High-affinity 1 : 2 recognition based on naphthyl-azocalix[4]arene and its application as a cleavable noncovalent connector in constructing responsive supramolecular polymeric materials

• Published in: Chemical science (Cambridge) Vol. 16; no. 16; pp. 766 - 776
• Main Authors: Yao, Shun-Yu, Ying, An-Kang, Geng, Wen-Chao, Chen, Fang-Yuan, Hu, Xin-Yue, Cai, Kang, Guo, Dong-Sheng
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 16.04.2025; The Royal Society of Chemistry
• Subjects: Affinity; Aqueous solutions; Chemistry; Connectors; Controlled release; Hypoxia; Recognition; Robustness (mathematics); Stimuli; Supramolecular polymers
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d5sc00075k

Macrocyclic hosts which can bind two guests simultaneously with high affinity, such as cucurbit[8]uril, are highly useful for a wide range of applications by acting as noncovalent connectors. However, the integration of stimuli-controlled release properties into such robust noncovalent connectors would be even more desirable. Here, we introduce Naph-SAC4A, a naphthyl-extended deep-cavity azocalix[4]arene with hypoxia-responsiveness, which exhibits exceptional 1 : 2 hosting abilities for organic dyes in aqueous solution with affinities ranging from 10 14 to 10 16 M −2 . Furthermore, Naph-SAC4A was employed as a robust hypoxia-cleavable noncovalent connector to construct linear supramolecular polymers and crosslinked supramolecular hydrogels. Both structures exhibit responsiveness to hypoxic stimuli. With its high-affinity 1 : 2 recognition, unique hypoxia-responsiveness, and easy accessibility, Naph-SAC4A holds great potential for smart supramolecular polymeric materials. Naph-SAC4A forms 1 : 2 host-guest complexes ( K total up to 10 16 M −2 ) with dyes, enabling modular hypoxia-responsive supramolecular polymers and hydrogels. This system shows broad potential in drug delivery, tissue engineering, and imaging diagnostics.