CAS Key Laboratory of Molecular Nanostructure and Nanotechnology and CAS Research and Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS) , Beijing 100190, People's Republic of China.
University of Chinese Academy of Sciences , Beijing 100049, People's Republic of China.
ACS Nano. 2017 Nov 28;11(11):11694-11700. doi: 10.1021/acsnano.7b06871. Epub 2017 Nov 15.
Polymorphic single-layered covalent organic frameworks (sCOFs) via on-surface synthesis have been investigated by employing the tetradentate monomer 1,3,6,8-tetrakis(p-formylphenyl)pyrene with D symmetry and ditopic linear diamine building blocks. Three kinds of well-ordered sCOFs, including rhombus, parallelogram, and Kagome networks, are observed on the graphite surface by scanning tunnel microscopy. The pore size and periodicity of sCOFs are tunable by employing diamine monomers with different lengths. Statistical analysis reveals that two types of quadrate networks are preferred at high concentration, whereas the occupancy of Kagome networks increases at low concentration. This trend can be understood by the differences in the network density of three kinds of networks. The reversibility and the self-sorting ability of the dynamic covalent reaction make it possible to control the polymorphic distribution similar to the principle demonstrated in supramolecular self-assembly.
通过使用具有 D 对称性的四齿单体 1,3,6,8-四（对甲酰基苯基）芘和双位点线性二胺构筑块，对通过表面合成得到的多晶型单层共价有机框架（sCOFs）进行了研究。通过扫描隧道显微镜在石墨表面观察到了三种有序的 sCOFs，包括菱形、平行四边形和Kagome 网络。通过使用具有不同长度的二胺单体，可以调节 sCOFs 的孔径和周期性。统计分析表明，在高浓度下，两种类型的正方形网络更倾向于占据主导地位，而在低浓度下，Kagome 网络的占有率增加。这种趋势可以通过三种网络的网络密度的差异来理解。动态共价反应的可逆性和自分类能力使得控制多晶型分布成为可能，类似于超分子自组装中所展示的原理。
