During the past four decades, supramolecular chemistry has been strongly influenced by several ‘cavitand’ receptor families, such as the cyclodextrins, calixarenes, cyclophanes, and cucurbiturils. Many other molecular receptors have been prepared and investigated in the last 20-30 years, but few have reached the widespread impact associated with the four host families mentioned above. Recently, pillar[<i>n</i>]arenes have attracted considerable attention as supramolecular hosts due to their rigid, “pillar”-like structure and their ease of functionalization. In the particular case of pillar[5]arene hosts, functionalization of the macrocyclic core by oxidation of one or more of the constituent hydroquinone units has been independently demonstrated by the groups of Stoikov, Xue and Ogoshi. We recently reported the voltammetric behavior of pillar[5]quinone, the fully oxidized macrocycle containing five equivalent 1,4-benzoquinone units connected by methylene bridges. In dichloromethane solution, our voltammetric data revealed that the uptake of the first five electrons follows a 2-1-2 pattern dictated by the pentagonal symmetry of the molecule and the minimization of electrostatic repulsions among the electrogenerated charges. Therefore, we were interested in expanding these voltammetric studies to structurally related redox-active, quinone-containing pillar[<i>n</i>]arenes. In this work, we will report the electrochemical behavior of 1,4-decamethoxypillar[5]arenes in which one to five of the aromatic units are oxidized to 1,4-benzoquinones (Fig. 1).

Electroreduction pattern of quinone units in pillar[5-n]arene[n]quinones

253rd National Meeting (2017)

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