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91.
两个新的氢键诱导液晶化合物的合成 总被引:3,自引:0,他引:3
通过4-丁氧基苯甲酸(4BA0与两个手性取代的苯乙烯基吡啶(VSZ及LSZ)间的氢键作用合成了2个新的液晶化合物,用DSC、偏光显微镜研究了其液晶行为,并由红外光谱证实了分子间氢键的存在,形成的复合物4BA-VSZ具有手性近晶C相。 相似文献
92.
An automated sample pretreatment of human blood plasma for liquid chromatographic determination of three antidepressant drugs, dibenzepine; a tricyclic antidepressant (TCA), reboxetine; a selective noradrenaline reuptake inhibitor (SNRI) and fluvoxamine; a selective serotonin reuptake inhibitor (SSRI), based on supported liquid membrane (SLM) for unsurpassed sample clean-up and analyte enrichment, has been developed. The chromatograms after enrichment of plasma blank and aqueous blank are virtually indistinguishable. The entire analytical procedure revealed good linearity and low detection limits of 5, 15 and 20 ng mL–1 for dibenzepine, reboxetine and fluvoxamine, respectively. No carry-over effects were noted. The repeatability of extraction at three concentrations in the range 40–150 ng mL–1 for the three drugs was between ca. 3% and 7% as relative standard deviation. The reproducibility relative standard deviation during three different days (replacing the membrane each day) was not significantly higher. 相似文献
93.
94.
Li Yan Liang Shao Ping Ren Yi Quan Zheng Man Geng Lu Guangzhou Institute of Chemistry Chinese Academy of Sciences Guangzhou China Key Laboratory of Polymer Materials for Electronics Guangdong China Graduate School of the Chinese Academy of Sciences Beijing China 《中国化学快报》2007,18(2):225-228
A series of novel liquid crystalline epoxides with lateral substituents were cured with anhydrides and the cure kinetics was investigated by non-isothermal DSC technique. The results showed that the lengths of lateral substituents have great effect on the value of Ea. The curing reaction became less active, when the liquid crystalline epoxides have long lateral substituents and were controlled by diffusion at the late stage of cure. A nematic structure was observed by POM and XRD. 相似文献
95.
A capillary gas chromatographic method is described for the quantitative determination of liquid paraffin in blood. Paraffin is extracted from blood into n-heptane. After solvent evaporation and dissolution of the residue in 100–200 μl n-heptane one μl is injected into a gas chromatograph fitted with a fused silica capillary column (Permabond® OV-1-CB-0.1, 10 m × 0.32 mm i.d.) and flame ionization detector. Analysis is performed by using an oven program [50°C (3 min)?285°C (5 min), rise 10%min]. The sensitivity (1.5 ng hexadecane) and the reproducibility prove the applicability of the method for the determination of liquid paraffin in blood and for the study of the stability of the liquid paraffin hollow fiber membranes used in an extracorporeal liver support system. 相似文献
96.
Diglycidyl ether of 4,4′-dihydroxybiphenol (BPDGE) is a liquid crystalline epoxy. The biphenyl epoxy (diglycidyl ether of 3,3′,5,5′-tetramethyl-4,4′-biphenyl, TMBPDGE) has found great applications in plastic encapsulated semiconductor packaging. Phenol novolac (PN) was used as curing agent. The reaction kinetics of BPDGE/PN and TMBPDGE/PN systems in the presence of triphenylphosphine (TPP) were characterized by an isoconversional method under dynamic conditions using differential scanning calorimetry (DSC) measurements. The results showed that the curing of epoxy resins involves different reaction stages and the values of activation energy are dependent on the degree of conversion. The effects of curing temperature on their phase structure have been investigated with polarized optical microscopy and Wide-angle X-ray diffraction. With proper curing process, BPDGE showed a nematic phase when cured with PN. 相似文献
97.
Laure Gouriou Štěpán Vysko?il Pavel Ko?ovský 《Journal of organometallic chemistry》2003,687(2):525-537
The reaction of iso-cinnamyl acetate with NaC(Me)(CO2Me)2, catalysed by Pd-‘MOP’ (MOP=2-methoxy-2′-diphenylphosphino-1,1′-binaphthalene) is known to proceed with a regiochemical memory effect that results in the predominant generation of the branched alkylation product. The analogous reaction employing ‘MAP’ as ligand (MAP=2-N,N-dimethylamino-2′-diphenylphosphino-1,1′-binaphthalene) proceeds with ‘normal’ regioselectivity to generate predominantly the linear isomer of product. A 2H-NMR based analysis, employing quadrupolar coupling in a chiral liquid crystal matrix, has been developed to facilitate the simultaneous study of the regiochemical and stereochemical outcome of the reaction of both enantiomers of iso-cinnamyl ester substrates in 2H-labelled but racemic samples. The analysis allows the comparison of relative rates of two competing isomerisation processes occurring in the π-allyl intermediates in the Pd-catalysed reaction, one of which facilitates asymmetric induction, the other resulting in loss of regiochemical memory. It is demonstrated that the two processes are partially coupled and that this then limits the attainment of high global enantiomeric excess in the branched product to reactions that proceed with low regiochemical retention. A key factor for the observation of high regiochemical memory is found to be the nucleophilicity of the malonate anion and the electrophilicity of the Pd-π-allyl intermediate with reduction in the reactivity of either partner resulting in the onset of substantial loss of memory. 相似文献
98.
Sodium-dicyclohexyl- 18-crown-6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)42? complex anion. By using L-cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag+, Cd2+ Co2+, Cu2+, Fe2+, Ni2+, Pb2+, Pd2+, Sr2+, Bi3+, Cr3+ and Fe3+ ions was investigated. In the presence of NH2OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu2+ and Pb2+ ions was diminished drastically. 相似文献
99.
Using cotton as a solid-phase extraction sorbent of the precolumn, an on-line coupled precolumn preconcentration-liquid chromatography system with fluorescence detection was developed for the determination of PAHs in aqueous samples. Four PAHs including fluorene, phenanthrene, fluoranthene and benzo[k]fluoranthene were preconcentrated by a precolumn packed with 30 mg of absorbent cotton and then separated by C18 analytical column. When 100 ml of sample was enriched, the proposed procedure provided detection limits in the range of 0.5-57 ng l−1. Several water samples spiked with PAHs were analyzed with recoveries in the range of 92-119% at spiking level of 100 ng l−1 for fluorene, phenanthrene and fluoranthene, and 10 ng l−1 for benzo[k]fluoranthene, respectively. 相似文献
100.
As12Se44—: a New Selenoarsenate Anion with a Polyarsenic Cage in the Compound [Co(NH3)6]2As12Se4 · 12 NH3 Orange coloured crystals of [Co(NH3)6]2As12Se4 · 12 NH3 were prepared by the reduction of As4Se4 with a solution of sodium in liquid ammonia and subsequent precipitation with CoBr2. The X‐ray structure determination shows them to contain the selenoarsenate anion As12Se44—, which consists of a central As12‐cage with four exo‐bonded, formally negatively charged Se atoms. The structure of the As12‐cage is equivalent to the main polyphosphorus building unit of a known organopolyphosphane and of tubular P12 in the compound (CuI)3P12. 相似文献