Macrocyclic Dinuclear Palladium Complex as a Novel Doubly Threaded [3]Rotaxane Scaffold and Its Application as a Rotaxane Cross-Linker

Koji Yamamoto; Riku Nameki; Hiromitsu Sogawa; Toshikazu Takata

doi:10.1002/anie.202007866

Macrocyclic Dinuclear Palladium Complex as a Novel Doubly Threaded [3]Rotaxane Scaffold and Its Application as a Rotaxane Cross-Linker

Angew Chem Int Ed Engl. 2020 Oct 5;59(41):18023-18028. doi: 10.1002/anie.202007866. Epub 2020 Aug 13.

Authors

Koji Yamamoto^{1

2}, Riku Nameki¹, Hiromitsu Sogawa^{1

3}, Toshikazu Takata¹

Affiliations

¹ Department of Chemical Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8503, Japan.
² Present address: Division of Molecular Science, Faculty of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan.
³ Present address: Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials, and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka, 564-8680, Japan.

PMID: 32578285
DOI: 10.1002/anie.202007866

Abstract

A dinuclear Pd^II complex possessing a cyclic ligand was developed as a novel doubly threaded [3]rotaxane scaffold and applied as a rotaxane cross-linker reagent. The dinuclear complex (PdMC)₂ was prepared by one-step macrocyclization followed by the double palladation reaction. ¹ H NMR analysis and UV/Vis measurements revealed the formation of a doubly threaded pseudo[3]rotaxane by the complexation of (PdMC)₂ with 2 equivalents of 2,6-disubstituted pyridine 3 through double metal coordination. The treatment of (PdMC)₂ with 2 equivalents of 4-vinylpyridine (VP) afforded a doubly threaded [3]rotaxane cross-linker (PdMC-VP)₂ . Radical co-polymerization of VP and t-butylstyrene in the presence of (PdMC-VP)₂ afforded a stable rotaxane cross-linked polymer (RCP). An elastic RCP was also prepared by using n-butyl acrylate as a monomer. The obtained RCPs exhibited higher swelling ability and higher mechanical toughness compared with the corresponding covalent cross-linked polymers.

Keywords: host-guest systems; macrocyclic ligands; metal coordination; palladium; rotaxanes.

Abstract

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