Materials based on polyanionic para-sulfonato-calix[ 4] arene and tetraphenylphosphonium (Ph4P+) or benzyltriphenylphosphonium (BzPh(3)P(+)) cations are built up via partial inclusion and extensive phenyl embracing in association with trivalent cations (Yb3+, Gd3+ and Er3+). The crystalline materials have layered structures and feature negatively-charged channels propagating through the solids.
Makha, M., Alias, Y., Raston, C., & Sobolev, A. (2007). Controlling the interplay of large organic ions : para-sulfonato-calixarene and phosphonium cations. New Journal of Chemistry, 31(5), 662-668. https://doi.org/10.1039/b615639h