A Bambusuril That Responds to Anion Binding in Its Absorption Spectrum

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Analytical Chemistry

Background:

• Bambusurils are macrocyclic compounds with potential applications in molecular recognition.
• Direct N-substitution on glycoluril frameworks is challenging but can significantly alter macrocyclic properties.

Purpose of the Study:

• To synthesize and characterize BU1, the first bambusuril derivative with phenyl groups directly attached to nitrogen atoms.
• To investigate the anion-binding properties of BU1 using spectroscopic and computational methods.
• To establish a novel method for evaluating anion affinity via optical responses.

Main Methods:

• Design and synthesis of the BU1 macrocycle.
• Characterization using UV-Vis spectroscopy and 1H NMR titrations.
• Molecular modeling to understand binding interactions and structural effects.

Main Results:

• Successful synthesis and characterization of BU1, featuring p-nitrophenyl substituents.
• BU1 exhibits distinct optical responses upon anion binding, enabling UV-Vis based affinity evaluation.
• 1H NMR confirmed 1:1 host-guest stoichiometry and yielded association constants.
• Complexes formed were relatively weak with halide and perchlorate anions.

Conclusions:

• Direct N-aryl substitution in bambusurils can lead to cavity distortion and reduced flexibility.
• These structural changes likely account for the decreased binding strength observed in BU1 compared to other bambusurils.
• BU1 represents a new platform for anion sensing with optical readouts.