Triarylboron-Linked Conjugated Microporous Polymers: Sensing and Removal of Fluoride Ions

A luminescent conjugated microporous polymer (BCMP-3) has been synthesized in high yield by a carbon-carbon coupling reaction using triarylboron as a building unit. BCMP-3 was fully characterized by using powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, C-13 solid-state NMR spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, and nitrogen and carbon dioxide adsorption. The new three-dimensional conjugated framework possess a high Brunauer-Emmett-Teller (BET) specific surface area up to 950 m(2)g(-1) with a pore volume of 0.768 cm(3)g(-1), good stability, and abundant boron sites in the skeleton. Under excited-light irradiation, BCMP-3 exhibits strong fluorescent emission at 488 nm with a high absolute quantum yield of 18% in the solid state. Polymer BCMP-3 acts as a colorimetric and fluorescent chemosensor with high sensitivity and selectivity for F- over other common anions. In addition, the polymer also works as an adsorbent for F- removal and shows good adsorption capacities of up to 24 mg g(-1) at equilibrium F- concentrations of 16 mg L-1 and a temperature of 298 K. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-second-order kinetics and Langmuir equations. Furthermore, we highlight that BCMP-3 is an adsorbent for fluoride removal that can be efficiently reused many times without loss of adsorption efficiency.