The host-guest properties of [1(5)]-paracyclophane ([1(5)]PCPs) are engendered by pi-metalation, which exhibits fantastic regioselectivity toward a macrocyclic molecule. The synthesis and characterization of mono-, di-, and trimetalated [1(5)] PCPs are discussed in this article, and the anion binding behavior of 3Ru-[1(5)]PCP-II6+, one of the trimetalated [1(5)]PCPs, driven by anion-pi interactions, is comprehensively demonstrated in both solution and the solid state. The anion binding properties of 3Ru-[1(5)]PCP-II6+ in solution are investigated by H-1 NMR titrations, showing selectivity toward ReO4- in both organic and aqueous solutions. The binding mode is unexpected; the anionic guest stacks over the host rather than threads it. This selectivity for ReO4- is also supported by water-nitromethane extraction experiments, which demonstrate that its partition from water into the organic phase by 3Ru-[1(5)]PCP-II center dot 6OTf is maintained to some extent in the presence of excess Cl-, SO42-, H2PO4-, NO3-, and ClO4-.