A stable dual-emission fluorescent system, R6G/Eu-MOF, was obtained by simple mixing Eu-MOF with fluorescent rhodamine 6G (R6G). This system not only achieved robust dual luminescence performance at 430 nm (Eu-MOF) and 555 nm (R6G) under single-wavelength excitation, but also endowed it significantly improved fluorescence stability. Orientin (OT), a bioactive traditional Chinese medicine (TCM) component, was found to efficiently quench the dual fluorescent emissions via the synergistic effect of dynamic quenching effect, photo-induced electron transfer and molecular interactions. Therefore, a rapid fluorescent assay for OT was developed based on the variations in fluorescence signals at 430 nm and 555 nm, as well as the alterations in the ratio between these two signals. This method can achieve highly sensitive determination of OT in the linear range of 1.1-220 µM, with a LOD of 0.26 µM at 430 nm and 0.16 µM at 555 nm (3σ/N). The R6G/Eu-MOF hybrid exhibits significantly lower detection limits and a broader linear range OT than either R6G or Eu-MOF alone. This work presents a simple strategy to improve the water stability of Eu-MOF, and also provides a rapid analysis of small molecule drug using a fluorescence approach based on dual-emission MOF hybrid system.
A triple-channel R6G@Eu-MOF fluorescent probe was developed for multi-signal sensing. • A six-channel sensor array was constructed using two solvent-dependent fluorescence responses. • The sensing mechanism involved hydrogen bonding and Eu excited-state/O–H oscillator coupling. • The platform enabled discrimination of organics, Baijiu, and other distilled liquors. Rapid discrimination of Baijiu is of interest for preliminary quality assessment and authenticity screening. In this work, a single-probe multi-channel fluorescent sensor array was developed based on R6G@Eu-MOF for Baijiu discrimination. By integrating rhodamine 6G (R6G) and Eu 3+ into one MOF platform, R6G@Eu-MOF provided three intrinsic emission signals at 550, 594, and 615 nm. Unlike conventional sensor arrays that usually require multiple sensing materials, this strategy expanded the three emission outputs into a six-channel response pattern by using DMF and ethanol as two distinct probe-dispersing microenvironments. Owing to differences in polarity, hydrogen-bonding ability, and chemical composition, different analytes induced characteristic fluorescence-response fingerprints. The response behavior was attributed to hydrogen-bonding interactions, modulation of the R6G microenvironment, coupling of the Eu excited state with O H oscillators, and possible inner filter effects. Based on this strategy, 16 representative organics and EtOH-water mixtures with different ratios were effectively discriminated. Under the current experimental conditions, 16 representative commercial Baijiu samples were clearly separated in the LDA analysis, and blind-sample validation showed a recognition accuracy of 90.6%. The array was also extended to other distilled liquors. This work provides a simple and material-efficient fluorescent-array strategy for pattern-recognition analysis of complex liquor samples. Scheme 1 Schematic illustration of R6G@Eu-MOF fluorescent sensor array for Baijiu discrimination. Download: Download high-res image (150KB) Download: Download full-size image
危险品化学品经营许可证（带存储）