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Rare-earth metal complexes derived from the acids Ph2C(X)CO2H (X= OH, NH2): Structural and ring opening polymerization (ROP) studies.

Collins, Jack; Santoro, Orlando; Prior, Timothy J.; Chen, Kai; Redshaw, Carl

Authors

Jack Collins

Orlando Santoro

Kai Chen

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Professor Carl Redshaw C.Redshaw@hull.ac.uk
Professor of Inorganic Materials Chemistry and REF Lead for Chemistry



Abstract

Treatment of Ln(NO3)3.6H2O (Ln = La, Ce) with an equimolar amount of 2,2’-diphenylglycine (DpgH) in ethanol afforded the corresponding hexacoordinated complexes (DpgH±)3Ln(NO3)3.H2O (DpgH± = zwitterionic 2,2’-diphenylglycine, Ln = La (1), Ce (2)). The spectroscopic and structural features of these compounds have been investigated. Similar reactions with the related benzilic acid (BenzH2) were unsuccessful. The catalytic behaviour of 1 and 2 in the homo- and copolymerization of epsilon-caprolactone (epsilon-CL) and rac-lactide (r-LA) has been investigated herein. In the case of epsilon-CL, the two complexes exhibited comparable activity, allowing for complete monomer conversion under aerobic and solvent-free conditions at 150 °C in 24 h. With respect to the ROP of r-LA, 1 was found to be completely inactive, while only 8% conversion was achieved in the presence of 2. Liquid oligomers were isolated during epsilon-CL/r-LA co-polymerization in the presence of both complexes. The catalytic activity of the pre-ligands DpgH and BenzH2 (i.e. metal-free) was also examined. Interestingly, only BenzH2 was found to be active, although it required a higher catalyst loading and the presence of benzyl alcohol as co-activator.

Citation

Collins, J., Santoro, O., Prior, T. J., Chen, K., & Redshaw, C. (2021). Rare-earth metal complexes derived from the acids Ph2C(X)CO2H (X= OH, NH2): Structural and ring opening polymerization (ROP) studies. Journal of molecular structure, 1224, https://doi.org/10.1016/j.molstruc.2020.129083

Journal Article Type Article
Acceptance Date Aug 12, 2020
Online Publication Date Aug 13, 2020
Publication Date Jan 15, 2021
Deposit Date Aug 13, 2020
Publicly Available Date Aug 14, 2021
Journal Journal of Molecular Structure
Print ISSN 0022-2860
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 1224
Article Number 129083
DOI https://doi.org/10.1016/j.molstruc.2020.129083
Keywords Lanthanide; Magic Acids; Diphenylglycine; Ring Opening Polymerization; Biodegradable
Public URL https://hull-repository.worktribe.com/output/3557437
Publisher URL https://www.sciencedirect.com/science/article/abs/pii/S0022286020314058?via%3Dihub