallopolymer

Alkyl and arylplatinum complexes with 1,5-cyclooctadiene ligand, [PtR₂(cod)] (R = Me, Ph, C₆H₄-p-CF₃, C₆F₅), react with secondary phosphines, PHR′₂ (R′ = i-Bu, t-Bu, Ph), to afford the mononuclear platinum complexes, cis-[PtR₂(PHR′₂)₂] (1a: R = Me, R′ = i-Bu; 1b: R = Me, R′ = t-Bu; 1c: R = Me, R′ = Ph; 2a: R = Ph, R′ = i-Bu; 2b: R = Ph, R′ = t-Bu; 2c: R = R′ = Ph; 3a: R = C₆H₄-p-CF₃, R′ = i-Bu; 3b: R = C₆H₄-p-CF₃, R′ = t-Bu; 3c: R = C₆H₄-p-CF₃, R′ = Ph; 4a: R = C₆F₅, R′ = i-Bu; 4c: R = C₆F₅, R′ = Ph) in 81–98% yields. Molecular structures of the complexes except for 1a, 1c and 2a were determined by X-ray crystallography. Complex 1b has a square-planar structure with Pt–C(methyl) bonds of 2.083(8) and 2.109(8) Å, while the Pt–C(aryl) bonds of 2b–c, 3a–c, 4a and 4c (2.055(1)–2.073(8) Å) are shorter than them. Thermal decomposition of 1b, 2a–c, and 3a–c releases methane, biphenyl or 4,4′-bis(trifluoromethyl)biphenyl as the organic products, which are characterized by NMR spectroscopy. The solid product of the thermal reactions of 2b and 2c were characterized as the metallopolymers formulated as [Pt(PR′₂)₂]_n (5b: R′ = ^tBu; 5c: R′ = Ph), based on the solid-state NMR and elemental analyses.     

Singularities of lightcone Gauss images of spacelike hypersurfaces in de Sitter space

We define the notions of lightcone Gauss images of spacelike hypersurfaces in de Sitter space. We investigate the relationships between singularities of these maps and geometric properties of spacelike hypersurfaces as an application of the theory of Legendrian singularities. We classify the singularities and give some examples in the generic case in de Sitter 3-space.     

Stationary solutions to the drift–diffusion model in the whole spaces

We study the stationary problem in the whole space ?ⁿ for the drift–diffusion model arising in semiconductor device simulation and plasma physics. We prove the existence and uniqueness of stationary solutions in the weighted L^p spaces. The proof is based on a fixed point theorem of the Leray–Schauder type. Copyright © 2008 John Wiley & Sons, Ltd.     

Klein–Gordon equations with homogeneous time-dependent electric fields

We consider a system associated to Klein–Gordon equations with homogeneous time-dependent electric fields. The upper and lower boundaries of a time-evolution propagator for this system were proven by Veseli? (J Oper Theory 25:319–330, 1991) for electric fields that are independent of time. We extend this result to time-dependent electric fields.     

Catalysis of Mononuclear Aquaruthenium Complexes in Oxygen Evolution from Water: A New Radical Coupling Path using Hydroxocerium(IV) Species

The mechanism of O₂ evolution from water catalyzed by a series of mononuclear aquaruthenium complexes, [Ru(terpy)(bpy)(OH₂)]²⁺, [Ru(tmtacn)(R₂bpy)(OH₂)]²⁺ (R=H, Me, and OMe; R₂bpy=4,4′‐disubstituted‐2,2′‐bipyridines), and [Ru(tpzm)(R₂bpy)(OH₂)]²⁺ (R=H, Me, and OMe), is investigated, where terpy=2,2′:6′,2′′‐terpyridine, bpy=2,2′‐bipyridine, tmtacn=1,4,7‐trimethyl‐1,4,7‐triazacyclononane, and tpzm=tris(1‐pyrazolyl)methane. The kinetics of O₂ evolution is investigated as a function of either the catalyst concentration or the oxidant concentration by employing Ce(NH₄)₂(NO₃)₆ as an oxidant; these catalysts can be classified into two groups that have different rate laws for O₂ evolution. In one class, the rate of O₂ evolution is linear to both the catalyst and Ce⁴⁺ concentrations, as briefly reported for [Ru(terpy)(bpy)(OH₂)]²⁺ (S. Masaoka, K. Sakai, Chem. Lett. 2009 , 38, 182). For the other class, [Ru(tmtacn)(R₂bpy)(OH₂)]²⁺, the rate of O₂ evolution is quadratic to the catalyst concentration and independent of the Ce⁴⁺ concentration. Moreover, the singlet biradical character of the hydroxocerium(IV) ion was realized by experimental and DFT investigations. These results indicate that the radical coupling between the oxygen atoms of a Ru^V?O species and a hydroxocerium(IV) ion is the key step for the catalysis of [Ru(terpy)(bpy)(OH₂)]²⁺ and [Ru(tpzm)(R₂bpy)(OH₂)]²⁺, while the well‐known oxo‐oxo radical coupling among two Ru^V?O species proceeds in the catalysis of [Ru(tmtacn)(R₂bpy)(OH₂)]²⁺. This is the first report demonstrating that the radical character provided by the hydroxocerium(IV) ion plays a crucial role in the catalysis of such ruthenium complexes in the evolution of O₂ from water.