We are interested in all aspects of supramolecular chemistry and functional materials, especially those involving transition metals. Our approach is to design molecule-based materials, implement methods for their synthesis, then investigate their properties. Molecular design, synthetic chemistry, and materials analysis underpin our research. In addition to advancing fundamental knowledge, our research is directed towards real-world applications in catalysis, gas storage and separations. We do a lot of crystallography - check out this animated adventure in crystallography.
The current focal points of our research are:
Metal-organic frameworks are essentially sponges for other molecules! MOF crystals look solid but they sustain networks of tiny pores. These pores are about the size of molecules, and the pore surfaces are prefect for capturing these incoming molecular guests. A vast area of pore surface (more than than any other known material) is available inside these innocuous looking crystals. In fact, if you could lie the surface areas flat about a teaspoon of MOF would extend over a football field. Researchers in this area are heading towards applications such as gas storageformethane-powered vehicles. Here the idea is that you pre-fill your methane fuel tank with a MOF. Since the methane molecules sit on the MOF surface they don't generate as pressure in your fuel tank and you can drive more safely and for longer distances. The sequestration of CO2 is also an emerging target. Capturing CO2 as it is emitted from a pollution source - or even directly snaffling it from air - would make a huge dent in atmospheric CO2 levels.
MOFs have two basic constituents: metal clusters, which act as nodes and organic ligands, which act as linkers. A tremendously diverse array of MOFs is possible and research efforts around the world have already brought hundreds of these materials to fruition in the lab. Their outstanding properties make this a vibrant and exciting field. Our contributions include the recent discovery of a series of MOFs in which one lattice is fully occupied while another is present to a varied extent. These partially interpenetrated frameworks both have open regions that can act as a reservoir for incoming gas molecules as well as tight spaces, which can discriminate and sort the guests bases on their size and chemical characteristics.
We are also captivated by multicomponent MOFs, which are frameworks built up from a number of different components. These MOFs feature complex - yet regular and periodic - pore architectures. We have synthesized the first quaternary MOFs (with three different ligands) and have developed a strategy for programming its void spaces in MOFs. These frameworks are modular: multiple functional groups can be introduced without changing the framework topology. This enables us to systematically control the pore architectures. We anticipate that unique functional properties will arise in other materials designed by this strategy.
Although it runs counter to our instincts (in that we prize the beauty and quality of MOF crystals), we have found that toasting them in a furnace at high temperatures leads to interesting carbon-based materials that act as potent catalysts.
In earlier work we introduced the concept of thermolabile groups in MOFs that serve to suppress framework interpenetration and mask reactive functional groups. Extensions to this work encompassed photolabile groups and MOFs with the ability to catalyse chemical reactions. Current work in the group is focused on extending this concept to generating reactive sites in MOFs and to tailoring MOF pores for adsorption applications. In addition, we are interested in ways by which MOFs can be interfaced with conductive surfaces for applications in sensing and electrocatalysis.
Dipyrrins are a versatile and fascinating class of ligands which have parallels with natural chromophores such as chlorophyll. Their ability to capture a significant fraction of sunlight means they have promise as components of renewable energy systems such as solar cells and devices that can generate hydrogen from water with the help of sunlight. We are interested in synthesizing new chromophoric metal complexes with dipyrrin ligands and investigating their spectroscopic and photofunctional properties. 'Dual chromophore' complexes, which feature dipyrrins in addition to another chromophore, are of particular interest. This programme extends to bodipys and azabodipys, which are boron-centered dipyrrin chromophores.