Conformationally mobile acyclic cucurbit[n]uril-type receptors derived from an S-shaped methylene bridged glycoluril pentamer

Name: Conformationally mobile acyclic cucurbit[n]uril-type receptors derived from an S-shaped methylene bridged glycoluril pentamer
Creator: Taylor & Francis
Published: 2021-05-01 21:20:47
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DataCite Commons2021-05-01 更新2024-07-28 收录

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https://tandf.figshare.com/articles/dataset/Conformationally_mobile_acyclic_cucurbit_n_uril-type_receptors_derived_from_an_S-shaped_methylene_bridged_glycoluril_pentamer/12849542

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资源简介：

We report the synthesis of the conformationally mobile S-shaped glycoluril pentamer building block 3a and two new acyclic CB[n]-type receptors P1 and P2. P1 (9 mM) and P2 (11 mM) have moderate aqueous solubility but their host•guest complexes are poorly soluble. Host P1 does not undergo intermolecular self-association whereas P2 does (Ks = 189 ± 27 M−1). 1 H NMR titrations show that P1 and P2 are poor hosts towards hydrophobic (di)cations 6–11 (P1: Ka = 375–1400 M−1; P2: Ka = 1950–19,800 M−1) compared to Tet1 and Tet2 (Tet1: Ka = 3.09 x 106 to 4.69 × 108 M−1; Tet2: Ka = 4.59 x 108 to 1.30 × 1010 M−1). Molecular modelling shows that P1 and P2 exist as a mixture of three different conformers due to the two S-shaped methylene bridged glycoluril dimer subunits that each possess two different conformations. The lowest energy conformers of P1 and P2 do not feature a well-defined central cavity. In the presence of guests, P2 adapts its conformation to form 1:1 P2•guest complexes; the binding free energy pays the energetic price of conformer selection. This energetically unfavourable conformer selection results in significantly decreased Ka values of P1 and P2 compared to Tet1 and Tet2.

本研究报道了构象柔性的S形甘脲五聚体构筑基元3a，以及两种新型非环状葫芦脲[n]（CB[n]）类受体P1与P2。P1与P2的水溶液溶解度适中，分别为9 mM与11 mM，但二者形成的主客体复合物溶解性较差。受体P1不会发生分子间自缔合，而P2则会发生自缔合，其自缔合常数Ks为189 ± 27 M⁻¹。氢核磁共振（¹H NMR）滴定实验结果表明，相较于受体Tet1与Tet2，P1与P2对疏水（二）阳离子6~11的结合能力较弱：其中P1的结合常数Ka介于375~1400 M⁻¹之间，P2的Ka则介于1950~19800 M⁻¹之间；而Tet1的Ka为3.09×10⁶~4.69×10⁸ M⁻¹，Tet2的Ka为4.59×10⁸~1.30×10¹⁰ M⁻¹。分子模拟结果显示，由于P1与P2含有两个亚甲基桥连的S形甘脲二聚体结构单元，且每个结构单元均可存在两种不同构象，因此二者均以三种不同构象的混合形式存在。P1与P2的最低能构象均不具备明确界定的中心空腔。当存在客体分子时，P2可通过调整自身构象形成1:1型的P2·客体复合物，其结合自由能需承担构象选择所需的能量代价。这种在能量上不利的构象选择过程，使得P1与P2的结合常数Ka显著低于Tet1与Tet2。

提供机构：

Taylor & Francis

创建时间：

2020-08-24