Incorporation of porphyrins into mesopores of MCM-41

To introduce porphyrins such as the alcoholic-hydroxyl-group-appended free base porphyrin derivative (HP) of 5-[4-(3-hydroxylpropyloxycabonyl)phenyl]-10,15,20-triphenylphorphine into mesopores of MCM-41, samples were treated with 0-4.0 mmol dm-3 HP toluene solutions and the materials obtained were characterized by various means. The framework structure of MCM-41 was not altered by the treatment. With increasing HP concentration, the specific surface area and pore size decreased; in contrast, the number of HP molecules in the material increased almost linearly from 0 to 0.17 groups nm-2. These facts reveal that the HP molecules are incorporated into mesopores of MCM-41. IR results indicated that the hydroxyl group of the HP molecule reacts with surface free SiOH groups of the MCM-41 by a dehydration reaction. Diffuse reflection UV-vis spectra of the HP-introduced material were almost the same as that of pure HP molecules. The Beers plot suggested that the HP molecules in the material are dispersed at an HP concentration less than 1.0 mmol dm-3, and above that concentration, aggregation or flattening of the HP molecules on the MCM-41 surface takes place.     

One-pot reactions of bicyclic zinc enolate generated from Ni-catalyzed reductive cyclization to furnish octahydro-4,7-ethanobenzofuran-9-one derivatives

The one-pot reactions of catalytically generated bicyclic zinc enolate with various electrophiles are reported. The zinc enolate as a key intermediate is efficiently delivered from Ni-catalyzed reductive cyclization of alkynyl cyclohexadienone. Employing aldehydes, imine, nitroalkene, and α,β-unsaturated carbonyl compounds as electrophiles, this new class of one-pot reactions gave multi-functionalized cis-hydrobenzofurans and octahydro-4,7-ethanobenzofuran-9-one derivatives in moderate to good yields.     

Visualization of flow and vortex structure around a swimming loach by dynamic stereoscopic PIV

Loach has a unique swimming style of bending the whole body and staying at the bottom of water. We studied the three-dimensional flow field around and behind the loach using stereoscopic-PIV. We captured flow fields in horizontal and vertical plane, and it seems loach leaves vortex tube arches. From the analysis of body motion and flow field, we propose flow structure with vortex tube arches connected along the loach body. After being released, they are separated and flow away and dissipate. This research article was submitted for the special issue on Animal locomotion: The hydrodynamics of swimming (Vol. 43, No. 5).     

Molecular crystalline capsules that release their contents by light

Here, we present single crystalline capsules of a photoresponsive molecule produced by simple recrystallization from organic solutions without direct human processing. During the crystal growth process, a movie was taken of the capsule taking in the organic solution. The capsules responded rapidly (<1 s) to the UV light stimuli and released the captured solution or solute. In principle, they can take in any substance dissolved in organic solvents, and their size can be controlled. Moreover, the capsule can be broken by multi-photon excitation using a near-infrared laser within the biological window. Furthermore, because the molecular packing in the crystal is unidirectional, the response can be controlled by the polarization of the light. This study shows the new potential of photoresponsive molecules.

A novel diarylethene formed “crystalline capsules” containing liquid inclusions, and chemicals trapped in the capsules were released by photoinduced breaking. Operations by multiphoton and linear polarized light were demonstrated.     

Expedient synthesis of potent cannabinoid receptor agonist (-)-CP55,940

[reaction: see text] A stereocontrolled synthesis of (-)-CP55,940, a potent cannabinoid receptor agonist, has been attained using a novel aldolization/retro-aldolization interconversion strategy, in which a temporarily generated chiral aldol motif plays essential roles.     

Structure of the oxidized 4H-SiC(0 0 0 1)-3 × 3 surface

We have determined the structure of the 4H-SiC(0 0 0 1)-3 × 3 surface after exposure to small amounts of molecular oxygen at room temperature using surface X-ray diffraction. The 3 × 3 reconstruction remains until at least an exposure of 10,000 L, but the diffracted intensities change, indicating structural changes. Comparison of the Patterson maps of the clean and oxidized surface shows that the main changes occur at the Si tetramer on top of the 3 × 3 surface. Atomic positions for several models were fitted to the experimental data. A model in which oxygen atoms are inserted into the Si tetramer gives the best fit to the experimental data. The best-fit atomic positions agree well with those obtained using density functional calculations.     

Reflection spectra of various kinds of oxide glasses and fluoride glasses in the vacuum ultraviolet region

Reflection spectra of silicate, borate, phosphate, fluorophosphate and fluoride glasses are studied in the spectral region of 2–13 eV in order to understand their dispersion behaviors in the visible region from the point of view of atomic structures.The absorption bands due to bridging oxygen ions or fluorine ions are found at 11.6 eV and 10.4–9.5 eV in silicate glasses, at 10.2 and 8.8 eV in borate glasses, at 9.5 eV in phosphate glasses, at 11.2 eV in fluorophosphate glasses and at 11 eV in fluorozirconate glasses.In silicate glasses, the bands due to nonbridging oxygen ions are found in the region 8.8-4.9 eV. They shift to lower energies with increasing ionic radius, in the order of Ca²⁺, Sr²⁺ and Ba²⁺, for the glasses containing low valency cations, while they shift to higher energies with increasing ionic radius, in the order of Ti⁴⁺, Zr⁴⁺ and Th⁴⁺ or in the order of Nb⁵⁺ and Ta⁵⁺, for the glasses containing high valency cations.In glasses containing large amounts of PbO, strong bands due to PB²⁺ ions appear in the lower energy regions of 6.3–5.6 eV and 5.2–4.7 eV.     

Recent progresses in the synthesis of functionalized isoxazoles

Isoxazole is an important pharmacophore that is critical for biological activity. The isoxazole ring ranks 33rd in frequency among the 351 ring systems found in marketed drugs, thus suggesting a great deal of interest in the synthesis of functional isoxazoles. In recent years, various approaches have been developed for the synthesis and functionalization of isoxazoles. This comprehensive survey summarizes the recent new synthetic approaches to functionalized isoxazoles, with particular focus on the last three years with regard to the following reaction types: (1) 1,3-dipolar cycloaddition, (2) condensation, (3) cycloisomerization, and (4) direct functionalization.     

Ab initio study of ultrafast photochemical reaction dynamics of phenol blue

Phenol blue (PB) is a primary skeletal structure part of indoaniline dyes and well-known as a solvatochromic dye. It has been recently observed by pump-probe (PP) transient absorption measurements that PB shows ultrafast ground state recovery within a few hundred femtoseconds after photoexcitation. In this work, the ultrafast photochemical reaction mechanism of PB has been investigated using direct ab initio (CASSCF) nonadiabatic molecular dynamics with the trajectory surface hopping (TSH) method. The swarm of trajectories starting from the S1 Franck-Condon (FC) point has mostly shown surface hops (nonadiabatic transitions) from the S1 state to the S0 state at 110-120 fs in the vicinity of an S1/S0 conical intersection and after decay to the S0 state bifurcated into two (Reverse and Forward) directions with almost the same branching ratio and reached the vicinity of the S0 minimum energy point at 200-300 fs, which is in good agreement with the fast time component of the ground state recovery in the PP measurements. After reaching the vicinity of the S0 minimum energy point, the trajectories showed a coherent vibration of bending motion between quinoneimine and aniline rings with a low frequency of 43 cm-1, which presumably corresponds to a coherently photoexcitation-induced vibrational mode with a low frequency recently observed by the PP measurements.