NanoPOP: Solution-Processable Fluorescent Porous Organic Polymer for Highly Sensitive, Selective, and Fast Naked Eye Detection of Mercury

Abstract

Fluorescence-based detection is one of the most efficient and cost-effective methods for detecting hazardous, aqueous Hg 2+ . We designed a fluorescent porous organic polymer (TPA-POP-TSC), with a "fluorophore" backbone and a thiosemicarbazide "receptor" for Hg 2+ -targeted sensing. Nanometer-sized TPA-POP-TSC spheres (nanoPOP) were synthesized under mini-emulsion conditions and showed excellent solution processability and dispersity in aqueous solution. The nanoPOP sensor exhibits exceptional sensitivity (K sv = 1.01 × 10 6 M −1 ) and outstanding selectivity for Hg 2+ over other ions with rapid response and full recyclability. Furthermore, the nanoPOP material can be easily coated onto a paper substrate to afford naked eye-based Hg 2+detecting test strips that are convenient, inexpensive, fast, highly sensitive, and reusable. Our design takes advantage of the efficient and selective capture of Hg 2+ by thiosemicarbazides (binding energy = −29.84 kJ mol −1 ), which facilitates electron transfer from fluorophore to bound receptor, quenching the sensor's fluorescence.

N-alkylation briefly constructs tunable multifunctional sensor materials: Multianalyte detection and reversible adsorption

“…As shown in Figures 8 A and 8D, upon the addition of Cu 2+ , the C1s binding energy of C=N in SPBI-c moved from 286.1 to 286.6 eV, and the N1s binding energy moved from 401.6 to 402.3 eV. These changes demonstrate the presence of a coordination effect between Cu 2+ and C=N in SPBI-c ( Li et al., 2019b ). Similar interactions were confirmed between SPBI-c and Fe 3+ ( Figures 8 B and 8E) or PA ( Figures 8 C and 8F).…”

“…As depicted in Figure 7 , the stretching vibration of C-N and C=N in SPBI-c are located at 1278 and 1618 cm −1 , respectively. After the addition of Cu 2+ , these stretching vibrations moved to 1272 and 1625 cm −1 , respectively, indicating an interaction between the N atoms in SPBI-c and Cu 2+ ( Wu et al., 2016 ; Li et al., 2019b ). Similarly, these stretching vibrations also moved after the addition of Fe 3+ to SPBI-c .…”

“…Moreover, the high-resolution C1s spectrum showed four peaks at 284.6, 285.1, 285.5, and 286.2 eV ( Figure S11 B), assigned to C-C/C=C, C-N/C-O, C=N, and C=O, respectively, in the terminal group of SPBI-c . The N1s spectrum could be divided into two peaks at 399.9 and 401.6 eV ( Figure S11 C), corresponding to C-N and C=N, respectively ( Jiao et al., 2019 ; Li et al., 2019b ). Thus, the XPS data further confirm the construction of a polymer skeleton.…”

“…According to the reported method ( Li et al., 2019b ; Zhang et al., 2019b ; Chen et al., 2021 ; Chen et al., 2020c ; Wang, et al., 2020 ), the effects of analytes on the FT-IR spectra and morphology of SPBIs were determined. Using SPBI-c as a representative compound, the changes in FT-IR spectra and SEM images before and after the addition of Cu 2+ or Fe 3+ were observed.…”

“…In addition, the interactions between polymeric sensors and analytes can be measured by XPS analysis ( Li et al., 2019b ; Zhao et al., 2019 ; Wang et al., 2020c ). Using SPBI-c as an example, the C1s and N1s binding energies in the system after the addition of Cu 2+ , Fe 3+ , and PA were determined.…”