A simple donor–acceptor probe for the detection of Cr3+ cations

Abstract

A simple probe (1, 1-(4-cyano-phenyl)-3-(4-dimethylamino-phenyl)-thiourea)) is prepared as a ligand for metal ions and characterized by elemental analysis, nuclear magnetic resonance (¹H/¹³C NMR), mass spectroscopy and Fourier transform infrared spectrometry (FTIR). The probe exhibits fluorescence enhancement upon exposure to chromium(III) in THF–water (v/v = 9/1) buffer solution (trihydroxymethyl aminomethane–hydrochloric acid (Tris–HCl), pH = 7.4). A chelation photo-induced electronic transfer (PET) mechanism is introduced to explain the enhancement of the fluorescence and its high selectivity and sensitivity. It is found that the probe has a detection limit of 8.18 × 10⁻⁷ M. Furthermore, fluorescence imaging experiments of the exciplex (1@Cr³⁺) in living human glioma cells (U251) evidence its potential for practical application in biological systems.