A new triazine functionalized luminescent covalent organic framework for nitroaromatic sensing and CO2 storage

Abstract

A new hexagonally ordered covalent organic framework (COF), TRIPTA has been synthesized using Schiff base condensation reaction between 1,3,5-tris-(4-aminophenyl)triazine (TAPT) and 1,3,5-triformylphloroglucinol (TFP). TRIPTA exhibits high crystallinity, a large BET surface area (609 m² g⁻¹) and pore volume (0.351 cm³ g⁻¹) and possesses high nitrogen content (14.97%). TRIPTA was found to be highly luminescent when suspended in polar solvents upon irradiation of UV light and can detect various nitroaromatic compounds with good sensitivity by fluorescence quenching at concentrations as low as in the range of 10⁻⁸ M. The maximum fluorescence quenching was observed for trinitrophenol (61.7% at 5.46 × 10⁻⁷ M) with a Stern–Volmer constant of 2.7 × 10⁶ M⁻¹. The COF also showed excellent CO₂ uptake capacity of 57.07 wt% at 273 K and 16.02 wt% at 298 K up to 5 bar pressure, with an initial heat of adsorption (Q_st) value 56.77 kJ mol⁻¹.