A Gadolinium Metal‐Based Fluorescent Probe for Selective Detection of Phenazopyridine Hydrochloride

ABSTRACT Rapid and accurate detection of phenazopyridine hydrochloride (PAP) is essential for protecting public health and safety. In this paper, gadolinium‐based coordination polymer [Gd(adip) 1/2 (NMP) 2 (CH 3 COO)]·H 2 O ( 1 ) has been synthesized using a solvothermal method centered on gadolinium metal with the ligand 5,5′‐(anthracene‐9,10‐diyl)‐diisophthalic acid (H 4 adip). It was characterized with various instruments and served as a fluorescence‐based sensing platform to measure PAP. Under 375 nm excitation, 1 displays an emission maximum at 427 nm and a shoulder peak at 409 nm. When used as a sensor, Compound 1 can quantitatively detect PAP in the 0–41.2 μM concentration range, with a LOD of 0.024 μM. Mechanistic studies have shown that the addition of PAP significantly quenches the fluorescence emission of 1 through the fluorescence resonance energy transfer (FRET) mechanism. In summary, 1 not only provides highly sensitive and selective detection of PAP, but is also reusable.