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91.
Dr. Shohei Yamashita Tatsuya Sudo Prof. Dr. Hidehiro Kamiya Prof. Dr. Yohei Okada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(50):e202201560
Surface ligands are essential tools for the stabilization of colloidal nanoparticles (NPs) in solvents. However, knowledge regarding the effects of the ligand shell, especially the ligand length, is insufficient and controversial. Here we demonstrate solution-based experiments on n-alkylphosphonate-capped TiO2 NPs to investigate the effects of ligand length and solution temperature on colloidal stability. A robust ligand-exchange process is achieved that draws free ligands and impurities away from the colloidal solution. In the case of 8 nm anatase NPs in toluene, the dodecylphosphonate ligand provided better colloidal stability than all the other n-alkylphosphonate ligands. In addition, relaxation studies suggested there is kinetic hysteresis in the dispersion/agglomeration transition. The proposed method is applicable to a wide range of surface ligands designed to maximize the colloidal stability of NPs. 相似文献
92.
Yohei SatoYusai Ito Shigeru Okada Masahiro MurakamiHiroki Abe 《Tetrahedron letters》2003,44(37):7035-7037
The green microalga Botryococcus braunii race B accumulates two types of triterpenoid hydrocarbons, botryococcenes and tetramethylsqualene. Both triterpenoids are synthesized via the non-mevalonate pathway. 相似文献
93.
A highly congested bicyclo[3.3.1]nonanone core of polycyclic polyprenylated acylphloroglucinols was constructed using a stereoselective Claisen rearrangement and an intramolecular aldol reaction as the key steps. The stereochemistry of C-4 appeared to control the ground state conformation of the cyclohexenone core, which determined the diastereoselectivity in the Claisen rearrangement. 相似文献
94.
Fukuzaki T Kobayashi S Hibi T Ikuma Y Ishihara J Kanoh N Murai A 《Organic letters》2002,4(17):2877-2880
[reaction: see text] Studies on the connection between the right and left segments of azadirachtin are described. The Ireland-Claisen rearrangement of Li-enolate of the modeled ester with dichlorodimethylsilane in toluene afforded the desired limonoid framework stereoselectively in good yield. 相似文献
95.
Radical cation Diels‐Alder reactions provide a powerful method for the construction of six‐membered ring systems between both electron‐rich dienes and dienophiles. However, the most recent examples of this class have been limited to β‐methylstyrenes as dienophiles; the use of non‐conjugated alkenes remains challenging. The present study describes the serendipitous development of novel radical cation Diels‐Alder reactions by electrocatalysis that use non‐conjugated alkenes as dienophiles. The key to successful transformation involves highly substituted cyclohexenyl radical cations that are stable enough to be reduced by intermolecular single electron transfer. 相似文献
96.
An efficient template-directed photoligation of oligodeoxynucleotide (ODN) using 7-deaza-2′-deoxyadenosine derivative VZA is described. When ODN containing VZA at the 5′ end was photoirradiated with ODNs containing a pyrimidine base at the 3′ end in the presence of template ODN, rapid and efficient ligation (cycloaddition reaction) was observed without any byproduct formation. ODNs containing VZA showed an extremely high reactivity as compared with those reported in previous photoligations. 相似文献
97.
We report on the photophysical characterization at the single-molecule level of a graft copolymer consisting of a polythiophene backbone and long polystyrene branches. The presence of the branches prevents the polymer chain from forming a collapsed conformational state. The photophysical properties of the resulting solution-like conformation are studied by measuring single-molecule photobleaching dynamics, emission polarization anisotropy and emission spectra. The results are compared with those obtained on the same polythiophene derivative without the branches. It is found that the presence of the branches is a decisive factor in determining the photophysical properties of the polymers on the single-molecule level. 相似文献
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100.
EC-backward-E electrochemistry through electrocatalytic formal [2+2] cycloaddition reaction between anodically activated aliphatic enol ethers and unactivated olefins possessing an alkoxyphenyl group was clearly described by using cyclic voltammetric studies and spin density observation with B3LYP/6-31G(d) calculations. The alkoxyphenyl group was found to regulate the electron transfer, which operates as an electron donor during the formation of the cyclobutane ring and as an electron acceptor from the anode to give the final product (EC-backward-E). 相似文献