Influence of Introduced Substituents on the Anion-selectivity of [14]Tetraazaannulene Complexes

Abstract

Nickel(II) complexes of [14]tetraazaannulene derivatives incorporating aromatic rings into their azaannulene framework were synthesized, and the anion-selectivity of the [14]tetraazaannulene nickel complexes 1 – 4 was evaluated by potentiometric measurements with solvent polymeric membrane electrodes. All of the [14]Tetraazaannulene nickel complexes, except 3, were found to exhibit high selectivity for the I⁻ ion over the SCN⁻ ion, although considerable interference of the ClO₄⁻ ion was observed in all 1 – 4 complexes. Concerning the anion-selectivities of 1 and 4, the incorporation of naphthalene rings into the azaannulene framework decreased not only the interference of the ClO₄⁻ ion but also the I⁻ ion-selectivity over the SCN⁻ ion. Comparison studies between the dibenzotetraaza[14]annulene nickel complexes 1 – 3 indicated that differences in the attached substituents of the [14]tetraazaannulene nickel complexes greatly influenced the ion-selectivity as ionophores. According to our computational results, the ionophoric properties of [14]tetraazaannulene nickel complexes 1 – 4 were influenced by their electrostatic properties rather than their topological properties.