Bis-triazolylated-1,4-dihydropyridine - Highly selective hydrophilic fluorescent probe for detection of Fe3+

A water-soluble ferric (Fe3+) ion sensor probe has been synthesized using one-pot multicomponent Hantzsch synthesis, followed by Cu (I) catalyzed Click reaction. The synthesized probe C1 shows selective binding towards Fe3+ ion through a turn-off fluorescence response among various metal ions tested in aqueous medium. C1 shows an average fluorescence lifetime of 4.9 x 10(-10) s, and its selectivity towards Fe3+ ion has also been studied by Stern-Volmer plot, detection limit and binding studies. The probe C1 forms a 1:1 complex with Fe3+ ion with an association constant of (K-a = 2.50 x 10(3) M-1), as evident from the Benesi-Hildebrand plot. Density Functional Theory (DFT) studies of the probe reveal a square pyramidal geometry. Both Fe2+ and Fe3+ bind strongly to the probe, but the complexation energy with Fe3+ is almost double that with Fe2+, validating the experimental results. The probe C1 has also been tested for its application in biological systems and the results of an anti-proliferation assay of the fluorescent probe C1 in the absence and presence of FeCl3 on various cell lines normal (L929) and cancerous (MCF-7, MDA-MB 231, A549 and HepG2) shows that the probe C1 would be non-cytotoxic, both in the absence and presence of Fe3+ ions in the cells. (C) 2017 Elsevier Ltd. All rights reserved.