2,3-Anthraceno[2.2.2]cryptand. Mutual interactions between the receptor and the signal transducing subunit

Abstract

As a complement to the study of 9,10- and 1,4-anthracenocryptands, 2,3-anthraceno[2.2.2]cryptand (1) was synthesized in order to examine the mutual influence of the two components: the cation-binding subunit and the pendent aromatic moiety. It was shown that the receptor subunit induces small perturbations to the absorption spectrum and the fine structure fluorescence spectrum of 1 that are typical of those of 2,3-disubstituted anthracene reference molecules. Conversely, the stability constants towards metal cations (K_s), determined from the electronic spectra using the LETAGROP programme, were found to be altered by the incorporated aromatic component, namely lowered by several orders of magnitude compared with those of [2.2.2]cryptand. For instance, logK_s values in CH₃CN for 1 were found to be: K⁺(8); Tl⁺(10); for [2.2.2]cryptand: K⁺(11); Tl⁺(12). The observed decrease of binding ability can be attributed to a relative lack of flexibility of the receptor and some hindrance to cation solvation due to the aromatic component.