Analysis and isolation of cationic rhenium(I) and ruthenium(II) multinuclear complexes using size-exclusion chromatography.

Various cationic rhenium(I) and ruthenium(II) mono- and multinuclear complexes were successfully separated by size-exclusion chromatography (SEC), using a 50:50 (v/v) mixture of methanol and acetonitrile with CH3CO2NH4 as an eluent. The logarithms of the molecular weights were accurately linear in the distribution coefficients: for linear-shaped rhenium(I) multinuclear complexes, log M(W) = -2.86K(SEC) + 5.24 (r = -0.990 and n = 15); for ring-shaped rhenium(I) multinuclear complexes, log M(W) = -2.94K(SEC) + 5.40 (r = -0.999; n = 5); for bimetallic complexes including ruthenium(II), log M(W) = -0.40K(SEC) + 3.37 (r = -0.959; n = 6). This separation method is applicable to the preparative-scale separation of cationic multinuclear complexes from a mixture.     

Directing group-controlled hydrosilylation: regioselective functionalization of alkyne

Pt(0)-catalyzed hydrosilylation of unsymmetric alkynes proceeds in a highly regioselective manner with a dimethylvinylsilyl (DMVS) group as the directing group. This hydrosilylation affords a single regioisomer of silylalkenes from propargylic and homopropargylic alcohol derivatives. DMVS also has an accelerating effect that allows group-selective hydrosilylation of the DMVS-attached alkyne prior to that of other alkynes. Combined hydrosilylation and transformation reactions of the resulting silylalkenes afford various tri-substituted alkenes and multi-oxy-functionalized compounds with high regioselectivity from unsymmetric alkynes.     

Facile preparation of various heteroaromatic compounds via azatitanacyclopentadiene intermediates

Coupling of acetylene, nitrile, and a titanium reagent, Ti(O-i-Pr)(4)/2 i-PrMgCl, generated new azatitanacyclopentadienes in a highly regioselective manner. Their subsequent reaction with sulfonylacetylene afforded pyridyltitanium compounds, which, upon reaction with electrophiles, gave substituted pyridines virtually as a single isomer. When optically active nitriles were used in this reaction, chiral pyridines were obtained without loss of the enantiopurity. Alternatively, the azatitanacyclopentadiene prepared from an unsymmetrical acetylene reacted with an aldehyde or another nitrile to give furans or pyrroles having four different substituents again in a regioselective manner.     

A Robust Point Spread Function Estimation for Out-of-Focus Blurred and Noisy Images Based on a Distribution of Gradient Vectors on the Polar Plane

The estimation of the point spread function (PSF) is a very important and indispensable task for practical image restoration. Various PSF estimation algorithms have been developed, especially for the out-of-focus blur. However, a majority of them are useless in an extremely noisy environment. This paper describes a new robust PSF estimation algorithm based on a distribution of gradient vectors on the logarithmic amplitude spectrum mapped to the polar plane. The proposed algorithm can estimate the out-of-focus PSF accurately and robustly, even for an image highly corrupted by noise. The effectiveness of the proposed algorithm is verified by applying it to the PSF estimation for out-of-focus blurred and noisy images.     

Large-dispersion-tolerance optical signal transmission system based on temporal imaging

A novel optical signal transmission system, which is highly tolerant of dispersion of the transmission fiber, is proposed. The system employs a dispersion fiber and a phase modulator in both the transmitter and the receiver. We analyzed the characteristics of the system, using the temporal imaging concept, and found that the output optical pulse is insensitive to dispersion of the transmission fiber if the parameters of the system are set to hold a specific condition. We report simulation results that confirm these characteristics of the proposed system.