The badly packed molecules generate porosity
Scientists at the University have developed a new porous material that could be used to separate molecules.
The material was built from oddly shaped molecules which pack together badly. Most molecules pack together in an efficient way to leave no spaces, rather like bricks in a wall, but the team at Liverpool have prepared hollow, cage-like molecules which react together to form scrambled structures with a variety of different shapes.
Shan Jiang, a PhD student in the Department of Chemistry, who led the study, said: “As in the computer game Tetris, these dissimilar shapes cannot pack together effectively and hence gaps, or ‘pores’, are left between them. Unlike Tetris, however, bad packing is good because it generates porosity. This is a completely new type of material and we are now trying to understand more about its properties by building molecular models to simulate the pores.”
Each molecular building block is around 1 nm in size – about 60,000 times smaller than the width of a human hair. The materials have high surface areas and could have applications, for example, in absorbing pollutants from the atmosphere or in speeding up certain chemical reactions.
Shan Jiang added: “We anticipate this type of material could be used as a molecular filter. This is because we can adjust the size of the pores in the solid by varying the ratio of molecular shapes. In principle, this might be exploited to separate valuable molecules from waste streams or to remove toxic molecules in a filter device, like a gas mask. To be scaled up, though, we would need to do other tests and the materials would need to be cost effective.”
The research, published in the journal Nature Communications, forms part of a broader five-year programme focusing on the synthesis of new functional materials. The project is funded by the Engineering and Physical Sciences Research Council (EPSRC).