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.