Ultrasound‐assisted synthesis of a Eu3+‐functionalized ZnII coordination polymer as a fluorescent dual detection probe for highly sensitive recognition of HgII and l‐Cys.

A new ZnII coordination polymer (CP) based on 2,3‐pyrazine dicarboxylic acid (H2pzdc) and 4,4′‐bipyridine (bpy) (ZCP) was synthesized using a facile slow evaporation method. Single‐crystal X‐ray diffraction revealed that ZCP is a two‐dimensional porous CP, [Zn2(pzdc)2(bpy)(H2O)2]n, with van der Waals forces as the dominant interaction within its layers forming a 63 network. Employing energetic ultrasound irradiation, nanoscale ZCP (nZCP) was successfully synthesized and Eu3+ ions were incorporated within its host lattice (Eu@nZCP). The resulting platform exhibits superior fluorescence characteristics and demonstrates notable optical durability. Therefore, it was used as a dual detection fluorescent sensing platform for the detection of mercury and l‐cysteine (l‐Cys) in aqueous media through a turn‐off/on strategy. In the turn‐off process, the fluorescence emission of Eu@nZCP progressively quenches by the addition of HgIIvia a photo‐induced electron transfer (PET) mechanism. The fluorescence of Eu@nZCP is quenched to establish a low fluorescence background through the incorporation of HgII. This devised turn‐on fluorescent system is suitable for the recognition of l‐Cys (based on the strong affinity of l‐Cys to the HgII ion) through a quencher detachment mechanism. This method attained a relatively wide linear range, spanning from 0.001 to 25 µM, with the low detection limit of 5 nM for the sensing of HgII. Also, the corresponding limit of detection (LOD) for l‐Cys is 8 nM in a relatively wide linear range, spanning from 0.001 to 40 µM. [ABSTRACT FROM AUTHOR]