Robust lanthanide metal–organic frameworks with "all-in-one" multifunction: efficient gas adsorption and separation, tunable light emission and luminescence sensing. Issue 10 (17th February 2021) - Li, Bo
Abstract : A robust lanthanide MOF platform displays all-in-one multifunction, including excellent gas uptake and separation, tunable light emission and efficient luminescence sensing. Abstract : Combining the porous structure and fluorescence properties of metal–organic frameworks (MOFs) with rational design to realize multifunction application is of great significance from an energy and environmental standpoint. Herein, a new series of lanthanide metal–organic frameworks (Ln–MOFs), {[Ln(L)(H2 O)]·4H2 O } n (1-Ln, where Ln = Eu, Tb, Gd, and Eu x Tb1− x ), were constructed by using a rigid 5-(2′, 5′-dicarboxylphenyl) picolinic acid ligand and Ln 3+ ions. 1-Ln was isostructural and exhibited a similar porous framework. Thermogravimetry analysis (TGA), powder X-ray diffraction (PXRD) and N2 adsorption measurements revealed that 1-Eu exhibits excellent thermal, water and chemical stabilities. As expected, 1-Eu-a (activated 1-Eu ) shows a high adsorption capacity for C2 H2 (109.2 cm 3 g −1 ) as well as excellent selective separation with ideal adsorbed solution theory (IAST) selectivity for C2 H2 /CO2 (4.1–3.3), C2 H2 /CH4 (23–17) and CO2 /CH4 (5.6–5.4) at room temperature. More importantly, density functional theory (DFT) calculations and breakthrough experiments were carried out, which highlight its great potential to address challenging industrially important separation. Moreover, a series of bimetallic MOFs 1-Eu x Tb1− x were constructed by changing the ratio of Eu 3+ and Tb 3+ and showed excellent linear color tunability (from green to red), indicating that they are suitable for barcode applications. Furthermore, luminescence studies revealed that 1-Eu is an excellent fluorescent probe for sensing Fe 3+ (LOD: 0.57 μM) and CrO4 2− /Cr2 O7 2− (LOD: 0.79/0.42 μM) ions in water, with a fast response, high sensitivity, selectivity and recyclability. To the best of our knowledge, 1-Eu is the first reported Ln–MOF material with all-in-one multifunction, including excellent gas adsorption and separation, tunable light emission and efficient luminescence sensing.