Preparation of porous organic polymer nanoparticles in miniemulsion for 2,4,6-trinitrophenol sensing

Abstract

Nitroaromatic explosives, especially 2,4,6-trinitrophenol (TNP), are not only endanger national security as high explosives, but also cause harm to environmental protection and human health by the pollution of the soil and groundwater from related industrial production, thus it is of great significance to achieve a highly sensitive and selective TNP detection, especially in pure water media. Here, two novel porous organic polymer nanoparticles PTATE2 and PTATE4 based on tetraphenylethene groups and electron-rich triphenylamine units were prepared successfully by Suzuki coupling (A2+B3, A4+B3) in miniemulsion, and fully characterized by FT-IR, NMR, SEM, nitrogen sorption isotherm, CV curves, UV–Vis absorption and fluorescence spectra. PTATE2 and PTATE4 possess spherical particle morphology with sizes of 90 nm and 64 nm, and porous structure with pore diameters of 4.3 and 4.8 nm, respectively, demonstrating that porous PTATE2 and PTATE4 nanoparticles were obtained. The fluorescent sensing properties of PTATE2 and PTATE4 towards nitroaromatic explosives in aqueous media show a sensitive and selective detection towards TNP, with the Stern-Volmer quenching constants and detection limits of 1.8 × 104 M−1 and 722 nM for PTATE2, 2.4 × 104 M−1 and 564 nM for PTATE4, respectively. Moreover, the spike/recovery tests in actual water samples indicates the recovery rates of TNP are 94.76%–103.82% by PTATE2 and 93.35%–100.72% by PTATE4, and the t-tests show that there is no significant difference between the determination results of present fluorescence sensing method based on PTATE2 and PTATE4 and HPLC analysis at 95% confidence level. The study of sensing mechanism demonstrates that the inner filter effect is dominant in the process of fluorescence quenching towards TNP.