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 (Hg2+) ions detection. Quantum chemical DFT calculations were performed to examine the adsorption of Hg(OOCCH3)2 on the surface of compound 7. The charge distributions before and after adsorption showed charge transfer from 7 to Hg(OOCCH3)2 which indicated that 7 was sensitive to Hg(OOCCH3)2 molecule for Hg+2 detection. The lowing in energy gap (ΔE), higher electrical conductivity and increased density of states (DOS) after Hg(OOCCH3)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 (Ba2+, Ca2+, Co2+, Hg2+, K+, Mg2+, Mn2+, Na+, NH4+ and Pd2+). A significant hyperchromic shift in compound 7 spectrum (UV/ and fluorescence) upon equimolar addition of Hg2+ ions indicated that the triazole-based compound (7) has exhibited selective interaction with Hg2+ ion in preference to other cations. The maximum chelation of compound (7) with Hg2+ was observed at pH 5.1 (slightly acidic medium). The compound (7) capability to recognize Hg2+ was observed even at 0.1 µM detectable limit, indicating greater sensitivity of 7 toward Hg2+. No significant effect of competitive metal ions on 7 – Hg2+ complex further authenticated robust selectivity and sensitivity of 7 toward sensing Hg2+ions. Binding mechanism indicated the formation of 2:1 complex of 7 - Hg2+. DFT and spectral findings complimented each other and proving the promising chemosensor candidacy of the compound 7 for Hg2+ ions.