Host-guest complexes of C-propyl-2-bromoresorcinarene with aromatic <i>N</i>-oxides^*

<p>The host-guest complexes of C-propyl-2-bromoresorcinarene with pyridine <i>N</i>-oxide, 3-methylpyridine <i>N</i>-oxide, quinoline <i>N</i>-oxide and isoquinoline <i>N</i>-oxide are studied using single crystal X-ray crystallography and ¹H NMR spectroscopy. The C-propyl-2-bromoresorcinarene forms <i>endo</i>-complexes with the aromatic <i>N</i>-oxides in the solid-state when crystallised from either methanol or acetone. In solution, the <i>endo</i>-complexes were observed only in methanol-d₄. In DMSO the solvent itself is a good guest, and crystallisation provides only solvate <i>endo</i>-complexes. The C-propyl-2-bromoresorcinarene shows remarkable flexibility when crystallised from either methanol or acetone, and packs into one-dimensional self-included chains. Of special note, crystallising C-propyl-2-bromoresorcinarene with 3-methylpyridine <i>N</i>-oxide from acetone results in a 2:2 dimeric capsular assembly organised through both C−H···π_host and N−O···(H−O)_host interactions.</p>