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31.
Dr. Ziyang Song Dr. Ling Miao Dr. Yaokang Lv Prof. Lihua Gan Prof. Mingxian Liu 《Angewandte Chemie (International ed. in English)》2023,62(38):e202309446
Organic small molecules as high-capacity cathodes for Zn-organic batteries have inspired numerous interests, but are trapped by their easy-dissolution in electrolytes. Here we knit ultrastable lock-and-key hydrogen-bonding networks between 2, 7-dinitropyrene-4, 5, 9, 10-tetraone (DNPT) and NH4+ charge carrier. DNPT with octuple-active carbonyl/nitro centers (H-bond acceptor) are redox-exclusively accessible for flexible tetrahedral NH4+ ions (H-bond donator) but exclude larger and rigid Zn2+, due to a lower activation energy (0.14 vs. 0.31 eV). NH4+ coordinated H-bonding chemistry conquers the stability barrier of DNPT in electrolyte, and gives fast diffusion kinetics of non-metallic charge carrier. A stable two-step 4e− NH4+ coordination with DNPT cathode harvests a high capacity (320 mAh g−1), a high-rate capability (50 A g−1) and an ultralong life (60,000 cycles). This finding points to a new paradigm for H-bond stabilized organic small molecules to design advanced zinc batteries. 相似文献
32.
Dr. Xiaona Li Cristina Di Carluccio He Miao Lvfeng Zhang Jintao Shang Prof. Dr. Antonio Molinaro Prof. Dr. Peng Xu Prof. Dr. Alba Silipo Prof. Dr. Biao Yu Prof. Dr. You Yang 《Angewandte Chemie (International ed. in English)》2023,62(43):e202307851
Cyclodextrins are widely used as carriers of small molecules for drug delivery owing to their remarkable host properties and excellent biocompatibility. However, cyclic oligosaccharides with different sizes and shapes are limited. Cycloglycosylation of ultra-large bifunctional saccharide precursors is challenging due to the constrained conformational spaces. Herein we report a promoter-controlled cycloglycosylation approach for the synthesis of cyclic α-(1→6)-linked mannosides up to a 32-mer. Cycloglycosylation of the bifunctional thioglycosides and (Z)-ynenoates was found to be highly dependent on the promoters. In particular, a sufficient amount of a gold(I) complex played a key role in the proper preorganization of the ultra-large cyclic transition state, providing a cyclic 32-mer polymannoside, which represents the largest synthetic cyclic polysaccharide to date. NMR experiments and a computational study revealed that the cyclic 2-mer, 4-mer, 8-mer, 16-mer, and 32-mer mannosides adopted different conformational states and shapes. 相似文献
33.
Qiuyue Ge Yangyang Liu Kejian Li Lifang Xie Xuejun Ruan Wei Wang Longqian Wang Tao Wang Wenbo You Liwu Zhang 《Angewandte Chemie (International ed. in English)》2023,62(27):e202304189
Solar-driven CO2 reduction reaction (CO2RR) is largely constrained by the sluggish mass transfer and fast combination of photogenerated charge carriers. Herein, we find that the photocatalytic CO2RR efficiency at the abundant gas-liquid interface provided by microdroplets is two orders of magnitude higher than that of the corresponding bulk phase reaction. Even in the absence of sacrificial agents, the production rates of HCOOH over WO3 ⋅ 0.33H2O mediated by microdroplets reaches 2536 μmol h−1 g−1 (vs. 13 μmol h−1 g−1 in bulk phase), which is significantly superior to the previously reported photocatalytic CO2RR in bulk phase reaction condition. Beyond the efficient delivery of CO2 to photocatalyst surfaces within microdroplets, we reveal that the strong electric field at the gas-liquid interface of microdroplets essentially promotes the separation of photogenerated electron-hole pairs. This study provides a deep understanding of ultrafast reaction kinetics promoted by the gas-liquid interface of microdroplets and a novel way of addressing the low efficiency of photocatalytic CO2 reduction to fuel. 相似文献
34.
Si-Yong Yin Qiansujia Zhou Dr. Chen-Xu Liu Prof. Dr. Qing Gu Prof. Dr. Shu-Li You 《Angewandte Chemie (International ed. in English)》2023,62(37):e202305067
Enantioselective synthesis of N−N biaryl atropisomers is an emerging area but remains underexplored. The development of efficient synthesis of N−N biaryl atropisomers is in great demand. Herein, the construction of N−N biaryl atropisomers through iridium-catalyzed asymmetric C−H alkylation is reported for the first time. In the presence of readily available Ir precursor and Xyl-BINAP, a variety of axially chiral molecules based on indole-pyrrole skeleton were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). In addition, N−N bispyrrole atropisomers could also be synthesized in excellent yields and enantioselectivity. This method features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations. 相似文献
35.
Dr. Jia-Hao Xie Yi-Ming Hou Zuolijun Feng Prof. Dr. Shu-Li You 《Angewandte Chemie (International ed. in English)》2023,62(10):e202216396
Herein, we report a synthesis of cyclohexanones bearing multi-continuous stereocenters by combining copper-catalyzed asymmetric conjugate addition of dialkylzinc reagents to cyclic enones with iridium-catalyzed asymmetric allylic substitution reaction. Good to excellent yields, diastereoselectivity and enantioselectivity can be obtained. Unlike the stereodivergent construction of adjacent stereocenters (1,2-position) reported in the literature, the current reaction can achieve the stereodivergent construction of nonadjacent stereocenters (1,3-position) by a proper combination of two chiral catalysts with different enantiomers. 相似文献
36.
Wenxuan Xue Yijie Jiang Prof. Dr. Hongcheng Lu Prof. Dr. Bo You Dr. Xu Wang Prof. Dr. Conghui Tang 《Angewandte Chemie (International ed. in English)》2023,62(52):e202314364
The utilization of a single-atom catalyst to break C−C bonds merges the merits of homogeneous and heterogeneous catalysis and presents an intriguing pathway for obtaining high-value-added products. Herein, a mild, selective, and sustainable oxidative cleavage of alkene to form oxime ether or nitrile was achieved by using atomically dispersed cobalt catalyst and hydroxylamine. Diversified substrate patterns, including symmetrical and unsymmetrical alkenes, di- and tri-substituted alkenes, and late-stage functionalization of complex alkenes were demonstrated. The reaction was successfully scaled up and demonstrated good performance in recycling experiments. The hot filtration test, catalyst poisoning and radical scavenger experiment, time kinetics, and studies on the reaction intermediate collectively pointed to a radical mechanism with cobalt/acid/O2 promoted C−C bond cleavage as the key step. 相似文献
37.
Liqun Fang Tingting Lin Ben Chen Haibo You Chunyan Wu Chu Chu Shengqiang Tong 《Journal of separation science》2023,46(4):2200764
In the present study, high-performance liquid chromatography micro-fraction bioactive evaluation and high speed countercurrent chromatography were performed on screening, identification and isolation of antioxidants from Citrus peel. Three compounds were screened as antioxidants and tyrosinase inhibitors using 2,2′-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation scavenging assay and tyrosinase activity test, then they were identified as eriocitrin, narirutin and hesperidin. Moreover, the solvent system ethyl acetate-n-butanol-water (6:4:10, v/v/v) was used for separation of ethyl acetate extract of Citrus peel by high speed countercurrent chromatography. In total, 0.45 mg of eriocitrin with 87.10% purity, 2.04 mg of narirutin with 95.19% purity and 1.35 mg of hesperidin with 95.19% purity were obtained from 20 mg of ethyl acetate extract of Citrus peel in a single run and then each component was subjected to 2,2′-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation scavenging assay and tyrosinase inhibition assay. Eriocitrin showed great antioxidant activity (the half-maximum concentration: 3.65 µM) and tyrosinase inhibition activity (the half-maximum concentration: 115.67 µM), while narirutin and hesperidin exhibited moderate activity. Tyrosinase inhibition activity for eriocitrin in vitro was reported for the first time. Furthermore, molecular docking between eriocitrin and mushroom tyrosinase was also studied. 相似文献
38.
固相萃取/液相色谱-串联质谱法测定果蔬中草铵膦的残留量 总被引:1,自引:0,他引:1
建立了果蔬中草铵膦残留量的液相色谱-串联质谱(LC-MS/MS)分析方法。样品经水提取、二氯甲烷除去脂溶性杂质,强阳离子固相萃取小柱净化,9-芴甲基氯甲酸酯(FMOC-Cl)衍生后,以C18色谱柱(4.6 mm×50 mm,1.8μm)进行分离,5 mmol/L乙酸铵水溶液(含0.1%甲酸)-乙腈(含0.1%甲酸)作为流动相梯度洗脱,电喷雾正离子模式电离(ESI+),多反应监测模式(MRM)检测,内标法定量。方法在0~200μg/L浓度范围内线性关系良好,相关系数(r2)大于0.995。方法检出限为10μg/kg,定量下限为20μg/kg。在不同食品基质中,草铵膦在20,200,500μg/kg加标水平下的平均回收率为80.8%~102.2%,相对标准偏差(RSD)为1.8%~7.9%。该法采用同位素内标定量,有效地消除了样品基质效应,灵敏度高、准确度好,适用于果蔬中草铵膦残留量的监控测定。 相似文献
39.
Dr. Dongdi Zhang Fan Cao Pengtao Ma Chao Zhang Prof. Dr. You Song Zhijie Liang Xiaojing Hu Prof. Jingping Wang Prof. Dr. Jingyang Niu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(49):17683-17690
By deliberately using a metastable polyanion [(NbO2)6P2W12O56]12? ( 1 ), which was formed in situ, we have discovered the unprecedented hexameric cluster {Mn15(Nb6P2W12O62)6} ( 2 ), in which the six polyanions [Nb6P2W12O61]10? are alternately connected by four intriguing trinuclear {MnIII3} moieties and four {MnII} linkers. This discovery is the first in which the phosphoniobotungstate has been made accessible by using transition‐metal ions; furthermore, polyanion 2 represents the largest niobotungstate cluster reported to date. Analysis by means of electrospray ionization mass spectrometry (ESI‐MS ) provides insight into the self‐assembly process, and the peaks observed relate to the different charge states of the parent cluster, thus confirming the stability of 2 . In addition, magnetic‐susceptibility measurements reveal that each {MnIII3} subunit is a separate single‐molecule magnet (SMM). This discovery results from the exploration of the reverse effect of metastable polyanion 1 possessing high reactivity, thereby turning a disadvantage into an advantage. This finding could define a new synthetic strategy for the design and synthesis of magnetic polyoxometalate (POM) clusters. 相似文献
40.
Byung Hyun Kang Hye Sook Min You Jeong Lee Bomi Choi Eun Ji Kim Jonghoon Lee Jeong-Rae Kim Kwang-Hyun Cho Tae Jin Kim Kyeong Cheon Jung Seong Hoe Park 《Experimental & molecular medicine》2015,47(3):e154
Analysis of the T-cell receptor (TCR) repertoire of innate CD4+ T cells selected by major histocompatibility complex (MHC) class II-dependent thymocyte–thymocyte (T-T) interaction (T-T CD4+ T cells) is essential for predicting the characteristics of the antigens that bind to these T cells and for distinguishing T-T CD4+ T cells from other types of innate T cells. Using the TCRmini Tg mouse model, we show that the repertoire of TCRα chains in T-T CD4+ T cells was extremely diverse, in contrast to the repertoires previously described for other types of innate T cells. The TCRα chain sequences significantly overlapped between T-T CD4+ T cells and conventional CD4+ T cells in the thymus and spleen. However, the diversity of the TCRα repertoire of T-T CD4+ T cells seemed to be restricted compared with that of conventional CD4+ T cells. Interestingly, the frequency of the parental OT-II TCRα chains was significantly reduced in the process of T-T interaction. This diverse and shifted repertoire in T-T CD4+ T cells has biological relevance in terms of defense against diverse pathogens and a possible regulatory role during peripheral T-T interaction. 相似文献