‘Click’ generated indole appended thiosemicarbazone–triazole cojoined organosilane: a sensor for the recognition of Hg2+ ions, in silico docking and in vitro cytotoxic evaluation

Abstract

Developing a simple, selective, rapid and low-cost method for the detection of heavy metal ions is a fascinating area of research in environmental and biological analysis. Herein, we describe the influence of Hg²⁺ ions on the UV-vis absorbance responses of designed indole appended thiosemicarbazone–triazole linked organosilane (3a). A highly efficient and stereoselective, Cu(I) catalyzed ‘click chemistry’ approach was employed to stitch diverse structural units in a single framework to produce the designed ligand 3a. Techniques such as infrared spectroscopy, nuclear magnetic resonance (¹H and ¹³C), single crystal X-ray crystallography, thermogravimetric analysis and mass spectrometry were used to characterize organosilane 3a and its precursor alkyne 2a. The UV-vis spectral analysis of ligand 3a with different metal cations showed a particular type of binding and identification for Hg²⁺ ions with negligible interferences from the other metal ions. With chemosensor 3a, the detection limit and association constant value for Hg²⁺ were calculated using the linear calibration curve and BH-plot respectively. Their binding interactions with Hg²⁺ ions were also evaluated through density functional theory (DFT). Additionally, the cytotoxicity of organosilane 3a was examined in the poeciliopsis lucida hepatocellular carcinoma-1 (PLHC-1) cell line which showed a higher EC₅₀ value of 51.28 ± 6.1384 μM. Furthermore, pharmacophore modelling and molecular docking studies were performed with Escherichia coli DNA gyrase II topoisomerase enzyme which revealed the effective association between ligands and proteins.