Multifunctional porous Tröger's base polymers with tetraphenylethene units: CO₂ adsorption, luminescence and sensing properties

Luminescent porous organic polymers have shown potential applications in sensing, light-harvesting, photocatalysis and photo-voltaic or electronic devices. In this paper, a luminescent porous Tröger's base polymer (LMOP-15) with a tetraphenylethene unit has been synthesized by a simple method through the reaction of 1,1,2,2-tetrakis(4-aminophenyl)ethene and dimethoxymethane in acid solution at room temperature. The N₂ adsorption of LMOP-15 at 77 K reveals the type I isotherm of microporous materials, and the calculated Brunauer-Emmett-Teller surface area is 484 m² g^-1. The CO₂ uptake capacity of LMOP-15 at 273 K and 1 bar is 48.8 cm³ g^-1, while the isosteric heat for CO₂ reaches 53.7 kJ mol^-1 due to the presence of the Tröger's base moiety. The CO₂/N₂ adsorption selectivity calculated from the initial slopes of the CO₂ and N₂ adsorption isotherms at 273 K is up to 61.7. LMOP-15 also exhibits strong green luminescence (λ_max = 517 nm) in ethanol suspension. Furthermore, LMOP-15 shows highly selective fluorescence quenching detection abilities for Cu²⁺ ions and picric acid.