Supramolecular Synthon Frustration Leads to Crystal Structures with Z′ > 1

Abstract

Supporting Information Details of Cambridge Structural Database (CSD) searchesCSD Searches were carried out using Cambridge Structural Database Version 5.27 (November 2006) with two updates. All searches not explicitly mentioned below were defined as shown in the manuscript with intermolecular contacts defined as distances shorter than the sum of the van der Waals radii of the two atoms. No restrictions were made on errors etc as high Z' structures can be prone to large residuals and other refinement problems and we did not wish to exclude these from searches.

Structural aspects of partial solid solution formation: two crystalline modifications of a chiral derivative of 1,5-dihydro-2H-pyrrol-2-one under consideration

“…Although the number of symmetry-independent molecules does not relate to the enthalpy or entropy of a solid phase directly, in all probability, Z′ > 1 provides more flexibility to accommodate the packing, which could contribute to or contradict the best crystal formative motif. 23,[28][29][30] Moreover, the presence of a second and more "extra" symmetrically independent molecule in crystals is often accompanied by the pseudosymmetry phenomenon, 31 which we exemplified earlier in glycerol derivatives 20,21 and a pair of mucochloric acid polymorphs.…”

Exploring the structural, electronic and optical properties of furan-2-carboxaldehyde and 2-acetylthiophene nicotinoylhydrazone

“…This can suggest that this form is the stable one. The tendency of -C(O)-NH-N= moiety to form strong bifurcated hydrogen bonds competes with the steric hindrance between the hydrazone molecules containing two rings causing such a twist of the molecules that they can not be related by crystallographic symmetry element, and hence leading to structures where the asymmetric unit contains more than one molecule (i.e., Z 0 [ 1) [31]. It is worth mentioning that nicotinohydrazide-derived hydrazones display two tautomeric forms.…”

Anion-tuning of supramolecular gel properties

“…The crystal structure reported previously of 3.12 is a hexane clathrate (or solvate, the solvent is present in channels and is incommensurate and therefore is not modelled in the reported structure) with a Z' value of 1 ( Figure 3.27a). 76,[142][143][144][145] However, in the new structure of 3.12 there is no solvent present, and the packing is compact (Figure 3.27b). The four crystallographically independent molecules found within this structure all show a similar approximate D 3h symmetry to the hexane structure of 3.12 (almost C 3 symmetry due to the twisting of the planes of the pyrazolate ligands, this twisting is opposite on neighbouring columns (related by P 1 symmetry) in both structures of 3.12).…”