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21.
Itaru Yamashita Youhei Kawabata Tadashi Kato Masakatsu Hato Hiroyuki Minamikawa 《Colloids and surfaces. A, Physicochemical and engineering aspects》2004,250(1-3):485-490
Small angle X-ray scattering (SAXS) is measured for the lamellar phase in aqueous systems of 1-o-β-3,7-dimethyoctyl-D-glucopyranoside (β-Glc(Ger)), which has recently been prepared by us, 1-o-β-decyl-D-glucopyranoside (β-GlcC10), and 1-o-β-octyl-D-glucopyranoside (β-GlcC8). The repeat distance d obtained from the position of the diffraction peak does not follow the swelling law d = 2δhc/hc, where δhc and hc are the thickness and the volume fraction of the hydrophobic layer, respectively. This may result from the fact that δhc increases and, equivalently, the surface area per surfactant molecule (as) decreases with increasing concentration. So we calculate δhc and as from the observed d value at each concentration using the above swelling law. The half-thickness δhc increases in the order β-GlcC8 < β-Glc(Ger) < β-GlcC10 at a fixed concentration. On the other hand, the data on as for β-GlcC10 and β-GlcC8 lie on the same line and the data for β-Glc(Ger) lies above this line. These results suggest that the cross-sectional area of the geranyl chain is larger than that of the glucose headgroup. Existence of water filled defects in bilayer sheets is also discussed based on the SAXS pattern and the concentration dependence of d. 相似文献
22.
The reaction of methyleneaziridine 1 with carbon pronucleophiles (2, H-CR3) proceeds smoothly in the presence of a palladium catalyst affording the corresponding hydrocarbonation products 5 in good to high yield. 相似文献
23.
As an elementary reaction of polycondensation reactions, rates of the reaction of 1,5-naphthalenedisulphonyl dichloride, a bifunctional fluorescent reagent, with excess α,ω-diaminooligomethylenes were measured by fluorometry in dilute solution. The rate constant, corresponding to that for the reaction of the first step of the polycondensation between the disulphonyl dichloride and the diamines, depended remarkably on the chain length of the diamines. By using 5-dimethylamino-1-naphthalenesulphonyl chloride, a monofunctional fluorescent reagent, and α-aminooligomethylenes, rates of model reactions between the monoamines and the monosulphonyl chloride, the diamines and the monosulphonyl chloride, as well as the monoamines and the disulphonyl dichloride were measured by fluorometry. The remarkable chain length dependence is explained by intramolecular catalysis by the primary amino group. 相似文献
24.
Hato M Yamashita I Kato T Abe Y 《Langmuir : the ACS journal of surfaces and colloids》2004,20(26):11366-11373
Temperature- and concentration-dependent aqueous phase diagram of a novel alkylglycoside, 1-O-phytanyl-beta-D-xyloside (beta-Xyl(Phyt)), was studied using small-angle X-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. The phases found in this system include an Lc phase, an Lalpha phase, an HII phase, two inverted cubic phases of crystallographic space groups Pn3m and Ia3d, and a fluid isotropic phase, FI. The phase diagram of the beta-Xyl(Phyt)/water system is similar to that for the 1-monooleylglycerol (MO)/water system, suggesting that the phase behavior is largely determined by the overall molecular shape rather than the details of surfactant molecular structure. Moreover, the structural parameters of the beta-Xyl(Phyt) liquid crystals are also similar to those of the MO/water, due primarily to the similar molecular dimensions of two molecules. As compared to the MO/water system, however, the beta-Xyl(Phyt)/water system displays a lower value of TK ( approximately 8.(5) degrees C) and a wider temperature window for the mesophases (8.(5)-120 degrees C). Moreover, beta-Xyl(Phyt) is chemically more robust than MO, as the ether linkage is more stable against hydrolysis than the ester linkage and the phytanyl chain is fully saturated. 相似文献
25.
The rates of reactions of 5-dimethylamino-1-naphthalenesulphonyl chloride (dansyl chloride) with butylamine in organic solvents have been measured in the presence of polymer such as polyoxyethylene (POE) or polystyrene (PS) as cosolvent and compared with those in the presence of cosolvents of low molecular weight analogues, viz. diethyloxyethane (DEE) and toluene (Tol.). Acceleration by cosolvent POE, compared with DEE, increases with increasing volume fraction of cosolvent and the effect depends on the degree of polymerization of the polymer cosolvent. Similarly, addition of cosolvent PS to ethyl acetate or chloroform results in increase in the reaction rate as compared with cosolvent Tol. The effect by PS also showed dependence on the degree of polymerization. The effect of polymer cosolvent on chemical reactions between two low molecular weight species is explained in terms of the thermodynamics of polymer solutions. 相似文献
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28.
Multi-step cascade reactions of O-propargylic oximes with isocyanates were carried out in the presence of copper catalysts to afford the corresponding 1,6-dihydropyrimidines in good yields. The multi-step reactions consisted of a 2,3-rearrangement, a [3+2] cycloaddition, decarboxylative ring opening involving a 1,4-hydrogen shift, and a 6π-electrocyclization. 相似文献
29.
Design of Ratiometric Fluorescent Probes Based on Arene–Metal‐Ion Interactions and Their Application to CdII and Hydrogen Sulfide Imaging in Living Cells 下载免费PDF全文
Ippei Takashima Miyuki Kinoshita Ryosuke Kawagoe Saika Nakagawa Prof. Dr. Manabu Sugimoto Prof. Dr. Itaru Hamachi Prof. Dr. Akio Ojida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2184-2192
Non‐coordinative interactions between a metal ion and the aromatic ring of a fluorophore can act as a versatile sensing mechanism for the detection of metal ions with a large emission change of fluorophores. We report the design of fluorescent probes based on arene–metal‐ion interactions and their biological applications. This study found that various probes having different fluorophores and metal binding units displayed significant emission redshift upon complexation with metal ions, such as AgI, CdII, HgII, and PbII. X‐ray crystallography of the complexes confirmed that the metal ions were held in close proximity to the fluorophore to form an arene–metal‐ion interaction. Electronic structure calculations based on TDDFT offered a theoretical basis for the sensing mechanism, thus showing that metal ions electrostatically modulate the energy levels of the molecular orbitals of the fluorophore. A fluorescent probe was successfully applied to the ratiometric detection of the uptake of CdII ions and hydrogen sulfide (H2S) in living cells. These results highlight the utility of interactions between arene groups and metal ions in biological analyses. 相似文献
30.
Self‐Replication and Amplification of Enantiomeric Excess of Chiral Multifunctionalized Large Molecules by Asymmetric Autocatalysis 下载免费PDF全文
Prof. Dr. Tsuneomi Kawasaki Mai Nakaoda Yutaro Takahashi Yusuke Kanto Nanako Kuruhara Kenji Hosoi Prof. Dr. Itaru Sato Arimasa Matsumoto Prof. Dr. Kenso Soai 《Angewandte Chemie (International ed. in English)》2014,53(42):11199-11202
Self‐replication of large chiral molecular architectures is one of the great challenges and interests in synthetic, systems, and prebiotic chemistry. Described herein is a new chemical system in which large chiral multifunctionalized molecules possess asymmetric autocatalytic self‐replicating and self‐improving abilities, that is, improvement of their enantioenrichment in addition to the diastereomeric ratio. The large chiral multifunctionalized molecules catalyze the production of themselves with the same structure, including the chirality of newly formed asymmetric carbon atoms, in the reaction of the corresponding achiral aldehydes and reagent. The chirality of the large multifunctionalized molecules controlled the enantioselectivity of the reaction in a highly selective manner to construct multiple asymmetric stereogenic centers in a single reaction. 相似文献