Spatially dependent H-bond dynamics at interfaces of water/biomimetic self-assembled lattice materials
Spatially dependent H-bond dynamics at interfaces of water/biomimetic self-assembled lattice materials
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DOI：
10.1073/pnas.2001861117
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发表时间：
2020-09
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影响因子：
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通讯作者：
Haoyuan Wang;Jackson C. Wagner;Wenfan Chen;Chenglai Wang;Wei Xiong
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文献类型：
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作者：
Haoyuan Wang;Jackson C. Wagner;Wenfan Chen;Chenglai Wang;Wei Xiong
发展仿生晶格自组装是具有挑战性的，因为这种材料需要类似于其生物类似物的柔性和结晶度。我们发现，这些材料表现出独特的微观和介观有序超快氢键动力学，这可能是晶格自组装的一个关键特征：超快动力学确保灵活性，而域级有序反映结晶度。如果没有超快瞬态振动和频发生显微镜，这种科学见解就无法揭示，该显微镜将超快界面光谱学与界面分子振动成像相结合-这是最先进的发展。理解自组装晶格材料中的氢键相互作用对于制备此类材料至关重要，但氢键（H键）的作用仍不清楚。为了深入了解材料内在空间尺度上的氢键相互作用，我们以空间分辨的方式研究了水和仿生自组装晶格材料（由十二烷基硫酸钠和β-环糊精组成）之间的超快氢键动力学。为了实现这一点，我们开发了一个红外泵浦，振动和频发生（VSFG）探头高光谱显微镜。通过这种高光谱成像方法，我们能够观察到β-环糊精的初级和次级OH基团表现出明显不同的动力学，表明不同的H键环境，尽管它们之间只有几埃的距离。我们还观察到另一种超快动力学，反映了结合水和β-环糊精的仲OH之间的氢键的减弱和恢复，其在自组装结构域内表现出空间均匀性，但结构域之间表现出异质性。恢复动力学进一步表明自组装结构域之间存在非均匀水合作用。氢键动力学的超快性质和介观和微观有序性可能有助于材料的灵活性和结晶度-晶格自组装的两个至关重要的因素-揭示自组装晶格材料的工程分子间相互作用。
Significance It is challenging to develop biomimetic lattice self-assemblies because such materials need to resemble the flexibility and crystallinity of their biological analog. We show that these materials exhibit unique micro- and mesoscopic-ordered ultrafast hydrogen-bond dynamics, which could be a key feature in the lattice self-assembly: the ultrafast dynamics ensure flexibility, whereas the domain-level ordering reflects crystallinity. This scientific insight cannot be revealed without the ultrafast transient vibrational sum-frequency generation microscope, which integrates ultrafast interfacial spectroscopy with interfacial molecular vibrational imaging––a state-of-the-art development. Understanding hydrogen-bond interactions in self-assembled lattice materials is crucial for preparing such materials, but the role of hydrogen bonds (H bonds) remains unclear. To gain insight into H-bond interactions at the materials’ intrinsic spatial scale, we investigated ultrafast H-bond dynamics between water and biomimetic self-assembled lattice materials (composed of sodium dodecyl sulfate and β-cyclodextrin) in a spatially resolved manner. To accomplish this, we developed an infrared pump, vibrational sum-frequency generation (VSFG) probe hyperspectral microscope. With this hyperspectral imaging method, we were able to observe that the primary and secondary OH groups of β-cyclodextrin exhibit markedly different dynamics, suggesting distinct H-bond environments, despite being separated by only a few angstroms. We also observed another ultrafast dynamic reflecting a weakening and restoring of H bonds between bound water and the secondary OH of β-cyclodextrin, which exhibited spatial uniformity within self-assembled domains, but heterogeneity between domains. The restoration dynamics further suggest heterogeneous hydration among the self-assembly domains. The ultrafast nature and meso- and microscopic ordering of H-bond dynamics could contribute to the flexibility and crystallinity of the material––two critically important factors for crystalline lattice self-assemblies––shedding light on engineering intermolecular interactions for self-assembled lattice materials.