Integrative self-assembly of covalent organic frameworks and fluorescent molecules for ultrasensitive detection of a nerve agent simulant

Binding of fluorescent molecules to the porous matrix through noncovalent interactions will synergistically expand their application spectrum. In this regard, we report an integrative self-assembly of molecule 1 with benzothiadizole and 9,9-dihexyl fluorene units, and covalent organic frameworks (COFs) via an emulsion-modulated polymerization process, within which molecules of 1 are able to interact with the scaffolds of COFs through CH-π interactions. Thus the π-π interactions between the fluorescent molecules are largely suppressed, giving rise to their remarkable monomer-like optical properties. Of particular interest is that, given by the specific interaction between COFs and a nerve agent simulant diethyl chlorophosphite (DCP), these assembled composites show the ability of ultrasensitive detection of DCP with a detection limit of ∼40 ppb. Moreover, the present integrative assembly strategy can be extended to encapsulate multiple fluorescent molecules, enabling the assemblies with white light emission. Our results highlight opportunities for the development of highly emissive porous materials by molecular self-assembly of fluorophores and molecular units of COFs.