High Pressure Coordination Chemistry

We recently found that by applying high pressure to crystals of a molecule containing a palladium metal atom and three sulfur atoms caused it to polymerise into a chain. The crystal also changed colour from orange to really deep black. This happened at a pressure of around 44,000 atmospheres and we are trying to find out the reasons for the colour change by doing spectroscopic measurements and carrying out theoretical calculations. Very recently we found another molecule containing palladium and six sulfur atoms which has not one but two colour changes: as the pressure is applied the crystals of this compound first turn from blue to grey, then at higher pressure they turn from grey to orange. We are going to look at some other palladium compounds, and some with other metals such as platinum and gold, to see what happens to them under pressure.We are also going to use pressure to look at what happens to molecules inside the channels of porous compounds made from metals such as copper. These are promising candidates for the efficient storage of gases like hydrogen which could be used as clean fuel sources for cars. We need to find out how and where the molecules interact with the inner surfaces of the channels, so that we can make them into better storage containers.The high pressure experiments are done in a small pressure cell only five centimeters across and we get very high pressures just by tightening some screws. We will be doing a lot of the work the UK's newest and biggest scientific facility, the Diamond Light Source in Oxfordshire, which produces very strong X-ray beams which we fire into the crystal in the high pressure cell - this lets us work out the structure of the molecules.