Two Stable Cd-MOFs as Dual-Functional Materials with Luminescent Sensing of Antibiotics and Proton Conduction

Abstract

Construction and investigation of dual-functional metal−organic frameworks (MOFs) with luminescent sensing and proton conduction provide widespread applications in clean energy and environmental monitoring fields. By selecting a phosphonic acid ligand 4-pyridyl-CH 2 N(CH 2 PO 3 H 2 ) 2 (H 4 L) and coligand 2,2′-biimidazole (H 2 biim), two cadmium-based MOFs [Cd 1.5 (HL)-(H 2 biim) 0.5 ] (1) and (H 4 biim) 0.5 •[Cd 2 (L)(H 2 biim)Cl] (2) with different structures and properties have been hydrothermally synthesized by controlling reaction temperature. Based on the excellent thermal and chemical stabilities, and good luminescent stabilities in water solution, 1 and 2 can serve as luminescent sensors of chloramphenicol (CAP) with different quenching constant (K SV ) values and detection limits (LODs) in water, simulated environmental system, and real fish water system. Meanwhile, different sensing effects and possible sensing mechanisms are analyzed in detail. Moreover, 1 and 2 can also serve as good proton-conducting materials. The proton conductivities can reach up to 1.41 × 10 −4 S cm −1 for 1 and 1.02 × 10 −3 S cm −1 for 2 at 368 K and 95% relative humidity (RH). Among them, 2 shows better luminescent sensing and proton conduction performance than 1, which indicates that different crystal structures have a great impact on the properties of MOFs. Through the discussion of the relationship between structures and properties in detail, the possible reasons for the differences in properties are obtained, which can provide theoretical guidance for the rational design of this kind of dual-functional MOFs in the future.

Heterometallic ZnHoMOF as a Dual-Responsive Luminescence Sensor for Efficient Detection of Hippuric Acid Biomarker and Nitrofuran Antibiotics

“…Prior studies have indicated that luminescent quenching effects are mainly caused by electron and energy transfer, as well as structure collapse [50,51]. As the first and foremost evaluation indicator, the stability of frameworks plays a crucial role and directly determines the actual values and application scenarios [52][53][54][55]. Fortunately, the structure collapse of ZnHoMOF can be excluded by comparing the PXRD profiles of reused crystalline materials with the original ones (Figure S9).…”

Photochromic Ln-Phosphonates Assembled by an Imidazole Derivative: Construction, Crystal Structures, and Light-Enhanced Proton Conductivity

“…The first approach is to reduce the activation energy of proton transfer or/and increase the number of proton carriers (such as H 2 O, NH 4 + , H 3 O + ). , However, it still confronts challenges in the current situation due to the fact that this method needs to comprehensively consider various factors that may affect the performance of proton conduction. The other approach is to introduce more acidic functional groups such as carboxylic acids, , sulfonic acids, , or phosphonic acids to enhance their acidity and hydrophilicity, thereby enriching the presence of hydrogen-bonding networks. − Evidently, the second method is more meaningful for improving proton conductivity owing to its chemical stability and structural diversity accompanied by the simple and facile operation procedure.…”