德国慕尼黑大学Corts Emiliano团队报道了在操作中成像的共价有机框架形成的早期阶段。相关研究成果于2024年6月5日发表在《自然》。

共价有机框架（COFs）是一类能够利用、转换和储存能量的功能材料。然而，经过近20年的研究，它们的合成条件没有一致的预测规则。这在一定程度上是因为在形成的早期阶段，成核和生长的图像不完整。

该文中，研究人员使用光学技术干涉散射显微镜（iSCAT）1，2，3对COF聚合和骨架形成进行操作性研究。研究人员观察到液-液相分离，指出在传统的COF合成中存在无表面活性剂（微）乳液形式的结构化溶剂。研究结果表明，溶剂的作用超越了溶解度，通过反应物和催化剂的分隔成为动力学调节剂。

利用这些观察结果，研究人员开发了一种使用室温而不是高温的COFs合成方案。这项工作将框架合成与液相图联系起来，从而能够积极设计反应环境，强调通过基于光散射的技术实现化学反应的可视化，可以成为推进合理材料合成的有力方法。

附：英文原文

Title: Early stages of covalent organic framework formation imaged in operando

Author: Gruber, Christoph G., Frey, Laura, Guntermann, Roman, Medina, Dana D., Corts, Emiliano

Issue&Volume: 2024-06-05

Abstract: Covalent organic frameworks (COFs) are a functional material class able to harness, convert and store energy. However, after almost 20years of research, there are no coherent prediction rules for their synthesis conditions. This is partly because of an incomplete picture of nucleation and growth at the early stages of formation. Here we use the optical technique interferometric scattering microscopy (iSCAT)1,2,3 for in operando studies of COF polymerization and framework formation. We observe liquid–liquid phase separation, pointing to the existence of structured solvents in the form of surfactant-free (micro)emulsions in conventional COF synthesis. Our findings show that the role of solvents extends beyond solubility to being kinetic modulators by compartmentation of reactants and catalyst. Taking advantage of these observations, we develop a synthesis protocol for COFs using room temperature instead of elevated temperatures. This work connects framework synthesis with liquid phase diagrams and thereby enables an active design of the reaction environment, emphasizing that visualization of chemical reactions by means of light-scattering-based techniques can be a powerful approach for advancing rational materials synthesis.

DOI: 10.1038/s41586-024-07483-0

Source: https://www.nature.com/articles/s41586-024-07483-0