Endo-/Exo- and Halogen Bonded Complexes of Conformationally Rigid Cethyl-2-bromoresorcinarene and aromatic N-oxides
Puttreddy, R., Beyeh, N. K., Ras, R. H. A., Trant, J., & Rissanen, K. (2017). Endo-/Exo- and Halogen Bonded Complexes of Conformationally Rigid Cethyl-2-bromoresorcinarene and aromatic N-oxides. CrystEngComm, 19 (30), 4312-4320. doi:10.1039/C7CE00975E
© The Royal Society of Chemistry 2017. This is a final draft version of an article whose final and definitive form has been published by RSC. Published in this repository with the kind permission of the publisher.
The host–guest complexes of conformationally rigid C-ethyl-2-bromoresorcinarene with aromatic N-oxides were studied using single crystal X-ray crystallography. Unlike that of the conformationally more flexible C-ethyl-2-methylresorcinarene, the C-ethyl-2-bromoresorcinarene cavity forms endo-complexes only with the small pyridine-N-oxides, such as pyridine N-oxide, 2-methyl-, 3-methyl- and 4-methylpyrdine N-oxide, and quinoline N-oxide. The larger 2,4,6-trimethylpyridine, 4-phenylpyridine and isoquinoline N-oxide, and 4,4-bipyridine N,N′-dioxide and 1,3-bis(4-pyridyl)propane N,N′-dioxide do not fit into the host cavity. Instead endo-acetone complexes are formed. Remarkably, differing from the anti–gauche endo-complex with C-ethyl-2-methylresorcinarene, the flexible 1,3-bis(4-pyridyl)propane N,N′-dioxide guest forms an anti–anti exo-complex with C-ethyl-2-bromoresorcinarene. The endo- and exo-complexes of C-ethyl-2-bromoresorcinarene and studied N-oxides manifest C–O⋯Br, C–H⋯π and C–Br⋯π interactions. ...