Encapsulation and characterization of proton-bound amine homodimers in a water-soluble, self-assembled supramolecular host
Encapsulation and characterization of proton-bound amine homodimers in a water-soluble, self-assembled supramolecular host
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DOI：
10.1073/pnas.0809806106
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发表时间：
2009-06-30
影响因子：
11.1
通讯作者：
Raymond, Kenneth N.
中科院分区：
文献类型：
--
作者：
Pluth, Michael D.;Fiedler, Dorothea;Raymond, Kenneth N.
在质子化过程中，环胺可以被包裹在水溶性的自组装超分子宿主中。环胺的氢键能力，以及旋转自由度的降低，允许在组装体内形成质子结合的同源二聚体，否则在水溶液中看不到。探讨了小N-烷基氮杂环丙烷、氮杂环丁烷、吡咯烷和哌啶形成均二聚体的共性。观察到N-烷基氮杂环丁烷(R=甲基、异丙基、叔丁基)、N-烷基氮杂环丁烷(R=异丙基、叔丁基)和N-甲基吡咯烷形成质子结合的均二聚体。在高浓度下，N-甲基氮杂环丙烷形成质子结合的同源三聚体。同源二聚体在很大的浓度范围内保持完好，因此建议进行合作封装。用G3(MP2)B3和G3B3计算了质子结合的同质二聚体中氢键的焓，认为质子结合的同质二聚体形成时的焓增加可能驱动客体包裹。
Cyclic amines can be encapsulated in a water-soluble self-assembled supramolecular host upon protonation. The hydrogen-bonding ability of the cyclic amines, as well as the reduced degrees of rotational freedom, allows for the formation of proton-bound homodimers inside of the assembly that are otherwise not observable in aqueous solution. The generality of homodimer formation was explored with small N-alkyl aziridines, azetidines, pyrrolidines, and piperidines. Proton-bound homodimer formation is observed for N-alkylaziridines (R = methyl, isopropyl, tert-butyl), N-alkylazetidines (R = isopropyl, tert-butyl), and N-methylpyrrolidine. At high concentration, formation of a proton-bound homotrimer is observed in the case of N-methylaziridine. The homodimers stay intact inside the assembly over a large concentration range, thereby suggesting cooperative encapsulation. Both G3(MP2)B3 and G3B3 calculations of the proton-bound homodimers were used to investigate the enthalpy of the hydrogen bond in the proton-bound homodimers and suggest that the enthalpic gain upon formation of the proton-bound homodimers may drive guest encapsulation.