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1.
Xiujuan Xu Jun Chen Xiaoliang Luo Jingjing Lu Haixin Zhou Wenbo Wu Prof. Hongbing Zhan Prof. Yongqiang Dong Prof. Shouke Yan Prof. Jingui Qin Prof. Zhen Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(45):14384-14391
Covalently functionalized reduced graphene oxide (RGO) sheet was prepared by treating nitrogen‐centered anions generated from poly(9,9′‐diheylfluorene carbazole) (PCF) with GO. The resultant hybrids with different chemical behavior were separated by centrifugation. The covalent modification was fully characterized by IR spectroscopy, UV/Vis spectroscopy, thermogravimetric analysis (TGA), Raman spectroscopy, TEM, and SEM. It was found that RGO‐PCF‐s, the soluble part, was split into small platelets with a size of about 200 nm, and the hydrophobic polymer PCF became hydrophilic after wrapping by RGO. The content of RGO in RGO‐PCF‐s was about 11.9 %, and the hybrid material showed good dispersion stability in water. Besides, RGO‐PCF‐i, the insoluble part, with larger size, displayed excellent optical‐limiting response, in which both nonlinear absorption and nonlinear scattering play important roles. As nitrogen‐centered anions are an important type of intermediates in chemistry, this one‐step “grafting‐to” strategy could be used to obtain RGO‐based materials with different applications. 相似文献
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Kenji Shirokane Takamasa Wada Makoto Yoritate Ryo Minamikawa Nobuaki Takayama Dr. Takaaki Sato Prof. Dr. Noritaka Chida 《Angewandte Chemie (International ed. in English)》2014,53(2):512-516
A chemoselective approach for the total synthesis of (±)‐gephyrotoxin has been developed. The key to success was the utilization of N‐methoxyamides, which enabled the direct coupling of the amide with an aldehyde and selective reductive nucleophilic addition to the amide in the presence of a variety of sensitive and electrophilic functional groups, such as a methyl ester. This chemoselective approach minimized the use of protecting‐group manipulations and redox reactions, which resulted in the most concise and efficient total synthesis of (±)‐gephyrotoxin described to date. 相似文献
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Yuta Yanagita Hugh Nakamura Kenji Shirokane Yusuke Kurosaki Dr. Takaaki Sato Prof. Dr. Noritaka Chida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(2):678-684
While the synthesis of amide bonds is now one of the most reliable organic reactions, functionalization of amide carbonyl groups has been a long‐standing issue due to their high stability. As an ongoing program aimed at practical transformation of amides, we developed a direct nucleophilic addition to N‐alkoxyamides to access multisubstituted amines. The reaction enabled installation of two different functional groups to amide carbonyl groups in one pot. The N‐alkoxy group played important roles in this reaction. First, it removed the requirement for an extra preactivation step prior to nucleophilic addition to activate inert amide carbonyl groups. Second, the N‐alkoxy group formed a five‐membered chelated complex after the first nucleophilic addition, resulting in suppression of an extra addition of the first nucleophile. While diisobutylaluminum hydride (DIBAL‐H) and organolithium reagents were suitable as the first nucleophile, allylation, cyanation, and vinylation were possible in the second addition including inter‐ and intramolecular reactions. The yields were generally high, even in the synthesis of sterically hindered α‐trisubstituted amines. The reaction exhibited wide substrate scope, including acyclic amides, five‐ and six‐membered lactams, and macrolactams. 相似文献
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Anthony S. R. Chesman David R. Turner Dr. Glen B. Deacon Prof. Stuart R. Batten Assoc. Prof. 《化学:亚洲杂志》2009,4(5):761-769
Additional cyclization : Dicyanonitrosomethanide, [C(CN)2(NO)]? undergoes nucleophilic addition and cyclization of 1,2‐diaminoethane and 1,3‐diaminopropane on the nitrile groups to form imidazolinyl and 1,4,5,6‐tetrahydropyrimidinyl groups, respectively. Ethanolamine has lower reactivity and fails to cyclize.
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利用酰胺化反应将聚苯胺(PANI)共价接枝到氧化石墨烯(GO)的表面,得到的杂化材料GO-PANI能很好地分散在常见的有机溶剂中。样品的XPS谱和红外光谱数据证实了在GO和PANI之间存在酰胺键。在316nm激光激发下,PANI和GO-PANI分别在420nm和416nm处显示出很强的荧光峰。GO-PANI的最大发射峰相对于PANI的发射峰蓝移了4nm,且荧光强度增强。开孔Z-扫描实验结果表明:与PANI相比,GO和PANI的共价键合使材料在532nm激光辐照下表现出更大的非线性消光系数和三阶非线性极化率虚部值,光限幅性能明显增强。 相似文献
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Shouchun Yin Hongyao Xu Xinyan Su Gang Li Yinlin Song Jackywingyip Lam Benzhong Tang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(7):2346-2357
Poly(1‐alkyne)s containing azobenzene pendant groups with different lengths of the spacer and terminal alkyloxy group {? [HC?C(CH2)mOCO? C6H4? N?N? C6H4? OCpH2p+1]n? , where m = 1, 2, 3, or 9 and p = 4, 7, or 12} were synthesized in satisfactory yields with the [Rh(nbd)Cl]2–Et3N catalyst. All the polymers were soluble in common organic solvents such as CHCl3 and tetrahydrofuran. Their structures and properties were characterized and evaluated with IR, NMR, thermogravimetric analysis, UV, and optical‐limiting and nonlinear optical analyses. All the polymers were thermally stable and decomposed at temperatures as high as ~300 °C. The optical‐limiting and nonlinear optical properties of the polymers were sensitive to their molecular structures. Polymers having shorter spacer lengths and longer terminal groups showed better performances and larger third‐order nonlinear optical susceptibility (up to 1.34 × 10?10 esu). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2346–2357, 2006 相似文献
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Shi Guo Yuta Nishina Alberto Bianco Ccilia Mnard‐Moyon 《Angewandte Chemie (International ed. in English)》2020,59(4):1542-1547
A method for the double functionalization of graphene oxide (GO) under mild alkaline conditions has been developed. Two functional groups were covalently linked to GO in two steps: the first group was attached by an epoxide ring‐opening reaction and the second, bearing an amine function, was covalently conjugated to benzoquinone attached to the GO. The doubly functionalized GO was characterized by several techniques, confirming the sequential covalent modification of the GO surface with two different functional groups. This method is straightforward and the reaction conditions are mild, allowing preservation of the structure and properties of GO. This strategy could be exploited to prepare multifunctional GO conjugates with potential applications in many fields ranging from materials science to biomedicine. 相似文献
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Dr. Chun Kiang Chua Prof. Zdeněk Sofer Jan Luxa Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8090-8095
Nitrogen functionalization of graphene offers new hybrid materials with improved performance for important technological applications. Despite studies highlighting the dependence of the performance of nitrogen‐functionalized graphene on the types of nitrogen functional groups that are present, precise synthetic control over their ratio is challenging. Herein, the synthesis of nitrogen‐functionalized graphene rich in amino groups by a Bucherer‐type reaction under hydrothermal conditions is reported. The efficiency of the synthetic method under two hydrothermal conditions was examined for graphite oxide produced by Hummers and Hofmann oxidation routes. The morphological and structural properties of the amino‐functionalized graphene were fully characterized. The use of a synthetic method with a well‐known mechanism for derivatization of graphene will open new avenues for highly reproducible functionalization of graphene materials. 相似文献
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Treatment of α,β‐unsaturated ketones with an electrophilic site at the γ‐position in the presence of trimethylsilyl cyanide with bis(iodozincio)methane afforded the (Z)‐silyl enol ether of the β‐cyclopropyl substituted ketone in good yields. The reaction proceeds by 1,4‐addition to form an enolate, and its sequential intramolecular nucleophilic attack to an adjacent electrophilic site. The reaction of γ‐ethoxycarbonyl‐α,β‐unsaturated ketone and bis(iodozincio)methane in the presence of trimethylsilyl cyanide afforded 1‐ethoxy‐1‐trimethylsiloxycyclopropane derivatives, which can be regarded as the homoenolate equivalent. Additionally, reaction of the obtained homoenolate equivalents with imines give 1‐(E)‐alkenyl‐2‐(1‐aminoalkyl)alkanols diastereoselectively. 相似文献
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Transition‐Metal‐Free Synthesis of N‐(1‐Alkenyl)imidazoles by Potassium Phosphate‐Promoted Addition Reaction of Alkynes to Imidazoles 下载免费PDF全文
The addition reaction of alkynes to N‐heterocycles by simply heating in DMSO with potassium phosphate is reported. Good yields with high stereoselectivity could be achieved for a range of substrates. The scope is quite general for both amines and phenylacetylenes. In addition, internal alkynes and α‐bromostyrene were also examined in this reaction. This process is efficient and useful for the synthesis of (Z)‐N‐(1‐alkenyl)imidazoles and related Z products. Thus, the reaction is useful because of the importance of the imidazole scaffold. 相似文献
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Chemoselective Reductive Nucleophilic Addition to Tertiary Amides,Secondary Amides,and N‐Methoxyamides 下载免费PDF全文
Minami Nakajima Yukiko Oda Takamasa Wada Ryo Minamikawa Dr. Kenji Shirokane Dr. Takaaki Sato Noritaka Chida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(52):17565-17571
As the complexity of targeted molecules increases in modern organic synthesis, chemoselectivity is recognized as an important factor in the development of new methodologies. Chemoselective nucleophilic addition to amide carbonyl centers is a challenge because classical methods require harsh reaction conditions to overcome the poor electrophilicity of the amide carbonyl group. We have successfully developed a reductive nucleophilic addition of mild nucleophiles to tertiary amides, secondary amides, and N‐methoxyamides that uses the Schwartz reagent [Cp2ZrHCl]. The reaction took place in a highly chemoselective fashion in the presence of a variety of sensitive functional groups, such as methyl esters, which conventionally require protection prior to nucleophilic addition. The reaction will be applicable to the concise synthesis of complex natural alkaloids from readily available amide groups. 相似文献
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Yongkang Yue Fangjun Huo Songyi Lee Prof. Caixia Yin Prof. Juyoung Yoon Prof. Jianbin Chao Prof. Yongbin Zhang Prof. Fangqin Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1239-1243
Owing to their ability to monitor pH in a precise and rapid manner, optical probes have widely been developed for biological and nonbiological applications. The strategies thus far employed to determine pH rely on two types of processes including reversible protonation of amine nitrogen atoms and deprotonation of phenols. We have developed a novel dual, colorimetric/fluorescence system for determining the pH of a solution. This system utilizes an o‐hydroxymerocyanine dye that undergoes a nucleophilic addition reaction that subsequently causes reversible structural changes interconverting a merocyanine to a spirocyanine and a spirocyanine to a spiropyran. It was demonstrated that the dye can be employed to measure the pH of solutions in the 2.5–5.75 and 9.6–11.8 ranges with color changes from yellow to dark blue and then to lavender. Moreover, the fluorescence response associated with the spirocyanine–spiropyran transformation of the dye occurring in alkaline solutions provides a precise method. 相似文献
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Wenqian Feng Dr. Linxian Li Chengwu Yang Dr. Alexander Welle Prof. Dr. Oliver Trapp Dr. Pavel A. Levkin 《Angewandte Chemie (International ed. in English)》2015,54(30):8732-8735
A UV‐induced 1,3‐dipolar nucleophilic addition of tetrazoles to thiols is described. Under UV irradiation the reaction proceeds rapidly at room temperature, with high yields, without a catalyst, and in both polar protic and aprotic solvents, including water. This UV‐induced tetrazole‐thiol reaction was successfully applied for the synthesis of small molecules, protein modification, and rapid and facile polymer–polymer conjugation. The reaction has also been demonstrated for the formation of micropatterns by site‐selective surface functionalization. Superhydrophobic–hydrophilic micropatterns were successfully created by sequential modifications of a tetrazole‐modified porous polymer surface with hydrophobic and hydrophilic thiols. A biotin‐functionalized surface could be fabricated in aqueous solutions under long‐wavelength UV irradiation. 相似文献
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Javad Azizian Khadijeh Yadollahzadeh Hasan Tahermansouri Davood Chobfrosh Khoei Akram Sadat Delbari 《合成通讯》2013,43(14):2110-2120
Urea polyfunctional derivatives were successfully synthesized via a one-pot, five-component nucleophilic addition/Ugi reaction sequence. Simplicity, solvent-free conditions, and good yields of products are advantages of this method. 相似文献
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Ludmila A. Oparina Oksana V. Vysotskaya Lidiya N. Parshina Nina K. Gusarova Boris A. Trofimov 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2087-2093
Under acid- or base-catalyzed conditions, thiols add regio- and chemos-electively either to vinyloxy or methacrylate group of vinyloxyalkyl-methacrylates to give polyfunctional methacrylates or polyfunctional vinyl ethers, respectively. 相似文献
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One‐Step Double Covalent Functionalization of Reduced Graphene Oxide with Xanthates and Peroxides 下载免费PDF全文
Florence Pennetreau Prof. Olivier Riant Prof. Sophie Hermans 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15009-15012
Radical functionalization of reduced graphene oxide has been achieved by reaction with a xanthate in the presence of peroxide as a radical initiator. X‐ray photoelectron spectroscopy, bulk elemental analyses, and thermogravimetric analyses showed that the xanthate grafting is covalent and efficient. The synthesis and use of seven xanthates and three peroxides showed that the highest grafting yield is obtained when xanthate and peroxide are introduced in stoichiometric amounts. It also revealed that the peroxide used as radical initiator is grafted at the graphenic surface during the functionalization. The method presented in this contribution therefore allows bifunctionalized reduced graphene oxide samples to be easily obtained in one single step. This method leads to undamaged graphene sheets with higher dispersibility than the pristine sample. 相似文献
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Allyloxyporphyrin‐Functionalized Multiwalled Carbon Nanotubes: Synthesis by Radical Polymerization and Enhanced Optical‐Limiting Properties 下载免费PDF全文
Dr. Aijian Wang Yu Fang Wang Yu Dr. Lingliang Long Prof. Dr. Yinglin Song Wei Zhao Dr. Marie P. Cifuentes Prof. Dr. Mark G. Humphrey Prof. Dr. Chi Zhang 《化学:亚洲杂志》2014,9(2):639-648
Allyloxyporphyrin‐functionalized multiwalled carbon nanotubes (MWCNT‐TPP) were synthesized by radical polymerization and characterized by FTIR, UV/Vis absorption, and X‐ray photoelectron spectroscopy; elemental analysis; TEM; and thermogravimetric analysis. Z‐scan studies revealed that this nanohybrid exhibits enhanced nonlinear optical (NLO) properties compared to a control sample consisting of a covalently unattached physical blend of MWCNTs and porphyrin, as well as to the separate MWCNTs and porphyrin. At the wavelengths used, the mechanism of enhanced optical limiting likely involves reverse saturable absorption, nonlinear scattering, and photoinduced electron/energy transfer between the MWCNTs and the porphyrin. The role of electron/energy transfer in the NLO performance of MWCNT‐TPP was investigated by Raman and fluorescence spectroscopy. 相似文献