Improving ratiometric-based analysis via designing intense bi-ligand metal-organic frameworks: dual-mode for detection of amoxicillin in milk and pharmaceutical samples.

The development of dual-emission metal-organic frameworks (MOFs) is essential for advancing luminescence-based applications. In this study, a highly fluorescent bi-ligand Eu-based MOF (BiL-Eu-MOF) was synthesized exploiting coordination-induced emission (CIE) and dual-antenna effect phenomena. Upon excitation, the BiL-Eu-MOF emits both blue (CIE effect) and intense red (dual-antenna effect) fluorescence, enabling ratiometric detection. Amoxicillin (AMX) selectively quenches the red emission via the inner filter effect, while the blue emission remains stable, serving as an internal reference. This property facilitates AMX detection using two methods: conventional spectrofluorometric and a smartphone-assisted visual approach. The spectrofluorometric method achieved a detection range of 5.0-250 μM with a detection limit of 0.34 μM, while the smartphone-based approach reached a detection limit of 3.3 μM. The BiL-Eu-MOF demonstrated high accuracy (98.1-102.7 %) and precision (RSD < 2 %) in milk and pharmaceutical samples, highlighting its potential as a simple, effective, and modification-free sensing platform.