The cover picture shows a novel pillararene entirely with both hydroxyl and methoxycarbonyl-methoxy groups and its host-guest property with a bis(imidazolium) salt. Pillararene, since it was first reported in 2008, has attracted a rising interest from many supramolecular chemists. Opportunities and challenges coexist in selective functionalization of pillararenes. Our group used a facile strategy (partial oxidation and reduction) to obtain the pillararene entirely with two types of functional groups from the initial starting compound, 1,4-dimethoxypillararene (DMP). Its self-assembly in the solid state showed that a water molecule had triple bonding with the host, which implied its potential application in new type of proton transmembrane channels. Thanks to this regioselective preparation, the host-guest property of this pillararene with a bis(imidazolium) salt was studied. More details are discussed in the article by Xue et al. on page 128–132.