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Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac ‐Lactide and ε ‐Caprolactone
Author(s) -
Ghosh Swarup,
Spannenberg Anke,
Mejía Esteban
Publication year - 2017
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201700176
Subject(s) - chemistry , cubane , lactide , polymerization , polymer chemistry , ring opening polymerization , monomer , zinc , schiff base , catalysis , solvent , crystal structure , stereochemistry , crystallography , medicinal chemistry , organic chemistry , polymer
New polynuclear zinc complexes containing tridentate Schiff base ligands were successfully synthesized and fully characterized. The solid‐state structure of the complexes was determined using single crystal X‐ray diffraction. The complexes display a tetranuclear cubane‐like core structure [Zn 4 O 4 ] and sowed good catalytic activity towards the ring‐opening polymerization ( ROP ) of rac ‐lactide ( rac ‐ LA ) and ε ‐caprolactone ( ε ‐ CL ) under solvent‐free conditions. The polylactic acid ( PLA ) obtained from rac ‐ LA showed isotactic enrichment, as proved by homonuclear decoupled 1 H‐ NMR analysis. These complexes also showed good activity and superior control towards the ROP of rac ‐ LA and ε ‐ CL in the presence of benzyl alcohol as a co‐initiator. Furthermore, kinetic studies demonstrated that the ROP of rac ‐ LA and ε ‐ CL has a first order dependence on both monomer ( rac ‐ LA and ε ‐ CL ) and catalyst concentration.