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121.
将二(3-二甲氨基丙基)丙二酰胺分别与溴代十六烷和溴代十四烷反应,生成的季铵盐化产物经丙酮-乙腈重结晶,得到含丙二酰胺基的不对称阳离子双子(Gemini)表面活性剂(命名为16-9-14),总收率为45.9%(以溴代十六烷计);利用红外光谱和核磁共振谱表征了合成产物的结构,采用电导法测定了其临界胶束浓度(CMC),采用滴体积法测定了其临界张力(γCMC),进而初步探讨了其发泡沫性能和乳化性能.结果表明,合成的Gemini表面活性剂的CMC为1.57×10-4 mol/L,γCMC为38.45mN/m;其发泡性能和乳化性能优于相应的单子表面活性剂. 相似文献
122.
Prof. Dr. Jilai Li Dr. Caiyun Geng Dr. Thomas Weiske Prof. Dr. Mingfei Zhou Prof. Dr. Jun Li Prof. Dr. Helmut Schwarz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17414-17418
Extensive high-level quantum-chemical calculations reveal that the rod-shaped molecule BeOBeC, which was recently generated in matrix experiments, exists in two nearly isoenergetic states, the 5Σ quintet (5 6 ) and the 3Σ triplet (3 6 ). Their IR features are hardly distinguishable at finite temperature. The major difference concerns the mode of spin coupling between the terminal beryllium and carbon atoms. Further, the ground-state potential-energy surface of the [2Be,C,O] system at 4 K is presented and differences between the photochemical and thermal behaviors are highlighted. Finally, a previously not considered, so far unknown C2v-symmetric rhombus-like four-membered ring 3[Be(O)(C)Be] (3 5 ) is predicted to represent the global minimum on the potential-energy surface. 相似文献
123.
Tian Du Ruiheng Gao Dr. Yunfeng Deng Cheng Wang Qian Zhou Prof. Yanhou Geng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):227-231
A series of 1,3-indandione-terminated π-conjugated quinoids were synthesized by alkoxide-mediated rearrangement reaction of the respective alkene precursors, followed by air oxidation. This new protocol allows access to quinoidal compounds with variable termini and cores. The resulting quinoids all show LUMO levels below −4.0 eV and molar extinction coefficients above 105 L mol−1 cm−1. The optoelectronic properties of these compounds can be regulated by tuning the central cores as well as the aryl termini ascribed to the delocalized frontier molecular orbitals over the entire molecular skeleton involving aryl termini. n-Channel organic thin-film transistors with electron mobility of up to 0.38 cm2 V−1 s−1 were fabricated, showing the potential of this new class of quinoids as organic semiconductors. 相似文献
124.
Dr. Baoyan Xing Dr. Sai Ge Prof. Jianguo Zhao Dr. Hui Yang Dr. Jie Song Dr. Yu Geng Dr. Yuying Qiao Prof. Ling Gu Prof. Peide Han Prof. Guibin Ma 《ChemistryOpen》2020,9(10):1018-1026
Solid-state NMR analysis on wurtzite alloyed CdSe1−xSx crystalline nanoparticles and nanobelts provides evidence that the 113Cd NMR chemical shift is not affected by the varying sizes of nanoparticles, but is sensitive to the S/Se anion molar ratios. A linear correlation is observed between 113Cd NMR chemical shifts and the sulfur component for the alloyed CdSe1−xSx (0<x<1) system both in nanoparticles and nanobelts (δCd=169.71⋅XS+529.21). Based on this correlation, a rapid and applied approach has been developed to determine the composition of the alloyed nanoscalar materials utilizing 113Cd NMR spectroscopy. The observed results from this system confirm that one can use 113Cd NMR spectroscopy not only to determine the composition but also the phase separation of nanomaterial semiconductors without destruction of the sample structures. In addition, some observed correlations are discussed in detail. 相似文献
125.
Jilai Li Caiyun Geng Thomas Weiske Helmut Schwarz 《Angewandte Chemie (International ed. in English)》2020,59(30):12308-12314
[V2O]+ remains “invisible” in the thermal gas‐phase reaction of bare [V2]+ with CO2 giving rise to [V2O2]+; this is because the [V2O]+ intermediate is being consumed more than 230 times faster than it is generated. However, the fleeting existence of [V2O]+ and its involvement in the [V2]+ → [V2O2]+ chemistry are demonstrated by a cross‐over labeling experiment with a 1:1 mixture of C16O2/C18O2, generating the product ions [V216O2]+, [V216O18O]+, and [V218O2]+ in a 1:2:1 ratio. Density functional theory (DFT) calculations help to understand the remarkable and unexpected reactivity differences of [V2]+ versus [V2O]+ towards CO2. 相似文献
126.
Wen‐Chao Geng Dongmei Zhang Chu Gong Zhihao Li Kevin M. Barraza Jesse L. Beauchamp Dong‐Sheng Guo Xinxing Zhang 《Angewandte Chemie (International ed. in English)》2020,59(31):12684-12688
The oxidation of antioxidants by oxidizers imposes great challenges to both living organisms and the food industry. Here we show that the host–guest complexation of the carefully designed, positively charged, amphiphilic guanidinocalix[5]arene pentadodecyl ether (GC5A‐12C) and negatively charged oleic acid (OA), a well‐known cell membrane antioxidant, prevents the oxidation of the complex monolayers at the air–water interface from two potent oxidizers hydroxyl radicals (OH) and singlet delta oxygen (SDO). OH is generated from the gas phase and attacks from the top of the monolayer, while SDO is generated inside the monolayer and attacks amphiphiles from a lateral direction. Field‐induced droplet ionization mass spectrometry results have demonstrated that the host–guest complexation achieves steric shielding and prevents both types of oxidation as a result of the tight and “sleeved in” physical arrangement, rather than the chemical reactivity, of the complexes. 相似文献
127.
Lei Jiang Haizhen Ding Siyu Lu Ting Geng Guanjun Xiao Bo Zou Hong Bi 《Angewandte Chemie (International ed. in English)》2020,59(25):9986-9991
Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co‐doped carbon dots (F,N‐doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N‐doped CDs increases with UV light irradiation (5 s–30 min), accompanied with a blue‐shift of the fluorescence emission from 586 nm to 550 nm. F,N‐doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N‐doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure‐triggered aggregation‐induced emission in the range 1.0 atm–0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high‐pressure conditions and enhances their anti‐photobleaching. 相似文献
128.
Shan-Shan Guo Xue Pang Yang Wang Zhu-Feng Geng Ju-Qin Cao Jun-Yu Liang 《Natural product research》2020,34(18):2595-2601
AbstractOne new sesquiterpene (α-iso-cubebenol acetate, 8), together with 9 known compounds (1-7, 9, 10) were isolated from the stems of Schisandra chinensis (Turcz.) Baill. by repeated silica gel column chromatography. Based on the results of MS, NMR spectra and comparing with literature data, the six dibenzocyclooctadiene lignans were identified as schizandrin A to C (1-3), schizandrin (4), schisantherin A (5) and gomisin J (6), the two sesquiterpenes were identified as α-iso-cubebenol (7) and α-iso-cubebenol acetate (8), while the two triterpenic acids were identified as ganwuweizic acid (9) and kadsuric acid (10). The antifeedant activity of the 10 compounds against Tribolium castaneum adults was tested. Gomisin J (6) exhibited activity at 1500?ppm concentration with 40.3% antifeeding index percentages. As for the dibenzocyclooctene lignans (compounds 1–3, 6), the number of methylenedioxies and the position of hydroxyl groups were the main factors to affect their antifeedant activities. 相似文献
129.
Xuefang Liu Chen Yang Feifang Zhang Huiliang Geng Bingcheng Yang 《Journal of separation science》2020,43(8):1474-1478
A novel weak cation exchanger is described by encapsulating silica with a (or multiple) layer(s) of maleic anhydride–modified polyvinyl alcohol coating(s). The preparation method is facile and fast, which is simply performed by dipping silica particles into maleic anhydride–modified polyvinyl alcohol solution as‐synthesized, then filtering and curing thermally, and finally generating a thin coating onto silica particles. Multiple layers of maleic anhydride–modified polyvinyl alcohol coatings can be generated by repeating above steps, offering an easy way to manipulate the capacity. The obtained weak cation exchanger demonstrated high separation efficiency and good selectivity toward common inorganic cations, for example, high plate count of 81 000 per meter was obtained for NH4+. Simultaneous separation of alkali and alkaline earth metals could be achieved within 14 min under isocratic conditions. 相似文献
130.
收缩扩张管内液氮空化流动演化过程试验研究 总被引:1,自引:1,他引:0
本文基于低温空化试验平台研究了收缩扩张流道内液氮非定常空化流动的演化过程. 试验采用高时空分辨率的高速摄像机对77 K液氮在不同空化数σ下空穴结构的演变进行了精细化的分析和研究. 利用试验得到的空穴长度和面积等数据, 定量分析了液氮空化流动的非定常特性与时空演变规律. 研究结果表明: (1)在相似来流速度和温度条件下, 随着空化数的减小, 液氮空化流动呈现四种典型流型, 空穴长度在2.5 h以内为初生空化、空穴长度在2.5 h ~ 7.5 h之间为片状空化、空穴长度在7.5 h ~ 15 h之间为大尺度云状空化, 空穴长度超过15 h为双云状空化, 且在大尺度云状空化和双云状空化阶段均捕捉到了回射流现象; (2)液氮空化流动从初生空化到双云状空化, 脱落空穴的尺度逐渐增大, 空穴面积脉动的幅值和准周期均有所增加. 同时, 在大尺度云状空化与双云状空化阶段, 喉口处堵塞效应对空化流动的影响显著增强; (3)相比于初生空化, 片状空化、大尺度云状空化以及双云状空化中脱落空穴的移动距离依次增加了0.97倍、2.65倍与2.68倍, 溃灭时间依次增加了1.18倍、3.59倍与4.47倍, 但溃灭速度依次减小了0.10倍、0.20倍与0.30倍. 除此之外, 对于双云状空化阶段, 存在两种显著不同的脱落空穴演化过程. 相似文献