Photon Factory Activity Report 2004 #22 Part B (2005)
Chemistry

18B/2004G238

Structural Studies on Hybrid Organic-Inorganic Coordination Assemblies
Wolfgang SCHMITT*, Jonathan P. HILL
National Institute for Materials Science, ICYS, Tsukuba, 1-1 Namiki, Ibaraki 305 0044, Japan
Introduction
Molecular recognition and engineering of 3D
architectures are key features of supramolecularchemistry. Hybrid organic-inorganic coordinationassemblies stand for a class of supramolecular compound
whose preparation is a very active area in chemical andmaterials research. The concept of hybrid organicinorganic materials realizes experimental strategies forcustomizing physical and chemical properties byinfluencing dimensionality and devolution pattern ofclassical inorganic structures within organic matrices. A
few of the key research areas under this purview include
catalysis and separation science, gas storage media,
optical, electronic and magnetic materials etc. [1,2].
Synthetic methodology
We have developed synthetic approaches yielding in
novel coordination assemblies where the architecture anddimension of the inorganic regions of the materials isinfluenced by the functionality and shape of organic
ligands. The crystallographic studies investigate
structure-directing effects of iminodiacetic acidsubstituted phenols and naphthol derivatives (L) whichIII
react with Fe salts to give dinuclear complexes with the3–general formulae [Fe2(µ-OH)(µ-CO3)L2]
and [Fe2(µ4–/6–O)(µ-CO3)L2] . The counterions of these complexes
bind through the carboxylate groups and other O-donors
to these negatively charged complexes and are further
linked to each other through water molecules forming
supramolecular coordination assemblies. Variation of theorganic ligand results in structures where the packing ofhydrophilic and hydrophobic portions results, for instance,in lamellar arrangements, dense hexagonal arrays or
open-framework networks [3].
Structure of K6[Fe2(O)(CO3)(CHNIDA)2] ·13.5H2O (1)From aqueous systems, we crystallized a rather
fascinating example of such hybrid organic-inorganic
coordination networks, K6[Fe2(µ-O)(µ-CO3)(CHNIDA)2]·13.5H2O (1) and investigated the structure at BL 18B(Fig. 1). Crystal data: red cuboctahedron 0.2 x 0.2 x 0.2
mm, T = 200 K, rhombohedral, R-3c, a = 35.475(4), c =43.4480(4) Å, V = 47354(10) Å3, Z = 36, R1(F) = 12.8.
IIIThe X-ray analysis reveals that the Fe centres of thedinuclear complex are doubly bridged by a carbonate andan oxo ligand O(1). N- and O-donors of the iminodiacetic
acid moiety occupy facial positions of the distorted
octahedral coordination polyhedra whilst the bridging Odonor and the N-donors coordinate in trans positions
III
relative to each other. The dinuclear Fe complexes in 1
are organized so that the polar O-donors together with the40

Users' Reportwater-bridged K+ ions form a honeycomb structure. The
resulting channels, with a cross-sectional diameter of12nm, run in direction of the crystallographic c-axis andare filled with naphthyl moieties of the ligands. TheIII
dinuclear Fe subunits penetrate the honeycomb wallswith the Fe··Fe axis nearly perpendicular to the c-axis.
The naphthalene moieties of each FeIII complex project
into neighbouring channels and the naphthalene meanplanes form angles of 40.7 and 51.4º to the c-axis [3].
COOHa)
OHChnidaN

COOH
COOHb)

Figure 1. a) [Fe2(µ-O)(µ-CO3)(CHNIDA)2]6– in 1. b)
Supramolecular structure of 1 viewing in [001]. Colour
code: Fe green, O red, N blue, K purple, C dark grey.

Currently we are investigating thermal stability and gas
adsorption properties and conductivity of these materials.
In addition we use 1 as a template for the production ofnanostructured materials.

References[1] Comprehensive Supramolecular Chemistry, Vols. 111(Eds.: J.-M. Lehn, J. L. Atwood, J. E. D. Davis, D. D.
MacNicol, F. Vögtle), Pergamon Press, Oxford, 1990–1996.
[2] O. M. Yaghi, et al., Nature, 423, 705, (2003).
[3] W. Schmitt, et al., Angew. Chem., Int. Ed. in press.
* schmitt.wolfgang@nims.go.jp