Memory of chirality generated by spontaneous crystallization and asymmetric synthesis using the frozen chirality

Asymmetric synthesis using frozen chirality generated by spontaneous crystallization was performed. Achiral asymmetrically substituted imide with a tetrahydronaphthyl group on the nitrogen atom crystallized in a chiral fashion, with space group P2(1)2(1)2(1). The molecular chirality generated by spontaneous crystallization was retained in cold THF. The half-life determined on the basis of decreasing optical activity followed by CD spectrometer was 7.8, 33.1, and 150.0 min at -20, -30, -40 degrees C, respectively. The energy barrier (DeltaG()) of racemization was calculated with the temperature dependence of the kinetic constant to be 18.24-18.36 kcal mol(-)(1) at 233-253 K. The memorized frozen chirality was transferred to permanent optically active alcohols by nucleophilic addition with n-buthyllithium.     

Development of a scanning microscopy by total internal reflection coupled with thermal lens spectroscopy

Non-destructive measurement of a small region on a solid/liquid interface is of great importance in physical chemistry and biochemistry, especially in the research of thin films and cell membranes. Optical methods for surface analysis with high lateral resolution are suitable methods for monitoring them. We now report a new scanning optical microscopic method to which total internal reflection coupled with a thermal lens technique was introduced. Its lateral resolution was estimated both experimentally and theoretically. To experimentally estimate the resolution, the grid patterns of thin photoresist films with well-defined lateral structures were measured. The experimental resolution was about 45 microm, which was almost same as the diameter of the excitation beam at a glass/sample interface. From this result, it was verified that this new scanning microscopy ideally worked.     

Enantioselective Borylative Dearomatization of Indoles through Copper(I) Catalysis

The enantioselective borylative dearomatization of a heteroaromatic compound has been achieved using a copper(I) catalyst and a diboron reagent. This reaction involves the regio‐ and enantioselective addition of active borylcopper(I) species to indole‐2‐carboxylates, followed by the diastereoselective protonation of the resulting copper(I) enolate to give the corresponding chiral indolines, which bear consecutive stereogenic centers.     

A class of dual fuzzy dynamic programs

In this paper we propose a large class of fuzzy dynamic programs. By use of the notion of dual binary relation we define a dual fuzzy dynamic program in the class. We establish two duality theorems between primal and dual fuzzy dynamic programs. One is for the two-parametric recursive equations. The other is for the nonparametric. We specify maximum–minimum process and minimum–minimum process in fuzzy environment and multiplicative–multiplicative process in quasi-stochastic environment. It is shown that the duality theorems hold between primal and dual programs.     

Polymer‐Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal–Organic Frameworks

A template‐assisted polymer‐derived ceramic route is investigated for preparing a series of silicoboron carbonitride (Si/B/C/N) foams with a hierarchical pore size distribution and tailorable interconnected porosity. A boron‐modified polycarbosilazane was selected to impregnate monolithic silica and carbonaceous templates and form after pyrolysis and template removal Si/B/C/N foams. By changing the hard template nature and controlling the quantity of polymer to be impregnated, controlled micropore/macropore distributions with mesoscopic cell windows are generated. Specific surface areas from 29 to 239 m² g^?1 and porosities from 51 to 77 % are achieved. These foams combine a low density with a thermal insulation and a relatively good thermostructural stability. Their particular structure allowed the in situ growth of metal–organic frameworks (MOFs) directly within the open‐cell structure. MOFs offered a microporosity feature to the resulting Si/B/C/N@MOF composite foams that allowed increasing the specific surface area to provide CO₂ uptake of 2.2 %.     

Thermodynamic properties of the solvent extraction of ion pairs of metal chelate cations with some anions

Thermodynamic quantities were determined for the extraction of ion pairs of tris(1,10-phenanthroline)iron(II) and tris(2,2'-bipyridine)iron(II) chelate cations with halide, pseudohalide and polythionate anions from aqueous phase into nitrobenzene. Ion pairs with larger anions have more negative enthalpy changes with higher extractability. No clear trend was observed for the entropy changes. Linear relationships were observed between the free energy changes and the reciprocal radii of monovalent counter anions.     

Reactions leading to the formation of O-3 on magnesium oxide

Ozonide ions were observed on MgO upon irradiation (254 nm) in the presence of O₂ at 25°C or upon reaction of O^-₂ on the surface with N₂O at 100°C. In the former case on O^-₂ intermediate is photodissociated to O and O^-. The latter subsequently reacts with O₂ forming O^-₃.     

Characterization of the dimeric one-electron electrolytic reduction products of 1-alkylpyridinium ions in acetonitrile

A chemical-electrochemical approach for the determination of the positions of coupling in the dimeric one-electron reduction products of 1-alkylpyridinium ions in acetonitrile is described. The procedure involves the treatment of a solution of the dimeric species with an appropriate quinone followed by electrochemical examination of the resulting solution. For 1-alkylpyridinium ions without ring substituents, the dimer is concluded to be the 4,4′ coupled isomer, based on the formation in the cases of 1-methyl-, 1-ethyl-, and 1-benzylpyridinium ions of the 1,1′-dialkyl-4,4′-bipyridinium monocation radical species on treatment of the dimeric species with 1,4-benzoquinone. The characteristics, particularly the quantitative nature, of this tetrahydrobipyridine-quinone reaction have been examined.