A dual-responsive RhB-doped MOF probe for simultaneous recognition of Cu²⁺ and Fe³

Based on the dual response of RhB@UiO-67 (1:6) to Cu²⁺ and Fe³⁺, a proportional fluorescent probe with (I₃₉₂/I₅₈₁) as the output signal was developed to recognize Cu²⁺ and Fe³⁺. Developing highly sensitive and selective trace metal ions probes is crucial to human health and ecological sustainability. In this work, a series of ratio fluorescent probes (RhB@UiO-67) were successfully synthesized using a one-pot method to enable fluorescence sensing of Cu²⁺ and Fe³⁺ at low concentrations. The proportional fluorescent probe RhB@UiO-67 (1:6) exhibited simultaneous quenching of Cu²⁺ and Fe³⁺, which was found to be of interest. Furthermore, the limits of detection (LODs) for Cu²⁺ and Fe³⁺ were determined to be 2.76 μM and 0.76 μM, respectively, for RhB@UiO-67 (1:6). These values were significantly superior to those reported for previous sensors, indicating the probe's effectiveness in detecting Cu²⁺ and Fe³⁺ in an ethanol medium. Additionally, RhB@UiO-67 (1:6) demonstrated exceptional immunity and reproducibility towards Cu²⁺ and Fe³⁺. The observed fluorescence quenching of Cu²⁺ and Fe³⁺ was primarily attributed to the mechanisms of fluorescence resonance energy transfer (FRET), photoinduced electron transfer (PET), and competitive absorption (CA). This work establishes a valuable foundation for the future study and utilization of Cu²⁺ and Fe³⁺ sensing technologies.