Host-guest complexes of C-propyl-2-bromoresorcinarene with aromatic N-oxides^*

* Dedicated to Professor Jerry L. Atwood on the occasion of his 75th Anniversary.

Abstract

The host-guest complexes of C-propyl-2-bromoresorcinarene with pyridine N-oxide, 3-methylpyridine N-oxide, quinoline N-oxide and isoquinoline N-oxide are studied using single crystal X-ray crystallography and ¹H NMR spectroscopy. The C-propyl-2-bromoresorcinarene forms endo-complexes with the aromatic N-oxides in the solid-state when crystallised from either methanol or acetone. In solution, the endo-complexes were observed only in methanol-d₄. In DMSO the solvent itself is a good guest, and crystallisation provides only solvate endo-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 N-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.

Keywords:

• Supramolecular chemistry
• resorcinarenes
• aromatic N-oxides
• hydrogen bonds
• crystal structure

Acknowledgements

The authors gratefully acknowledge financial support from the Academy of Finland (RP grant no. 298817, KR: grant nos. 265328, 263256 and 292746; RHAR: grant no. 272579), the University of Jyvaskyla, Aalto University, Finland, and the University of Windsor, ON, Canada.

Notes

* Dedicated to Professor Jerry L. Atwood on the occasion of his 75th Anniversary.