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

• Published in: Journal of organic chemistry Vol. 87; no. 21; pp. 14422 - 14432
• Main Authors: Paulino, Micael, Pérez-Juste, Ignacio, Cid, María Magdalena, Da Silva, José P., Pereira, M. Manuela A., Basílio, Nuno
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 04.11.2022
• Subjects: beta-Cyclodextrins - chemistry; Chalcone - chemistry; Chalcones - chemistry; Hydrogen-Ion Concentration
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.2c01875

Stimuli-responsive supramolecular receptors are important building blocks for the construction of self-assembled functional materials. We report the design and synthesis of a pH- and light-responsive 2-hydroxychalcone−β-cyclodextrin conjugate (1-Ct) and its characterization by spectroscopic and computational methods. 1-Ct follows the typical reaction network of trans-chalcone-flavylium photoswitches. Upon light irradiation, 1-Ct can be photochemically converted into the cis-chalcone/hemiketal forms (1-Cc/1-B) under neutral pH conditions or to the flavylium cation (1-AH + ) at acidic pH values. This stimuli-responsive β-cyclodextrin host, 1-Ct, was found to form stronger intramolecular self-inclusion complexes (K intra = 14) than 1-AH + (K intra = 3) and weaker than 1-Cc/1-B (overall K intra = 179), allowing control over their stability and binding properties by combinations of pH and light stimuli.