Mechanical Bonds and Topological Effects in Radical Dimer Stabilization

详细信息    查看全文

• 作者：Marco Frasconi ; Takashi Kikuchi ; Dennis Cao ; Yilei Wu ; Wei-Guang Liu ; Scott M. Dyar ; Gokhan Barin ; Amy A. Sarjeant ; Charlotte L. Stern ; Raanan Carmieli ; Cheng Wang ; Michael R. Wasielewski ; William A. Goddard III ; J. Fraser Stoddart
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 6, 2014
• 年：2014
• 卷：136
• 期：31
• 页码：11011-11026
• 全文大小：1082K
• ISSN：1520-5126

文摘

While mechanical bonding stabilizes tetrathiafulvalene (TTF) radical dimers, the question arises: what role does topology play in catenanes containing TTF units? Here, we report how topology, together with mechanical bonding, in isomeric [3]- and doubly interlocked [2]catenanes controls the formation of TTF radical dimers within their structural frameworks, including a ring-in-ring complex (formed between an organoplatinum square and a {2+2} macrocyclic polyether containing two 1,5-dioxynaphthalene (DNP) and two TTF units) that is topologically isomeric with the doubly interlocked [2]catenane. The separate TTF units in the two {1+1} macrocycles (each containing also one DNP unit) of the isomeric [3]catenane exhibit slightly different redox properties compared with those in the {2+2} macrocycle present in the [2]catenane, while comparison with its topological isomer reveals substantially different redox behavior. Although the stabilities of the mixed-valence (TTF₂)^鈥? dimers are similar in the two catenanes, the radical cationic (TTF^鈥?)₂ dimer in the [2]catenane occurs only fleetingly compared with its prominent existence in the [3]catenane, while both dimers are absent altogether in the ring-in-ring complex. The electrochemical behavior of these three radically configurable isomers demonstrates that a fundamental relationship exists between topology and redox properties.