A biscalix[4]arene-based ditopic hard/soft receptor for K+/Ag+ complexation

✍ Scribed by Jan Budka; Pavel Lhoták; Ivan Stibor; Veronika Michlová; Jan Sykora; Ivana Cisarová

• Publisher: Elsevier Science
• Year: 2002
• Tongue: French
• Weight: 327 KB
• Volume: 43
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)00343-x

✦ Synopsis

A biscalixarene bearing tert-butylated and de-tert-butylated calix[4]arene unit connected by four ethylenoxy bridges has been prepared. This compound adopts the pinched cone conformation (C 2v symmetry) and hence, is suitably preorganised for Ag + complexation. X-ray crystallography showed that the silver cation (soft) is sandwiched by the two distal coplanar phenyl rings of the de-tert-butylated part of the molecule possessing a h 1 binding mode. The complexation of the K + cation (hard) into the central cavity created by the bridging moieties leads to a change of conformation (C 4v symmetry) and hence, to the complete loss of complexation ability towards the Ag + cation.