TY - JOUR
T1 - Heterolepic β ‐Ketoiminate Zinc Phenoxide Complexes as Efficient Catalysts for the Ring Opening Polymerization of Lactide
AU - Ghosh, S.
AU - Schafer, P.M.
AU - Dittrich, D.
AU - Scheiper, C.
AU - Steiniger, P.
AU - Fink, G.
AU - Ksiazkiewicz, A.N.
AU - Tjaberings, A.
AU - Wolper, C.
AU - Groschel, A.H.
AU - Pich, A.
AU - Herres-Pawlis, S.
AU - Schulz, S.
N1 - Funding Information:
Financial support by Evonik Industries (P.S., A.T., A.H.G.) and the University of Duisburg Essen (St.S.) is acknowledged. A.H.G. is grateful for financial support from the DFG through the Emmy-Noether Program (No. 376920678). P.M.S. thanks the Hanns-Seidel-Foundation (fellowship) for funding (Bundesministerium f?r Bildung und Forschung, BMBF). S.H.-P. thanks Total Corbion PLA for lactide donations.
Publisher Copyright:
© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
PY - 2019/7/1
Y1 - 2019/7/1
N2 - Zinc phenoxide complexes (LZnOAr)-Zn-1 1-4 (L-1=Me2NC2H4NC(Me)CHC(Me)O) and (LZnOAr)-Zn-2 5-8 (L-2=Me2NC3H6NC(Me)CHC(Me)O) with donor-functionalized beta-ketoiminate ligands (L-1/2) and OAr substituents (Ar=Ph 1, 5; 2,6-Me-2-C6H3 2, 6; 3,5-Me-2-C6H3 3, 7; 4-Bu-C6H4 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 CDCl3 solution. 1-8 are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH2Cl2 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 H-1-NMR analyses of polylactic acid (PLA) formed with rac-LA proved isotactic enrichment of the PLA microstructure.
AB - Zinc phenoxide complexes (LZnOAr)-Zn-1 1-4 (L-1=Me2NC2H4NC(Me)CHC(Me)O) and (LZnOAr)-Zn-2 5-8 (L-2=Me2NC3H6NC(Me)CHC(Me)O) with donor-functionalized beta-ketoiminate ligands (L-1/2) and OAr substituents (Ar=Ph 1, 5; 2,6-Me-2-C6H3 2, 6; 3,5-Me-2-C6H3 3, 7; 4-Bu-C6H4 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 CDCl3 solution. 1-8 are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH2Cl2 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 H-1-NMR analyses of polylactic acid (PLA) formed with rac-LA proved isotactic enrichment of the PLA microstructure.
KW - aluminum complexes
KW - coordination chemistry
KW - diastereoselective synthesis
KW - epsilon-caprolactone
KW - ketoiminate
KW - lactide
KW - lewis pairs
KW - magnesium
KW - polymerization reactions
KW - single-site catalysts
KW - stereoselective polymerization
KW - structural-characterization
KW - substituent effects
KW - tridentate ketiminate ligands
KW - zinc
KW - COORDINATION CHEMISTRY
KW - STRUCTURAL-CHARACTERIZATION
KW - ALUMINUM COMPLEXES
KW - STEREOSELECTIVE POLYMERIZATION
KW - TRIDENTATE KETIMINATE LIGANDS
KW - LEWIS PAIRS
KW - MAGNESIUM
KW - EPSILON-CAPROLACTONE
KW - DIASTEREOSELECTIVE SYNTHESIS
KW - SINGLE-SITE CATALYSTS
U2 - 10.1002/open.201900203
DO - 10.1002/open.201900203
M3 - Article
SN - 2191-1363
VL - 8
SP - 951
EP - 960
JO - Chemistry Open
JF - Chemistry Open
IS - 7
ER -