Host-guest complexes of a cryptand based on 5H-cyclopenta[2,1-b:3,4b′]pyridine moieties: prediction of ion selectivity by quantum chemical calculations XVI.

Selective alkaline and earth alkaline metal ion encapsulation by six different Lehn-type cryptands was predicted by DFT (B3LYP/LANL2DZp) computational chemistry. All cryptands contain three identical moieties connected by the aliphatic nitrogen atom, constructing a very structurally flexible system for accommodating different-sized metal cations. Inspiration for selected hosts was taken from already well-known Lehn-type Cryptand [phen.phen.phen] where one phenanthroline was substituted by 5H-cyclopenta[2,1-b:3,4b′]pyridine in which the CH2– group was replaced by a series of heteroatoms forming the selected series of investigated hosts. The ion selectivity and the ability of the hosts to adjust their structure to accommodate the metal cations successfully were based on energy and geometric criteria. Medium-size cations have been proven to be best fitted for the selected host series. [ABSTRACT FROM AUTHOR]