A Bifunctional Europium–Organic Framework with Chemical Fixation of CO₂ and Luminescent Detection of Al³⁺

A novel three-dimensional lanthanide–organic framework {[Eu­(BTB)­(phen)]·4.5DMF·2H₂O}_<i>n</i> (<b>1</b>) has been synthesized. Structural characterization suggests that framework <b>1</b> possesses one-dimensional channels with potential pore volume, and the large channels in the framework can capture CO₂. Interestingly, investigations on the cycloaddition reaction of CO₂ and epoxides reveal that compound <b>1</b> can be considered as an efficient catalyst for CO₂ fixation with epoxides under 1 atm pressure. Importantly, <b>1</b> can be reused at least five times without any obvious loss in catalytic activity. Furthermore, the luminescent explorations of <b>1</b> reveal that <b>1</b> can act as a recyclable sensor of Al³⁺, and the corresponding detection limit can reach 5 × 10^–8 M (1.35 ppb), which is obviously lower than the United States Environmental Protection Agency’s recommended level of Al³⁺ in drinking water (200 ppb). These results show that <b>1</b> has a level of sensitivity higher than that of other reported MOF-based sensors of Al<sup>3+