The preparation of a 9,9′-spirobi[9H-9-silafluorene]-based porous organic polymer for fluorescence sensing of iodide ions and 2,2-dinitrophenol

Abstract

Because of its rigid and pseudotetrahedral structure and its strong σ*(Si–C)–π* hyperconjugation effect, compounds based on 9,9′-spirobi[9H-9-silafluorene] (SSF) have high fluorescence. However, SSF-based porous organic polymers (POPs) have not been reported so far. Herein, the first SSF-based POP, termed TSSF, was synthesized via Friedel–Crafts arylation polymerization reaction of cyanuric chloride (CC) or Trichlorotriazine (TCT) with SSF using anhydrous aluminum trichloride (AlCl₃) as a catalyst and 1,2-dichloroethane as a solvent. TSSF can fluorescently sense iodide ions (I⁻) and 2,4-dinitrophenol (DNP) in tetrahydrofuran (THF) with high fluorescence quenching constants (K_SV) for I⁻ and DNP of 1.64 × 10⁴ and 2.61 × 10⁴ L mol⁻¹, respectively. The fluorescence quenching of TSSF by I⁻ resulted from the Förster resonance energy transfer (FRET) mechanism, the heavy-atom effect, and inner filter effect (IFE), and that by DNP originated from the combined action of the photo-induced electron transfer (PET) mechanism, FRET mechanism, and IFE. The S–V equations were corrected for the IFE.