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.

Ordered Microporous Layered Lanthanide 1,3,5‐Benzenetriphosphonates Pillared with Cationic Organic Molecules

“…They are readily dispersed in ethanol, suggesting delamination to nanosheets. It was also shown that the layered ZnBPs were transformed to zeolite‐like 3D open‐framework materials by topotactic pillaring with zinc ions assisted by cation exchange with alkali metal ions 7c. These results clearly show potential of metal organophosphonate layers as versatile nanoparts towards tailored nanospace.…”

“…It is well‐known that these inorganic layered materials can be transformed to various types of nanostructured materials, such as organically intercalated layers, porous pillared‐layer materials, ordered mesoporous materials, zeolite‐like and open‐framework crystalline materials, exfoliated nanosheets, and nanotubes/nanorolls 9. 10 We have shown that these strategies are also applicable to layered inorganic–organic hybrids, such as metal organophosphonates and 2D MOFs/coordination polymers 7b,c. 11 The layered ZnBP system also demonstrated the validity of this approach.…”

Robust Metal‐Organic Frameworks Based on Tritopic Phosphonoaromatic Ligands

“…H 6 btp is the simplest ligand belonging to this class of molecules and it is by far the most widely employed to date . It was also the first of the series ever to be investigated, by the Clearfield group in 2006 .…”

New layered copper 1,3,5-benzenetriphosphonates pillared with N-donor ligands: their synthesis, crystal structures, and adsorption properties

“…[39][40][41][42][43] The use of tri-functional or higher functional organophosphonic acids has been explored to avoid the formation of such conventional dense pillared layered structures and several groups including us have successfully synthesized metal organophosphonates with unique framework structures and properties. [44][45][46][47][48][49][50][51][52] For example, using tri-functional organophosphonic acid 1,3,5-benzenetriphosphonic acid (BTP = H 6 btp), we synthesized a layered zinc phosphonate Zn 2 [C 6 H 3 (PO 3 ) 2 PO 3 H]•0.5H 2 bpy•H 2 O (ZnBP-bpy), which is composed of anionic metal phosphonate layers and protonated 4,4′-bipyridine cations, by a hydrothermal reaction. 49 Interestingly, ZnBP-bpy shows a topotactic transformation to a zeolite-like open-framework with selective cation exchange properties.…”