Zinc complexes containing coumarin-derived anilido-aldimine ligands as catalysts for ring opening polymerization of L-lactide.

Chi-Tien Chen,Min-Chian Wang,Tzu-Lun Huang

doi:10.3390/molecules20045313

Abstract

The coumarin-derived ligand precursors L1H–L6H have been prepared. Treatment of these ligand precursors with 1.2 equiv. of ZnEt2 in toluene affords zinc ethyl complexes (LZnEt) 1–6 (where L = coumarin-derived ligands bearing different functional groups). Reaction of ligand precursor L3H with 1.5 equiv. of Zn[N(SiMe3)2]2 in toluene affords the zinc amide complex, L3ZnN(SiMe3)2, 7. All these compounds were characterized by NMR spectroscopy and elemental analysis. The molecular structures are reported for 1 and 7. The catalytic activities of complexes 1–7 towards the ring opening polymerization of l-lactide in the presence of 9-AnOH have been investigated.

Highlights

Biocompatibility, and permeability properties demonstrated by polylactide, development of well-defined metal complexes involved in ring opening polymerization as catalysts/initiators has recently become attractive [1,2,3,4]
Molecules 2015, 20 have encouraged diverse research groups to synthesize similar chelating ligand precursors and examine the bonding and electronic features related to these ligands
Ligand precursors L1H–L6H were prepared in a straightforward fashion by the condensation between 4-(mesitylamino)-2-oxo-2H-chromene-3-carbaldehyde and substituted anilines or aliphatic amines to afford the target compounds in fair to high yield

Summary

Introduction

Biocompatibility, and permeability properties demonstrated by polylactide, development of well-defined metal complexes involved in ring opening polymerization as catalysts/initiators has recently become attractive [1,2,3,4]. We introduce similar bonding mode as found in the anilido-aldimine ligand into coumarin molecules whose derivatives demonstrate biological activity [20,21,22,23], or are sensitive fluorescent probes [24] or organic dyes [25], to prepare several coumarin-derived anilido-aldimine ligand precursors. We expect those precursors to have the potential to work as mono anionic dentate ligands upon reacting with zinc reagents. The catalytic activities of these zinc complexes towards the ring opening polymerization of L-lactide in the presence of alcohols have been investigated

Methods

Results

Conclusion