SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF CALIX[4]ARENE-TRIESTER-MONOQUINONES

Calix[4]arene-based monoquinones having three efficient ligating group s of alkoxycarbomethyl ethers were prepared and their ionophoric prope rties were investigated by electrochemical technique. Calix[4]-trieste r-monoquinones 3a and 3b were prepared from calix[4]arene and p-tert-b utylcalix[4]arene by the selective trialkylation followed by oxidation with Tl(NO3)(3) and Tl(CF3CO2)(3), respectively. X-ray crystal struct ural analysis revealed that the ligand 3a adopted a partial cone confo rmation with an anti quinone moiety. MM+ calculations suggested that t he energy difference between the two conformations is relatively small (<3.5 kcal mole(-1)). Electrochemical studies also showed that the mo noquinones 3a and 3b form strong complexes with Na+ ion, and the posit ive shifts in the reduction potential exceeded those of the closely re lated diquiones 5a and 5b.