Enhancing sensor performance through the surface functionalization of SBA-15 with 2-chloroquinoline-3-carbaldehyde and sulphaguanidine verified via DFT insights

• The surface modification of SBA-15 with 2-Chloroquinoline-3-carbaldehyde and Sulphaguanidine was performed, and SBA-Pr-CQC-SG was synthesized. • This novel nanomaterial was characterized using a range of advanced analytical techniques, including FT-IR, EDX, SEM, N 2 adsorption-desorption, and TGA analysis. • The fluorescence properties of SBA-Pr-CQC-SG were investigated, revealing its potential as a chemosensor for the selective detection of Pb²⁺ ions in aqueous media with a LOD of 23 × 10⁻ 7 M. A novel fluorescent nanomaterial, SBA-Pr-CQC-SG, was synthesized by functionalizing SBA-15 with (3-aminopropyl)triethoxysilane, followed by modification with 2-chloroquinoline-3-carbaldehyde and sulfaguanidine. The material was systematically characterized by FT-IR, EDX, SEM, N 2 adsorption-desorption, and TGA, confirming its successful fabrication, structural stability, and porosity. Fluorescence studies demonstrated that SBA-Pr-CQC-SG exhibits high sensitivity and selectivity toward Pb 2+ ions in aqueous media. To gain molecular-level insight into the sensing mechanism, DFT calculations were performed. Geometry optimization, MEP mapping, Mulliken charge distribution, and FMO analyses all confirmed that Pb 2+ preferentially interacts with the N3 and O1 atoms of the probe. The practical applicability of the sensor was validated using real water samples. Overall, these findings demonstrate that SBA-Pr-CQC-SG is a robust, selective, and efficient sensing platform for Pb 2+ detection, offering both strong theoretical validation and reliable performance in real environmental samples.