Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide

Divambal Appavoo; Bernard Omondi; Ilia A. Guzei; Juanita L. Van Wyk; Orpah Zinyemba; James Darkwa

doi:10.1016/j.poly.2013.11.011

Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide

Divambal Appavoo, Bernard Omondi, Ilia A. Guzei, Juanita L. Van Wyk, Orpah Zinyemba, James Darkwa

Chemical Sciences

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64 Citations (Scopus)

Abstract

3,5-Dimethylpyrazole (L), reacts with [Cu(OAc)₂] or [Zn(OAc)₂]; and either C₆H₅COOH, 4-OH-C ₆H₅COOH, 3,5-NO₂-C₆H₅COOH or 2-Cl-C₆H₅COOH to afford the corresponding metal complexes: [Cu(C₆H₅COO)₂(L)₂] (1), [Cu(2-Cl-C₆H₄COO)₂(L)₂] (2), [Cu(3,5-NO₂-C₆H₃COO)₂(L) ₂] (3), [Cu(4-OH-C₆H₄COO)₂(L) ₂] (4), [Zn(C₆H₅COO)₂(L) ₂] (5), [Zn(2-Cl-C₆H₄COO)₂(L) ₂] (6), [Zn(3,5-NO₂-C₆H₃COO) ₂(L)₂] (7), [Zn(4-OH-C₆H₄COO) ₂(L)₂] (8). The diamagnetic zinc complexes were characterized by IR, NMR spectroscopy and elemental analysis; while the paramagnetic copper complexes were only characterized by IR spectroscopy, elemental analysis and 1 and 2 were further characterized by single crystal X-ray diffraction studies. All eight complexes are very good initiators for the ring opening polymerization (ROP) of ε-caprolactone and d,l-lactide at elevated temperatures, under solvent-free conditions and in toluene respectively; producing polycaprolactone (PCL) and poly(d,l-lactide) (PLA) of moderate molecular weights (ca 4757 Da for PCL and 2484 Da for PLA) and narrow polydispersity indices (1.36 for PCL and 1.42 for PLA). The ¹³C{ ¹H} NMR spectra indicate the stereochemistry of PLA is heterotactic.

Original language	English
Pages (from-to)	55-60
Number of pages	6
Journal	Polyhedron
Volume	69
DOIs	https://doi.org/10.1016/j.poly.2013.11.011
Publication status	Published - 17 Feb 2014

Keywords

Copper
Initiators
Pyrazole
Ring opening polymerization
Zinc
d,l-Lactide
ε-Caprolactone

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

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@article{2ddfaceb3d7c479f9d9073d8aea4e352,

title = "Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide",

abstract = "3,5-Dimethylpyrazole (L), reacts with [Cu(OAc)2] or [Zn(OAc)2]; and either C6H5COOH, 4-OH-C 6H5COOH, 3,5-NO2-C6H5COOH or 2-Cl-C6H5COOH to afford the corresponding metal complexes: [Cu(C6H5COO)2(L)2] (1), [Cu(2-Cl-C6H4COO)2(L)2] (2), [Cu(3,5-NO2-C6H3COO)2(L) 2] (3), [Cu(4-OH-C6H4COO)2(L) 2] (4), [Zn(C6H5COO)2(L) 2] (5), [Zn(2-Cl-C6H4COO)2(L) 2] (6), [Zn(3,5-NO2-C6H3COO) 2(L)2] (7), [Zn(4-OH-C6H4COO) 2(L)2] (8). The diamagnetic zinc complexes were characterized by IR, NMR spectroscopy and elemental analysis; while the paramagnetic copper complexes were only characterized by IR spectroscopy, elemental analysis and 1 and 2 were further characterized by single crystal X-ray diffraction studies. All eight complexes are very good initiators for the ring opening polymerization (ROP) of ε-caprolactone and d,l-lactide at elevated temperatures, under solvent-free conditions and in toluene respectively; producing polycaprolactone (PCL) and poly(d,l-lactide) (PLA) of moderate molecular weights (ca 4757 Da for PCL and 2484 Da for PLA) and narrow polydispersity indices (1.36 for PCL and 1.42 for PLA). The 13C{ 1H} NMR spectra indicate the stereochemistry of PLA is heterotactic.",

keywords = "Copper, Initiators, Pyrazole, Ring opening polymerization, Zinc, d,l-Lactide, ε-Caprolactone",

author = "Divambal Appavoo and Bernard Omondi and Guzei, {Ilia A.} and {Van Wyk}, {Juanita L.} and Orpah Zinyemba and James Darkwa",

year = "2014",

month = feb,

day = "17",

doi = "10.1016/j.poly.2013.11.011",

language = "English",

volume = "69",

pages = "55--60",

journal = "Polyhedron",

issn = "0277-5387",

publisher = "Elsevier Ltd.",

}

TY - JOUR

T1 - Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide

AU - Appavoo, Divambal

AU - Omondi, Bernard

AU - Guzei, Ilia A.

AU - Van Wyk, Juanita L.

AU - Zinyemba, Orpah

AU - Darkwa, James

PY - 2014/2/17

Y1 - 2014/2/17

N2 - 3,5-Dimethylpyrazole (L), reacts with [Cu(OAc)2] or [Zn(OAc)2]; and either C6H5COOH, 4-OH-C 6H5COOH, 3,5-NO2-C6H5COOH or 2-Cl-C6H5COOH to afford the corresponding metal complexes: [Cu(C6H5COO)2(L)2] (1), [Cu(2-Cl-C6H4COO)2(L)2] (2), [Cu(3,5-NO2-C6H3COO)2(L) 2] (3), [Cu(4-OH-C6H4COO)2(L) 2] (4), [Zn(C6H5COO)2(L) 2] (5), [Zn(2-Cl-C6H4COO)2(L) 2] (6), [Zn(3,5-NO2-C6H3COO) 2(L)2] (7), [Zn(4-OH-C6H4COO) 2(L)2] (8). The diamagnetic zinc complexes were characterized by IR, NMR spectroscopy and elemental analysis; while the paramagnetic copper complexes were only characterized by IR spectroscopy, elemental analysis and 1 and 2 were further characterized by single crystal X-ray diffraction studies. All eight complexes are very good initiators for the ring opening polymerization (ROP) of ε-caprolactone and d,l-lactide at elevated temperatures, under solvent-free conditions and in toluene respectively; producing polycaprolactone (PCL) and poly(d,l-lactide) (PLA) of moderate molecular weights (ca 4757 Da for PCL and 2484 Da for PLA) and narrow polydispersity indices (1.36 for PCL and 1.42 for PLA). The 13C{ 1H} NMR spectra indicate the stereochemistry of PLA is heterotactic.

AB - 3,5-Dimethylpyrazole (L), reacts with [Cu(OAc)2] or [Zn(OAc)2]; and either C6H5COOH, 4-OH-C 6H5COOH, 3,5-NO2-C6H5COOH or 2-Cl-C6H5COOH to afford the corresponding metal complexes: [Cu(C6H5COO)2(L)2] (1), [Cu(2-Cl-C6H4COO)2(L)2] (2), [Cu(3,5-NO2-C6H3COO)2(L) 2] (3), [Cu(4-OH-C6H4COO)2(L) 2] (4), [Zn(C6H5COO)2(L) 2] (5), [Zn(2-Cl-C6H4COO)2(L) 2] (6), [Zn(3,5-NO2-C6H3COO) 2(L)2] (7), [Zn(4-OH-C6H4COO) 2(L)2] (8). The diamagnetic zinc complexes were characterized by IR, NMR spectroscopy and elemental analysis; while the paramagnetic copper complexes were only characterized by IR spectroscopy, elemental analysis and 1 and 2 were further characterized by single crystal X-ray diffraction studies. All eight complexes are very good initiators for the ring opening polymerization (ROP) of ε-caprolactone and d,l-lactide at elevated temperatures, under solvent-free conditions and in toluene respectively; producing polycaprolactone (PCL) and poly(d,l-lactide) (PLA) of moderate molecular weights (ca 4757 Da for PCL and 2484 Da for PLA) and narrow polydispersity indices (1.36 for PCL and 1.42 for PLA). The 13C{ 1H} NMR spectra indicate the stereochemistry of PLA is heterotactic.

KW - Copper

KW - Initiators

KW - Pyrazole

KW - Ring opening polymerization

KW - Zinc

KW - d,l-Lactide

KW - ε-Caprolactone

UR - http://www.scopus.com/inward/record.url?scp=84890444578&partnerID=8YFLogxK

U2 - 10.1016/j.poly.2013.11.011

DO - 10.1016/j.poly.2013.11.011

M3 - Article

AN - SCOPUS:84890444578

SN - 0277-5387

VL - 69

SP - 55

EP - 60

JO - Polyhedron

JF - Polyhedron

ER -

Bis(3,5-dimethylpyrazole) copper(II) and zinc(II) complexes as efficient initiators for the ring opening polymerization of ε-caprolactone and d,l-lactide

Abstract

Keywords

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