Structural phases of hexamethylenetetramine–pimelic acid (1/1): a unified description based on a stacking model

Gardon, M.; Pinheiro, C.B.; Chapuis, G.

doi:10.1107/S0108768103011297

Figure 5
Representation of the three different stacking sequences deduced from the model. The left-hand schemes represent the cross sections perpendicular to $[{\bf c}_{L}^{}]$ of the corresponding stacking sequence along $[{\bf a}_{L}^{}]$ . Each rectangle (each containing an ABAB sequence) symbolizes the cross section of two unit cells. The right-hand schemes represent the corresponding reciprocal lattice. The stacking translations $[{\bf t}_{\pm}^{} = {\bf a}_{L}^{}\pm {{1}\over{4}}{\bf c}_{L}^{}]$ are also indicated by arrows. (a) The structure of Phase I resulting from a sequence of translations constrained by a given probabilistic parameter $[\eta]$ . The diffuse scattering streaks are schematized by dashed lines in the reciprocal-lattice representation. (b) The structure of Phase II resulting from a perfect alternating sequence of translations $[{\bf t}_{+}^{}]$ and $[{\bf t}_{-}^{}]$ . The unusual absence distribution is well emphasized on the reciprocal-lattice representation. (c) The structure of Phase III where ordered domains appear owing to the large probability of having a sequence of the same translation $[{\bf t}_{+}^{}]$ or $[{\bf t}_{-}^{}]$ . The domain walls corresponding to the interface between orientational domains can also be reproduced. The cells of both orientational domains are indicated. The corresponding reciprocal unit cells are reported together with the different class of reflections.

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ISSN: 2052-5206

Volume 59| Part 4| July 2003| Pages 527-536

doi:10.1107/S0108768103011297

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