Flexible thiourea linked covalent organic frameworks

Exploring covalent organic frameworks with new linkages is regarded as an efficient method to modulate the corresponding properties, and a new linkage is essential to the progress of this field. Herein, condensation of 1,3,5-triformylphloroglucinol with 1,1 '-(1,4-phenylene)bis(thiourea), 1,1 '-(2,5-dimethyl-1,4-phenylene)bis(thiourea) or 1,1 '-(3,3 '-dimethyl-[1,1 '-biphenyl]-4,4 '-diyl)bis(thiourea) were applied to construct COFs with thiourea linkages for the first time.