Light-up covalent organic frameworks with flexible wall design for chemical sensing.

Covalent organic frameworks (COFs) are a novel type of nanoporous and crystalline polymers with a precise and highly conjugated skeleton, making them promising candidates for constructing emissive materials. However, the strong high conjugation structures between adjacent layers easily lead to aggregation-caused quenching (ACQ) of emission properties. In this study, we have designed COFs with a flexible skeleton to suppress ACQ effects, enhancing their luminescence activity. In addition, the high density of nitrogen and oxygen atoms on these flexible walls serves as binding sites for hydrogen bonding interactions, indicating sensitivity and selectivity towards nitro-explosives. This strategy establishes a new approach for creating luminescent materials for chemical sensors. [ABSTRACT FROM AUTHOR]