New and efficient catalysts for enantioselective borohydride reduction of ketones and imines

Optically active aldiminato cobalt(II) complexes have been found to catalyze the enantioselective reduction of ketones with sodium borohydride affording the corresponding optically active secondary alcohols in high chemical yields with high enantioselectivities. The enantioselective borohydride reduction is also applicable to not only C=O bonds in aromatic ketones but also to C=N bonds in aromatic imines.     

Preparation and structural determination of methyl 3-C-p-tolylsulfonyl-2-C-p-tolylthio-β-d-glucopyanoside derivatives and their 5a-carba-dl-analogs having non-chair conformation in solutions

Methyl 4,6-O-benzylidene-2,3-dideoxy-3-C-p-tolylsulfonyl-2-C-p-tolylthio-β-d-glucopyranoside and its 5a-carba-dl-analog exit mainly in a non-chair conformation in solutions, but the latter occupies a chair conformation in a solid state.     

Properties and cage lactone synthesis of diels-alder adducts from 2-pyrones

New cage lactones were synthesized by the photocyclization of the tricyclodienolactones 1a, 1b, 2 which were available from the Diels-Alder reactions of 2-pyrones with p-benzoquinones or norbornadiene. Retro-Diels-Alder reactions of cross-adducts between 2-pyrone-mono-adducts and p-benzoquinone were also described.     

Modulation of transient stress distributions for controlling femtosecond laser-induced cracks inside a single crystal

After the photoexcitation by a femtosecond laser pulse inside a LiF single crystal, four cracks appear in the <110> directions of the crystal from the photoexcited region. In our previous study, we found that a femtosecond laser-induced stress wave is responsible for generation and elongation of cracks inside a LiF single crystal. This finding suggests that we can control laser-induced cracks by modulating laser-induced stress waves. In this study, we applied parallel fs laser irradiation with a spatial light modulator to generate multiple stress waves at the same time, and found the modulation of crack formation; one crack became thinner and shorter than any other cracks. By a pump-probe imaging of dynamics of crack generation, we showed that the constructive interference of stress waves at a crack tip could compress the crack, which results in a thinner and shorter crack.     

Guidelines proposed for designing organic ferromagnets by using a quantum chemical approach

For predicting the characteristics of organic ferromagnetic substances, we have previously proposed a simple rule for conjugated organic molecules based on molecular orbital coefficients by the simple Hückel??s nonbonding molecular orbital (NBMO) method. In this work, we extended the rule to systems including heteroatoms to become more widely applicable to various magnetic polymers. It was proven that the linkage between molecules having an NBMO conserves the original NBMO levels even for the supermolecule after the linkage. In addition, we have also proposed an index to estimate the amount of possessing ferromagnetic property. The reliability of the rule and index is examined by applying both the density functional theory (DFT) with functional methods, i.e., B3LYP, B3PW91, BLYP, PBEPBE, and PBEP86, and the complete active space SCF (CASSCF) calculations to several model molecules.     

Interconvertible multiple photoluminescence color of a gold(i) isocyanide complex in the solid state: solvent-induced blue-shifted and mechano-responsive red-shifted photoluminescence

In this study, we report the interconvertible tetracolored solid state photoluminescence of gold(i) isocyanide complex 2 upon various external stimuli through solid state structural changes. Soaking complex 2 in acetone yields blue emission as a result of the formation of 2B. The subsequent removal of acetone yields 2G through a crystal-to-crystal phase transition, which exhibits green emission. This green-emitting solid 2G exhibits stepwise emission color changes to yellow and then to orange upon mechanical stimulation by ball-milling, which corresponds to the formation of 2Y and 2O, respectively. 2B could be recovered upon the addition of acetone to 2G, 2Y, and 2O. Thus, these four emitting solid states of 2 can be switched between repeatedly by means of acetone soaking and the application of mechanical stimulation. Importantly, single crystal and powder X-ray diffraction (PXRD) studies fully show the detailed molecular arrangements of 2B, 2G, and 2Y. This is the first mechanochromic compound to show interconvertible four color emission in the solid state. We also present the first example of using PXRD measurements and the Rietveld refinement technique for the structural analysis of a ground powder in a luminescence mechanochromism study. We obtained complete molecular-level structural information of the crystalline states of 2B, 2G, 2Y, and 2O. In comparison with a more solvophobic analogue 1, we suggest that the weak interaction of 2 with acetone in the solid state would allow a solvent inclusion/release mode, which is an important structural factor for the unprecedented multicolor mechanochromic luminescence.     

Effect of Motif‐Programmed Artificial Proteins on the Calcium Uptake in a Synthetic Hydrogel

Motif‐programmed artificial proteins with mineralization‐related activity were covalently immobilized onto the surface of a hydrogel, poly(2‐hydroxyethyl methacrylate) (PHEMA). We investigated the influence of assaying conditions upon the ability of three selected proteins (PS64, PS382 and PS458) to modulate calcification in vitro. A long‐term assay measuring the real amount of calcium phosphate phase in the protein‐modified PHEMA showed that all proteins enhanced the uptake of calcium by the hydrogel. For PS382 and PS458, this is a behaviour opposite to that displayed when the same proteins were tested in a free state by a rapid solution assay. Such difference may be attributed to a restricted mobility of the proteins due to immobilization.

     

LP narrowing: A new strategy for finding all solutions of nonlinear equations

An efficient algorithm is proposed for finding all solutions of systems of n nonlinear equations. This algorithm is based on interval analysis and a new strategy called LP narrowing. In the LP narrowing strategy, boxes (n-dimensional rectangles in the solution domain) containing no solution are excluded, and boxes containing solutions are narrowed so that no solution is lost by using linear programming techniques. Since the LP narrowing is very powerful, all solutions can be found very efficiently. By numerical examples, it is shown that the proposed algorithm could find all solutions of systems of 5000-50,000 nonlinear equations in practical computation time.     

Synthesis of crystallized mesoporous transition metal oxides by silicone treatment of the oxide precursor

Ordered mesoporous transition metal oxides were successfully crystallized after strengthening the amorphous framework by a silica layer, which efficiently protected the original mesoporous structure against crystallization and resulting mass transfer.