TY - JOUR
T1 - Ring opening polymerization ofd,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes
AU - Appavoo, Divambal
AU - Spencer, Lara C.
AU - Guzei, Ilia A.
AU - Gómez-García, Carlos J.
AU - van Wyk, Juanita L.
AU - Darkwa, James
N1 - Publisher Copyright:
© The Royal Society of Chemistry 2021.
PY - 2021/4/12
Y1 - 2021/4/12
N2 - 1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2]n(3) and [Cu{(3,5-NO2)2-C6H3COO}2L]n(4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in1,2·7H2O,3and (ii) regular chains in3and4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1-4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions andd,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with1as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups.
AB - 1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2]n(3) and [Cu{(3,5-NO2)2-C6H3COO}2L]n(4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in1,2·7H2O,3and (ii) regular chains in3and4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1-4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions andd,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with1as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups.
UR - http://www.scopus.com/inward/record.url?scp=85104239134&partnerID=8YFLogxK
U2 - 10.1039/d1ra00339a
DO - 10.1039/d1ra00339a
M3 - Article
AN - SCOPUS:85104239134
SN - 2046-2069
VL - 11
SP - 13475
EP - 13485
JO - RSC Advances
JF - RSC Advances
IS - 22
ER -