No abstract

In this contribution we investigated the ion complexation of Bühl's cryptand, dodeka(ethylene)octamine by quantum chemical methods (B3LYP/LANL2DZp). This cryptand is an isomer of a well‐known Lehn‐type cryptand [TriPip222]. The ion selectivity was determined based on the energetic criteria derived by model reactions starting from solvated metal ions and empty dodeka(ethylene)octamine, and by comparing the M–N bond length in [M ⊂ dodeka(ethylene)octamine]m+ and [M(NH3)6]m+. We calculated that Bühl's cryptand will complex best Na+ followed by Li+ as alkaline cations and Ca2+ followed by Mg2+ as alkaline earth metal ions. Based on this data we conclude that Bühl's cryptand offers a smaller cavity to nest ions than the Lehn‐type [TriPip222].

In supramolecular chemistry, a metal ion in a box as in Bühl's cryptand, should not move freely. The cation requires good interactions with the donor atoms and a complementary size. This was illustrated by Ms. Angelina Hans, graduate of the art class, Lothar‐von‐Faber‐Schule, Staatliche Fachoberschule, Nürnberg. More details are discussed in the article by Ralph Puchta, Daniel Walther, Matthias März, Svetlana Begel, and Rudi van Eldik on page 701.