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

Abstract

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.

Keywords:

• Selective ion complexation
• cryptand
• host-guest chemistry
• DFT

Acknowledgments

D.Ć. thanks the Ministry of Education, Science and Technological Development of the Republic of Serbia (Agreement No. 451-03-9/2023-14/200122). We thank Johannes Endres, TH Nürnberg for technical support, Prof. Tim Clark and Prof. Petra Imhof for hosting this work at the CCC, and the Regionales Rechenzentrum Erlangen (RRZE) for a generous allotment of computer time.

Disclosure statement

No potential conflict of interest was reported by the authors.