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Hybrid 2D and 3D Frameworks Based on ϵ‐Keggin Polyoxometallates: Experiment and Simulation
Author(s) -
Dolbecq Anne,
MellotDraznieks Caroline,
Mialane Pierre,
Marrot Jérôme,
Férey Gérard,
Sécheresse Francis
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500230
Subject(s) - chemistry , ion , protonation , bridging (networking) , molecule , chloride , crystallography , tetrahedron , hydrothermal synthesis , hydrothermal circulation , derivative (finance) , inorganic chemistry , chemical engineering , organic chemistry , computer science , engineering , computer network , financial economics , economics
The ϵ‐Keggin polyoxomolybdate {ϵ‐PMo V 8 Mo VI 4 O 40– x (OH) x M 4 } is a versatile building unit, with M being either a Zn II or a La III capping ion located at the vertices of a slightly distorted tetrahedron. The charge of the Keggin unit depends on the number of protonated oxo bridging ligands, which has been shown to vary from 0 to 5. The Keggin entity can thus be either an anion (M = Zn, x = 0) or a cation (M = La, x = 3–5). The Zn derivative has been generated in situ by hydrothermal synthesis and forms a 2D material built from the connection of the cations by 4,4'‐bipyridine ligands linked to the capping Zn II ions. The reaction of the chloride salt of the La derivative with di‐, tri‐ and tetrasubstituted benzenecarboxylate ligands has allowed us to isolate 2D and 3D materials. The 3D materials seem to be the first examples of hybrid open frameworks based on Keggin building blocks. The 3D framework built from the connection of ϵ‐Keggin units by trimesate ions exhibits tunnels filled only by water molecules, which can be partly removed and reintroduced at room temperature. Besides these experimental results, simulation has allowed us to generate two virtual hybrid structures derived from those of known silicates by replacing the Si ions by hypothetical ϵ‐Keggin cations and the O ‐bridging ligands by terephthalate ions, thus showing that 3D frameworks with large pores can be envisioned in the chemistry of hybrid organic–inorganic materials based on ϵ‐Keggin units and motivating further experimental investigations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)