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Issue 29, 2015
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Hydrate smaller than the anhydrate

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Anhydrous 5,6-dimethylbenzimidazole (dMBzIm) crystals are obtained from an aqueous solution at ambient pressure, but above 0.25 GPa the hemihydrate dMBzIm·½H2O is formed. It can be stored for over a year in open vials. Counter-intuitively, the volume of dMBzIm·½H2O is smaller than that of the anhydrate. Ambient and high-pressure structures of dMBzIm and dMBzIm·½H2O crystals grown in situ in a diamond-anvil cell have been determined by X-ray diffraction methods. The isostructural phase transition observed in dMBzIm at 0.25 GPa coincides with the changed preference to hemihydrate crystallization. The significantly different ambient and high-pressure hydration preferences of imidazole and benzimidazole derivatives have been explained by the interplay of interactions and the efficiency of crystal packing measured by the size and volume of voids.

Graphical abstract: Hydrate smaller than the anhydrate

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Publication details

The article was received on 09 Apr 2015, accepted on 01 Jun 2015 and first published on 02 Jun 2015

Article type: Paper
DOI: 10.1039/C5CE00694E
Citation: CrystEngComm, 2015,17, 5468-5473

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    Hydrate smaller than the anhydrate

    W. Zieliński and A. Katrusiak, CrystEngComm, 2015, 17, 5468
    DOI: 10.1039/C5CE00694E

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