A tetraoxacalix[2]arene[2]triazine based fluorogenic probe for the sensing of Fe3+: Computational and living–cell imaging applications

Abstract

Herein, we have reported a feasibility study of highly selective and sensitive fluorogenic chemosensor (probe TOCT) derived from tetraoxacalix [2] arene [2] triazine for Fe3+ sensing in aqueous media. The probe TOCT has been fabricated and verified by 1H–NMR, HR–LCMS,FT–IRand 13C–NMR. The sensing properties of probe TOCT toward various metal ions were confirmed by fluorescence titration study as well as competitive study. The intensity of probe TOCT reduced with the amount of Fe3+ when it was excited at 300 nm in CH3CN:H2O (95/5, v/v, pH = 7) media. The probe demonstrated a ‘turn–off’ response toward Fe3+, in the presence of possible competing ions. The detection limit value of probe TOCT for Fe3+ sensing was computed to be 12.5 nM. The possible molecular structure of complex between probe TOCT and Fe3+ was also proposed on the basis of HR–LCMS and FT–IR. The stoichiometry of TOCT–Fe3+ complex was identified to be 1:1 to the methodology of Job's plot. The binding ability was studied through the equation of Benesi–Hildebrand which was computed to be 8.90 × 104 M–1 for Fe3+. To support the intensity enhancement and quenching studies, we reported computational experiments based on the density functional theory (DFT). Moreover, a great potential has been detected for probe TOCT as a fluorescent chemosensor in biological applications to monitor Fe3+ in living cells.