Two new series of guanidine-pyridine ligands have been synthesised by the reaction of various chloroformamidinium chlorides with 8-aminoquinoline or 2-picolylamine. The ligands were treated with either zinc chloride or zinc acetate to prepare the corresponding complexes, which were tested as initiators in the solvent-free ring-opening polymerisation of D, L-lactide. The effect of the guanidine ligand on the catalytic activity of the zinc complexes was investigated. A great number of the synthesised complexes showed appreciable polymerisation activity. 13 new zinc guanidine complexes have been structurally characterised, including the first examples of structures comprising a tetraethylguanidine unit. The experimental results were complemented by a density functional study, which has probed the influence of substituents at the guanidine unit. Especially for the tetraethylguanidine systems, insights into the strength of delocalisation within guanidine moieties are provided.
- sustainable chemistry
- ring-opening polymerization
- density functional calculations
- biodegradable polymers
Borner, J., Vieira, I. D., Jones, M. D., Doring, A., Kuckling, D., Florke, U., & Herres-Pawlis, S. (2011). Zinc complexes with guanidine-pyridine hybrid ligands - guanidine effect and catalytic activity. European Journal of Inorganic Chemistry, 2011(28), 4441-4456. https://doi.org/10.1002/ejic.201100540