A molecular level study of selective cation capture by a host–guest mechanism for 25,26,27,28-tetramethoxycalix[4]arene in MClO4 solution (M = Na,K)

25,26,27,28-Tetramethoxycalix[4] arene selectively captures cations by changing the conformation. In this study, a hybrid approach of ab initio molecular orbital calculation and statistical mechanics for molecular liquid was utilised to understand the capture mechanism in electrolyte solution phase at molecular level. The association free energy and solvation structure were evaluated on the basis of statistical mechanics for molecular liquids. The selectivity is correctly reproduced by the computation, namely cone conformer captures Na⁺ while K⁺ is recognised by the partial-cone conformer.