Hydrogen bond-stabilised N-alkylammonium resorcinarene halide cavitands

Abstract

A family of hydrogen bond-stabilised N-alkylammonium resorcinarene chloride and bromide cavitands were synthesised and characterised with ¹H NMR and ESI mass spectrometry. The seven compounds exhibit interestingly either self-inclusion or guest complexation in the solid state evidenced by single crystal X-ray diffraction. The four dimers show self-inclusion of the upper rim propyl chains and consist of two hydrogen-bonded resorcinarene tetracations and six halide anions, while the remaining two halide anions are located in between the dimers linking them via hydrogen bonding. Small solvent molecules such as dichloromethane, methanol, n-butanol or chloroform are complexed into the resorcinarene cavity in three 1:1 or 1:2 host–guest complexes. While included, the methanol and butanol molecules are simultaneously hydrogen bonded to the halide anion enhancing the complex formation. The complementary self-inclusion results in a nearly perfect cone conformation of the resorcinarene core in the dimers, while the host–guest complexes are much more distorted.

Keywords:

• resorcinarenes
• tetrabenzoxazines
• ammonium halides
• hydrogen bonding
• X-ray structure

Acknowledgements

The authors gratefully acknowledge the financial support from the Academy of Finland (K.R., proj. 212588 and 218325) and the University of Jyväskylä (K.B. and K.R., academy professorship grant). M.C. is grateful to K.R., University of Zagreb and University of Jyväskylä for giving him an opportunity to work in his research group.

Notes

^† Present address: Enamine Ltd, 23 Alexandra Matrosova Street, 01103 Kiev, Ukraine.

^‡ Dedicated to the memory of Prof. Dmitry Rudkevich.