Synthesis and structural characterization of zinc complexes supported by amino-benzotriazole phenoxide ligands: Efficient catalysts for ring-opening polymerization of ε-caprolactone and β-butyrolactone

Two amino-benzotriazole phenol ligands, 2-(2H-benzotriazol-2-yl)-6-((diethylamino)methyl)-4-alkyl-phenol (alkyl = CH3, C1DEABTP-H, and alkyl = C8H17, C8DEABTP-H) were prepared through the Mannich condensation of 4-alkyl-2-(2H-benzotriazol-2-yl)phenol with the mixtures of excess paraformaldehyde and diethylamine under reflux conditions. Zinc complexes supported by amino-benzotriazole phenoxide ligands (C1DEABTP− and C8DEABTP−) were synthesized and fully characterized. The reaction of ZnEt2 with DEABTP-H (1 equiv.) produces the tetra-coordinated dimeric zinc complexes [(μ-C1DEABTP)ZnEt]2 (1) and [(μ-C8DEABTP)ZnEt]2 (2). Experimental results indicate that complex 1 catalyzes the ring-opening polymerization of ε-caprolactone and β-butyrolactone with good catalytic activities in a controlled character.

Graphical abstractZinc complexes supported by amino-benzotriazole phenoxide ligands (C1DEABTP− and C8DEABTP−) were synthesized and fully characterized. Complex [(μ-C1DEABTP)ZnEt]2 (1) catalyzes the ring-opening polymerization of ε-caprolactone and β-butyrolactone in the presence of 9-anthracenemethanol with good catalytic activities in a controlled character.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Zinc complexes bearing the DEABTP− ligand are synthesized and fully characterized. ► Complex 1 catalyzes the polymerization of ε-caprolactone in a “living” fashion. ► Complex 1 catalyzes the polymerization of β-butyrolactone in a “controlled” manner.