A new aza-crown macrocyclic fluorescent chemosensor (N3O2 donor atoms) for magnesium ions in aqueous ethanol solution

Abstract

A new N₃O₂ aza-crown macrocyclic ligand (L) bearing two fluorophore naphthalene moieties was synthesized and characterized by IR, ¹H and ¹³C NMR, DEPt-135, HSQCGP, and microanalysis as well as by mass spectrometry. Comparative studies on the effect of various metal cations such as Cr(III), Cu(II), Cu(I), Zn(II), Cd(II), Pb(II), Na(I), Ni(II), Co(II), Ba(II), Fe(II), Fe(III), Al(III), La(III), Au(III), Mg(II), Cs(I), Ca(II), Hg(II), K(I), Mn(II) and Ag(I) on the fluorescence of L were investigated in aqueous ethanol. The macrocycle was found to be a sensitive and selective fluorescent chemosensor for Mg²⁺. The binding constant value was established as 1.36 × 10⁵ M⁻¹ along with 1 : 1 stoichiometry for Mg²⁺–L. The detection limit was 2.51 × 10⁻⁸ M with a rapid response time. Chemical inputs of Mg²⁺ and Fe³⁺ ions satisfy the conditions of an INHIBIT molecular logic gate.