Acyclic Cucurbit[n]uril‐Type Receptors: Aromatic Wall Extension Enhances Binding Affinity, Delivers Helical Chirality, and Enables Fluorescence Sensing

Abstract We report the linear extension from M1 to M2 to anthracene walled M3 which adopts a helical conformation (X‐ray) to avoid unfavorable interactions between sidewalls. M3 is water soluble (=30 m m ) and displays enhanced optical properties ( ϵ =1.28×10 5 m −1 cm −1 , λ max =370 nm) relative to M2 . The binding properties of M3 toward guests 1 – 29 were examined by 1 H NMR and ITC. The M3 ⋅guest complexes are stronger than the analogous complexes of M2 and M1 . The enhanced binding of M3 toward neuromuscular blockers 25 , 27 – 29 suggests that M3 holds significant promise as an in vivo reversal agent. The changes in fluorescence observed for M3 ⋅guest complexes are a function of the relative orientation of the anthracene sidewalls, guest concentration, K a , and guest electronics which rendered M3 a superb component of a fluorescence sensing array. The work establishes M3 as a next generation sequestering agent and a versatile component of fluorescence sensors.