α-Naphtholbenzein based heterocyclic sensor for detection of Cu(II) ions

Abstract

Present research work illustrates the ‘Click’ generation of 4-((1-((1-benzyl-1H-1,2,3-triazol-4-yl) methoxy) naphthalen-4-yl) (phenyl)methylene) naphthalen-1(4H)-one α-NBT, a heterocyclic compound analyzed as an optical chemosensor for the selective detection of Cu(II) ions. The molecule is synthesized by [3 + 2] cycloaddition reaction of α-naphtholbenzein based terminal alkyne 2 with 1-(azidomethyl) benzene 3 under Cu(I)-catalyzed conditions (CuAAC) and is further characterized for its structural components by various spectroscopic techniques like IR, NMR (1H, 13C) and Mass spectrometry. Being having significant absorption in UV–Visible region, the receptor molecule α-NBT is analyzed for its chemosensing characteristics by UV–Visible and fluorescence spectroscopy and found to be very selective towards Cu(II) ions among a range of metal ions including Na(I), K(I), Ba(II), Cr(III), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(I), Zn(II), Cd(II), Hg(II), Pb(II), Th(IV) and Ce(III) in CH3CN:H2O (4:1, v/v) solvent system. From the recorded spectral responses with change in concentration of Cu(II) ions, the binding ratio of α-NBT:Cu(II) complexation is calculated as 2:1 with the limit of detection of Cu(II) ions as 3.12 µM and binding constant for ligand–metal interaction equal to 0.15 x 105 M−1.