Inorganic-Organic Hybrid Framework Materials

Our research is concerned with the synthesis, characterisation, crystal growth and application of novel inorganic-organic hybrid framework materials. These materials are of particular interest because within one material the benefits of both types of chemistry are present. The inorganic region of the structure provides the stability required for many applications and the potential to include one or more different types of metal centre, each with its own particular magnetic, electronic and catalytic properties, while the organic sections, through careful choice of their structure and the functional groups present, enable the functionality and the overall framework architecture of the material to be rationally designed. Control of the amounts of each region also allows the hydrophilicity/ hydrophobicity of the internal surface of the material to be tuned for the particular process the material is being designed. These hybrid materials will help in the developement of more envir onmentally benign, more efficient and lower cost processes attractive to the chemical, petroleum and pharmaceutical industries.

The research has initally focussed on investigating the synthesis of novel group 13 metal phosphonate and diphosphonate materials with particular emphasis on rationally designing the pore architecture of the resultant microporous material. New materials that have been produced include the framework aluminium butylenediphosphonate material, shown above, that contains a one-dimensional channel system. The pore architecture of this type of material may be designed through several methods including substitution of the diphosphonate groups for other groups, substitution of metal cations for other metal cations and by using different diphosphonatate groups to form the framework structure of the material.

We have also begun to investigate the crystal growth of porous hybrid framework materials using atomic force microscopy to monitor the details of the crystal surface structure from which we gain an understanding of the fundamental crystal growth processes involved. Such studies on the metal organic framework material, HKUST-1, have revealed that sprial growth is prominent on the surface of crystals of this material, as shown above.

Germanate-based Microporous Materials

Germanate-based microporous materials are currently of great interest as a new range of microporous materials is being discovered, some of which are exhibiting the largest pore structures reported for solely inorganic crystalline microporous materials. Our work is aimed at synthesising, characterising and applying new large pore germanate-based materials, such as that shown above that we recently produced using an amine templating agent. We are also investigating the isomorphous substitution behaviour of these germanate-based materials and how properties, such as thermal stability, are effected by such modification.

All the above research involves the use of an array of solid-state synthetic and characterisation techniques including: solvothermal synthesis, single, micro-crystal and powder X-ray diffraction (XRD), atomic force microscopy (AFM), magic angle spinning solid state nuclear magnetic resonance (MAS SSNMR) and infra-red spectroscopy (IR), thermal analysis (TGA/ DSC) and porosimetry.