Synthesis and Conformational Characteristics of Nonsymmetric Pillar[5]arene

A new nonsymmetric pillar[5]arene of ethoxymethoxypillar[5]arene (EMpillar[5]arene) has been synthesized. By 2D ROESY analysis of EMpillar[5]arene, the ethoxy and methoxy moieties were completely separated at the upper and lower rims, respectively. Moreover, by the variable-temperature (1)H NMR measurements of EMpillar[5]arene, the rotational movement of phenolic units in EMpillar[5]arene was slow on the NMR time scale or did not occur.