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Construction of Metallacage‐Cored Supramolecular Gel by Hierarchical Self‐Assembly of Metal Coordination and Pillar[5]arene‐Based Host−Guest Recognition
Author(s) -
Liu Yuezhou,
Shi Bingbing,
Wang Hu,
Shangguan Liqing,
Li Zhengtao,
Zhang Mingming,
Huang Feihe
Publication year - 2018
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201800655
Subject(s) - supramolecular chemistry , molecule , chemistry , heteronuclear molecule , crystallography , supramolecular assembly , nuclear magnetic resonance spectroscopy , organometallic chemistry , polymer chemistry , stereochemistry , organic chemistry , crystal structure
In this work, a Pd 2 L 4 metallacage 2• ([BF 4 ] − ) 4 with four pillar[5]arene units is first prepared and characterized by 1D multinuclear NMR ( 1 H, 11 B, and 19 F NMR), 2D 1 H− 1 H correlation spectra, 1 H− 13 C heteronuclear single quantum coherence, and diffusion‐ordered NMR spectroscopy, and electrospray ionization time‐of‐flight mass spectrometry. By the introduction of a ditopic guest molecule 3 into a chloroform solution of 2• ([BF 4 ] − ) 4 , a supramolecular polymer network gel is successfully constructed based on the metal coordination interactions and host−guest recognition between the pillar[5]arene units of 2• ([BF 4 ] − ) 4 and neutral ditopic guest molecule 3 . The temperature and pH responsivenesses of the supramolecular gel are studied, which are further employed for the controlled release of different cargos. As a demonstration, emodin and methylene blue are trapped in the cavities of the metallacage and in the pores of the supramolecular gel, respectively. Methylene blue is first released along with the gel–sol transition while emodin is then released by the further addition of acid to destroy the metallacage. This study explores the use of metallacage‐cored supramolecular network gels for sequential controlled release and contributes to the development of smart and adaptive materials.