Spectroscopy investigations on chemosensor activities of isatin-hydrazones toward Ag+ and Hg2+ ions

In this paper, isatin-hydrazone was synthesized using SBA-Pr-N-Is-But-SO₃H as nanocatalyst via the two-component reaction of isatin with hydrazine hydrate in an expeditious reaction with high yield of production. The sensing properties were evaluated in EtOH: H₂O (1:9) for the different cation (K⁺, Ca²⁺, Na⁺, Cu²⁺, Zn²⁺, Cr³⁺, Mn²⁺, Co²⁺, Al³⁺, Pb²⁺, Ag⁺, Cd²⁺, Ni²⁺, Hg²⁺, and Mg²⁺). The obtained results revealed that these compounds could be applied as chemosensor for the sensitive detection of Hg²⁺ and Ag⁺ ions using UV–Vis spectroscopy and fluorescence spectroscopy, respectively. The detection limit was calculated to be 1.17 × 10^–6 M for Hg²⁺ ions and 1.4 × 10^–6 M for Ag⁺ ions. Also, isatin-hydrazone was treated with 4-flurobenzaldehyde to obtain 4-fluorobenzaldehyde-N-(2-oxo-1,2-dihydro-3H-indole-3-indole-3-ylidene)hydrazone which could sensitively select Hg²⁺ ions among different ions using fluorescence spectroscopy. The detection limit of the colorimetric sensor to detect the Hg²⁺ ions is 3.6 × 10^–6 M. At the end of the reaction, the nanocatalyst was recovered and reused.

Graphical Abstract