A fluorescent chemosensor for selective detection of chromium (III) ions in environmentally and biologically relevant...

A simple single step one pot multicomponent reaction was performed to synthesize N-(tert-butyl)-2-(furan-2-yl)imidazo[1,2-a]pyridine-3-amine (TBFIPA). The synthesized TBFIPA was subjected to library of cations to study its ability for selective and sensitive detection of specific metal ions. Selective detection of chromium ions by TBFIPA were found from the significant hypsochromic shift (335 nm → 285 nm) in the UV-Visible spectra. The fluorescent TBFIPA displays complete quenching of fluorescence under UV lamp (365 nm) only in the presence of chromium without the interference of common metal ions. Binding constant (k_a) obtained from Benesi-Hildebrand plot is 0.21 × 10⁵ M^-1, limit of detection (LOD) and limit of quantification (LOQ) of TBFIPA toward Cr³⁺ ions are 4.70 × 10^-7 M and 1.56 × 10^-7 M, respectively. The mechanism proposed during complex formation were supported by stoichiometric Job continuous variation plot, ¹H NMR titration and ESI-MS spectroscopic data. All the experimental confirmation for complex formation were corroborated with theoretical DFT studies optimized using RB3LYP/6-31G(d) basis set. The selectivity and sensitivity of TBFIPA toward Cr³⁺ ions are found suitable to design a user-friendly silica based portable test kit. Alongside, TBFIPA was successfully utilized for imaging onion epidermal cells. Furthermore, the results obtained for biological, environmental, and industrial samples provided solid evidence to estimate chromium ions using TBFIPA in these real samples.