Pillar[4]arene[1]quinone-based pseudo[3]rotaxanes by cooperative Host-Guest binding

ABSTRACT

Formation of pseudo[3]rotaxane assemblies by P4Q1 and H with bis-imidazolium and bis-pyridinium guests was established by NMR spectral analyses and high-resolution mass spectrometric analyses. Cooperativity in the formation of pseudo[3]rotaxane assemblies was thoroughly investigated from the binding constant values derived from ¹H NMR titration experiments. The results indicated the preferential 1:1 host-guest binding of pillar[4]arene[1]quinone and 2:1 host-guest binding by functionalized pillar[4]arene[1]quinone via positive cooperativity. The presence of hydrogen bonding functional groups attached to the quinone motif of pillar[4]arene[1]quinone facilitated the inclusion formation, which resulted in the formation of pseudo[3]rotaxanes.

Graphical abstract

KEYWORDS:

• Pseudo[3]rotaxanes
• Pillar[5]arene
• Cooperativity
• Host-guest
• Pillar[4]arene[1]quinone

Acknowledgments

The authors acknowledge Council of Scientific and Industrial Research [01(3001)/19/EMR-II] for financial assistance. The authors also sincerely acknowledge the NMR facility created under DST-FIST program (SR/FST/CSI- 255/2013(C)) and LC-MS facility created under UGC-SAP programme in Department of Chemistry, The Gandhigram Rural Institute (Deemed to be University)

Author contributions

The manuscript was written through contributions of all authors.

Disclosure statement

No potential conflict of interest was reported by the author(s).

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Additional information

Funding

This work was supported by the Council of Scientific and Industrial Research, India [01(3001)/19/EMR-II].