Direct observation of transient species and chemical reactions in a pore observed by synchrotron radiation

Abstract

Here, we have described the direct observation of transient chemical species and chemical reactions using synchrotron radiation. Direct observation of transient and unstable chemical species by X-ray diffraction can greatly enhance our understanding of chemical reactions. On top of that, the use of pores in coordination networks has various applications and is a promising method to elucidate the structure of molecular species that do not inherently crystallize. In particular, kinetic assembly of coordination networks can generate interactive sites in the pores, which is very useful for trapping unstable species. Thus, the methodology using porous coordination networks, i.e., crystalline molecular flasks, allows us to observe a variety of crystalline phase reactions. At the same time, the development of synchrotron radiation and X-ray detectors has made it possible to challenge the microscopic crystals found in MOF crystals. This means that structural analysis is now possible with a smaller amount of target guest sample. In addition, spectroscopic methods and theoretical calculations have been developed to elucidate the electronic structure of these chemical species.