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Solid-State Transformations of Zinc 1,4-Benzenedicarboxylates Mediated by Hydrogen-Bond-Forming Molecules

The zinc 1,4‐benzenedicarboxylates [Zn3(bdc)3(H2O)3]⋅4 DMF (1; bdc=1,4‐benzenedicarboxylate), [Zn(bdc)(H2O)]⋅DMF (2), and [Zn(bdc)]⋅DMF (3) crystallise at room temperature from mixtures of toluene/dimethylformamide (DMF) under concentrated, dilute and dry conditions, respectively. The structure of p...

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Bibliographic Details
Published in:Chemistry : a European journal 2001-12, Vol.7 (23), p.5168-5175
Main Authors: Edgar, Mark, Mitchell, Robert, Slawin, Alexandra M. Z., Lightfoot, Philip, Wright, Paul A.
Format: Article
Language:English
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Summary:The zinc 1,4‐benzenedicarboxylates [Zn3(bdc)3(H2O)3]⋅4 DMF (1; bdc=1,4‐benzenedicarboxylate), [Zn(bdc)(H2O)]⋅DMF (2), and [Zn(bdc)]⋅DMF (3) crystallise at room temperature from mixtures of toluene/dimethylformamide (DMF) under concentrated, dilute and dry conditions, respectively. The structure of phase 1 (monoclinic: P21/c, a=13.065(1), b=9.661(1), c=18.456(1) Å, β=106.868(2)°) consists of layers containing stacks of three zinc cations linked by mono‐ and bidentate bdc groups. Structure 1 converts to the known phase 2 by an irreversible, reconstructive phase transformation, whereas 2 and 3 interconvert reversibly upon the loss or addition of water. Removal of all solvent molecules included during crystallisation gives poorly crystalline [Zn(bdc)] (4), which is readily converted to highly crystalline solids upon contact with hydrogen‐bond‐forming molecules such as water, DMF and small alcohols. The crystal structures of the mono‐ and dihydrates [Zn(bdc)(H2O)] (6) and [Zn(bdc)(H2O)2] (7) have been determined ab initio from powder X‐ray diffraction data (compound 6, monoclinic: C2/c, a=17.979(1), b=6.352(1), c=7.257(1) Å, β=91.477(1)°; compound 7, monoclinic: C2/c, a=14.992(1), b=5.0303(2), c=12.098(1) Å, β=103.82(1)°). The methanol adduct [Zn3(bdc)3]⋅6 CH3OH (5) is the same as that prepared previously by direct crystallisation. Comparison of these adduct structures with those prepared directly reveal that they are formed by in situ recrystallisations. Subsequent removal of included molecules gives amorphous [Zn(bdc)], which can be recrystallised again when placed in contact with hydrogen‐bond‐forming molecules. Preparation, polymorphism, and inclusion properties of zinc/benzenedicarboxylate organic–inorganic hybrid materials. Solid‐state recrystallizations of two‐ and three‐dimensionally connected lattices (an example is illustrated here) are monitored, showing that such framework materials depend critically on the properties of the solvents employed in their preparation and that their subsequent selectivity arises as a consequence of inclusion and recrystallisation and not as a result of pre‐formed micropores.
ISSN:0947-6539
1521-3765
DOI:10.1002/1521-3765(20011203)7:23<5168::AID-CHEM5168>3.0.CO;2-S