A controlling parameter of topological defects in two-dimensional covalent organic frameworks
A controlling parameter of topological defects in two-dimensional covalent organic frameworks
复制标题
二维共价有机框架中拓扑缺陷的控制参数
DOI：
10.1039/d0nr05303a
复制
发表时间：
2020
期刊：
影响因子：
6.7
通讯作者：
Sun Zhao-Yan
中科院分区：
文献类型：
--
作者：
Zhu You-Liang;Zhao Huan-Yu;Fu Cui-Liu;Li Zhan-Wei;Sun Zhao-Yan
合成具有长程分子有序性的共价有机框架是一个突出的挑战，因为预先设计的拓扑对称性的缺陷容易形成和破坏结晶。拓扑缺陷的物理起源和控制参数仍然知之甚少。通过分子动力学模拟，我们发现，五边形的组合[C4 + C4]和[C4 + C2]和七边形的[C3 + C3]和[C3 + C2]是初始缺陷的生长动力学与不受控制和抑制的成核，进一步诱导更复杂的缺陷。通过将单体添加到单个核中来实现生长，可以显著减少缺陷，与先前的模拟和实验很好地吻合。为了理解缺陷的性质，我们提出了一个参数φ来描述两个单体之间的偏转角范围，在该范围内允许化学反应。参数φ与缺陷布居数呈单调关系，通过密度泛函理论计算证明了其可计算性。当φ < 20时，我们甚至可以观察到四种组合的无缺陷生长，而不考虑生长动力学。研究结果对筛选和设计合成高质量单晶的缩合反应具有重要意义。
Synthesis of covalent organic frameworks with long-range molecular ordering is an outstanding challenge due to the fact that defects against predesigned topological symmetries are prone to form and break crystallization. The physical origins and controlling parameters of topological defects remain scarcely understood. By virtue of molecular dynamics simulations, we found that pentagons for combination [C4 + C4] and [C4 + C2] and heptagons for [C3 + C3] and [C3 + C2] were initial defects for growth dynamics with both uncontrolled and suppressed nucleation, further inducing more complex defects. The defects can be significantly reduced by achieving the growth with monomers added to a single nucleus, agreeing well with previous simulations and experiments. To understand the nature of defects, we proposed a parameter φ to describe the range of biased rotational angle between two monomers, within which chemical reactions are allowed. The parameter φ shows a monotonic relationship with defect population, which is demonstrated to be highly computable by using density functional theory calculations. When φ < 20, we can even observe defect-free growth for the four combinations, irrespective of growth dynamics. The results are essential for screening and designing condensation reactions for the synthesis of single crystals of high quality.