Metal ions sensing properties of some phenylquinoxaline derivatives

Abstract

The sensitivity and selectivity properties of three phenylquinoxaline derivatives to different metal ions were investigated by absorption and fluorescence spectroscopy. The absorption and fluorescence responses of the phenylquinoxaline derivatives were examined towards the following metal ions Ag⁺, Mg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺ and Hg²⁺, in THF solution. All investigated samples exhibit sensitivity and selectivity to Ag⁺, Co²⁺ and Cu²⁺ ions compared to other metal ions (Mⁿ⁺ = Mg²⁺, Ni²⁺, Zn²⁺, Cd²⁺ and Hg²⁺). The gradual addition of Ag⁺, Co²⁺ and Cu²⁺ ions to a Q-Ox sample solution generates new absorption bands (with maxima at 244, 675 and 294 nm, in presence of the Ag⁺, Co²⁺ and Cu²⁺ ions, respectively) while the emission intensities were weakly quenched, except in presence of Ag⁺ ions, when the emission was almost completely quenched (quenching efficiency at 426 nm, (I₀ - I) / I₀ × 100% = 91%). Absorption and fluorescence results show the formation of 1:2 metal complexes with Ag⁺ ions and 1:1 stoichiometry for a complexation between Q-Ox and Co²⁺ or Cu²⁺ ions. The following characteristics of these phenylquinoxaline derivatives have been calculated and discussed: the effects of the interfering ions, the binding constants and the detection limit of Ag⁺, Co²⁺ and Cu²⁺ ions.

Keywords: Absorption/fluorescence spectroscopy; Phenylquinoxaline derivatives; Sensors; Silver, cobalt and copper ions.