An Experimental and Quantum (QTAIM) Performance Study of a Proposed Molecular Chemosensor: A Quinazolinone-Based Sensor for Hg²⁺ Ion Detection

This work synthesized a novel colorimetric ligand based on the compound quinazolinone (Sensor) and investigated it. The sensing activity of the sensor toward different cation was studied. The sensor demonstrated a highly selective colorimetric sensing toward Hg2+ with a detection limit of 0.1 ppb and visual color change from colorless to Purple in methanol-water solvents (v/v, 10,90). The cation binding character was determined using visual inspection, UV-Vis, and fluorescence analyses. In the computational part, the interaction between the receptor and Hg2+ ion was investigated using density functional theory (TD-DFT) and quantum theory of atoms in molecules (QTAIM) in the solution phase (in the presence of water as solvent and the CPCM model). Theoretical studies have shown that electronic properties such as energy gap, absorption energy, charge/energy transfer, and optical properties change dramatically in the presence of Hg2+ cations. Also, the effect of the electric field on the electronic properties of the sensor/Hg2+ complex improved the Hg2+ cation adsorption process.