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

Abstract

Developing a simple, selective, rapid and low-priced 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. The techniques of 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 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+ was 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 higher EC50 value of 51.28 ± 6.1384 µM. Further, pharmacophore modelling and molecular docking studies were performed with Escherichia coli DNA gyrase II topoisomerase enzyme which revealed the effective association between ligand and protein.

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