Post‐Functionalization of Fluorinated Dibenzosulfone‐Based Conjugated Polymer for Smart ‘Turn‐off’ Sensing of Cu²⁺ Ions

Abstract

Post‐functionalization of conjugated polymeric backbone with various N‐containing heterocycles through nucleophilic aromatic substitution reaction (SNAr) demonstrates crucial tailoring of their photophysical properties. This study explores an approach of post‐polymerization modification of a fluorinated dibenzosulfone‐based conjugated polymer aiming to incorporate functional groups having coordinating sites to bind metal ions. The resulting polymers, namely BDT‐DBTS‐IM, BDT‐DBTS‐TR, and BDT‐DBTS‐PY, revealed successful substitution reactions with imidazole, triazole, and pyridine respectively, and showed significant changes in their absorption and emission properties. Notably, BDT‐DBTS‐IM demonstrated exceptional performance as a chemosensor, exhibiting a dramatic fluorescence turn‐off response specifically to copper ions (Cu2+) with the limit of detection of 26 nM and Stern‐Volmer quenching constant (KSV) of 8.2×105 Lmol‐1. This high selectivity and sensitivity are attributed to the ability of the imidazole group to form a stable complex with Cu2+, resulting in both static and dynamic quenching efficiently. Our findings underscore the potential of post‐polymerization modifications to significantly enhance the functionality of conjugated polymers. The ability of BDT‐DBTS‐IM to detect trace levels of copper ions with high precision highlights its practical utility in environmental and biological monitoring. This research not only demonstrates an approach for post‐polymeric modification through SNAr reaction but also opens new avenues for developing sensors.