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杯芳烃衍生聚合物用作毛细管气相色谱固定相的研究 总被引:13,自引:0,他引:13
合成了两种不同构象的杯芳烃衍生聚合物(杯芳冠醚聚硅氧烷c-c[4]c5-pso和二乙氧基杯[4]芳烃聚硅氧烷p-c[4]-pso),并将其用作毛细管气相色谱固定液,使用温度高达320℃,对不同的极性化合物,特别是对酚类异构体有很好的分离能力。同时也研究了分离机理。 相似文献
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杯芳烃固定液分子识别的热力学性质 总被引:3,自引:0,他引:3
用毛细管气相色谱法测得了5组芳香族位置异构体在杯芳冠醚聚硅氧烷(C[4]C5_PSO),二乙氧基杯芳烃聚硅氧烷(C[4]E_PSO)和二丁氧基杯芳烃聚硅氧烷(M_C[4]B_PSO)3种杯芳烃固定液上的热力学参数ΔH、ΔS、ΔG,然后用热力学及超热力学的方法探讨了杯芳烃对异构体的分子识别特性和保留机理。 相似文献
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给出了1,3-二辛氧基杯[4]芳烃冠醚-6(25,27-bis-octyloxy-calix[4]arene-26,28-crown-6, BOC6)和杯[4]芳烃双冠醚-6(1,3-alternate biscrown-6, BisC6)晶体结构参数, 用NMR(CDCl3作溶剂)和XAFS(X-ray absorption fine structure)方法研究了邻硝基苯甲醚(o-nitro-phenyl methyl ether, NPME)和正辛醇(n-octyl alcohol, OA)溶液中BOC6和BisC6与碱金属离子的配位行为. 结果表明: 铯离子的嵌入使得杯芳冠醚分子中冠醚链的对称性明显提高; 在溶液中,配合物分子中铯离子的配位数为7, 7个氧的配位是一种稳定结构. 相似文献
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用量子化学从头算法,在RHF/6-31G(d,p)水平上优化了八种不对称方酸染料的分子构型,并对它们的分子内电荷转移程度与暗衰值,光敏值和最大吸收波长的定量关系进行研究,发现不对称方酸染料的分子内电荷转移性质,是影响不对称方酸染料光导性和最大吸收波长的重要因素。 相似文献
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聚乙二醇及其单醚在咪唑N-烷基化反应中的应用 总被引:4,自引:1,他引:4
本文报道了在咪唑N-烷基化反应中以聚乙二醇(PEG)及其单醚作为相转移催化剂合成C_4-C_(16) N-烷基咪唑及咪唑N-烷基衍生物的新方法。该法反应条件温和,操作简便,收率可达70%左右。测定了N-烷基咪唑化合物的物理性能,~1H NMR和红外光谱,并讨论了反应条件和烷基化试剂的碳链结构对反应的影响。 相似文献
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丙烯酰胺型阴离子表面活性单体与丙烯酰胺共聚物水溶液的流变特性 总被引:2,自引:0,他引:2
以丙烯酰胺型阴离子表面活性单体2-丙烯酰胺基十四烷基磺酸钠(NaAMC14S)为共单体,与丙烯酰胺(AM)的水溶液均相共聚合,使NaAMC14S的浓度分别处于临界胶束浓度上下,分别制备了具有无规结构与微嵌段结构的两类共聚物;用红外光谱法对共聚物的结构进行了表征,使用乌氏粘度法测定了特性粘数,相对表示出了共聚物的分子量;采用荧光探针法与表观粘度法重点研究了两类共聚物的疏水缔合性与水溶液的流变特性.研究结果表明,具有微嵌段结构的共聚物具有很强的疏水缔合性,当其水溶液的浓度达0.2wt%后,表观粘度迅速提高;其水溶液的切力变稀行为具有明显的可逆性,表现出强的抗剪切性能.本研究中特别发现,具有微嵌段结构的共聚物其盐水溶液的表观粘度远高于纯水溶液的表观粘度,当共聚物浓度为0.3wt%、CaCl2浓度为2wt%时,溶液的表观粘度竟然提高了3个数量级,表现出独特的正性盐敏性(即遇盐变稠). 相似文献
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Fürstenberg A Deligeorgiev TG Gadjev NI Vasilev AA Vauthey E 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(30):8600-8609
The fluorescence enhancement mechanisms of a series of DNA stains of the oxazole yellow (YO) family have been investigated in detail using steady-state and ultrafast time-resolved fluorescence spectroscopy. The strong increase in the fluorescence quantum yield of these dyes upon DNA binding is shown to originate from the inhibition of two distinct processes: 1) isomerisation through large-amplitude motion that non-radiatively deactivates the excited state within a few picoseconds and 2) formation of weakly emitting H-dimers. As the H-dimers are not totally non-fluorescent, their formation is less efficient than isomerisation as a fluorescent contrast mechanism. The propensity of the dyes to form H-dimers and thus to reduce their fluorescence contrast upon DNA binding is shown to depend on several of their structural parameters, such as their monomeric (YO) or homodimeric (YOYO) nature, their substitution and their electric charge. Moreover, these parameters also have a substantial influence on the affinity of the dyes for DNA and on the ensuing sensitivity for DNA detection. The results give new insight into the development and optimisation of fluorescent DNA probes with the highest contrast. 相似文献
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自1978年B.V. L′vov提出石墨炉内探针原子化技术以来,许多作者对该技术进行了研究,并将其应用于实际样品的测定,国内亦有人作过系统的评述,但对元素在石墨探针表面上的原子化机理却报道不多。本文应用X射线衍射分析与其它一些实验,观察和研究了镉和铝在石墨探针表面上原子化过程中的形态变化,阐明了镉和铝的原子化历程。 相似文献
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Detection of biogenic monoamines in nanomolar concentrations is of great importance for probing the brain chemistry and for their analytics in biological fluids. The sensitivity enhancement of amperometric detection of neurotransmitters (NTs) and their metabolites after their electrophoretic separation on a microchip is presented and is based on coupled enzymatic reactions. The current response of the analyte is amplified by cyclic oxidation on a gold electrode mediated by reduced nicotinamide dinucleotide coenzyme and glucose oxidase enzyme present in the electrophoresis buffer. Using this approach, detection limits of about 10 nM for NTs and their metabolites can be reached. 相似文献
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E. S. Zhavoronok I. N. Senchikhin V. V. Vysotskii V. I. Roldugin 《Polymer Science Series B》2017,59(4):421-429
The supramolecular structure of a number of epoxy oligomers, monofunctional epoxy compounds, their mixtures, an oligoamine curing agent, and curing systems on their basis is studied by dynamic light scattering. In all of the starting oligomers and their mixtures, light scattering centers are detected that may be considered as the associates (aggregates) of oligomer molecules. The structure of associates that is determined by the flexibility of the oligomer chain, its branching degree, and the presence of proton-donor groups capable of hydrogen bonding is suggested. The relationship between the rate of curing of epoxy oligomers and their mixtures with oligoamine and the associate structure of oligomers and the nature of the substituent at the glycidyl group of the oligomer is ascertained. 相似文献
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Biogenic polyamines (PAs) are involved in the growth and development of normal cells, and their intracellular concentration is stable. The concentration of PAs in cancer cells is significantly increased to promote and sustain their rapid proliferation. Over the years, synthetic PAs, which differ in their structure, have demonstrated high antitumor activity and are involved in clinical trials. The chemical synthesis of PAs and their conjugates require the correct choice of synthetic pathways—methods for constructing conjugates and the orthogonal protection of amino groups. The most common methods of synthesis of PA conjugates are acylation of regioselectively protected PAs or their alkylation under the conditions of the Fukuyama reaction. One of the most promising methods of PA synthesis is the use of a multicomponent Ugi reaction, which allows various PAs to be obtained in high yields. In this review, we describe and analyze various approaches that are used in the synthesis of polyamines and their conjugates. 相似文献
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Porous glass plates were modified via their interaction with molybdenum(V) chloride, followed by a treatment with humid air at 473°C. The extent of the reaction is characterized on the basis of IR spectra of OH groups on the starting glass surface and grafted layer. The photochromism of the resulting plates is exhibited under their UV irradiation as a progressive blue coloration. The suggested photoreduction mechanism consists in splitting-off oxygen atoms from bridge bonds?Mo?O?Mo?, with transition of molybdenum atoms to the pentavalent state. The subsequent discoloration of the plates is provided by their heating in air at 473°C. The full reversibility of the photoreduction and oxidation processes is observed in their multiple repetitions. 相似文献