Metal Ion Selective Self‐Assembly of a Ligand Functionalized Polymer into [1+1] Macrocyclic and Supramolecular Polymer Structures via Metal–Ligand Coordination

• Published in: Macromolecular rapid communications. 2020-01, Vol.41 (1), p.e1900305-n/a
• Main Authors: Xu, Xiaowen, Guyse, Joachim F. R., Jerca, Valentin Victor, Hoogenboom, Richard
• Format: Article
• Language: English
• Subjects: [1+1] metallomacrocycle; Assembly; Chemical reactions; Chemical synthesis; Coordination Complexes - chemistry; Coordination compounds; Copper; Cyclization; Ions - chemistry; Iron; Ligands; Metal complexes; Metal concentrations; Metal ions; Metals - chemistry; metal–ligand coordination; Nickel; Organic chemistry; Polyethylene Glycols - chemistry; Polymers; Polymers - chemistry; Pyridines; Supramolecular polymers; Transition metals; Zinc
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201900305

The design and synthesis of polymer‐based metallomacrocycles relying on metal–ligand interactions remain a challenge in the polymer field. Instead of utilizing chemical reactions to synthesize macrocycles, a general approach is proposed to construct metallomacrocyclic structures through supramolecular self‐assembly of a specific macroligand with suitable transition metal ions. Therefore, a new ditopic macroligand (L) consisting of PEG end‐capped with 2,6‐bis(1,2,3‐triazol‐4‐yl)pyridine derivatives is prepared via CuAAC “click” reaction. Four types of metal (Fe2+, Zn2+, Ni2+, and Cu2+) complexes are obtained by simply mixing a solution of metal ions and L in appropriate concentrations. The investigation of the coordination chemistry suggests that coordination of L with Cu2+ results in the formation of a [1+1] metallomacrocycle, while the other metal complexes exclusively lead to the formation of linear metallopolymers and/or larger aggregates. This work provides new insights into designing metallomacrocycles and may have potential application in the synthesis of catenanes and other cyclic or cycle‐based topological architectures. A new ditopic macroligand is synthesized by end‐functionalization of poly(ethyleneglycol) with 2,6‐bis(1,2,3‐triazol‐4‐yl)pyridine derivatives. The macroligand is coordinated with four metal ions (Fe2+, Zn2+, Ni2+, and Cu2+) to obtain metal complexes. The complex formation is investigated by UV–vis spectroscopy. Complexation of the macroligand with Cu2+ results in a [1+1] metallomacrocycle, while the other metal complexes only result in larger aggregates.