Novel highly selective quinoline-based fluorescent chemosensors for quantitative analysis of Cu(II) ion in water and food.

While copper (Cu ²⁺ ) is a vital cofactor in numerous enzymatic processes, its homeostasis is critical. Selective sensors for Cu ²⁺ in food matrices are paramount for ensuring adherence to safety regulations and dietary interaction studies. In this work, novel derivatives of 8-aminoquinoline (L1-L4) with extended π-conjugation and various N-substituents were synthesized and evaluated as fluorescent sensors for Cu ²⁺ . The 2-pyridinecarbonyl-substituted derivative L3 exhibited sharp fluorescence quenching selectively in the presence of Cu ²⁺ . This compound presents high selectivity for Cu ²⁺ even in the presence of other metal ions. The L3-based fluorescent sensor provides a Cu ²⁺ detection limit of 77 nM, surpassing many existing sensors. The quantifications of Cu ²⁺ in water, food supplements, and wines using this sensor have demonstrated good agreement with those obtained using the standard ICP technique. Notably, L3 also facilitates Cu ²⁺ detection in microliter sample volumes at subnanomole levels using paper-based sensors, opening doors for portable and cost-effective on-site testing.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier B.V. All rights reserved.)