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 hostguest 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 hostguest chemistry is also reproduced in crystals, therefore enabling their visualization by X-ray crystallography. Furthermore, a new method based on crystalline-state hostguest chemistry was developed for the singlecrystal 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.

An Iodine‐Vapor‐Induced Cyclization in a Crystalline Molecular Flask

“…The advent of crystalline molecular flasks (CMFs) has provided a breakthrough in the crystallographic visualization of chemical processes and species . This stems from the ability of the flexible coordination polymer in question, which is derived from 2,4,6‐tris(4‐pyridyl)‐1,3,5‐triazine (tpt) linkers and zinc halide nodes, to swell and contract upon solvent addition and loss, and undergo guest exchange in a single‐crystal‐to‐single‐crystal manner .…”

Criegee Intermediates Beyond Ozonolysis: Synthetic and Mechanistic Insights

“…Minireviews ozonide intermediates have been visualized in the crystalline state. [25] Ap orous coordination assembly [(ZnI 2 ) 3 (tpt) 2 • x(solvent)] n (tpt = tri(4-pyridyl)-1,3,5-triazine) serves as the crystalline sponge,which bears defined cavities and encapsulates guest/target ozonides molecules that hardly crystalize under normal conditions (Figure 5).…”

Isolating reactive metal-based species in Metal–Organic Frameworks – viable strategies and opportunities

“…Some of the initial uses of MOFs as a crystallisation matrix have demonstrated this point with electron rich guests being organised and characterised by X-ray crystallography in the pores of crystalline sponge hosts. 34,39,[150][151][152][153][154][155] More recently, this concept has been extended to reactive metal-based species by installing a reactive cartridge into the pore network. 20 Finally, inspired by the importance of metal nanoclusters (MNCs) in catalysis, a number of reports have now shown the precise structural characterisation of MNCs.…”