Azaindole modified imine moiety as fluorescent probe for highly sensitive detection of Fe3+ ions

An azaindole based schiff base AzIm was synthesized that serve as a luminescent turn “off” switch for the detection of Fe3+ ions. The photoluminescence intensity of AzIm was quenched significantly in the presence of 30 μM Fe3+ ions. The sensing response of the probe was tested at different ranges of pH and at different cation concentrations between 2 and 25 μM. Analytical characteristics were evaluated using standard Benesi-Hildebrand equation and the system displayed micromolar sensitivity for these ions. The specific diminished emission signal upon Fe3+ binding was interpreted in terms of the enhanced photoelectron transfer from azaindole group, which induces very fast and efficient non-radiative decay of the excited states of the sensor. In addition, practical utilization of luminescent AzIm was further supported by significant ion selective stability against the presence of extraneous charged species that makes this system compatible for quantitative analysis of environmental samples.