Salicylaldehyde built fluorescent probe for dual sensing of Al3+, Zn2+ ions: Applications in latent fingerprint, bio-imaging & real sample analysis

Abstract

This Schiff base chemosensor (SNN) detected dual ions, Al³⁺ and Zn²⁺ ions selectively. Fluorescence spectrum investigations showed that Al³⁺ ions increased fluorescence intensity, notably at 493 nm. Introducing Zn²⁺ ions caused a significant blue shift of roughly ∼65 nm at a wavelength of 434 nm, resulting in a notable change in fluorescence intensity. When binding Al³⁺/Zn²⁺ ions, the SNN receptor uses three methods. Inhibition of photoinduced electron transfer (PET), excited state intramolecular proton transfer (ESIPT), and restriction of CN isomerization. The jobs plot method found that SNN + Al³⁺ and SNN + Zn²⁺ complexations had a 1:1 stoichiometry. DFT, LC-HRMS, and ¹H NMR titration confirm this conclusion. The probe SNN's limit of detection (LOD) for Al³⁺/Zn²⁺ ions was 3.99 nM and 1.33 nM. Latent fingerprint (LFP), food samples, pharmaceutical products, and E. coli pathogen bio-imaging have all used the SNN probe to identify Al³⁺ and Zn²⁺ ions.

Keywords: Al(3+)/Zn(2+); Bio-imaging; Food/pharmaceutical samples; Latent fingerprint; PET/ESIPT.