Highly selective detection of picric acid from multicomponent mixtures of nitro explosives by using COP luminescent probe

- A series of luminescence-tunable covalent organic polymers (COPs) are synthesized.
- COP-612 exhibits high selectivity for detecting PA in the presence of other nitroaromatic explosives.
- The luminescent emission wavelength of COP-616 reaches 838 nm.

Currently, it is still a great challenge for highly selective detection of picric acid in the presence of other nitro explosives. In this work, we have synthesized a series of porous luminescent covalent organic polymers (COPs) through copolymerization of the 2,7-Dibromopyrene (DBP) and 1,3,6,8-Tetrabromopyrene (TBP) in different ratios by using Ni-catalyzed Yamamoto reaction. All the solid COPs show high luminescent intensity, owing to the extended π conjugated systems in the synthesized COPs. By exploring the luminescent quenching property of COPs for nitro explosives, we find that all the COPs exhibit high selectivity for detecting PA, especially for COP-612. Further study indicates that even in the presence of other nitroaromatic explosives, COP-612 still exhibits high selectivity for detecting PA, i.e., the competitive nitro explosives show no influence on the sensing property of COP-612 for PA, which suggests that COP-612 is an excellent candidate for selectively detecting PA in practical applications. In addition, the luminescent emission wavelength of COP-616 reaches 838 nm, which provides potential applications in the areas of bioimaging, organic light-emitting diodes and chemosensors.