A water-responsive calix[4]resorcinarene system: self-assembly and fluorescence modulation

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Physical Chemistry

Background:

• Calix[4]resorcinarene macrocycles are versatile molecular platforms.
• Understanding their self-assembly in solution is crucial for applications.
• Solvent effects on macrocycle behavior are not fully elucidated.

Purpose of the Study:

• To investigate the impact of water content on calix[4]resorcinarene self-assembly.
• To analyze how water influences the fluorescence properties of these macrocycles.
• To explore the potential of water-responsive calixarene systems.

Main Methods:

• Synthesis of two novel calix[4]resorcinarene macrocycles.
• Preparation of tetrahydrofuran (THF)/water mixtures with varying water percentages.
• Characterization of self-assembled structures using techniques like dynamic light scattering (DLS).
• Monitoring fluorescence quenching upon water addition.

Main Results:

• In pure THF, macrocycles form flattened structures.
• In THF/water mixtures up to 53% water, large giant vesicles (500-5000 nm) and small micelles (3.4-3.5 nm) coexist.
• Above 53% water, assemblies shift to unimodal micelles (140-160 nm).
• Fluorescence quenching occurs with increasing water content due to nonradiative deactivation.

Conclusions:

• Water content is a critical factor regulating the self-assembly and fluorescence of these calix[4]resorcinarene macrocycles.
• The observed transitions in assembly size and morphology highlight water's role as a responsive element.
• These findings provide a foundation for designing advanced water-responsive calixarene-based materials.