Cationic guests direct molecular capsule formation and the impact towards the extended self-assembly in combinatorial supramolecular systems

ABSTRACT

Four multi-component complexes based on p-sulfonatocalix[4]arene anion, the methyltriphenylphosphonium cation, lanthanide ions (Gd(III)) and different ionic liquid-based cations (1-methyl-3-butylimidazolium, 1-methyl-3-octylimidazolium and 1,4-bis((3-methylimidazolidinyl)methyl)benzene) were synthesised and structurally characterised. Common bilayer arrangements are formed in the extended structures of all four complexes, though the bilayer thicknesses varies depending on the components involved. Molecular capsule formation is facilitated by the inclusion of methyltriphenylphosphonium, 1-methyl-3-butylimidazolium and 1,4-bis((3-methylimidazolidinyl)methyl)benzene cations, but not in the case of the 1-methyl-3-octylimidazolium cation. Molecular capsule size depends on the nature of the included guest cation, and methyltriphenylphosphonium cations fill compact spaces between calixarenes in these new bilayer arrays.

GRAPHICAL ABSTRACT

KEYWORDS:

• P-sulfonatocalix[4]arene
• imidazolium
• phosphonium
• self-assembly
• host-guest

Acknowledgments

The authors would like to acknowledge the facilities, and the scientific and technical assistance of the Australian Microscopy & Microanalysis Research Facility at the Centre for Microscopy, Characterisation & Analysis, The University of Western Australia, a facility funded by the University, State and Commonwealth Governments. IL and SJD would like to thank the Royal Society for supporting this work under the Newton Mobility Grant (NI170151).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Royal Society Newton Mobility Grant [NI170151]. In memory of Prof. C. David Gutsche, whose pioneering work in calixarenes made so much more even possible.