Acyclic Cucurbit[<i>n</i>]uril‐Type Receptors: Aromatic Wall Extension Enhances Binding Affinity, Delivers Helical Chirality, and Enables Fluorescence Sensing
Steven Murkli, Jared Klemm, David King, Peter Y. Zavalij, Lyle Isaacs
Abstract
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.