Zinc complexes supported by (benzimidazolyl)pyridine alcohol ligands as highly efficient initiators for ring-opening polymerization of ε-caprolactone

• Air-stable zinc complexes bearing NNO ligands were synthesized and characterized.
• In combination with MeLi, zinc complexes were highly efficient for the ROP of ε-CL.
• The polymers obtained in the absence of BnOH were mainly cyclic PCLs.
• The linear PCLs were produced in the presence of BnOH.

A series of air-stable zinc complexes (1–3) supported by (benzimidazolyl)pyridine alcohol ligands {tridentate [N,N,O]} has been synthesized and well characterized by FT-IR, 1H and 13C NMR, elemental analysis and single-crystal X-ray diffraction analysis. In combination with methyllithium, these zinc complexes were proved to be highly efficient initiators for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). The ROP of ε-CL in the absence or presence of benzyl alcohol, as well as the influences of monomer concentration, reaction temperature and the substituent on the ligand, were investigated in detail.

In combination with methyllithium, the air-stable zinc complexes (1–3) supported by (benzimidazolyl)pyridine alcohol ligands were highly efficient for the ring-opening polymerization of ε-caprolactone. The cyclic PCLs formed in the absence of BnOH; whereas the linear PCLs were obtained in the presence of BnOH.Figure optionsDownload as PowerPoint slide