A coumarin and 1,8-napthyridine conjugated novel molecular hybrid: Synthesis, DFT insights and unveiling the selective fluorescent sensing of Hg2+ ions with live-cell imaging application.

Herein, we have used a simple synthetic strategy to access a novel non-sulfur fluorescent molecular probe coumarin and 1,8-napthyridine conjugated probe DNCS. The developed probe has great selectivity and sensitivity for detecting Hg²⁺ ions. Our photophysical properties evaluation for the synthesized probe with different metal ions (Ba²⁺, Al³⁺, Ca²⁺, Bi³⁺, Ce³⁺, Cd²⁺, Cu²⁺, Sr²⁺, Co²⁺, Fe²⁺, Cr³⁺, Fe³⁺, Mn²⁺, Hg²⁺, Zn²⁺, Pb²⁺, Ni²⁺, and Sn²⁺) unveiled the very selective and sensitive fluorescence sensing behavior with Hg²⁺ ions in the energy window of near UV and visible light radiation in an organic aqueous solvent mixture (EtOH and water). The limit of detection (LOD) of 9.04 x10^-5 M and binding constant of 2.56 × 10³ M^-1 were obtained for the probe DNCS with Hg²⁺ ions, and 1:1 stoichiometric complexation. Our bioimaging experiments demonstrated that the developed probe exhibited fluorescent sensing behaviors towards Hg²⁺ ions with HCT 116 cells. Moreover, the current studies present the electronic properties of the DNCS probe computed through DFT computation studies at the B3LYP/6-311G(d,p) level of theory. We are confident that the developed fluorescent probe has the potential for the efficient fluorometric detection of Hg²⁺ ions and plays a significant role in environmental and human health protection.