2-Hydroxychalcone-β-Cyclodextrin Conjugate with pH-Modulated Photoresponsive Binding Properties

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Stimuli-responsive supramolecular receptors are key for creating self-assembled functional materials.
• Chalcone-based photoswitches offer dynamic molecular behavior.
• β-cyclodextrin hosts provide versatile platforms for molecular recognition.

Purpose of the Study:

• To design and synthesize a novel pH- and light-responsive 2-hydroxychalcone-β-cyclodextrin conjugate.
• To characterize the conjugate's photochemical and supramolecular properties.
• To investigate the influence of pH and light on its self-inclusion complexation behavior.

Main Methods:

• Synthesis of the 2-hydroxychalcone-β-cyclodextrin conjugate.
• Spectroscopic characterization techniques (e.g., NMR, UV-Vis).
• Computational modeling to understand structural and binding properties.

Main Results:

• The conjugate (1-Ct) exhibits reversible photochemical transformations between trans-chalcone, cis-chalcone/hemiketal, and flavylium cation forms depending on pH and light.
• Intramolecular self-inclusion complexation constants were determined for different forms: K_intra = 14 for 1-Ct, K_intra = 3 for 1-AH+, and K_intra = 179 for 1-Cc/1-B.
• The stability and binding properties of the supramolecular complexes can be precisely controlled by manipulating pH and light stimuli.

Conclusions:

• A novel stimuli-responsive supramolecular receptor based on a 2-hydroxychalcone-β-cyclodextrin conjugate was successfully synthesized and characterized.
• The conjugate demonstrates tunable self-inclusion complexation behavior modulated by pH and light, offering a mechanism for controlled molecular assembly.
• This work provides a foundation for developing advanced self-assembled functional materials with switchable properties for diverse applications.