title: Formation of zeolite-like zinc 1,3,5-benzenetriphosphonate open-frameworks by topotactic pillaring of anionic layers.
abstract: An ab initio powder X-ray crystal structure analysis revealed that layered zinc 1,3,5-benzenetriphosphonates containing interlayer tetramethylammonium (ZBP-TMA) or 4,4'-bipyridinium cations (ZBP-bpy) are transformed to novel isomorphous 3D open-framework compounds ZBP-M (M: K, Rb, and Cs) by treatment in aqueous alkali metal chloride solutions. ZBP-Ms have a pillared layer-type of anionic framework containing 2D zigzag channels connected with cage-like spaces. The potassium atoms in ZBP-K are located near 8MR windows in the 2D zigzag channels, and the potassium cations are successfully exchanged with ammonium cations retaining the open-framework structure. The ammonium form (ZBP-NH4) showed remarkable cation exchange selectivity for Rb(+) and Cs(+) in a mixture of alkali metal cations. It is assumed that zinc ions partially dissolved from the starting layered ZBP precursors are intercalated in ZBP layers to form pillared layered 3D open-frameworks. These results clearly show that topotactic pillared layer approaches are applicable not only to zeolite-related materials but also to novel open-framework metal organophosphonates.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan. k-maeda@cc.tuat.ac.jp
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Maeda
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takamatsu
authors.forename: Miki
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Kanako
authors.initials: K
authors.lastname: Kawawa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kondo