Wirt-Gast-Komplexe von [bfu.bfu.bfu]: Vorhersage von Ionenselektivitäten mittels quantenchemischer Rechnungen XIII

Abstract

Abstract The CH2–O–C2H4–O–CH2 moieties in Lehn’s cryptand [2.2.2] have been substituted by 2,2′-bifurane groups to get the cryptand [bfu.bfu.bfu]. The ion selectivity of this new cryptand was investigated by DFT calculations (RB3LYP/LANL2DZp, RB3LYP/LACVP*, RBP86/LANL2DZp and RBP86/LACVP*) based on model equations and analysis of the [M ⊂ bfu.bfu.bfu] n+ cryptate structures. The cryptand [bfu.bfu.bfu] is best suited for the alkali cations Na+ and K+, and the alkaline earth cation Sr2+ followed by Ca2+. The cavity of [bfu.bfu.bfu] is thus similar to that in [phen.phen.phen] or [bpy.bpy.bpy]. The selectivity of [bfu.bfu.bfu] is due to the flexibility of the OCCO und CN···NC dihedral angles. The results are independent of the selected DFT methods.