Janusene as a silver ion scavenger: insights from computation

Abstract

Janusene is a [3,3]ortho-cyclophane that possesses four aromatic moieties of which two are held together in a quasi-parallel or in a cleft-shaped arrangement. The multiple coordination sites available in janusene were tested by bonding of Ag⁺ ions in different positions of the janusene structure, leading to 35 systems. Our results evidence that janusene is able to stabilize up to five Ag⁺ ions simultaneously. Due to the symmetric coordination positions, several isomers have been obtained with systems containing up to 4 Ag⁺ ions. Janusene–Ag⁺ interactions, for all systems, are partially covalent in nature, mainly stabilized by ΔE_orb and ΔE_ele interactions. MEP isosurfaces reveal that the different Ag⁺ coordination modifies the janusene electron density, thus modulating the reactivity of its rings. Janusene is also able to stabilize, by ≈−130 kcal mol⁻¹, a [Ag_A⋯Ag_B]²⁺ interaction at short distances, in the cleft between facial rings. Interestingly, these interactions are enhanced by coordination of other Ag⁺ ions, increasing the lateral rings’ orbital interactions to the stabilization of the [Ag_A⋯Ag_B]²⁺ interaction. This study reveals the presence of some unusual and previously unexplored features of janusene's electronic structure.