Synthesis, photoelectric properties and cytotoxicity of novel coumarin-based molecular probes for transition metal ions detection: Theory and experiment

Four coumarin-based molecular probes were synthesized via the reaction of phenylhydrazine and coumarin derivatives. Their binding properties toward various anions (F⁻, Cl⁻, Br⁻, I⁻, SO₃²⁻, H₂PO₄⁻, CH₃COO⁻, HS⁻) and cations (Li⁺, Na⁺, Mg²⁺, Al³⁺, K⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺) were systematically investigated using UV–Vis absorption spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The results demonstrated that the probes exhibited high selectivity, sensitivity and specificity for Cu²⁺, Co²⁺, Fe³⁺ with distinct colorimetric changes upon host-guest interaction, enabling visual detection. These findings establish a promising approach for trace ion sensing. Theoretical studies revealed that the observed red shifts in the UV–Vis spectra originated from electron transitions involving the highest occupied molecular orbital (HOMO). Furthermore, cytotoxicity assays confirmed the probes' biocompatibility, suggesting their potential for intracellular ion detection in living cells.