A Luminescent Cerium MOF for Rapid, Nanomolar and Recyclable Detection of Alkaloid Berberine and Fungicide Dimethomorph in Environmental Water and Food Samples.

Abstract

The development of rapid, selective, and biocompatible fluorescence-based sensors capable of simultaneously detecting structurally distinct analytes remains a significant challenge in analytical chemistry. Here, we report the design and synthesis of a new luminescent cerium-based metal-organic framework (Ce-MOF: [Ce6O4(OH)4(C13H7O6N)6]·9H2O·1DMF), constructed from 2,5-bis(allyloxy)terephthalic acid (H2L) at room temperature. The cerium centers within the framework exhibit mixed oxidation states (+3 and +4), imparting unique photo-physical properties. The Ce-MOF displays strong luminescence upon excitation at 315 nm, with an emission maximum at 430 nm (emission range: 335-550 nm). Leveraging this property, the MOF was employed as a dual-mode sensor for the selective detection of berberine (BBR) and dimethomorph in aqueous media. To the best of our knowledge, this is the first MOF-based sensing platform capable of detecting these two analytes individually with high efficiency. The sensor demonstrates remarkable selectivity and sensitivity, achieving detection limits of 4.5 ± 0.4 nM for BBR and 52.3 ± 0.9 nM for dimethomorph, with an ultrafast response time of <5 s. The practical utility of the sensor was validated by successfully detecting dimethomorph in real food samples (apples, potatoes, and cucumbers) and soil matrices. Furthermore, the MOF retained its sensing performance for at least three consecutive cycles, underscoring its stability and reusability. Mechanistic insights obtained from steady-state and time-resolved photoluminescence spectroscopy, UV-vis studies, and DFT calculations revealed that fluorescence quenching occurs via photoinduced electron transfer (PET) for BBR. Meanwhile, the inner filter effect (IFE) is responsible for the detection of dimethomorph by our probe. This dual-mode sensing mechanism highlights Ce-MOFs' potential as versatile platforms for real-time, on-site monitoring of environmental pollutants and foodborne