Macrocyclic π-Conjugated Carbopolyanions and Polyradicals Based upon Calix[4]arene and Calix[3]arene Rings

摘要

Calix[4]arene- and calix[3]arene-based polyether precursors to polyradicals are synthesized. π-Conjugated carbanions, such as calix[4]arene-based tetraanion and calix[3]arene-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 calix[4]arene-based S = 2 tetraradical. However, ESR spectroscopy suggests that the predominant product from oxidation of calix[3]arene-based trianion is the corresponding triradical dimer. The related calix[3]arene-based S = 1 diradical is found to be monomeric. Additional characterization of octaradical 1~(8·) and pentaradical 2~(5·), which were described in a preliminary communication, is presented.