Open AccessHeterolepic β ‐Ketoiminate Zinc Phenoxide Complexes as Efficient Catalysts for the Ring Opening Polymerization of Lactide
Author(s) -
Ghosh Swarup,
Schäfer Pascal M.,
Dittrich Dennis,
Scheiper Christoph,
Steiniger Phillip,
Fink Gerhard,
Ksiazkiewicz Agnieszka N.,
Tjaberings Alexander,
Wölper Christoph,
Gröschel André H.,
Pich Andrij,
HerresPawlis Sonja,
Schulz Stephan
Publication year - 2019
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.201900203
Subject(s) - lactide , polymerization , ring opening polymerization , polymer chemistry , monomer , steric effects , substituent , zinc , tacticity , catalysis , chemistry , molar mass distribution , polymer , polylactic acid , medicinal chemistry , stereochemistry , organic chemistry
Zinc phenoxide complexes L 1 ZnOAr 1 – 4 (L 1 =Me 2 NC 2 H 4 NC(Me)CHC(Me)O) and L 2 ZnOAr 5 – 8 (L 2 =Me 2 NC 3 H 6 NC(Me)CHC(Me)O) with donor‐functionalized β ‐ketoiminate ligands (L 1/2 ) and OAr substituents (Ar=Ph 1 , 5 ; 2,6‐Me 2 ‐C 6 H 3 2 , 6 ; 3,5‐Me 2 ‐C 6 H 3 3 , 7 ; 4‐Bu‐C 6 H 4 4 , 8 ) with tuneable electronic and steric properties were synthesized and characterized. 1 – 8 adopt binuclear structures in the solid state except for 5 , while they are monomeric in CDCl 3 solution. 1 – 8 are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH 2 Cl 2 at ambient temperature and the catalytic activity is controlled by the electronic and steric properties of the OAr substituent, yielding polymers with high average molecular weight ( M n ) and moderately controlled molecular weight distribution (MWDs). 1 and 5 showed a living polymerization character and kinetic studies on the ROP of L –LA with 1 and 5 proved first order dependencies on the monomer concentration. Homonuclear decoupled 1 H‐NMR analyses of polylactic acid (PLA) formed with rac ‐LA proved isotactic enrichment of the PLA microstructure.