Dramatic Structural Rearrangements in Porous Coordination Networks

Abstract

With the use of ab initio X-ray powder diffraction, a family of isostructural crystalline porous coordination networks, [(ZnX(2))(3)(TPT)(2)](n)· (solvent) (X = I, Br, Cl), has been studied at elevated temperatures of 573-723 K. Upon heating, all three networks exhibited crystalline-to-amorphous-to-crystalline (CAC) phase transformations to three new networks, [(ZnI(2))(3)(TPT)(2)](n), [(ZnBr(2))(3)(TPT)(2)](n)·(H(2)O) and [(ZnBr(2))(μ-Br)(ZnBr)(TPT)](n), and [(ZnCl(2))(μ-Cl)(ZnCl)(TPT)](n), respectively. A set of control experiments was used to obtain detailed mechanistic aspects of the CAC transformations. We demonstrate how bonds are broken and formed in these significant molecular rearrangements and how the initial arrangement plays a crucial role in the formation of the new networks after the CAC transformations. The structural information in the amorphous phase is retained and passed from a metastable to a more stable crystal, thus, reinforcing the notion that coordination networks are flexible and chemically active.

The Crystalline Sponge Method in Water

“…[a] Under influence of the solvent the crystals converted into a different non‐porous structure: refcode IZUVAB in the CSD. [b] RUM‐3 finally decomposes in pure water, but did allow for the elucidation of ϵ ‐caprolactam, which was introduced from an aqueous solution.…”

Selective Trapping of Labile S3 in a Porous Coordination Network and the Direct X-ray Observation

“…19,20 These features can be used for many applications, e.g. as a crystalline molecular flask in which unstable species can be encapsulated and analyzed by crystallography.…”

Unstable Species Chemistry Explored by Powder Structure Analysis

“…We demonstrated that it is possible to perform ab initio powder structure determination of porous coordination networks using low resolution data; totally different coordination networks can be selectively prepared from the same starting materials by thermodynamic and kinetic control; a robust porous coordination network can be prepared from the kinetic product which can be prepared instantly and in a large scale. [1][2][3][4][5] We also demonstrated that a pore in porous networks can be used as a crystalline molecular flask. 6 The robust networks maintain crystallinity and enable direct observation of unstable species by X-ray diffraction.…”