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Kröckert KW, Garg F, Heck J, Heinz MV, Lange J, Schmidt R, Hoffmann A, Herres-Pawlis S. ATRP catalysts of tetradentate guanidine ligands - do guanidine donors induce a faster atom transfer? Dalton Trans 2024. [PMID: 38258473 DOI: 10.1039/d3dt03392a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Tripodal tetradentate N donor ligands stabilise the most active ATRP catalyst systems. Here, we set out to synthesise the new guanidine ligand TMG-4NMe2uns-penp, inspired by p-substituted tris(2-pyridylmethyl)amine (TPMA) ligands. The impact of changing pyridine against guanidine donors was examined through solid state and solution experiments and density functional theory (DFT) calculations. In the solid state, the molecular structures of copper complexes based on the ligands TMG-4NMe2uns-penp, TMG-uns-penp and TMG3tren were discussed concerning the influence of a NMe2 substituent at the pyridines and the guanidine donors. In solution, the TMG-4NMe2uns-penp system was investigated by several methods, including UV/Vis, EPR and NMR spectroscopy indicating similar properties to that of the highly active TPMANMe2 system. The redox potentials were determined and related to the catalytic activity. Besides the expected trends between these and the ligand structures, there is evidence that guanidine donors in tripodal ligand systems lead to a better deactivation and possibly a faster exchange within the ATRP equilibrium than TPMA systems. Supported by DFT calculations, it derives from an easier cleavable Cu-Br bond of the copper(II) deactivator species. The high activity was stated by a controlled initiator for continuous activator regeneration (ICAR) ATRP of styrene.
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Affiliation(s)
- Konstantin W Kröckert
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Felix Garg
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Joshua Heck
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Michel V Heinz
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Justin Lange
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Regina Schmidt
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Alexander Hoffmann
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1a, 52074 Aachen, Germany.
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Kirchhecker S, Nguyen N, Reichert S, Lützow K, Eselem Bungu PS, Jacobi von Wangelin A, Sandl S, Neffe AT. Iron(ii) carboxylates and simple carboxamides: an inexpensive and modular catalyst system for the synthesis of PLLA and PLLA-PCL block copolymers. RSC Adv 2023; 13:17102-17113. [PMID: 37293470 PMCID: PMC10244980 DOI: 10.1039/d3ra03112h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 05/30/2023] [Indexed: 06/10/2023] Open
Abstract
The combination of inexpensive Fe(ii) acetate with low molecular weight aliphatic carboxamides in situ generates an effective catalyst system for the ring opening polymerisation of lactones. PLLAs were produced in melt conditions with molar masses of up to 15 kg mol-1, narrow dispersity (Đ = 1.03), and without racemisation. The catalytic system was investigated in detail with regard to Fe(ii) source, and steric and electronic effects of the amide's substituents. Furthermore, the synthesis of PLLA-PCL block copolymers of very low randomness was achieved. This commercially available, inexpensive, modular, and user-friendly catalyst mixture may be suitable for polymers with biomedical applications.
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Affiliation(s)
- Sarah Kirchhecker
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | - Ngoc Nguyen
- Institute for Technical and Macromolecular Chemistry, University of Hamburg Bundesstrasse 55 20146 Hamburg Germany
| | - Stefan Reichert
- Department of Chemistry, University of Hamburg Martin-Luther-King-Platz 6 20146 Hamburg Germany
| | - Karola Lützow
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | - Paul S Eselem Bungu
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
| | | | - Sebastian Sandl
- Department of Chemistry, University of Hamburg Martin-Luther-King-Platz 6 20146 Hamburg Germany
| | - Axel T Neffe
- Institute of Active Polymers, Helmholtz-Zentrum Hereon Kantstr. 55 14513 Teltow Germany
- Institute for Technical and Macromolecular Chemistry, University of Hamburg Bundesstrasse 55 20146 Hamburg Germany
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Rittinghaus RD, Herres-Pawlis S. Catalysts as Key Enablers for the Synthesis of Bioplastics with Sophisticated Architectures. Chemistry 2023; 29:e202202222. [PMID: 36173968 PMCID: PMC10098652 DOI: 10.1002/chem.202202222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Indexed: 01/05/2023]
Abstract
Bioplastics are one of the answers to environmental pollution and linear material flows. The most promising bioplastic polylactide (PLA) is already replacing conventional plastics in a number of applications. The properties of PLA, however, do not fit for all potential application areas, but they can be altered by the introduction of comonomers. The copolymerization of lactide (LA) with other lactones like ϵ-caprolactone (CL) has been established for several years. Nevertheless, controlling copolymerizations remains a challenge due to the high complexity of the system. Copolymerization of LA with other monomer classes is much less investigated, but has the chance to overcome the limitations in material properties that occur when only lactones are used. The crucial factor for all copolymerizations is the catalyst. It dominates the reaction kinetics and determines the resulting microstructure. In this review, copolymerization catalysts for LA are presented divided into catalysts for the synthesis of lactone block copolymers, lactone random copolymers, and multimechanistically synthesized copolymers. The selected catalysts are highlighted either owing to their industrially applicable polymerization conditions or their non-standard mechanism.
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Affiliation(s)
- Ruth D Rittinghaus
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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Hermann A, Becker T, Schäfer MA, Hoffmann A, Herres‐Pawlis S. Effective Ligand Design: Zinc Complexes with Guanidine Hydroquinoline Ligands for Fast Lactide Polymerization and Chemical Recycling. CHEMSUSCHEM 2022; 15:e202201075. [PMID: 35803895 PMCID: PMC9795895 DOI: 10.1002/cssc.202201075] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 07/07/2022] [Indexed: 06/15/2023]
Abstract
In this study, the synthesis of two new guanidine hydroquinoline ligands served as basis for six new zinc guanidine complexes. Two of these complexes showed very high activity in the lactide polymerization under industrial conditions. The lactide polymerization was demonstrated in solution and melt conditions observing high activity and molar masses up to 90 000 g mol-1 . Density functional theory studies elucidated the high activity of the complexes associated with the influence of the ligand backbone and the use of triflate counterions. On the way towards a circular economy, polymerization and depolymerization go hand in hand. So far, guanidine complexes have only shown their good activity in the ring opening polymerization of esters, and guanidine complexes with pure N donors have not been tested in recycling processes. Herein, the excellent ability of zinc guanidine complexes to catalyze both polymerization and depolymerization was demonstrated. The two most promising zinc complexes efficiently mediated the methanolysis of polylactide into methyl lactate under mild reaction conditions.
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Affiliation(s)
- Alina Hermann
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 1a52074AachenGermany
| | - Tabea Becker
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 1a52074AachenGermany
| | - Martin A. Schäfer
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 1a52074AachenGermany
| | - Alexander Hoffmann
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 1a52074AachenGermany
| | - Sonja Herres‐Pawlis
- Institute of Inorganic ChemistryRWTH Aachen UniversityLandoltweg 1a52074AachenGermany
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