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Anion binding behavior of heterocycle-strapped calix[4]pyrroles
Journal of Inclusion Phenomena and Macrocyclic Chemistry ( IF 1.7 ) Pub Date : 2009-07-28 , DOI: 10.1007/s10847-009-9645-3
Dustin E Gross 1 , Dae-Wi Yoon , Vincent M Lynch , Chang-Hee Lee , Jonathan L Sessler
Affiliation  

A comparative study of the halide and benzoate anion binding properties of a series of phenyl, pyrrole, and furan-strapped calix[4]pyrroles has been carried out. These receptors, which have previously been shown to bind the chloride anion (Yoon et al., Angew. Chem., Int. Ed. 47(27):5038–5042, 2008), were found to bind bromide and benzoate anion (studied as the corresponding tetrabutylammonium salts) with near equal affinity in acetonitrile, albeit less well than chloride, as determined from ITC measurements or NMR spectroscopic titrations. This stands in marked contrast to the parent octamethylcalix[4]pyrrole, where the carboxylate anion affinities are substantially higher than those for bromide anion under identical conditions. This finding is rationalized in terms of tighter binding cavity present in the strapped systems. For all three anions for which quantitative data could be obtained (i.e., Cl−, Br−, PhCO2−), the pyrrole-strapped system displayed the highest affinity, although the relative enhancement was found to depend on the anion in question. In the specific case of fluoride anion binding to the pyrrole-strapped receptor, two modes of interaction are inferred, with the first consisting of binding to the calix[4]pyrrole via NH-anion hydrogen bonds, followed by a process that involves deprotonation of the strapped pyrrolic NH proton. A single crystal X-ray diffraction analysis provides support for the first of these modes and further reveals the presence of a methanol molecule bound to the fluoride anion.

中文翻译:

带杂环的杯[4]吡咯的阴离子结合行为

对一系列苯基、吡咯和呋喃连接的杯[4]吡咯的卤化物和苯甲酸盐阴离子结合特性进行了比较研究。这些先前已被证明与氯阴离子结合的受体(Yoon 等人,Angew. Chem., Int. Ed. 47(27):5038–5042, 2008),被发现与溴化物和苯甲酸盐阴离子结合(研究根据 ITC 测量或 NMR 光谱滴定确定,在乙腈中具有几乎相同的亲和力,尽管不如氯化物好。这与母体八甲基杯[4]吡咯形成鲜明对比,在相同条件下,羧酸根阴离子的亲和力显着高于溴化物阴离子的亲和力。这一发现在捆绑系统中存在的更紧密的结合腔方面是合理的。对于可以获得定量数据的所有三种阴离子(即,Cl-、Br-、PhCO2-),吡咯束缚系统显示出最高的亲和力,尽管发现相对增强取决于所讨论的阴离子。在氟阴离子与吡咯束缚的受体结合的特定情况下,推断出两种相互作用模式,第一种包括通过 NH-阴离子氢键与杯 [4] 吡咯结合,然后是一个涉及去质子化的过程束缚的吡咯NH质子。单晶 X 射线衍射分析为这些模式中的第一个提供了支持,并进一步揭示了与氟阴离子结合的甲醇分子的存在。尽管发现相对增强取决于所讨论的阴离子。在氟阴离子与吡咯束缚的受体结合的特定情况下,推断出两种相互作用模式,第一种包括通过 NH-阴离子氢键与杯 [4] 吡咯结合,然后是一个涉及去质子化的过程带状吡咯 NH 质子。单晶 X 射线衍射分析为这些模式中的第一个提供了支持,并进一步揭示了与氟阴离子结合的甲醇分子的存在。尽管发现相对增强取决于所讨论的阴离子。在氟阴离子与吡咯束缚的受体结合的特定情况下,推断出两种相互作用模式,第一种包括通过 NH 阴离子氢键与杯 [4] 吡咯结合,然后是涉及去质子化的过程带状吡咯 NH 质子。单晶 X 射线衍射分析为这些模式中的第一个提供了支持,并进一步揭示了与氟阴离子结合的甲醇分子的存在。接下来是一个涉及带状吡咯 NH 质子去质子的过程。单晶 X 射线衍射分析为这些模式中的第一个提供了支持,并进一步揭示了与氟阴离子结合的甲醇分子的存在。接下来是一个涉及带状吡咯 NH 质子去质子的过程。单晶 X 射线衍射分析为这些模式中的第一个提供了支持,并进一步揭示了与氟阴离子结合的甲醇分子的存在。
更新日期:2009-07-28
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