Fumed-Si-Pr-Ald-Barb as a Fluorescent Chemosensor for the Hg²⁺ Detection and Cr₂O₇²⁻ Ions: A Combined Experimental and Computational Perspective

Abstract

The surface of fumed silica nanoparticles was modified by pyridine carbaldehyde and barbituric acid to provide fumed-Si-Pr-Ald-Barb. The structure was identified and investigated through diverse techniques, such as FT-IR, EDX, Mapping, BET, XRD, SEM, and TGA. This nanocomposite was used to detect different cations and anions in a mixture of H2O:EtOH. The results showed that fumed-Si-Pr-Ald-Barb can selectively detect Hg2+ and Cr2O72− ions. The detection limits were calculated at about 5.4 × 10−3 M for Hg2+ and 3.3 × 10−3 M for Cr2O72− ions. A computational method (DFT) was applied to determine the active sites on the Pr-Ald-Barb for electrophilic and nucleophilic attacks. The HOMO-LUMO molecular orbital was calculated by B3LYP/6-311G(d,p)/LANL2DZ theoretical methods. The energy gap for the Pr-Ald-Barb and Pr-Ald-Barb+ion complexes was predicted by the EHOMO and ELUMO values. The DFT calculation confirms the suggested experimental mechanism for interacting the Pr-Ald-Barb with ions.

Keywords

• fumed-Si-Pr-Ald-Barb
• fumed silica
• chemosensor
• fluorescent chemosensor
• Hg²⁺
• Cr₂O₇²⁻ ions