Visualization of solution chemistry by X-ray crystallography using porous coordination networks

Abstract

Porous coordination networks have two distinctive characteristics: robust coordination frameworks and fluid pores wherein molecules are mobile. These characteristics allow solution chemistry to be performed in the crystalline state, thus enabling single-crystal X-ray observation of various reactions and host-guest complexation usually observed in solution. From this viewpoint, porous coordination networks can be used as a tool for visualizing solution-based chemical reactions. Using this tool, we have visualized chemical reactions within porous coordination network crystals to elucidate the reaction mechanisms and to determine the molecular structures of the products and intermediates. When the nanospace of porous coordination networks is cleverly designed on the basis of the structures of hollow molecular hosts in solution, solution-like host-guest chemistry is also reproduced in crystals, therefore enabling their visualization by X-ray crystallography. Furthermore, a new method based on crystalline-state host-guest chemistry was developed for the single-crystal X-ray analysis of trace amounts of noncrystalline compounds using porous coordination networks. In this account, we review and discuss the visualization of unique solution-like phenomena by single-crystal X-ray analysis using porous coordination networks as crystalline hosts.