Sesquiterpene lactone glycosides from the roots of Ferula varia

Seven new sesquiterpene lactone glycosides (1-7) were isolated from the H2O-soluble fraction from the MeOH extract of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations of compounds 1 and 2 were determined by modified Mosher's method.     

Solid-state ligand-driven light-induced spin change at ambient temperatures in bis(dipyrazolylstyrylpyridine)iron(II) complexes

We previously reported that an Fe(II) complex ligated by two (Z)-2,6-di(1H-pyrazol-1-yl)-4-styrylpyridine ligands (Z-H) presented a solid state ligand-driven light-induced spin change (LD-LISC) upon one-way Z-to-E photoisomerization, although modulation of the magnetism was trivial at ambient temperatures (Chem. Commun.2011, 47, 6846). Here, we report the synthesis of new derivatives of Z-H, Z-CN and Z-NO(2), in which electron-withdrawing cyano and nitro substituents are introduced at the 4-position of the styryl group to attain a more profound photomagnetism at ambient temperatures. Z-CN and Z-NO(2) undergo quantitative one-way Z-to-E photochromism upon excitation of the charge transfer band both in acetonitrile and in the solid state, similar to the behavior observed for Z-H. In solution, these substituents stabilized the low-spin (LS) states of Z-CN and Z-NO(2), and the behavior was quantitatively analyzed according to the Evans equation. The photomagnetic properties in the solid state, on the other hand, cannot be explained in terms of the substituent effect alone. Z-CN displayed photomagnetic properties almost identical to those of Z-H. Z-CN preferred the high-spin (HS) state at all temperatures tested, whereas photoirradiated Z-CN yielded a lower χ(M)T at ambient temperatures. The behavior of Z-NO(2) was counterintuitive, and the material displayed surprising photomagnetic properties in the solid state. Z-NO(2) occupied the LS state at low temperatures and underwent thermal spin crossover (SCO) with a T(1/2) of about 270 K. The photoirradiated Z-NO(2) displayed a higher value of χ(M)T and the modulation of χ(M)T exceeded that of Z-H or Z-CN. Z-NO(2)·acetone, in which acetone molecules were incorporated into the crystal lattice, further stabilized the LS state (T(1/2) > 300 K), thereby promoting large modulations of the χ(M)T values (87% at 273 K and 64% at 300 K) upon Z-to-E photoisomerization. Single crystal X-ray structure analysis revealed that structural factors played a vital role in the photomagnetic properties in the solid state. Z-H and Z-CN favored intermolecular π-π stacking among the ligand molecules. The coordination sphere around the Fe(II) nucleus was distorted, which stabilized the HS state. In contrast, Z-NO(2)·acetone was liberated from such intermolecular π-π stacking and coordination distortion, resulting in the stabilization of the LS state.     

Change of acoustic characteristics caused by platform screen doors in train stations

Railway companies are encouraged to install platform screen doors (PSDs) for safety reason in Japan. The PSDs might affect train noises in stations, but the effects are not well understood. The aim of the present study is to clarify the effects of PSDs on acoustic characteristics. PSDs can be principally classified by two types, i.e., mobile full-height (MFH) and mobile half-height (MHH). Train noises were recorded in ground and underground train stations with MFH, MHH and without PSDs. The noises were evaluated by noise level, the maximum peak of the interaural cross-correlation function (IACC), and the width of the first decay (W_Φ(0)) of the autocorrelation function. Noise level emitted by trains was reduced by PSDs in both aboveground and underground stations. IACC was decreased by PSDs in both ground and underground stations, suggesting that PSDs made train noises more diffused. W_Φ(0) was decreased by PSDs in both ground and underground stations, which means that the train noises in station with PSDs have higher spectral centroid, suggesting that the PSDs blocked the lower frequency components of train noises.     

(1,4,7,10-Tetraazacyclododecane) (diamine or alanine)-Cobalt(III) complexes

(1,4,7,10-Tetraazacyclododecane) [diamine or (S)-alanine]-cobalt(III) complexes [diamine = ethylenediamine, 2-(aminomethyl)pyridine, (R)-1,2-propanediamine, (R,R)-1,2-diaminocyclohexane, trimethylenediamine and 2-methyl-1,3-diaminopropane] are prepared and characterized spectroscopically. The ligand field transitions occur at lower energies than those of the corresponding tetraamine analogues. Severe distortions caused by the too small size of the cyclic ligand are one of the origins. The distortions also exert influence upon circular dichroism spectra.     

Investigation for the cyclization efficiency of linear tetrapeptides: Synthesis of tentoxin B and dihydrotentoxin

Investigation of the cyclization efficiency of N-methyl linear tetrapeptides using a molecular modeling study and chemical synthesis is described. The linear peptide with two N-methyl groups, MeAla-Leu-MePhe-Gly, forms γ-turn like conformation with the amine at N-terminus and the carbonyl at C-terminus in closer proximity to give the desired cyclic tetrapeptide, dihydrotentoxin. In addition, synthesis of tentoxin B by the combination of Fmoc solid-phase peptide synthesis and cyclization in solution phase has been reported. An unusual amino acid, an L-N-methyl-β-hydroxyphenylalanine derivative, which was assembled on solid support, was prepared from ethyl cinnamate. Cyclic tetrapeptide formation and cleavage of benzyl ether were optimized with DIPCI/HOBt/DIPEA and Et₃SiH/Pd(OH)₂, respectively.     

Controlling the incorporation and release of C60 in nanometer-scale hollow spaces inside single-wall carbon nanohorns

We succeeded in large-scale preparation of single-wall carbon nanohorns (SWNH) encapsulating C60 molecules in a liquid phase at room temperature using a "nano-precipitation" method, that is, complete evaporation of the toluene from a C60-SWNH-toluene mixture. The C60 molecules were found to occupy 6-36% of the hollow space inside the SWNH, depending on the initial quantity of C60. We showed that the C60 in C60@SWNHox was quickly released in toluene, and the release rate decreased by adding ethanol to toluene. Numerical analysis of the release profiles indicated that there were fast and slow release processes. We consider that the incorporation quantity and the release rate of C60 were controllable in/from SWNHs because SWNHs have large diameters, 2-5 nm.     

Activation of mouse macrophages by in vivo and in vitro treatment with a cyanine dye, lumin.

The cyanine photosensitizer, lumin, is a potent macrophage activating agent: 4 days after administration of small amounts of lumin to mice (20-40 ng mouse-1), peritoneal macrophages exhibited a greatly enhanced Fc-mediated ingestion activity; higher doses (more than 3000 ng mouse-1) did not have this effect. The in vitro photodynamic activation of macrophages in mouse peritoneal cells exposed to white fluorescent light (3 J m-2 s-1) was also studied in media containing various concentrations of lumin. A short light exposure (45 J m-2) with 10 ng lumin ml-1 produced a maximum ingestion activity of macrophages. Lumin has absorption peaks at 670 and 760 nm. Therefore we designed experiments in which peritoneal cells were exposed to a red fluorescent light (emission, 660 nm; 0.5 J m-2 s-1). In a medium containing 3 ng lumin ml-1 with 7.5 J m-2 of red light, a markedly enhanced ingestion activity of macrophages was observed. The photodynamic treatment of peritoneal macrophages alone did not stimulate phagocytic activity, but the photodynamic treatment of a mixture of non-adherent (B and T) cells and macrophages resulted in a greatly enhanced ingestion activity of macrophages. Thus non-adherent cells are required for the photodynamic activation of macrophages, implying that an activating factor is generated within the non-adherent cells and transmitted to the macrophages. This hypothesis was confirmed by the observation that co-cultivation of photodynamically treated non-adherent cells with untreated macrophages resulted in a greatly enhanced ingestion capacity.     

Direct Enantioselective Vinylogous Mannich Reaction of Ketimines with γ‐Butenolide by Using Cinchona Alkaloid Amide/Zinc(II) Catalysts

A direct enantioselective vinylogous Mannich reaction of ketimines with γ‐butenolide has been developed. Good yields and enantioselectivities were observed for the reaction of various ketimines by using a cinchona alkaloid amide/Zn(OTf)₂ catalyst and Et₃N. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts.