An isolated water droplet in the aqueous solution of a supramolecular tetrahedral cage.
An isolated water droplet in the aqueous solution of a supramolecular tetrahedral cage.
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DOI：
10.1073/pnas.2012545117
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发表时间：
2020-12-29
影响因子：
11.1
通讯作者：
Havenith M
中科院分区：
文献类型：
--
作者：
Sebastiani F;Bender TA;Pezzotti S;Li WL;Schwaab G;Bergman RG;Raymond KN;Toste FD;Head-Gordon T;Havenith M
使用在水中催化底物的超分子组装，我们证明了纳米笼封装了一个在结构和动力学上与任何已知的水相不同的水团簇。它在客体包裹的驱动力中发挥着重要作用：非常不寻常的被包裹的水滴的释放为客体在水溶液中对超分子结构的高亲和力结合创造了强大的热力学驱动。在纳米限制条件下，水在环境条件下表现出低维的冰形成和液-固相变，但具有映射到水相图的已知区域的结构和动力学特征。利用太赫兹(THz)吸收光谱和从头算分子动力学，我们研究了环境水在超分子四面体中的组装，并确定在宿主的纳米腔内存在一个由9±1个水分子组成的动态网络。对Ga4L612−主体中水的低频吸收光谱和理论分析表明，包裹的水滴的结构和动力学与任何已知的水相都不同。进一步的推断是，非常不寻常的包封水滴的释放为Ga4L612−超分子结构在水溶液中的高亲和力结合创造了强大的热力学驱动因素。
Using a supramolecular assembly that catalyzes substrates in water, we show that the nanocage encapsulates a water cluster that is structurally and dynamically distinct from any known phase of water. It plays an important role in the driving force for guest encapsulation: The release of the highly unusual encapsulated water droplet creates a strong thermodynamic drive for the high-affinity binding of guests in aqueous solution for the supramolecular construct. Water under nanoconfinement at ambient conditions has exhibited low-dimensional ice formation and liquid–solid phase transitions, but with structural and dynamical signatures that map onto known regions of water’s phase diagram. Using terahertz (THz) absorption spectroscopy and ab initio molecular dynamics, we have investigated the ambient water confined in a supramolecular tetrahedral assembly, and determined that a dynamically distinct network of 9 ± 1 water molecules is present within the nanocavity of the host. The low-frequency absorption spectrum and theoretical analysis of the water in the Ga4L612− host demonstrate that the structure and dynamics of the encapsulated droplet is distinct from any known phase of water. A further inference is that the release of the highly unusual encapsulated water droplet creates a strong thermodynamic driver for the high-affinity binding of guests in aqueous solution for the Ga4L612− supramolecular construct.