摘要:
IntroductionWe have described earlier the syntheses and crystal structures of the diquinoline derivatives1and2.1,2While1packs efficiently without guest inclusion, its dibromo derivative2prefers to form clathrate inclusion compounds by inclusion of small polyhalogenated guests. Compound2is the prototype of a family of lattice inclusion hosts that have been designed using analyses of the molecular structure of2and knowledge of its intermolecular properties. These compounds are prepared in a simple modular fashion by condensing two aromatic wings onto a central cyclic linker group, and then completing the synthesis by placement of the benzylic bromo sensor groups.3–6A variety of weak host–host and host–guest non-covalent forces (such as face–face and edge–face aryl–aryl, halogen–halogen, halogen–nitrogen, and edge–edge C–H⋯N dimer interactions) compete for the combination of best overall energy in the resulting clathrate structure.During this investigation the oxygenated analogues3and4were prepared but, to our surprise, the latter compound did not function as a host molecule.7In both solid3and4the ether oxygen interacts efficiently with two 1,3-periaromatic hydrogens of an adjacent molecule to produce an intermolecular six-membered cycle involving two C–H⋯O weak hydrogen bonds (Fig. 1).8–10In crystalline4this ether–1,3-periaromatic hydrogen interaction (Fig. 2) played a key role in preventing inclusion behaviour. The frequency of occurrence of this motif in the crystallographic literature, and itsobserved geometries, have been surveyed by us.7Schematic illustration of the ether–1,3-periaromatic hydrogen interaction between an ether R2O and naphthalene.7Part of the crystal structure of4showing the highly effective ether–1,3-periaromatic hydrogen interaction. The bromine atoms are coloured red-brown, and the C–H⋯O weak hydrogen bonds indicated by red and white dashed lines.7This present communication reports the very different solid state behaviour observed for the related thia-substituted analogues5and6.
ISSN:1466-8033
DOI:10.1039/b109794f
出版商:RSC
年代:2001
数据来源: RSC