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Kamil Dziubek & Andrzej Katrusiak

DIFFERENCES IN MOLECULAR ENVIRONMENTS OF POLYMORPHS. Kamil Dziubek & Andrzej Katrusiak. In dealing with a polymorphic s ystem perhaps the fundamental question is how similar or how different are the various crystal structures.(Joel Bernstein 2002).

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Kamil Dziubek & Andrzej Katrusiak

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  1. DIFFERENCES IN MOLECULAR ENVIRONMENTS OF POLYMORPHS Kamil Dziubek & Andrzej Katrusiak In dealing with a polymorphic systemperhaps the fundamental question is how similar or how different are the various crystal structures.(Joel Bernstein 2002)

  2. What can be different in crystal structures?How can these differences be measured? Chemical composition Patterns of H-bonding (graph-set analysis) Intermolecular interactions Hirshfeld surfaces Intermolecular distances (distancestruct-1vs. distancestruct-2 plot) Z. Kristallogr. 219 (2004) 1-11

  3. Phase transitions in 1,3-cyclohexanedione Etter et al., J.Am.Chem.Soc.,108 (1986) 5871-5876. Katrusiak, J. Mol. Struct., 269 (1992) 329-354.

  4. Polymorphism of maleic hydrazide Cradwick, Nature, 258 (1975) 774. Katrusiak, Acta Cryst. C49, (1993) 36-39.

  5. Polymorphism of resorcinol Robertson, Proc. Royal Soc. London , 157 (1936) 79-99. Robertson; Ubbelohde, Proc. Royal Soc. London , 167 (1938) 122-135.

  6. ‘Pseudopolymorphs’ ? Acta Cryst B51 (1995) 999-1003

  7. Advantages of the d-d plots • Totally user-immune (independent of the unit-cell or symmetry assignment, or atoms labelling and choise of molecules) • Provides quantitative measures how similar or how diferent structures are, in [Å]’s • Very simple – pen and paper required... or can be facilitated by programs. Disadvantages NONE(?)

  8. Applications of d-d plots • Comparing polymorphs • Analysis of structures with several symmetry-independent molecules • Measuring differences between isostructural crystals • Comparing the same phase at different thermodynamical conditions • Data validation

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