High pressure chemistry
The PIs working in this area:
Chemistry is the center of natural science. Its core mission is to create and understand new substances. The new substances and the understanding of them in the view of chemistry are the foundation of further research in other subjects. High pressure science and techniques provide a new dimension for chemistry, in which you can create numerous new compounds and materials, which will revolutionize human understanding for substances and change human’s life.
The central question of chemistry is the chemical reaction. The basis of the investigation on chemical reactions is the understanding of the static and dynamic structures of the substances. Different from the traditional high temperature solid phase reactions, solution reactions, and gas phase reactions, the pressure employed for the proceeding of chemical reactions can be carefully controlled, with which the reactants can be "pushed" over the reaction barrier quasi-statically, which is much easier to be characterized. For example, the collision process in the solution reaction, as well as the gas phase reaction, is actually a tiny dynamic pressure process. This dynamic process will be “frozen” in some special geometry by the applied static pressure, which will make it easier to study the reaction process, and will also be of great help for the study of the “real” atmospheric chemical reaction.
High pressure chemistry is still a new subject. For a long time, chemists in this area mainly focused on pressure around or less than 1GPa, studied the effects of pressure on chemical reactions, and prepare new materials (such as superhard materials) under high temperature and high pressure conditions. Systematical study on the chemical reactions (especially the organic reactions) still needs to be developed.
In HPSTAR, the research areas of high pressure chemistry include (but not limited to) the following aspects:
1. The phase relationship of chemical elements under high pressure. Element is the basis of chemistry. Chemical properties of elements under high pressure and atmospheric pressure are clearly different. The phase relationship of the elements under high pressure is the foundation of the study of the periodic law under high pressure. HPSTAR conducts systematic research in the area.
2. The HP-HT synthesis of new materials. Simulating high temperature and pressure inside the earth, these two variables can be combined to create a variety of new compounds.
3. The polymerization of unsaturated compounds. Under high pressure atoms tend to get higher coordination number. Triple bonds and double bonds would polymerize under applied pressure, forming conjugated double bonds or single bonds. Different from the reactions under ambient pressure, the monomers are not limited to neutral molecules, and unsaturated ions with a high charge density (such as cyanide) can also get polymerized. Such reactions are not only of theoretical significance, but also have great application values. For example, systems containing transition metals and alkali metals can be applied to alkali metal battery cathode materials.
4. Hydrogen bonds and hydrogen transfer. Hydrogen bonds, as well as van der Waals interactions are very sensitive to pressure. Molecular crystals constructed by the hydrogen bond network have very complex phase relations under high pressure, which has an important influence on the origin and evolution of life. Under high pressure the distance between the donor and acceptor of proton is compressed, it is easier for proton to overcome the barrier (or tunneling).