Stereoselective synthesis of benzyl-protected β-galactosides by propionitrile-mediated glycosylation

β-Selective galactosylation was studied using a series of 2-O-benzylated phenyl 1-thio-galactosides and glycosyl acceptors in propionitrile with BSP-TTBP-Tf₂O. The glycosylation enabled us to synthesize useful precursors of N-acetyllactosamine and core 1 O-glycoserine derivatives in a highly convergent manner.     

Synthesis of zinc 3-hydroxymethyl-porphyrins possessing carbonyl groups at the 13- and/or 15-positions for models of self-aggregative chlorophylls in green photosynthetic bacteria

Zinc 3-hydroxymethyl-protopyropheophorbide-d derivatives 1, 2, and 3 possessing carbonyl group(s) at the 13/15-, 13-, and 15-positions, respectively, and 4 lacking the C=O group were prepared from naturally occurring chlorophyll-a. Zinc porphyrins 1 and 2 possessing the 13-C=O self-aggregated in an aqueous micellar solution, similarly to the self-aggregates of BChls-c/d/e in the main light-harvesting antenna systems of green photosynthetic bacteria, whereas 3 and 4 lacking the 13-C=O failed to make such well-ordered aggregates. These results indicated that both the presence of the C=O group and its situation at the 13-position were preferable for formation of the well-ordered J-aggregates.     

New reactions of a dibenzo[a,e]pentalene

Reduction of dibenzo[a,e]pentalene 3 (denoted as dibenzopentalene hereafter) with excess lithium gave dilithium dibenzopentalenide 1. Since oxidation of 1 with iodine gave 3, redox behavior between 1 and 3 is controllable and reversible. Reaction of 3 with methyllithium gave lithium 5-methyldibenzopentalenide 5, the formation of which was evidenced by some trapping experiments and X-ray crystallographic analysis. Reactions of 3 with halogens gave 5,10-dihalodibenzopentalenes, 8 and 9. Some optical properties of novel dibenzopentalene derivatives are also demonstrated.     

Synthesis of hexagonal nickel hydroxide nanosheets by exfoliation of layered nickel hydroxide intercalated with dodecyl sulfate ions

One-nanometer-thick nickel hydroxide nanosheets were prepared by exfoliation of layered nickel hydroxides intercalated with dodecyl sulfate (DS) ions. The shape of the nanosheets was hexagonal, as was that of the layered nickel hydroxides intercalated with DS ions. The nickel hydroxide nanosheets exhibited charge-discharge properties in strong alkaline electrolyte. The morphology of the nanosheet changed during the electrochemical reaction.     

One-Step Synthesis of Cyclobutene-Annulated Fullerenes through a Cascade Reaction

The physicochemical properties of fullerene-based materials typically vary depending on the type and mode of addition of functional groups; therefore, developing fullerene derivatives with novel structures is imperative for further progress in materials science. In this study, we develop an efficient one-step strategy for synthesizing cyclobutene-annulated fullerene derivatives (cyclobutenofullerenes) and characterize their electronic properties. Despite the steric strain, cyclobutenofullerenes can be easily prepared via a one-step reaction of C₆₀ with a secondary propargylic phosphate. Structural analysis of the reaction intermediates suggests that the cascade reaction proceeds through a formal [2+2] cycloaddition of C₆₀ with an allene, caused by the 1,3-migration of the propargylic phosphate, followed by an additional 1,3-migration and the subsequent 1,2-elimination of the phosphodiester moiety.     

Size-selective photocatalytic reactions by titanium(IV) oxide coated with a hollow silica shell in aqueous solutions

A novel core-shell composite photocatalyst, commercially available titanium(IV) oxide (TiO(2)) particles directly incorporated into a hollow amorphous silica shell, was fabricated by successive coating of TiO(2) with a carbon layer and a silica layer followed by heat treatment to remove the carbon layer. The composite induced efficient photocatalytic reactions when relatively small substrates were used, such as methanol dehydration and decomposition of acetic acid, without any reduction in the intrinsic activity of original TiO(2), but did not exhibit efficient photocatalytic activity for decomposition of large substrates, methylene blue and polyvinyl alcohol. The unique size-selective properties of the composites are due to their structural characteristics, i.e., the presence of a pore system and a void space in the silica shell and between the shell and medial TiO(2) particles, respectively. The loading of alkylsilyl groups on the surface of the composite led to highly photostable floatability: the floated sample also induced efficient photocatalytic reaction for decomposition of acetic acid while retaining floatation at the gas/water interface.     

Label-free detection of protein-protein interactions at the GaAs/water interface through surface infrared spectroscopy: discrimination between specific and nonspecific interactions by using secondary structure analysis

Here, we propose a label-free detection of protein-protein interactions that enables simultaneous qualitative analysis of target proteins by using Fourier transform infrared (FTIR) absorption spectroscopy in multiple internal reflection geometry (MIR-FTIR). Using this method, the target proteins were detected based on the peak height of the amide I and amide II bands, while discrimination of specific and nonspecific signals is made based on the secondary structure of the analytes, which is determined through second-derivative analysis of the amide I band. As a model system, an antigen peptide was immobilized on the surface of GaAs, which was transparent to mid-infrared light, and the interaction with its antibody was examined in aqueous media. We demonstrated that the binding of the antibody to the antigen immobilized on a GaAs surface selectively gave rise to beta-sheet amide I vibrations (1639 and 1690 cm-1), while no structurally related signals were induced by nonspecifically adsorbed proteins. The peak height of the beta-peak (1639 cm-1) in the amide I band linearly increased with the antiserum concentration as well as that of the amide II band. The detection limit (S/N = 3) was a 1:36 000 dilution for the amide I signal. In addition, through the use of surface-sensitive MIR-FTIR, the present sensor selectively detected the antigen-antibody interactions at the surfaces without being affected by the presence of bulk species, enabling rapid and wash-free detection. Our method provides not only rapid label-free detection of protein-protein interactions but a more accurate discrimination between specific and nonspecific interactions through the use of the secondary structure of the target proteins as a measure for the specific signals.     

Inner sequence based invariant subspaces in

A closed subspace is said to be invariant if it is invariant under the Toeplitz operators and . Invariant subspaces of are well-known to be very complicated. So discovering some good examples of invariant subspaces will be beneficial to the general study. This paper studies a type of invariant subspace constructed through a sequence of inner functions. It will be shown that this type of invariant subspace has direct connections with the Jordan operator. Related calculations also give rise to a simple upper bound for , where are zeros of a Blaschke product.