Macrocycle Size-Controlled Dynamic and Static Chirality in Donor–Acceptor [2]Catenanes
Kai Lan, Rong Luo, Jin Yin, Jiao Ming, Dongmei Zhang, Qianqian Wang, Yan Hu, Jiaming Huang, Jiyong Jiang, Jiayi Luo, Ping Li, Chenghao Liu, Jiarong Miao, Yaoxi Long, Zhichang Liu, Cheng Yang, Chuyang ChengAbstract
Chiral [2]catenanes, a prominent class of mechanically interlocked molecules (MIMs), can exhibit either static or dynamic mechanostereochemistry. Controlling these mechanostereochemical states without altering the covalent connectivity, however, remains challenging. Herein, we report a series of chiral [2]catenanes derived from ExBox and cycloparaphenyleneperylene (CPPP), whose dynamic behavior is altered by the size of the CPPP macrocycle. We identified a sharp, size-dependent threshold: The conformational stereogenic unit of [7]CPPP is kinetically locked, whereas those of [8]CPPP and [9]CPPP are dynamic at room temperature. This conformational stereochemistry strongly biases the co-conformational stereochemistry in the catenane, effectively resulting in a single dominant diastereomer. This effective coupling of the two stereogenic units allows the conformational stereochemistry to be biased by the ion pairing of the interlocked cationic ring with a chiral anion. This research highlights the potential of mechanically interlocked architectures for controlling the dynamic mechanostereochemistry.