Crystalline materials with uniform molecular-sized pores are desirable for a broad range of applications, such as sensors, catalysis, and separations. However, it is challenging to tune the pore size of a single material continuously and to reversibly distinguish small molecules (below 4 angstroms). We synthesized a series of ionic covalent organic frameworks using a tetraphenoxyborate linkage that maintains meticulous synergy between structural rigidity and local flexibility to achieve continuous and reversible (100 thermal cycles) tunability of “dynamic pores” between 2.9 and 4.0 angstroms, with resolution below 0.2 angstroms. This results from temperature-regulated, gradual amplitude change of high-frequency linker oscillations. These thermoelastic apertures selectively block larger molecules over marginally smaller ones, demonstrating size-based molecular recognition and the potential for separating challenging gas mixtures such as oxygen/nitrogen and nitrogen/methane.

中文翻译：

---

通过共价有机框架中的温度调节振荡进行分子识别，分辨率低于 0.2 埃


具有均匀分子大小孔的晶体材料适用于广泛的应用，例如传感器、催化和分离。然而，连续调节单一材料的孔径并可逆地区分小分子（4埃以下）是具有挑战性的。我们使用四苯氧基硼酸酯键合成了一系列离子共价有机骨架，该骨架保持结构刚性和局部柔性之间的精细协同作用，以实现“动态孔”在2.9至4.0埃之间的连续可逆（100个热循环）可调性，分辨率低于0.2埃。这是由高频连接器振荡的温度调节、逐渐幅度变化造成的。这些热弹性孔径选择性地阻挡较大的分子而不是稍小的分子，证明了基于尺寸的分子识别以及分离具有挑战性的气体混合物（例如氧气/氮气和氮气/甲烷）的潜力。