Calixarene- and calixarene-based polyether precursors to polyradicals are synthesized. π-Conjugated carbanions, such as calixarene-based tetraanion and calixarene-based trianion, are prepared and studied using NMR spectroscopy and voltammetry. A 4-fold-symmetric conformer for the tetraanion and two non-interconverting conformers (3-fold- and 2-fold-symmetric) for the trianion are found on the NMR time scale. Oxidation of the tetraanion gives the corresponding calixarene-based S = 2 tetraradical. However, ESR spectroscopy suggests that the predominant product from oxidation of calixarene-based trianion is the corresponding triradical dimer. The related calixarene-based S = 1 diradical is found to be monomeric. Additional characterization of octaradical 18. and pentaradical 25., which were described in a preliminary communication, is presented.
ASJC Scopus subject areas
- Colloid and Surface Chemistry