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961.
Chiral Separations in Normal‐phase Liquid Chromatography: Updating a Screening Strategy with a Chlorine‐containing Polysaccharide‐based Selector 下载免费PDF全文
Jie Zhou Shanshan Chen Pei Luo Chong Sun Lingchang Meng Qiuzheng Du Fang Sun 《中国化学会会志》2015,62(12):1059-1067
The screening conditions of an existing column and mobile phase selection strategy for chiral compounds in normal‐phase high performance liquid chromatography (NP‐HPLC) were tested for their applicability on Chiralpak IC, which is a chiral stationary phase (CSP) made by immobilising cellulosic tris (3,5‐dichlorophenyl‐carbamate) on silica gel. In this study, the applicability of the optimization steps of the existing separation strategy was examined using 36 compounds representing the three possible resolution situations that occur after screening. The cumulative number of separated compounds is 27 (75.0 %), and the cumulative number of baseline separated compounds is 19 (52.8 %). 相似文献
962.
Xi Dai Tao Zhang Zhi-Fang Du Xiang-Jian Cao Ming-Yu Chen Sheng-Wen Hu Jun-Ying Miao Bao-Xiang Zhao 《Analytica chimica acta》2015
We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO3−) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO3− based on the Michael addition reaction with a limit of detection 5.3 × 10−8 M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application. 相似文献
963.
Paecilomycines A and B,Novel Diterpenoids,Isolated from Insect‐Pathogenic Fungi Paecilomyces sp. ACCC 37762 下载免费PDF全文
Kun Zhou Xiao‐Ling Zhao Li‐Ping Han Meng‐Meng Cao Chuan Chen Bao‐Zhong Shi Du‐Qiang Luo 《Helvetica chimica acta》2015,98(5):642-649
Two new diterpenoids, named paecilomycine A ( 1 ) and paecilomycine B ( 2 ), including a novel skeleton with a five‐membered lactone ring, together with three known labdane diterpenoids, rel‐(1R,3S,4aS,5R,8aS)‐5‐[(3E)‐4‐carboxy‐3‐methylbut‐3‐en‐1‐yl]decahydro‐3‐hydroxy‐1,4a‐dimethyl‐6‐methylidenenaphthalene‐1‐carboxylic acid ( 3 ), botryosphaerin E ( 4 ), and agathic acid ( 5 ), were isolated from solid culture of the insect pathogenic fungi strain Paecilomyces sp. The structures of all compounds were established on the basis of comprehensive spectroscopic studies. The relative configurations of 1 and 2 were determined by single‐crystal X‐ray diffraction analyses. 相似文献
964.
965.
Rui‐Chun Luo Chao Li Xi‐Wen Du Jing Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(16):4869-4873
Monodisperse non‐noble metal nanocrystals (NCs) that are highly uniform in shapes and particle size are much desired in various advanced applications, and are commonly prepared by either thermal decomposition or reduction, where reactive organometallic precursors or/and strong reducing agents are mandatory; however, these are usually toxic, costly, or suffer a lack of availability. Bulk Group 12 metals can now be converted into ligand‐protected, highly crystalline, monodisperse spherical metal NCs with precisely controlled sizes without using any precursors and reducers. The method is based on low‐power NIR‐laser‐induced size‐selective layer‐by‐layer surface vaporization. The monodisperse Cd NCs show pronounced deep‐UV (DUV) localized surface plasmon resonance making them highly competitive DUV‐plasmonic materials. This approach will promote appreciably the emergence of a wide range of monodisperse technically important non‐coinage metal NCs with compelling functionalities. 相似文献
966.
The novel microgels, poly[di(ethylene glycol) methyl ether methacrylate-co-2-methoxyethyl acrylate] poly(DEGMMA-co-MEA) microgels, were synthesized. The poly(DEGMMA-co-MEA) microgels were thermo-sensitive and exhibited a volume phase transitive temperature(VPTT) of 14–22 ?C. The incorporation of hydrophobic comonomer MEA shifted the VPTT of poly(DEGMMA-co-MEA) microgels to lower temperatures. The interfacial interaction of poly(DEGMMA-co-MEA) microgels and three model proteins, namely fibrinogen, bovine serum albumin and lysozyme, was investigated by quartz crystal microbalance(QCM). An injection sequence of "microgel-after-protein" was then established for the real-time study of the interaction of proteins and the microgels at their swollen and collapsed states by using QCM technique. The results indicated that the interfacial interaction of poly(DEGMMA-co-MEA) microgels and adsorbed protein layers was mainly determined by the electrostatic interaction. Because poly(DEGMMA-co-MEA) microgels were negatively charged in Tris-HCl buffer solution(p H = 7.4), the microgels did not adsorb on negatively charged fibrinogen and bovine serum albumin layers but strongly adsorbed on positively charged lysozyme layer. Stronger interaction between lysozyme and the microgels at collapsed state(i.e. at 37 ?C) was observed. Furthermore, the incorporation of MEA might weaken the interaction between poly(DEGMMA-co-MEA) microgels and proteins. 相似文献
967.
In this work, a flame-retardant polypropylene(PP)/ramie fiber(RF) composite was prepared. The ramie fibers were wrapped chemically by a phosphorus- and nitrogen-containing flame retardant(FR) produced via in situ condensation reaction so as to suppress their candlewick effect. Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM) demonstrated that the ramie fibers wrapped chemically by FR(FR-RF) were obtained successfully. Thermogravimatric test showed that the PP/FR-RF composite had more residue and better thermal stability at high temperatures than the PP/RF composite. Cone calorimeter(CC) results indicated that the peak of heat release rate(PHRR) and total heat release(THR) correspondingly decreased by 23.4% and 12.5% compared with the values of neat PP/RF. The PP/FR-RF composite created a continuous and compact char layer after the combustion. Combining FTIR analysis of char residue after CC test with heat conduction coefficient results, it could be concluded that the charring of FR on RF greatly weakened the candlewick effect of RF, and more char residue in the RF domain facilitated the formation of more continuous and compact char layer in the whole combustion zone, consequently protected PP composites during combustion, resulting in the better flame retardancy of PP/FR-RF composite than that of PP/RF composite. 相似文献
968.
969.
Vladimir P. Petrović Dušica Simijonović Zorica D. Petrović Svetlana Marković 《Chemical Papers》2015,69(9):1244-1252
One-pot anti-Mannich reaction of vanillin, aniline and cyclohexanone was successfully catalyzed by ionic liquid triethanolammonium chloroacetate, at room temperature. Yield of the obtained Mannich base was very good and excellent diastereoselectivity was achieved. Mechanism of the reaction was investigated using the density functional theory. The reaction started with a nucleophilic attack of aniline nitrogen at the carbonyl group of vanillin. The intermediate α-amino alcohol formed in this way was further subjected to protonation by the triethanolammonium ion yielding the imminium ion. Theoretically, the obtained imminium ion and the enol form of cyclohexanone can build the protonated Mannich base via the anti and syn pathways. The chloroacetic anion spontaneously abstracts the proton yielding the final product of the reaction anti 2-[1-(N-phenylamino)-1-(4-hydroxy-3-methoxyphenyl)]methylcyclohexanone (MB-H). The syn pathway requires lower activation energy but the anti pathway yields a thermodynamically more stable product, which implies that the examined Mannich reaction is thermodynamically controlled. 相似文献
970.
Single‐Crystal‐to‐Single‐Crystal Transition in an Enantiopure [7]Helquat Salt: The First Observation of a Reversible Phase Transition in a Helicene‐Like Compound 下载免费PDF全文
Dr. Naba K. Nath Lukáš Severa Dr. Roman A. Kunetskiy Prof. Ivana Císařová Prof. Michal Fulem Prof. Květoslav Růžička Dr. Dušan Koval Dr. Václav Kašička Dr. Filip Teplý Prof. Panče Naumov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13508-13512
Here it is reported that crystals of an enantiopure [7]helquat salt undergo reversible thermal solid–solid phase transition at 404 K. Differential scanning calorimetry (DSC), capillary electrophoresis (CE), and X‐ray diffraction analysis were used to unravel the mechanistic details of this process. The single‐crystal‐to‐single‐crystal course enabled direct monitoring of the structural changes by in situ variable‐temperature X‐ray diffraction, thus providing the first direct evidence of a solid phase transition in a helicene‐like compound. 相似文献