Unveiling Role of Metals in Mononuclear Metal‐Complexes for Chemodosimetric Detection of S2− from aqueous medium: Experimental and DFT Corroboration with Real‐Field Application

Abstract

AbstractHerein, we have reported two isostructural mononuclear metal complexes [M(HL)2(ClO4)2], wherein, M= Co2+ (viz. SN‐1) and Ni2+ (viz. SN‐2) and HL is NNO donor Schiff‐base ligand i. e. ((E)‐2‐methyl‐2‐((pyridin‐2‐ylmethylene)amino)propan‐1‐ol) for unveiling as molecular sensor for S2− (sulphide) like hazardous entity. The molecular probes have been characterized by SCXRD, 1H‐NMR, FT‐IR, HRMS etc. X‐ray diffraction studies confirm the mono‐nuclear structures of both the complexes. Interestingly, SN‐1 exhibited remarkable sensitivity towards S2− by naked eye colour change in purely aqueous medium with detection limit of 33.5 nM and binding constant of 11.05 × 108 M−1 while the SN‐2 didn't show any subtle chromogenic changes upon interaction with the targeted analyte. Judicious choice of metal centre plays a pivotal role for such discriminative interacting behaviour. Spectroscopic and DFT studies shed light on the mechanistic pathway of host‐guest interaction, indicating a S2− mediated chemodosimetric approach following HSAB principle. Impressively, the SN‐1 has also been explored towards fabrication of test strips for on‐field detection of H2S/S2− via. “Dip‐Stick” approaches. In a nutshell, the presently developed simple mono‐nuclear metal complex can be utilised for detecting gasotransmitter like H2S/S2− from purely aqueous medium that may be helpful in fabricating “point‐of‐care” devices in coming days for better understanding of H2S as a key role maker in various health related issues.