Abstract
Calixarenes are organic molecules which contain several aromatic units (in this work four) connected by methylene (""calixarenes"") or sulfur (""thiacalixarenes"") bridges. Calix[4]arenes can exist in four defined conformations: cone-, partial cone-, 1,2- and 1,3-alternating (Fig. 1).
The conformational stability of a (thia)calix[4]arene is controlled by the size of the substituents on the upper or the lower rim, or by other interactions (e.g. hydrogen bonds). These compounds are very attractive for supramolecular chemists, since they have the shape of a cavity, being able to exhibit host-guest interaction according to the substitution 1,2.
The calixarene skeleton itself is not reducible. Therefore it's necessary to introduce a suitable redox probe in the calixarene frame in order to use electrochemical methods for investigations of calixarene properties.
For the purpose of this study the nitro group was chosen because its electrochemical reduction proceeds easily in a well-defined way.