Fumed-Si-Pr-Ald-Barb as a Fluorescent Chemosensor for the Hg[sup.2+] Detection and Cr[sub.2]O[sub.7][sup.2−] Ions: A Combined Experimental and Computational Perspective

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 H[sub.2]O:EtOH. The results showed that fumed-Si-Pr-Ald-Barb can selectively detect Hg[sup.2+] and Cr[sub.2]O[sub.7] [sup.2−] ions. The detection limits were calculated at about 5.4 × 10[sup.−3] M for Hg[sup.2+] and 3.3 × 10[sup.−3] M for Cr[sub.2]O[sub.7] [sup.2−] 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 E[sub.HOMO] and E[sub.LUMO] values. The DFT calculation confirms the suggested experimental mechanism for interacting the Pr-Ald-Barb with ions.