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Ring‐opening polymerization of rac‐lactide catalyzed by Al(III) and Zn(II) complexes incorporating Schiff base ligands derived from pyrrole‐2‐carboxaldehyde |
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| Authors: | Ernesto Rufino‐Felipe Nazario Lopez Fabio A Vengoechea‐Gómez Luis‐Guillermo Guerrero‐Ramírez Miguel‐Ángel Muñoz‐Hernández |
| Affiliation: | 1. Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico;2. Centro Universitario de Ciencias Exactas e Ingenierías, Departamento de Química, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico |
| Abstract: | A series of Al(III) chloride LAl‐Cl]; Al(III) alkoxide LAl‐OR]2; and Zn(II) LZn]2 complexes with Schiff base ligands were obtained. 1H NMR and X‐ray diffraction studies indicate that LAl‐Cl] complexes have Cs symmetry and the Al center is penta‐coordinated. The Al(III) alkoxide complex L5Al‐OiPr]2 is a dimer bridged by OiPr? with the Al center in a distorted octahedral environment. Zn complexes LZn]2 are double helix dimers with tetra‐coordinated Zn centers. The catalytic activity for the ring‐opening polymerization of rac‐lactide was evaluated. The best activity in this series is shown by the aluminium chloride complex with a flexible three‐carbon bridge; more flexible four‐carbon bridges lower the activity. |
| Keywords: | Al and Zn complexes bis(pyrrolidene) Schiff base ligands polylactide rac‐lactide ring‐opening polymerization |
