Dual functional flexible 1,3,6,8-tetraphenylpyrene (TPPy)-based covalent organic frameworks for fluorescence...

In recent years, covalent organic frameworks (COFs) containing pyrene have been used for fluorescent detection of nitroaromatic compounds or capture radioiodine. But there are no reported dual functional COFs containing pyrene with fluorescence sensing and iodine capture. Herein, we have designed and synthesized two dual functional flexible TPPy-based COFs (HTAPPy and TTAPPy) by solvothermal method using NOP - 6 - CHO and TPT - 3 - CHO to react with 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl)tetraaniline (TAPPy). The flexible TPPy-based COFs possess rich micropores, excellent thermal stability, and large BET surface areas of 1766 and 1216 m² g^-1, respectively. It was found that HTAPPy and TTAPPy are outstanding sensors for 2,4-dinitrophenol (DNP), with quenched constants of 1.48 × 10⁴ and 1.55 × 10⁴ L mol^-1, respectively. HTAPPy and TTAPPy have the excellent iodine adsorption capacity for iodine vapor at 77 °C (2.96 and 3.04 g g^-1) and 23.80 and 23.60 mg g^-1 for 100 mg L^-1 iodine-cyclohexane solution and 282.40 and 273.46 mg g^-1 for 300 mg L^-1 iodine-water solution. The fluorescence sensing mechanism and capturing iodine mechanism were studied.