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801.
Ryota Sakamoto Dr. Shoko Kume Dr. Manabu Sugimoto Prof. Dr. Hiroshi Nishihara Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(6):1429-1439
Azobenzene derivatives modified with dithiolato‐bipyridine platinum(II) complexes were synthesized, revealing their highly extended photoresponses to the long wavelength region as well as unique photocontrollable tristability. The absorptions of trans‐ 1 and trans‐ 2 with one azobenzene group on the dithiolene and bipyridine ligands, respectively, cover the range from 300 to 700 nm. These absorptions are ascribed, by means of time‐dependent (TD)DFT calculations, to transitions from dithiolene(π) to bipyridine(π*), namely, interligand charge transfer (CT), π–π*, and n–π* transitions of the azobenzene unit, and π–π* transitions of the bipyridine ligand. In addition, only trans‐ 1 shows distinctive electronic bands, assignable to transitions from the dithiolene(π) to azobenzene(π*), defined as intraligand CT. Complex 1 shows photoisomerization behavior opposite to that of azobenzene: trans‐to‐cis and cis‐to‐trans conversions proceed with 405 and 312 nm irradiation, which correspond to excitation with the intraligand CT, and π–π* bands of the azobenzene and bipyridine units, respectively. In contrast, complex 2 shows photoisomerization similar to that of azobenzene: trans‐to‐cis and cis‐to‐trans transformations occur with 365 and 405 nm irradiation, respectively. Irradiation at 578 nm, corresponding to excitation of the interligand CT transitions, results in cis‐to‐trans conversion of both 1 and 2 , which is the longest wavelength ever reported to effect the photoisomerization of the azobenzene group. The absorption and photochromism of 4 , which has azobenzene groups on both the dithiolato and bipyridine ligands, have characteristics quite similar to those of 1 and 2 , which furnishes 4 with photocontrollable tristability in a single molecule using light at 365, 405, and 578 nm. We also clarified that 1 and 2 have high photoisomerization efficiencies, and good thermal stability of the cis forms. Complexes 3 and 5 have almost the identical photoresponse to those of their positional isomers, complexes 2 and 4 . 相似文献
802.
Synthesis of 6-hydroxy-2-naphthoic acid from 2,6-diisopropylnaphthalene using NHPI as a key catalyst
Ryota Nakamura 《Tetrahedron》2009,65(18):3577-4102
A new strategy to 6-hydroxy-2-naphthoic acid (HNPA) and 4-hydroxybenzoic acid from 2,6-diisopropylnaphthalene and p-cymene, respectively, was developed using the NHPI-catalyzed aerobic oxidation as a principal reaction. 2,6-Diisopropylnaphthalene was oxidized by the oxidation with O2 (1 atm) by NHPI (10 mol %) combined with Co(OAc)2 (0.5 mol %) to give 6-acetyl-2-isopropylnaphthalene, which then was converted to 6-isopropyl-2-naphthoic acid under O2 (1 atm) in the presence of Co(OAc)2 (0.5 mol %) and Mn(OAc)2 (0.5 mol %). Esterification of the resulting acid followed by the aerobic oxidation produced methyl 6-hydroxy-2-naphthoate whose hydrolysis led to the desired HNPA. An alternative route involves the oxidation of 6-acetyl-2-isopropylnaphthalene to 6-acetyl-2-naphthol on which subsequent oxidation and deacetylation gave HNPA. This method was successfully extended to the synthesis of 4-hydroxybenzoic acid from p-cymene. 相似文献
803.
Satoru Hiroto Naoki Aratani Dr. Naoki Shibata Prof. Dr. Yoshiki Higuchi Prof. Dr. Takahiro Sasamori Dr. Norihiro Tokitoh Prof. Dr. Hiroshi Shinokubo Prof. Dr. Atsuhiro Osuka Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(13):2388-2390
Pyridine attacks : Nucleophilic addition of pyridine derivatives to a doubly linked corrole, which is a stable singlet biradical species, occurs at the bay area with high regioselectivity to provide zwitterionic dimers (see picture; Ar=C6F5). Charge transfer between the anionic corrole and the pyridinium groups induces effective fluorescence quenching of the corrole dimer, which can be utilized for selective fluoride ion recognition.
804.
Takeshi Higuchi Dr. Atsunori Tajima Kiwamu Motoyoshi Hiroshi Yabu Prof. Dr. Masatsugu Shimomura Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(28):5125-5128
Divide and conquer : Polymer nanoparticles with phase‐separation structures prepared with block copolymers and homopolymer blends were used to fabricate unique suprapolymer structures by cross‐linking one polymer moiety and dissolving the other (see scheme; PI=polyisoprene, PSt=polystyrene).
805.
We have fabricated a unique memristive device by molecular engineering and demonstrated that the leakage current tuning in the device is 100 times more efficient than that in a standard device. Molecular analogs of the memristive matrices used here are an electrochemically active conjugated Co(III) polymer (CP) and a nonconjugated Co(III) polymer (NCP), which have been synthesized in good yield and characterized by (1)H NMR spectroscopy. Redox switching of an organic-metallic hybrid polymer generates bistable states with a large ON/OFF ratio that supports random flip-flops for several hours. Thus, we provide a synthetic solution to leakage current restriction, one of the fundamental problems faced when fabricating state-of-the-art electronic devices. 相似文献
806.
Ishikawa T Saito T Kurosawa A Watanabe T Maruyama S Ichikawa Y Yamada R Okuzawa H Sato H Ueno K 《Chemical & pharmaceutical bulletin》2011,59(4):472-475
Preliminary examination for the structure-activity relationship of quinone monooxime derivatives on cytotoxicity against HeLa S3 cell and further trials using eight different cell lines suggested that 2-aryl-6,7-methylenedioxy-1,4-naphthoquinone-1-oxime methyl ethers, carrying 2-methoxy-4,5-methylenedioxyphenyl, 7-methoxy-2-methylbenzofuran-4-yl, and 2-methoxycarbonyl-3,4-dimethoxyphenyl as the 2-aryl substituent, were potential candidates for anti-cancer drugs. 相似文献
807.
Chrysophanol and 1,8-di-O-hexylchrysophanol derivatives having nucleic acid bases at position 5 were synthesized. Furthermore, derivatives of menadione substituted at position 11 (type A naphthoquinone derivatives) or methylmenadione substituted at position 7 (type B naphthoquinone derivatives) modified with nucleic acid bases, amines and thiocyano, selenocyano or thioacetyl groups were synthesized. The cytotoxic effects of these derivatives on HCT 116 cells, which poorly express P-glycoprotein (P-gp), and Hep G2 cells, which stably express P-gp, were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results were compared with those obtained using 5-fluorouracil (5-FU), which has been used clinically. Several of these derivatives exhibited markedly higher potent cytotoxic effects not only on HCT cancer cells but also Hep G2 cancer cells as compared with 5-FU. 相似文献
808.
Both therapy and diagnosis, theragnosis, are indispensable for personalized medicine. Gold nanoparticles (Au NPs) have photochemical properties and attenuate X-rays,
which are useful for photothermal therapy and X-ray computed tomography (CT) imaging, respectively. Polyethylene glycol (PEG)-modified
dendrimers (PEGylated dendrimers) have been used as drug carriers with prolonged blood circulation. In this study, Au NP-loaded
PEGylated dendrimers were prepared as agents for photothermal therapy and CT imaging. Au NPs were grown in the PEGylated dendrimer
by adding gold ions and reductants under various conditions to improve the properties. Both size and surface plasmon absorption
of the Au NPs increased, dependent on the seeding growth conditions. Au NPs with near infrared absorption were also prepared
by seeding growth from Au NP-loaded PEGylated dendrimers using formaldehyde. The Au NPs thus grown showed enhanced photothermogenic
properties and CT intensities, enabling efficient photocytotoxicity and the enhancement of the blood pool in mice by CT imaging.
Therefore, Au NP-loaded PEGylated dendrimers are a potential agent for theragnosis. 相似文献
809.
M Higuchi K Nakamura S Horike Y Hijikata N Yanai T Fukushima J Kim K Kato M Takata D Watanabe S Oshima S Kitagawa 《Angewandte Chemie (International ed. in English)》2012,51(33):8369-8372
Charged up: A novel porous coordination polymer with a charged organic surface (COS) comprising a zwitterionic organic linker, viologen, has been synthesized. The COS shows strong Lewis acidity accompanied with flexibility, and the isosteric heat of H(2) adsorption is 9.5?kJ?mol(-1) , which is comparable to that of open metal sites (OMSs). 相似文献
810.