Cyclodextrin‐Based Catenanes Platformed with meso‐Arylporphyrin

• Published in: European journal of organic chemistry Vol. 27; no. 22
• Main Authors: Asai, Kaoru, Mao, Qiyue, Nakagami, Atsuki, Kitagishi, Hiroaki
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 10.06.2024; Wiley Subscription Services, Inc
• Subjects: Binding; Catenanes; Chemistry; Chemistry, Organic; Cyclodextrins; host-guest chemistry; Inclusion complexes; Metathesis; NMR; Nuclear magnetic resonance; Physical Sciences; Porphyrins; Rotaxanes; Science & Technology; supramolecular chemistry; COMPLEX; TETRAARYLPORPHYRINS; BEHAVIOR; Catenanes; INCLUSION; host-guest chemistry; cyclodextrins; supramolecular chemistry; porphyrins; METATHESIS
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.202400081

Among mechanically interlocked supramolecular systems with cyclodextrins (CDs), successful examples of CD‐based catenanes are limited compared to a number of CD rotaxanes owing to the synthetic difficulties. We herein demonstrate an efficient synthesis of a CD‐based catenane using a meso‐arylporphyrin (Por) platform. Using Por modified with two olefin‐terminated oxyethylene chains at the cis‐meso‐positions, an interlocked Por‐CD catenane was synthesized via olefin metathesis in the presence of per‐O‐methylated β‐CD (TMe‐β‐CD) in water. The novel Por‐CD catenane was obtained in 30 % isolated yield, which was characterized by MALDI‐TOF mass and NMR spectroscopies. In the latter part, we demonstrate determination of the binding constants between TMe‐β‐CD and meso‐(4‐sulfonatophenyl)porphyrin using Por‐CD catenane, 2,6‐di‐O‐methyl‐β‐CD (DMe‐β‐CD), and 13C‐labeled TMe‐β‐CD (13C‐TMe‐β‐CD). The host‐guest exchange reaction from the Por‐CD catenane/DMe‐β‐CD to the Por‐CD catenane/TMe‐β‐CD complexes was directly monitored through 1D HMQC spectroscopy. The ratio of these complexes revealed the difference in the binding affinities of DMe‐β‐CD and TMe‐β‐CD to Por. The stable 1 : 2 inclusion complex between meso‐tetrakis(4‐sulfonatophenyl)porphyrin (TPPS) and TMe‐β‐CD has been well‐studied for many years. This study is the first to determine the respective binding constants, K1 and K2, using the model system, to be 3.0×107 M−1 and 3.4×107 M−1, respectively. “Padlock” structures comprising cyclodextrin (CD) catenanes were successfully constructed using a strong intermolecular interaction of CD with meso‐arylporphyrin in water. A water soluble Grubbs's catalyst was used for interlocking CD onto the porphyrin. The novel catenane compounds were useful to elucidate the highly specific intermolecular interactions of methylated CD to meso‐(4‐sulfonatophenyl)porphyrins in water.