A supramolecular self-assembly material based on cucurbituril and cationic TPE as ultra-sensitive probe of energetic pentazolate salts

The successful synthesis of the pentazolate anion (cyclo-N-5(-)) has been a great breakthrough in the field of energetic materials. However, the detection methods for these energetic materials based on the pentazolate anion are quite rare. Herein, two fluorescent probes for cyclo-N-5(-) anion were designed. Sensor 1 (TPE2N) was synthesized with a tetraphenylethylene functionalized by two cationic groups which can generate strong electrostatic interactions with pentazolate anion and result in specific fluorescent changes. Sensor 2 was designed based on sensor 1 and supramolecular cucurbit[7]uril (CB[7]). The unique structural features of CB[7] provide sites for the interaction between the cations and N-5(-) anion in its cavity, which would generate a platform for the detection and enhance the recognition performance. Isothermal titration calorimetry (ITC) experiment and fluorescence titration experiment indicate the binding molar ratio between sensor 1 with CB[7] is 1:2. Both sensors display typical aggregation-induced emission (AIE) features and good water-solubility. The sensors demonstrate excellent sensitivity to pentazole hydrazine salt with high enhancement constant (sensor 1: 1.34 x 10(6); sensor 2: 3.78 x 10(6)) and low limit of detection (LOD: sensor 1 = 4.33 mu M; sensor 2 = 1.54 mu M). The formation of an AIE-based supramolecular sensor effectively improves the sensitivity to N-5(-) anion. In addition, the probes also have good selectivity of N-5(-) anion salts. The research would shed some light on the design of novel fluorescent sensors to detect pentazolate-based molecules and provides an example of supramolecular chemistry combined with fluorescent probes. (c) 2023 China Ordnance Society. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).