title: Dynamic [2]catenanes based on a hydrogen bonding-mediated bis-zinc porphyrin foldamer tweezer: a case study.
abstract: This paper describes the self-assembly of a new class of three-component dynamic [2]catenanes, which are driven or stabilized by intramolecular hydrogen bonding, coordination, and electrostatic interaction. One of the component molecules 2, consisting of an aromatic oligoamide spacer and two peripheral zinc porphyrin units, was designed to adopt a folded preorganized conformation, which is stabilized by consecutive intramolecular three-centered hydrogen bonds. Component molecule 3 is a linear secondary ammonium bearing two peripheral pyridine units, which was designed to form a 1:1 complex with 24-crown-8 (5). The 1H NMR and UV-vis experiments in CDCl3-CD3CN (4:1 v/v) revealed that, due to the preorganized U-shaped feature, 2 could efficiently bind 3 through the cooperative zinc-pyridine coordination to generate highly stable 1:1 complex 2.3. Adding 5 to the 1:1 solution of 2 and 3 led to the formation of dynamic three-component [2]catenane 2.3.5 as a result of the threading of 3 through 5. 1H NMR studies indicated that in the 1:1:1 solution (3 mM) [2]catenane 2.3.5 was generated in 55% yield at 25 degrees C. The yield was increased with the reduction of the temperature and [2]catenane could be produced quantitatively in a 1:1:2 solution ([2]=3 mM) at -13 degrees C. Replacing 3 with 1,2-bis(4,4'-bipyridinium)ethane (4) in the three-component solution could also give rise to similar dynamic [2]catenane 2.4.5 albeit in slightly lower yield.
authors.affiliation: State Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Wen-Ya
authors.initials: WY
authors.lastname: Lu
authors.forename: Jun-Li
authors.initials: JL
authors.lastname: Hou
authors.forename: Chuang
authors.initials: C
authors.lastname: Li
authors.forename: Zong-Quan
authors.initials: ZQ
authors.lastname: Wu
authors.forename: Xi-Kui
authors.initials: XK
authors.lastname: Jiang
authors.forename: Zhan-Ting
authors.initials: ZT
authors.lastname: Li
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: Yu
mesh_terms: D043863:Catenanes / Q000138:chemical synthesis / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D043863:Catenanes; D008665:Metalloporphyrins; D009942:Organometallic Compounds; C017802:zinc hematoporphyrin