<p>A naphthocoumarin-thiazole conjugate <b>(7)</b> was prepared and tested as a selective chromogenic probe of Mn²⁺ ions. The high selectivity was exhibited in UV–Vis spectroscopic studies, which showed a strong bathochromic shift and a distinct concentration-dependent reaction to Mn²⁺ coordination with little spectral change in the presence of competing alkali, alkaline earth, and transition metal ions. Density functional theory (DFT) simulations were able to give electronic information on the sensing behavior of the material, showing a moderate HOMO-LUMO gap, high electrophilicity index, and sites on the heteroatoms with a high electron density, which contribute to efficient ligand-to-metal charge transfer, which is in agreement with the experimental optical response. Molecular docking was used as a qualitative analysis, supporting the structural compatibility of the conjugate in the active site of human STK10 and suggesting possible binding interactions, but not experimentally validated kinase inhibition. In silico ADMET and SMARTCyp modeling also indicated tolerable pharmacokinetics and manageable metabolic liability, suggesting the feasibility of future scaffold functional development. In general, this work has positioned compound <b>(7)</b> as a strong and selective Mn²⁺ biosensing platform, and computational simulations have provided mechanistic insights and suggestions for optimizing it.</p> Graphical Abstract <p></p>