Triazine-based conjugated microporous polymers with N,N,N′,N′-tetraphenyl-1,4-phenylenediamine, 1,3,5-tris(diphenylamino)benzene and 1,3,5-tris[(3-methylphenyl)-phenylamino]benzene as the core for high iodine capture and fluorescence sensing of o-nitrophenol

Abstract

A series of novel triazine-based conjugated microporous polymers (TCMPs), TTPPA, TTDAB and Tm-MTDAB, were constructed via a Friedel–Crafts polymerization reaction between 2,4,6-trichloro-1,3,5-triazine (TCT) and derivatives of triphenylamine (N,N,N′,N′-tetraphenyl-1,4-phenylenediamine (TPPA), 1,3,5-tris(diphenylamino)benzene (TDAB) and 1,3,5-tris[(3-methylphenyl)-phenylamino]benzene (m-MTDAB)). TTPPA possesses a high BET surface area (>512 m² g⁻¹), a large pore volume (0.2997 cm³ g⁻¹), good stability, and displays excellent guest uptake of 4.90 g g⁻¹ in iodine vapour. Thus, TTPPA, to the best of our knowledge is the most effective polymer of all the CMPs reported to date. Surprisingly, despite poor porosity, both TTDAB and Tm-MTDAB also show excellent adsorption capacity of I₂ vapour (3.13 and 3.04 g g⁻¹). Two methods to release the adsorbed iodine were explored: slow release into ethanol and quick release upon heating (with a high degree of control). The three TCMPs exhibit outstanding performance for the reversible adsorption of iodine in gas phase as well as in solution. Spectral studies indicate that effective sorption sites, twisted propeller-like conformation, and charge-transfer interactions ensured well-defined host–guest interactions and consequently controlled the uptake of iodine. Furthermore, the three TCMPs exhibited extremely high detection sensitivity and selectivity towards o-nitrophenol.