Two‐Photon‐Responsive Supramolecular Hydrogel for Controlling Materials Motion in Micrometer Space

Spatiotemporal control of fluidity inside a soft matrix by external stimuli allows real‐time manipulation of nano/micromaterials. In this study, we report a two‐photon‐responsive peptide‐based supramolecular hydrogel, the fluidity of which was dramatically controlled with high spatial resolution (10 μm×10 μm×10 μm). The off–on switching of the Brownian motion of nanobeads and chemotaxis of bacteria by two‐photon excitation was successfully demonstrated.     

Simple evaluation of the adsorption states of benzene molecule on the hydroxyl,H+ and Na+ sites of Y-zeolite surfaces by using UV absorption spectroscopy

Chemical properties of benzene molecules adsorbed on the hydroxyl, H⁺ and Na⁺ sites of Y-zeolite surfaces were investigated by using UV absorption and FT-IR spectroscopies. The analyses on the IR peaks assigned to a C–H out-of-plane vibration mode revealed two different adsorption states of benzene: (1) a benzene molecule located a little distance from the hydroxyl groups of zeolite inner walls, and (2) a benzene molecule positioned a short distance from the H⁺ or Na⁺ sites of zeolite walls. Furthermore, the electronic properties of benzene molecules adsorbed on these Y-zeolites were investigated by UV absorption measurements. The vibrational splitting in UV absorption spectra of benzene provided the information about IR-inactive skeletal vibrations of the benzene ring, such as C–C–C in-plane bending and breathing modes. The benzene molecules strongly interacting with H⁺ or Na⁺ sites of Y-zeolites showed smaller breathing vibration energy as compared to benzene in gas or liquid phases, clearly indicating the stabilization of the benzene ring. In contrast, the benzene molecules weakly interacting with hydroxyl groups of siliceous USY zeolite were barely stabilized.     

Synthesis of Cyclobutenes and Allenes by Cobalt‐Catalyzed Cross‐Dimerization of Simple Alkenes with 1,3‐Enynes

Cobalt‐catalyzed cross‐dimerization of simple alkenes with 1,3‐enynes is reported. A [2+2] cycloaddition reaction occurred, with alkenes bearing no allylic hydrogen, by reductive elimination of a η³‐butadienyl cobaltacycle. On the other hand, aliphatic alkenes underwent 1,4‐hydroallylation by means of exo‐cyclic β‐H elimination. These reactions can provide cyclobutenes and allenes that were previously difficult to access, from simple substrates in a highly chemo‐ and regioselective manner.     

Direct Synthesis of Benzofuro[2,3‐b]pyrroles through a Radical Addition/[3,3]‐Sigmatropic Rearrangement/Cyclization/Lactamization Cascade

A straightforward synthetic method for the construction of benzofuro[2,3‐b]pyrrol‐2‐ones by a novel domino reaction through a radical addition/[3,3]‐sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O‐phenyl‐conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C?C bonds, a C?O bond, and a C?N bond in a single operation, leading to pyrrolidine‐fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3‐b]pyrrol‐2‐one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed.     

Molecular dynamics simulation of dissociation behavior of various crystalline celluloses treated with hot-compressed water

The dissociation behavior of the crystalline cellulose polymorphs I_β, II, III_I, and IV_I (Cell I_β, etc.) at 503 K and 100 bar was studied by molecular dynamics simulation, and the mechanism of the experimental liquefaction during treatment with hot-compressed water was elucidated. The results showed that the mini-crystals of Cell I_β and Cell IV_I exhibited similar resistance to dissociation, which implies the occurrence of crystal transformation from Cell IV_I to Cell I. On the other hand, the mini-crystal of Cell II gradually dissociated into the water environment with the progress of time in the simulation. The water molecules gradually penetrated the Cell II crystal, especially along the (1 \(\overline{1}\) 0) crystal plane. In contrast, the dissolution behavior differed for the surface and the core areas of the mini-crystal of Cell III_I. The cellulose chains on the surface were dissociated into the water environment, whereas the ordered structure of the chains in the core region was maintained for the entire simulation period. The detailed investigation showed that the core part of Cell III_I was transformed into Cell I at an early stage of the simulation: Cell I is resistant to dissociation of the structure even in the hot-compressed water environment. It can be confirmed that the stability of these four crystals under high temperature and pressure conditions follows the order: Cell II < III_I < IV_I ≈ I_β.     

Conformational effects in organoaluminum-promoted pinacol-type rearrangement

Conformational effects on the reaction course were examined in organoaluminum-promoted pinacol-type rearrangement, using stereo-defined unsymmetrical β-mesyloxy alcohols as the probe, where combinational use of DIBAL-Et₂AlCl achieved highly selective migration.     

Structure of oxazolomycin,a novel β-lactone antibiotic

The structure of oxazolomycin exhibiting antitumor activity has been elucidated.     

Bayes-optimal solution to inverse halftoning based on statistical mechanics of the Q-Ising model

On the basis of statistical mechanics of the Q-Ising model, we formulate the Bayesian inference to the problem of inverse halftoning, which is the inverse process of representing gray-scales in images by means of black and white dots. Using Monte Carlo simulations, we investigate statistical properties of the inverse process, especially, we reveal the condition of the Bayes-optimal solution for which the mean-square error takes its minimum. The numerical result is qualitatively confirmed by analysis of the infinite-range model. As demonstrations of our approach, we apply the method to retrieve a grayscale image, such as standard image Lena, from the halftoned version. We find that the Bayes-optimal solution gives a fine restored grayscale image which is very close to the original. In addition, based on statistical mechanics of the Q-Ising model, we are sucessful in constructing a practically useful method of inverse halftoning using the Bethe approximation.      

Direct perfluoroalkylation of non-activated aromatic C-H bonds of phenols

A simple procedure for the perfluoroalkylation of the aromatic ring of phenols under mildly basic conditions is described. Treatment of a variety of phenols with perfluoroalkyl iodide in the presence of the radical initiator V-70L and Cs₂CO₃ provided the corresponding perfluoroalkylated products in moderate to good yields. Generally, the reaction proceeded smoothly at room temperature to yield regioselectively perfluoroalkylated products.     

Determination of hyaluronic acid by high-performance liquid chromatography of the oligosaccharides derived therefrom as 1-(4-methoxy)phenyl-3-methyl-5-pyrazolone derivatives

Hyaluronic acid (HA) was digested with various kinds of depolymerizing enzymes and the products were analysed by high-performance liquid chromatography (HPLC) after derivatization with 1-(4-methoxy)phenyl-3-methyl-5-pyrazolone (PMPMP). As hyaluronate 4-glycanohydrolase (EC 3.2.1.35) from sheep testis showed a high efficiency for depolymerization, giving the tetra- and hexasaccharides abundantly, and is inexpensive, a method for the specific determination of HA was established, based on digestion by this enzyme followed by determination of the tetra- or hexasaccharide derived therefrom as the PMPMP derivatives by HPLC with UV detection. This method allowed the determination of HA in the range 0.5–50 μg with high reproducibility.