On February 3, the research group led by Prof. Zhou Xingping from the School of Chemistry and Chemical Engineering of HUST published a research paper entitled "Switchable Polymerization Triggered by Fast and Quantitative Insertion of Carbon Monoxide into Cobalt‐Oxygen Bonds" in the form of "Hot Paper" on Angewandte Chemie International Edition. Huazhong University of Science and Technology is the signature unit of the first author, and Wang Yong, the post-doc from the School of Chemistry and Chemical Engineering is the first and corresponding author of the paper. Prof. Zhou Xingping from HUST and Prof. Rinaldo Poli from University of Toulouse are also the corresponding authors; Prof. Xie Xiaolin, Zhao Yajun, Zhu Shuaishuai and Prof. Xu Jing from Shandong Agricultural University are the co-authors.
In this paper, a strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)-N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine] from ring-opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co-O bond, allowing for in situ transformation of the ROCOP active species (Salen)CoIII-OR into the OMRP photoinitiator (Salen)CoIII-CO2R. The proposed mechanism, which involves CO coordination to (Salen)CoIII-OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on-demand sequence control can be achieved for the one-pot synthesis of polyester-b-polyacrylate diblock copolymers (Đ<1.15).
CO-triggered switch from cobalt mediated ROCOP to OMRP for the one-pot synthesis of polyester-b-polyacrylate
This research is sponsored by National Key R&D Plan (No.2016YFB0302400) and NSFC (No.21604027) of China.
Link of the paper: https://onlinelibrary.wiley.com/doi/10.1002/anie.201914216
