Integrative self-assembly of covalent organic frameworks and fluorescent molecules for ultrasensitive detection of a ner
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Published online 18 November 2020 | https://doi.org/10.1007/s40843-020-1517-8
Integrative self-assembly of covalent organic frameworks and fluorescent molecules for ultrasensitive detection of a nerve agent simulant 1
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Yanjun Gong , Yongxian Guo , Changkun Qiu , Zongze Zhang , Fenghua Zhang , Yanze Wei , 1 2* 1* 1* Shuping Wang , Yanke Che , Jingjing Wei and Zhijie Yang ABSTRACT 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 selfassembly of fluorophores and molecular units of COFs. Keywords: covalent organic frameworks, sensor, noncovalent interactions, nerve agent, self-assembly
INTRODUCTION Nerve agent is a colorless and highly toxic gas. It has unique toxicological concerns owing to the existence of an unpredictable asymptomatic latent phase that takes place prior to the onset of lifethreatening pulmonary edema. Therefore, the development of sensitive and selective sensors for this chemical has attracted considerable
attention [1–3]. Fluorescence sensing, on the basis of fluorescence enhancement or fluorescence quenching induced by the target analytes, has attracted intensive attention because it features with high sensitivity, antiinterference ability, cost-effectiveness and portability, etc. [4–13]. The development of methods for signal amplification and discrimination remains critical and is of great value in practical use [14–18]. High-luminous-efficiency porous materials with specific recognition ability have advantages of sensitive and selective detection due to large surface areas. To meet these challenges, various strategies and sensing systems have been developed, among which porous matrices hold great promise because their porous structures facilitate the accessibility of target analytes to the binding sites by decreasing the diffusion resistance [19–22]. Particularly, the immobilization of fluorophores within the porous matrix through either covalent or noncovalent interactions can largely reduce the undesired molecular agg
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