The dynamic art of growing COF crystals

Growth modulation leads to large, high-quality covalent organic framework crystals Diamonds consist of an ordered array of tetrahedral carbon atoms, held together by strong covalent bonds. Despite this simple structure, making diamond crystals is difficult, requiring extremely high pressures and temperatures that can only be achieved deep in Earth's crust or through sophisticated experiments. Building covalent organic frameworks (COFs) similarly involves the ordered spatial arrangement, in a two- or three-dimensional crystalline network, of organic units linked together by strong covalent bonds. Growing single crystals of robust COFs is challenging because it requires the dynamic formation and cleavage of strong covalent bonds. On page 48 of this issue, Ma et al. (1) report a simple method for growing large, high-quality single crystals of COF networks held together by strong imine covalent bonds.