A successful separation of position-dependent inductive effects for the basicities of quinolines

The substituent effects on the basicities of 3-, 4-, 5-, 6-, and 7-substituted quinolines were separated into inductive(ρ_iσ_i) and pi-electronic(ρ_πσ_π) components for each position by means of the LSFE equation, whose C_ij (=ρ_i/ρ_i,4α) set derived was essentially equal to that for the solvolysis of 1-(1-naphthyl)ethyl chlorides.     

Importance of dual resonance susceptibilities for pi-donor and pi-acceptor substituents regarding a quantitative description of substituent effects. The case of basicity of pyridine N-oxides

Basicities of m- and p-substituted pyridine N-oxides in water were successfully described by means of the generallized LArSR equation which potentially allows dual resonance effect.     

Highly Emissive Boron Ketoiminate Derivatives as a New Class of Aggregation‐Induced Emission Fluorophores

A series of boron ketoiminate derivatives that exhibited clear aggregation‐induced emission (AIE) characteristics (in THF: Φ_PL≤0.01; in the solid state: Φ_PL=0.30–0.76) were prepared by the reactions of 1,3‐enaminoketone derivatives with boron trifluoride–diethyl etherate. The structures and optical properties were investigated by UV‐visible spectroscopy, photoluminescent (PL) spectroscopy, and X‐ray single‐crystal measurements. These results indicate that the AIE characteristics were derived from molecular motions of the boron‐chelating rings with a boron? nitrogen (B? N) bond. Furthermore, the optical properties were controllable by steric hindrance of the substituted groups on the nitrogen atom.     

Studies on constituents of fruit body of Polyporus umbellatus and their cytotoxic activity.

From the crude drug Chorei, the fruit body of Polyporus umbellatus, seven new components named polyporusterone A, B, C, D, E, F and G, were isolated and their structures were determined on the basis of the spectral data. These compounds showed cytotoxic action on leukemia 1210 cell proliferation.     

Electronic nature of the aza substituent of pyridyl and quinolyl groups for reactivities in an insulated system

A new set of σ^o values was determined for all positions of pyridyl and quinolyl groups, reliably excluding steric effect by perihydrogen, on the basis of the rates of the alkaline hydrolysis of substituted 2-methylbenzoates and pyridylmethyl and quinolylmethyl 2-methylbenzoates in 70% aq acetone.     

Experimental and theoretical determination of the accurate interaction energies in benzene-halomethane: the unique nature of the activated CH/pi interaction of haloalkanes

The CH/pi interaction energies between benzene and halomethanes (CH(2)Cl(2) and CHCl(3)) were accurately determined. Two-color ionization spectroscopy was applied to the benzene-CH(2)Cl(2) and -CHCl(3) clusters, and the binding energies in the neutral ground state, i.e. the CH/pi interaction energies in these model cluster systems, were precisely evaluated on the basis of the dissociation threshold measurements of the clusters in the cationic state and the ionization potential value of the bare molecule. The experimentally determined interaction energies were 3.8 +/- 0.2 and 5.2 +/- 0.2 kcal mol(-1) for benzene-CH(2)Cl(2) and -CHCl(3) respectively, and the remarkable enhancement of the CH/pi interaction energy with chlorine-substitution was quantitatively confirmed. The experimental interaction energies were well reproduced by the high-level ab initio calculations. The theoretical calculations clarified the unique nature of the activation of the CH/pi interaction by the chlorine-substitution.     

Structural analysis of Si(111)-√21 × √21-(Ag,Cs) surface by reflection high-energy positron diffraction

We have investigated the Si(111)-√21 × √21-(Ag, Cs) superstructure using reflection high-energy positron diffraction. Rocking curve analysis based on the dynamical diffraction theory reveals that Cs atoms are located at a height of 3.04 Å above the underlying √3 × √3-Ag structure and that they form a triangular structure with a side length of 10.12 Å. The structure of the Si(111)-√21 × √21-(Ag, Cs) surface is significantly different from those of the Si(111)-√21 × √21-Ag and Si(111)-√21 × √21-(Ag, Au) surfaces, probably because of the different electronic structures of the alkali and noble metal atoms.