The team at Fudan University and East China University of Science and Technology (Shanghai, China) used a chalice-shaped molecule (calixarene) with four binding sites as the “scaffold” for the metal polymer. They attached four poly(aminopyridine) chains to the calixarenes, which bundles the four chains and aligns them in parallel. Synthesis of the chains can be carried out stepwise from individual building blocks or several larger blocks can be linked together. By using an iterative synthetic procedure in which protective groups and end caps are bound and then removed, the team is able to produce chains of equal length. They then carry out the metalation. The nitrogen atoms of the chain molecules can bind nickel. Their distance from each other exactly matches the distance of metal–metal bonds, causing the nickel atoms to link together in a single line. The four poly(aminopyridine) chains wrap around the nickel chain in a helix, as shown by X-ray structure analysis, and stabilize it. The team was thus able to synthesize polymers with a nickel backbone and precisely controlled length. They produced versions with three to 21 nickel atoms. Interestingly, the distance between nickel atoms decreases as the chain length increases, strengthening the Ni–Ni bonds.
Metal-Backboned Polymers with Well-Defined Lengths
Essentially, the researchers have shown how new materials can be created from polymers given a metallic backbone resulting in something conductive, thermally stable, and has interesting optoelectronic properties. Further research is needed, but there are implications for possible applications in polymers used in display manufacturing. The researchers also say that their strategy could be expanded to copper and cobalt which could offer further more potential use cases in display manufacturing.
Reference
Zeng, K., Yang, Y., Xu, J., Wang, N., Tang, W., Xu, J., Zhang, Y., Wu, Y., Xu, Y., Wang, G., Chen, P., Wang, B., Sun, X., Jin, G., Peng, H., Angew. Chem. Int. Ed. 2023, e202216060; Angew. Chem. 2023, e202216060.
