An Expandable Hydrogen-Bonded Organic Framework Characterized by Three-Dimensional Electron Diffraction
An Expandable Hydrogen-Bonded Organic Framework Characterized by Three-Dimensional Electron Diffraction
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DOI：
10.1021/jacs.0c04885
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发表时间：
2020-07-22
影响因子：
15
通讯作者：
Cooper, Andrew, I
中科院分区：
文献类型：
--
作者：
Cui, Peng;Grape, Erik Svensson;Cooper, Andrew, I
2-D氢键有机骨架（HOF）分子晶体在活化过程中被溶剂从晶体孔中除去后发生了不寻常的结构转变。构象灵活的宿主分子ABTPA在激活过程中调整其分子构象以启动框架扩展。三维电子衍射（3D ED）表征了微晶活化相，表明ABTPA采用面外蒽基作为自适应结构锚点。这些单元改变方向，在活化结构中产生一个扩展的、密度较低的框架材料。多孔HOF ABTPA-2具有稳定的动态孔隙度(SA(BET) = 1 183 m（2) g(-1)）和负面积热膨胀。我们使用晶体结构预测（CSP）来了解结构转化背后的潜在能量学，并讨论了CSP在这种柔性分子中面临的挑战。
A molecular crystal of a 2-D hydrogen-bonded organic framework (HOF) undergoes an unusual structural transformation after solvent removal from the crystal pores during activation. The conformationally flexible host molecule, ABTPA, adapts its molecular conformation during activation to initiate a framework expansion. The microcrystalline activated phase was characterized by three-dimensional electron diffraction (3D ED), which revealed that ABTPA uses out-of-plane anthracene units as adaptive structural anchors. These units change orientation to generate an expanded, lower density framework material in the activated structure. The porous HOF, ABTPA-2, has robust dynamic porosity (SA(BET) = 1 183 m(2) g(-1)) and exhibits negative area thermal expansion. We use crystal structure prediction (CSP) to understand the underlying energetics behind the structural transformation and discuss the challenges facing CSP for such flexible molecules.