Cation binding by 21,31-diphenyl-l 2,42-dioxo-7,10,13-trioxa-1,4(3,1)-diquinoxalina-2 (2,3),3(3,2)-diindolizinacyclopentadecaphane and its acyclic analog

The binding of cations Li⁺, Na⁺, K⁺, Cs⁺, Ag⁺, Zn²⁺, Ni²⁺, Co²⁺, NH₄ ⁺ (group I), H⁺, Mg²⁺, Al³⁺, Ga³⁺ (group II), and Ca²⁺, Pb²⁺ (group III) by 2¹,3¹-diphenyl-l ²,4²-dioxo- 7,10,13-trioxa-l,4(3,1)-diquinoxalina-2(2,3),3(3,2)-diindolizinacyclopentadecaphane (1), which contains two indolizine and two quinoxaline fragments and 3,6,9-trioxaundecanes spacer, and by its acyclic analog (2) was studied using cyclic voltammetry in MeCN/0.1 M Bu₄NBF₄. It was concluded that the ions of group I are not bound by these compounds, the ions of group II exhibit the reversible redox-switched binding by the carbamoyl groups of the quinoxaline fragments, whereas the ions of group III are bound not only by the initial compounds and radical cations 1 and 2, but also by dication 1. This binding of the Ca²⁺ and Pb²⁺ ions stabilizes dication 1.