Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide
1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L1) and bis(3,5-dimethylpyrazol-1-yl)methane (L2), react with [Zn(OAc)2] and 4-OH-C6H4COOH, 2-Cl-C6H4COOH, 3,5-(NO2)2-C6H3COOH and C6H5COOH to form the corresponding zinc(II) complexes [Zn(4-OH-C6H4COO)2L1] (1), [Zn(2-Cl-C6H4COO)2L1] (2), [Zn{3,5-(NO...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-01-01
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| Series: | Results in Chemistry |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2211715621001661 |
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| author | Divambal Appavoo Juanita L. van Wyk Lara C. Spencer Ilia A. Guzei James Darkwa |
| author_facet | Divambal Appavoo Juanita L. van Wyk Lara C. Spencer Ilia A. Guzei James Darkwa |
| author_sort | Divambal Appavoo |
| collection | DOAJ |
| description | 1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L1) and bis(3,5-dimethylpyrazol-1-yl)methane (L2), react with [Zn(OAc)2] and 4-OH-C6H4COOH, 2-Cl-C6H4COOH, 3,5-(NO2)2-C6H3COOH and C6H5COOH to form the corresponding zinc(II) complexes [Zn(4-OH-C6H4COO)2L1] (1), [Zn(2-Cl-C6H4COO)2L1] (2), [Zn{3,5-(NO2)2-C6H3COO}2L1] (3), [Zn4(C6H5COO)8(L1)2]n (4) and [Zn{3,5-(NO2)2-C6H3COO}2L2] (5). All five zinc complexes were characterized by a combination of NMR and IR spectroscopy, mass spectrometry and elemental analysis. Complexes 4 and 5 were further characterized by single-crystal X-ray diffractometry. Complex 4 is polymeric, with two different pentacoordinate Zn centres in two different coordination environments. Complex 5 has a distorted tetrahedral geometry around the zinc. These Zn(II) complexes (1–5) successfully initiate the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and D,L-lactide at elevated temperatures, and under solvent-free conditions and in toluene, respectively. The polycaprolactone (PCL) and poly(D,L-lactide) (PLA) obtained are of moderate molecular weights and medium polydispersity indices. The end groups of the polymers, determined by MALDI-ToF MS, are mainly hydroxyl groups and the stereochemistry of PLA is predominantly isotactic as determined with 13C{1H} NMR spectroscopy. |
| first_indexed | 2024-04-12T02:13:23Z |
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| id | doaj.art-68348aeb19704e9ca2efc1558213856d |
| institution | Directory Open Access Journal |
| issn | 2211-7156 |
| language | English |
| last_indexed | 2024-04-12T02:13:23Z |
| publishDate | 2022-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Results in Chemistry |
| spelling | doaj.art-68348aeb19704e9ca2efc1558213856d2022-12-22T03:52:19ZengElsevierResults in Chemistry2211-71562022-01-014100261Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactideDivambal Appavoo0Juanita L. van Wyk1Lara C. Spencer2Ilia A. Guzei3James Darkwa4Department of Chemical Sciences, University of Johannesburg, P.O. Box X524, Auckland Park 2006, South AfricaDepartment of Chemical Sciences, University of Johannesburg, P.O. Box X524, Auckland Park 2006, South AfricaDepartment of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United StatesDepartment of Chemical Sciences, University of Johannesburg, P.O. Box X524, Auckland Park 2006, South Africa; Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, United StatesDepartment of Chemical Sciences, University of Johannesburg, P.O. Box X524, Auckland Park 2006, South Africa; Corresponding author at: Department of Chemical Sciences, University of Johannesburg, P.O. Box X524, Auckland Park 2006, South Africa.1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L1) and bis(3,5-dimethylpyrazol-1-yl)methane (L2), react with [Zn(OAc)2] and 4-OH-C6H4COOH, 2-Cl-C6H4COOH, 3,5-(NO2)2-C6H3COOH and C6H5COOH to form the corresponding zinc(II) complexes [Zn(4-OH-C6H4COO)2L1] (1), [Zn(2-Cl-C6H4COO)2L1] (2), [Zn{3,5-(NO2)2-C6H3COO}2L1] (3), [Zn4(C6H5COO)8(L1)2]n (4) and [Zn{3,5-(NO2)2-C6H3COO}2L2] (5). All five zinc complexes were characterized by a combination of NMR and IR spectroscopy, mass spectrometry and elemental analysis. Complexes 4 and 5 were further characterized by single-crystal X-ray diffractometry. Complex 4 is polymeric, with two different pentacoordinate Zn centres in two different coordination environments. Complex 5 has a distorted tetrahedral geometry around the zinc. These Zn(II) complexes (1–5) successfully initiate the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and D,L-lactide at elevated temperatures, and under solvent-free conditions and in toluene, respectively. The polycaprolactone (PCL) and poly(D,L-lactide) (PLA) obtained are of moderate molecular weights and medium polydispersity indices. The end groups of the polymers, determined by MALDI-ToF MS, are mainly hydroxyl groups and the stereochemistry of PLA is predominantly isotactic as determined with 13C{1H} NMR spectroscopy.http://www.sciencedirect.com/science/article/pii/S2211715621001661PyrazoleZincRing opening polymerizationε-CaprolactoneD,L-lactide |
| spellingShingle | Divambal Appavoo Juanita L. van Wyk Lara C. Spencer Ilia A. Guzei James Darkwa Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide Results in Chemistry Pyrazole Zinc Ring opening polymerization ε-Caprolactone D,L-lactide |
| title | Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide |
| title_full | Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide |
| title_fullStr | Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide |
| title_full_unstemmed | Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide |
| title_short | Pyrazolyl-based zinc(II) carboxylate complexes: synthesis, characterization and catalytic behaviour in ring opening polymerization of ε-caprolactone and D,L-lactide |
| title_sort | pyrazolyl based zinc ii carboxylate complexes synthesis characterization and catalytic behaviour in ring opening polymerization of ε caprolactone and d l lactide |
| topic | Pyrazole Zinc Ring opening polymerization ε-Caprolactone D,L-lactide |
| url | http://www.sciencedirect.com/science/article/pii/S2211715621001661 |
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