Identification of a novel click-derived 1,2,3-triazole as selective Hg2+ ion detector: computational and experimental investigations

A new triazole-substituted compound (7), namely {5-((2-methyl-4-(3-methyl-4-(prop-2-ynyloxy) benzyl) phenoxy) methyl)-1-(3-(nitrophenoxy) propyl)-1h-1, 2, 3-triazole}, was synthesized through the coupling of azido and propargylated precursors via click approach using 1,3-dipolar cycloaddition reaction. This compound was further explored for its selectivity and sensitivity toward mercury (Hg 2+ ) ions detection. Quantum chemical DFT calculations were performed to examine the adsorption of Hg(OOCCH 3 ) 2 on the surface of compound 7. The charge distributions before and after adsorption showed charge transfer from 7 to Hg(OOCCH 3 ) 2 which indicated that 7 was sensitive to Hg(OOCCH 3 ) 2 molecule for Hg +2 detection. The lowing in energy gap (Δ E ), higher electrical conductivity and increased density of states (DOS) after Hg(OOCCH 3 ) 2 adsorption further depicted the potential of 7 as a chemical sensor for Hg +2 sensing. The photophysical potential of compound (7) was examined by employing a range of cations (Ba 2+ , Ca 2+ , Co 2+ , Hg 2+ , K + , Mg 2+ , Mn 2+ , Na + , NH 4+ and Pd 2+ ). A significant hyperchromic shift in compound 7 spectrum (UV/ and fluorescence) upon equimolar addition of Hg 2+ ions indicated that the triazole-based compound (7) has exhibited selective interaction with Hg 2+ ion in preference to other cations. The maximum chelation of compound (7) with Hg 2+ was observed at p H 5.1 (slightly acidic medium). The compound (7) capability to recognize Hg 2+ was observed even at 0.1 µM detectable limit, indicating greater sensitivity of 7 toward Hg 2+ . No significant effect of competitive metal ions on 7 – Hg 2+ complex further authenticated robust selectivity and sensitivity of 7 toward sensing Hg 2+ ions. Binding mechanism indicated the formation of 2:1 complex of 7 - Hg 2+ . DFT and spectral findings complimented each other and proving the promising chemosensor candidacy of the compound 7 for Hg 2+ ions. Graphic abstract