A mechanochemically synthesised solid solution enables engineering of the sorption properties of a Werner clathrate

Non-stoichiometric molecular mixed crystals have potential as functional materials, the properties of which can be tailored by rationally changing their composition. The guidelines for their preparation were summarized over thirty years ago by Alexander Kitaigorodsky. Here those principles are revised in light of new studies on the acridine/phenazine system, and solvent-assisted grinding is presented as a convenient synthetic procedure to afford a more homogeneous product than traditional solvent-evaporation methods. Finally, the proposed prerequisite of crystal isostructurality/isomorphicity for the pure compounds, which seems to be violated in the present case, is discussed.

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“…Indeed many solid solutions of non‐isostructural crystals are known; they show limited solubility 8b. 9a, 23…”

Section: Discussionmentioning

confidence: 99%

Kitaigorodsky Revisited: Polymorphism and Mixed Crystals of Acridine/Phenazine

Schur

Nauha²,

Lusi³

et al. 2014

Chemistry A European J

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“…Recently there has been renewed interest in Werner clathrates 5,6 and Lusi and Barbour 7 have described polymorphism associated with an order-disorder phase transition of the guest in the [Ni(NCS) 2 (4-phenylpyridine) 4 ] clathrate dependent on the thermal range investigated. The host preferentially discriminated in favour of one of the three isomers of xylene in solid-vapour competition experiments 8 and Batisai and co-workers 9 explored the preparation of phases by mechanochemical techniques which resulted in a series of solid solutions. Different sorption properties were exhibited by these solid solutions compared with the pure Werner complexes.…”

Section: Introductionmentioning

confidence: 99%

Isoquinoline-based Werner clathrates with xylene isomers: aromatic interactions vs. molecular flexibility

2015

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The crystal structures of the Werner clathrates Ni(NCS)2(isoquinoline)4 (H) with para-xylene (px), meta-xylene (mx) and ortho-xylene (ox) have been elucidated. The kinetics of thermal decomposition of the three inclusion compounds were performed using the isothermal technique of Flynn and Wall. Selectivity of H for the xylene isomers was determined for both the liquid and vapour phase binary mixtures of the xylenes. The chosen ligand has a larger aromatic system to improve the possible π interactions between H and the selected guests. The planarity of the isoquinoline ligand causes H rigidity and its selectivity was compared to a related Werner complex containing the more flexible 4-phenylpyridine.

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“…While investigating the separation properties of a Werner complex [17][18][19] we found that one of its clathrates undergoes a single-crystal to single-crystal transformation in which the crystal symmetry is increased while the unit cell metrics are preserved. The transformation is associated with an orderdisorder phase transition involving the guest.…”

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confidence: 99%

“…Remarkably, despite their structural similarity, the same behaviour was not observed in other clathrates of the same host. [17][18][19] Crystals of [Ni(NCS) 2 ppp 4 ]•2m-xyl (1) (ppp = para-phenylpyridine, m-xyl = meta-xylene) were obtained following a previously reported procedure. A single crystal was selected and its crystal structure determined with the diffraction data collected at 100 K (1 100 ).…”

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confidence: 99%