Neutral Isocyanide-Templated Assembly of Pillar[5]arene [2] and [3]Pseudorotaxanes

Unprecedented pillar[5]arene–isocyanide pseudorotaxane inclusion complexes are reported. Extensive 1H-NMR experiments reveal remarkably strong binding affinities of alkyl diisocyanide guests (Ka >105 M-1 in CDCl3) by pillar[5]arenes. Characterised by multinuclear 1H...

Anion-Responsive Pseudo[3]rotaxane from a Difunctionalized Pillar[4]arene[1]quinone and a Bis-Imidazolium Cation

Synthesis of a new functionalized pillar[4]arene[1]quinone and its host-guest complexation with a bis-imidazolium dication was demonstrated. 1D/2D NMR spectroscopic analyses and high-resolution mass spectrometric analyses showed the formation of the pseudo[3]rotaxane assembly upon host-guest complexation. ¹H NMR titration experiments revealed the role of hydrogen bonding motifs in bringing positive cooperativity by comparing the binding constants for the host-guest complexation of pillar[4]arene[1]quinone with a bis-imidazolium guest. Anion-responsiveness of the pseudo[3]rotaxane assembly was also demonstrated.