1
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Flores-Romero V, LeBlanc J, Chen Z, Lavoie GG. Ti and Zr complexes bearing guanidine-phenolate ligands: coordination chemistry and polymerization studies. RSC Adv 2024; 14:25889-25899. [PMID: 39156754 PMCID: PMC11328681 DOI: 10.1039/d4ra05146g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2024] [Accepted: 08/05/2024] [Indexed: 08/20/2024] Open
Abstract
A series of group 4 bis(isopropoxide) complexes M[N^O]2(OiPr)2, stabilized by guanidine-phenolate N^O ligands, have been prepared and used as catalysts for the polymerization of unpurified rac-lactide under solvent-free conditions at 130 °C. The resulting polylactic acid (PLA) presented heterotactic bias (P r = 0.56-0.62) with molecular weights similar to those obtained in control experiments with Zr(OiPr)4·iPrOH, Ti(OiPr)4, and Sn(Oct)2. The molecular weights were lower than expected for living polymerization due to chain transfer and/or transesterification. Zr complexes were more active than the Ti homologues, with rate constants ranging from 1.17-3.21 × 10-4 s-1, comparable to that observed with the free guanidine-phenol ligands. The corresponding bis(guanidine-phenolate) titanium dichloride complexes Ti[N^O]2Cl2 were also prepared and tested in ethylene polymerization. The low activity (up to 1.1 kgPE mol-1 h-1) was associated to the strong electron-donating ability of the guanidine moiety and to the trans-N,N-cis-O,O-cis-Cl,Cl coordination mode of the guanidine-phenolate ligand.
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Affiliation(s)
| | - Jesse LeBlanc
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
| | - Zichuan Chen
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
| | - Gino G Lavoie
- York University 4700 Keele Street Toronto Ontario M3J 1P3 Canada
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2
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Young MS, LaPointe AM, MacMillan SN, Coates GW. Highly Enantioselective Polymerization of β-Butyrolactone by a Bimetallic Magnesium Catalyst: An Interdependent Relationship Between Favored and Unfavored Enantiomers. J Am Chem Soc 2024; 146:18032-18040. [PMID: 38874569 DOI: 10.1021/jacs.4c04716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Herein, we report that (S,S)-prophenolMg2(μ-OnBu)(THF)2 ((S,S)-1, prophenol = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) is a highly enantioselective (kR/kS = 140) precatalyst for ring-opening polymerization of rac-β-butyrolactone (β-BL) to isotactic poly(3-hydroxybutyrate) (i-PHB), a high performance, biodegradable polyester. Precatalyst (S,S)-1 polymerizes (R)-β-BL with an inversion of stereochemistry to (S)-PHB with a m% (percentage of adjacent linkages with a meso configuration) of 98% at 41% conversion and Tm of 165 °C under a variety of conditions. Complex (S,S)-1 demonstrates unique polymerization kinetics, as it does not polymerize the preferred enantiomer, (R)-β-BL, alone. Mechanistic studies revealed that (S)-β-BL is needed to convert (S,S)-1 into the active enantioselective polymerization catalyst. To the best of our knowledge, (S,S)-1 produces i-PHB with the highest degree of isotacticity observed from a polymerization of rac-β-BL. This study informs the design and understanding of future enantioselective and earth-abundant metal catalysts for ring-opening polymerization of β-lactones.
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Affiliation(s)
- Morgan S Young
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Anne M LaPointe
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Geoffrey W Coates
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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3
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Abdul Rahman M, Neal TJ, Garden JA. Cooperative heterometallic catalysts: balancing activity and control in PCL- block-PLA copolymer synthesis. Chem Commun (Camb) 2024; 60:5530-5533. [PMID: 38695674 DOI: 10.1039/d4cc01664e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Heterometallic cooperativity is gaining momentum in cyclic ester ring-opening polymerisation, yet remains surprisingly underexplored in their block copolymerisations. Here, we report the first homogeneous heterometallic "ate" catalysts for poly(ε-caprolactone)-poly(lactic acid) block copolymers, showcasing the substantial differences in the polymer structures observed upon exchanging Zn for Mg or Ca.
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Affiliation(s)
| | - Thomas J Neal
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Jennifer A Garden
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
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4
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Peprah F, Tarantola GE, Plaman AS, Vu EL, Huynh AB, Durr CB. Synthesis and catalytic activity of single-site group V alkoxide complexes for the ring-opening polymerization of ε-caprolactone. Dalton Trans 2024; 53:7073-7080. [PMID: 38567482 DOI: 10.1039/d4dt00422a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The synthesis, characterization, and ring-opening polymerization (ROP) activity of a family of niobium and tantalum alkoxide catalysts was studied. The final catalysts are made in a two-step synthesis, first by reacting the desired homoleptic metal ethoxide with a phenolketoimine ligand to form a series of synthetic intermediates, followed by reaction with catechol to produce a catalytic platform with a single ethoxide initiator. By using two separate ligands, the electronic properties of the catalyst can be tuned, and the molecular weight of the polymer can be increased. It was found that synthetic intermediates adopted a mer geometry both in solution and in the solid state. This mer geometry was retained for the final catechol derivatives, however in one case, where catechol was substituted for 3-methoxycatechol, the molecule adopted a highly distorted fac geometry. Catalytic ROP activity of the synthetic intermediates and final catechol derivatives with ε-caprolactone was studied through a kinetic analysis. In all seven cases studied the reactions proceeded through the expected coordination-insertion mechanism, following pseudo first-order kinetics and increasing in Mn linearly vs. conversion. The single-initiator catechol derivatives increased the Mn by three times compared to that of the three-initiator synthetic intermediates with little decrease in the overall reaction rate. Both the nature of the ligand and metal were found to impact the rate of reaction in these systems. By switching from an electron donating ligand to an electron withdrawing ligand, the rate was found to nearly double. Tantalum species were faster than their niobium counterparts by ∼3 times in the synthetic intermediates and ∼1.5 times in the catechol derivatives. This observed periodicity supports recent literature findings in this area.
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Affiliation(s)
- Frank Peprah
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Grace E Tarantola
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Alyson S Plaman
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Emily L Vu
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Alyssa B Huynh
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Christopher B Durr
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
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5
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Hughes JWJ, Babula DJ, Stowers-Veitch F, Yuan K, Uzelac M, Nichol GS, Ingleson MJ, Garden JA. NacNac-zinc-pyridonate mediated ε-caprolactone ROP. Dalton Trans 2023; 52:17767-17775. [PMID: 37981810 PMCID: PMC10696559 DOI: 10.1039/d3dt03344a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 11/10/2023] [Indexed: 11/21/2023]
Abstract
Herein we report the synthesis, isolation and polymerisation activity of two new zinc compounds based on a 2,6-diisopropylphenyl (Dipp) β-diiminate (NacNac) ligand framework with zinc also ligated by an amidate (2-pyridonate or 6-methyl-2-pyridonate) unit. The compounds crystallised as either monomeric (6-Me-2-pyridonate derivative) or dimeric (2-pyridonate) species, although both were found to be monomeric in solution via1H DOSY NMR spectroscopy, which was supported by DFT calculations. These observations suggest that both complexes initiate ring-opening polymerisation (ROP) through a single-site monometallic mechanism. High molecular weight poly ε-caprolactone (PCL) was achieved via exogenous initiator-free ROP conditions with both catalysts. An increase in the 2-pyridonate initiator steric bulk (6-Me- vs. 6-H-) resulted in an improved catalytic activity, facilitating complete monomer conversion within 1 h at 60 °C. Pyridonate end-groups were observed by MALDI-ToF mass spectrometry, contrasting with previous observations for DippNacNac-Zn acetate complexes (where no acetate end groups are observed), instead this more closely resembles the reactivity of DippNacNac-Zn alkoxide complexes in ROP (where RO end groups are observed). Additional major signals in the MALDI-ToF spectra were consistent with cyclic PCL species, which are attributed to back-biting ring-closing termination steps occuring in a process facilitated by the pyridonate unit being an effective leaving group. To the best of our knowledge, these complexes represent the first examples of pyridonate, and indeed amidate, initated ROP.
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Affiliation(s)
- Jack W J Hughes
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Dawid J Babula
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | | | - Kang Yuan
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Marina Uzelac
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Gary S Nichol
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Michael J Ingleson
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
| | - Jennifer A Garden
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK.
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6
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Impemba S, Manca G, Tozio I, Milione S. Ring-Opening Polymerization of rac-β-Butyrolactone Promoted by New Tetradentate Thioether-Amide Ligand-Type Zinc Complexes. Polymers (Basel) 2023; 15:4366. [PMID: 38006091 PMCID: PMC10675234 DOI: 10.3390/polym15224366] [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: 10/10/2023] [Revised: 10/27/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
In this work, thioether-amide ligands featuring a combination of hard amide groups with soft donor groups have been employed to develop new zinc catalysts for the ring-opening polymerization of cyclic esters. All complexes were prepared in high yields through alkane elimination reactions with diethyl zinc and characterized using nuclear magnetic resonance (NMR) spectroscopy. Density functional theory (DFT) characterization provided insight into the parameters that influence catalytic activity, such as steric hindrance at the metal center, Lewis acidity and electronic density of thioether-amide ligands. In the presence of one equivalent of isopropanol, all complexes were active in the ring-opening polymerization of rac-β-butyrolactone. Quantitative conversion of 100 monomer equivalents was achieved within 1 h at 80 °C in a toluene solution. Number-average molecular weights increased linearly with monomer conversion; the values were in optimal agreement with those expected, and polydispersity index values were narrow and relatively constant throughout the course of polymerization. The most active complex was also effective in the ring-opening polymerization of ε-caprolactone and L-lactide. To propose a reliable reaction path, DFT calculations were undertaken. In the first step of the reaction, the acidic proton of the alcohol is transferred to the basic nitrogen atom of the amide ligand coordinated to the zinc ion. This leads to the alcoholysis of the Zn-N bond and the formation of an alcoholate derivative that starts the polymerization. In subsequent steps, the reaction follows the classical coordination-insertion mechanism.
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Affiliation(s)
- Salvatore Impemba
- Center for Colloid and Surface Science, Department of Chemistry, University of Florence, Via della Lastruccia, 3, 50019 Sesto Fiorentino, Firenze, Italy;
| | - Gabriele Manca
- CNR-ICCOM, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Firenze, Italy;
| | - Irene Tozio
- Department of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, Italy;
| | - Stefano Milione
- Department of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, Italy;
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7
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Su RR, Ganta PK, Cheng CA, Hu YT, Chang YC, Chang CJ, Ding S, Chen HY, Wu KH. Ring-opening polymerization of ε-caprolactone and L-lactide using ethyl salicylate-bearing zinc complexes as catalysts. MOLECULAR CATALYSIS 2023. [DOI: 10.1016/j.mcat.2023.112965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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8
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Jiang J, Choi J, Yoon S. Living ring-opening polymerization of β-butyrolactone initiated by mononuclear zirconium compounds containing sterically hindered N, O-chelate and anionic dimethylamide ligands †. RSC Adv 2023; 13:10379-10383. [PMID: 37020882 PMCID: PMC10068430 DOI: 10.1039/d3ra00338h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/23/2023] [Indexed: 04/05/2023] Open
Abstract
The ring-opening polymerization of β-lactones into polyhydroxyalkanoates (PHA), biodegradable polymers with high molecular weight and narrow polydispersity, is of significant interest. The mononuclear zirconium compound containing sterically hindered N,O-chelate and anionic dimethylamide ligands was used as an initiator for the polymerization of β-butyrolactone (BBL), resulting in polyhydroxylbutyrate (PHB) with a number-average molecular weight of 12 000 g mol−1. Kinetic studies demonstrate a first-order dependence on β-butyrolactone (BBL) concentration at room temperature, accompanied by narrow molecular weight distributions (ca. 1.03–1.07), indicating a well-controlled living polymerization. The ring-opening polymerization of β-lactones into polyhydroxyalkanoates (PHA), biodegradable polymers with high molecular weight and narrow polydispersity, is of significant interest.![]()
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Affiliation(s)
- Jianwei Jiang
- Department of Chemistry, Chung-Ang UniversitySeoul 06974Republic of Korea
| | - Jihyun Choi
- Department of Chemistry, Chung-Ang UniversitySeoul 06974Republic of Korea
| | - Sungho Yoon
- Department of Chemistry, Chung-Ang UniversitySeoul 06974Republic of Korea
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9
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Ghosh S, Schulte Y, Wölper C, Tjaberings A, Gröschel AH, Haberhauer G, Schulz S. Cooperative Effect in Binuclear Zinc Catalysts in the ROP of Lactide. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Swarup Ghosh
- Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, S07S03C30, 45141 Essen, Germany
| | - Yannick Schulte
- Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, S07S03C30, 45141 Essen, Germany
| | - Christoph Wölper
- Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, S07S03C30, 45141 Essen, Germany
| | - Alexander Tjaberings
- Faculty of Chemistry, University of Münster and Center for Soft Nanoscience (SoN), Busso-Peus-Strasse 10, 48149 Münster, Germany
| | - André H. Gröschel
- Faculty of Chemistry, University of Münster and Center for Soft Nanoscience (SoN), Busso-Peus-Strasse 10, 48149 Münster, Germany
| | - Gebhard Haberhauer
- Organic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, S07S05C39, 45141 Essen, Germany
| | - Stephan Schulz
- Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 7, S07S03C30, 45141 Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE), Carl-Benz-Straße 199, 47057 Duisburg, Germany
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10
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De Hoe GX, Şucu T, Shaver MP. Sustainability and Polyesters: Beyond Metals and Monomers to Function and Fate. Acc Chem Res 2022; 55:1514-1523. [PMID: 35579567 PMCID: PMC9178795 DOI: 10.1021/acs.accounts.2c00134] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Poor waste management and unchecked consumption underpin our current
paradigm of plastics use, which is demonstrably unsustainable in the
long term. Nonetheless, the utility and versatility of plastics suggest
that the notion of a plastic-free society is also unsustainable. Responses
to this conundrum are increasing, and among these are research efforts
focused on the development of more sustainable plastics. This Account,
written by trained chemists, reflects an academic research journey
culminating in an appreciation of the importance of improving and
enabling the overarching systems that plastics exist within. Our primary
initial focus was on catalyst development because catalysts are key
drivers of sustainability by improving the efficiency and ease of
polymerization. Metal catalysts ranging in ligand structure and the
incorporated metal(s) were developed for the preparation of traditional
polyesters such as poly(lactic acid) and polycaprolactone. The central
themes in these works were stereocontrol (tacticity), efficiency (polymerization
rate), and versatility (monomer scope). Alongside insights gained
by systematically varying catalyst structure came impressive results
gained through collaboration, including the remarkably high activity
of novel heterometallic zinc catalysts toward various cyclic esters. This catalysis work was complemented by and slowly transitioned
to a focus on polymer functionality and monomer design. Several fundamental
studies focus on polymer topology, specifically star-shaped polyesters,
tuned arm number, length, and tacticity. These reports feature emphases
on the end of life (solvolysis) and physical properties of polymers,
which were increasingly important themes as work shifted toward new
methods of incorporating functionality in polymers produced by ring-opening
polymerization. Three key highlights demonstrate this shift: the first
two rely upon the exploitation of olefin metathesis (cross- and ring-closing)
to functionalize polyesters or polyethers, and the third involves
the manipulation of ring-opening polymerization equilibrium to enable
selective monomer recovery from a polyester. Our foundational work
on 1,3-dioxolan-4-one (DOX) monomers is then discussed because this
emerging class of molecules offers a distinct synthetic pathway toward
functional polyesters, both conventional and novel. With this DOX
framework, polyesters that are usually challenging to synthesize (e.g.,
poly(mandelic acid)) are accessible because polymerization is driven
by the concomitant, controlled extrusion of small molecules (acetone
or formaldehyde). After these polyester-focused highlights,
the foundation of our
ongoing work is presented, namely, that polymer sustainability must
be viewed from a systems-level perspective, including economic and
social components alongside the environmental considerations. Material
design must be driven by practice, and we have to involve key players
in academia, industry, and government in a concerted effort to enable
positive and robust change. The key goal is to develop sustainable
systems that retain plastics in their highest value state for as long
as possible by designing materials and products for a particular (and
assured) end-of-life fate, whether that be reuse, recycling, (bio)degradation,
or energy recovery.
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Affiliation(s)
- Guilhem X. De Hoe
- Department of Materials, School of Natural Sciences, University of Manchester, Manchester M1 3BB, United Kingdom
- Henry Royce Institute, University of Manchester, Sustainable Materials Innovation Hub, Manchester M13 9BL, United Kingdom
| | - Theona Şucu
- Department of Materials, School of Natural Sciences, University of Manchester, Manchester M1 3BB, United Kingdom
- Henry Royce Institute, University of Manchester, Sustainable Materials Innovation Hub, Manchester M13 9BL, United Kingdom
| | - Michael P. Shaver
- Department of Materials, School of Natural Sciences, University of Manchester, Manchester M1 3BB, United Kingdom
- Henry Royce Institute, University of Manchester, Sustainable Materials Innovation Hub, Manchester M13 9BL, United Kingdom
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11
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Chellali JE, Alverson AK, Robinson JR. Zinc Aryl/Alkyl β-diketiminates: Balancing Accessibility and Stability for High-Activity Ring-Opening Polymerization of rac-Lactide. ACS Catal 2022. [DOI: 10.1021/acscatal.2c00858] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jonathan E. Chellali
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Alexander K. Alverson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Jerome R. Robinson
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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12
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Bruckmoser J, Henschel D, Vagin S, Rieger B. Combining high activity with broad monomer scope: indium salan catalysts in the ring-opening polymerization of various cyclic esters. Catal Sci Technol 2022. [DOI: 10.1039/d2cy00436d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
An indium salan-type catalyst shows very high activities in the ring-opening polymerization of various cyclic esters, including β-butyrolactone, γ-butyrolactone, lactide, ε-caprolactone and ε-decalactone.
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Affiliation(s)
- Jonas Bruckmoser
- WACKER-Chair of Macromolecular Chemistry, Catalysis Research Center, Technical University of Munich, 85748 Garching, Germany
| | - Daniel Henschel
- WACKER-Chair of Macromolecular Chemistry, Catalysis Research Center, Technical University of Munich, 85748 Garching, Germany
| | - Sergei Vagin
- WACKER-Chair of Macromolecular Chemistry, Catalysis Research Center, Technical University of Munich, 85748 Garching, Germany
| | - Bernhard Rieger
- WACKER-Chair of Macromolecular Chemistry, Catalysis Research Center, Technical University of Munich, 85748 Garching, Germany
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13
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Gruszka W, Sha H, Buchard A, Garden JA. Heterometallic cooperativity in divalent metal ProPhenol catalysts: combining zinc with magnesium or calcium for cyclic ester ring-opening polymerisation. Catal Sci Technol 2022. [DOI: 10.1039/d1cy01914g] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The first heterobimetallic lactide ROP catalysts based on two divalent metals outperform the homobimetallic analogues, attributed to the increased Lewis acidity of Mg or Ca (monomer coordination) and enhanced polarity of Zn–Et/OR (propagation).
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Affiliation(s)
- Weronika Gruszka
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK
| | - Haopeng Sha
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK
| | - Antoine Buchard
- Department of Chemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Jennifer A. Garden
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, EH9 3FJ, UK
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14
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Omar R, Shaik M, Griggs C, Jensen JD, Boyd R, Oncel N, Webster DC, Du G. Star-shaped Poly(hydroxybutyrate)s from bio-based polyol cores via zinc catalyzed ring-opening polymerization of β-Butyrolactone. Eur Polym J 2021. [DOI: 10.1016/j.eurpolymj.2021.110756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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15
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Efficient Bulky Organo-Zinc Scorpionates for the Stereoselective Production of Poly( rac-lactide)s. Polymers (Basel) 2021; 13:polym13142356. [PMID: 34301114 PMCID: PMC8309543 DOI: 10.3390/polym13142356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/17/2022] Open
Abstract
The direct reaction of the highly sterically demanding acetamidinate-based NNN'-scorpionate protioligand Hphbptamd [Hphbptamd = N,N'-di-p-tolylbis(3,5-di-tertbutylpyrazole-1-yl)acetamidine] with one equiv. of ZnMe2 proceeds in high yield to the mononuclear alkyl zinc complex [ZnMe(κ3-phbptamd)] (1). Alternatively, the treatment of the corresponding lithium precursor [Li(phbptamd)(THF)] with ZnCl2 yielded the halide complex [ZnCl(κ3-phbptamd)] (2). The X-ray crystal structure of 1 confirmed unambiguously a mononuclear entity in these complexes, with the zinc centre arranged with a pseudotetrahedral environment and the scorpionate ligand in a κ3-coordination mode. Interestingly, the inexpensive, low-toxic and easily prepared complexes 1 and 2 resulted in highly efficient catalysts for the ring-opening polymerisation of lactides, a sustainable bio-resourced process industrially demanded. Thus, complex 1 behaved as a single-component robust initiator for the living and immortal ROP of rac-lactide under very mild conditions after a few hours, reaching a TOF value up to 5520 h-1 under bulk conditions. Preliminary kinetic studies revealed apparent zero-order dependence on monomer concentration in the absence of a cocatalyst. The PLA materials produced exhibited narrow dispersity values, good agreement between the experimental Mn values and monomer/benzyl alcohol ratios, as well as enhanced levels of heteroselectivity, reaching Ps values up to 0.74.
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16
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Gruszka W, Garden JA. Advances in heterometallic ring-opening (co)polymerisation catalysis. Nat Commun 2021; 12:3252. [PMID: 34059676 PMCID: PMC8167082 DOI: 10.1038/s41467-021-23192-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 04/12/2021] [Indexed: 11/09/2022] Open
Abstract
Truly sustainable plastics require renewable feedstocks coupled with efficient production and end-of-life degradation/recycling processes. Some of the most useful degradable materials are aliphatic polyesters, polycarbonates and polyamides, which are often prepared via ring-opening (co)polymerisation (RO(CO)P) using an organometallic catalyst. While there has been extensive research into ligand development, heterometallic cooperativity offers an equally promising yet underexplored strategy to improve catalyst performance, as heterometallic catalysts often exhibit significant activity and selectivity enhancements compared to their homometallic counterparts. This review describes advances in heterometallic RO(CO)P catalyst design, highlighting the overarching structure-activity trends and reactivity patterns to inform future catalyst design.
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Affiliation(s)
- Weronika Gruszka
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK
| | - Jennifer A Garden
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, UK.
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Gesslbauer S, Hutchinson G, White AJP, Burés J, Romain C. Chirality-Induced Catalyst Aggregation: Insights into Catalyst Speciation and Activity Using Chiral Aluminum Catalysts in Cyclic Ester Ring-Opening Polymerization. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05245] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sami Gesslbauer
- Department of Chemistry, Molecular Science and Research Hub, Imperial College London, Wood Lane, London W12 0BZ, U.K
| | - George Hutchinson
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Andrew J. P. White
- Department of Chemistry, Molecular Science and Research Hub, Imperial College London, Wood Lane, London W12 0BZ, U.K
| | - Jordi Burés
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K
| | - Charles Romain
- Department of Chemistry, Molecular Science and Research Hub, Imperial College London, Wood Lane, London W12 0BZ, U.K
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Gaston AJ, Greindl Z, Morrison CA, Garden JA. Cooperative Heterometallic Catalysts for Lactide Ring-Opening Polymerization: Combining Aluminum with Divalent Metals. Inorg Chem 2021; 60:2294-2303. [PMID: 33512999 DOI: 10.1021/acs.inorgchem.0c03145] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
While homometallic (salen)Al catalysts display excellent performance in lactide ring-opening polymerization (ROP), heterometallic (salen)Al complexes have yet to be reported. Herein, we describe four heterobimetallic (salen)Al catalysts and show that the choice of the heterometal is key. Cooperative Al/Mg and Al/Zn combinations improved the catalyst activity by a factor of up to 11 compared to the mono-Al analogue, whereas the mono-Mg and mono-Zn analogues were completely inactive. In contrast, Al/Li and Al/Ca heterocombinations stunted the polymerization rate. Kinetic and computational studies suggest that Al/Mg and Al/Zn cooperativity arises from the close intermetallic proximity facilitating chloride bridging (thus enhancing initiation), which promotes a rigid square pyramidal geometry around the Al center and further increases the available monomer coordination sites. This work also translates the use of ab initio molecular dynamics calculations to ROP, introducing a useful method of investigating catalyst flexibility and revealing that ligand strain and molecular rigidity can enhance heterometallic catalyst performance.
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Affiliation(s)
- Anand J Gaston
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, U.K
| | - Zoe Greindl
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, U.K
| | - Carole A Morrison
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, U.K
| | - Jennifer A Garden
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, U.K
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Rosen T, Rajpurohit J, Lipstman S, Venditto V, Kol M. Isoselective Polymerization of rac-Lactide by Highly Active Sequential {ONNN} Magnesium Complexes. Chemistry 2020; 26:17183-17189. [PMID: 32871022 DOI: 10.1002/chem.202003616] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/31/2020] [Indexed: 11/10/2022]
Abstract
The coordination chemistry and the activities in the ring-opening polymerization catalysis of racemic lactide (LA) of magnesium complexes of a series of {ONNN}-type sequential monoanionic ligands are described. All ligands include pyridyl and substituted-phenolate as peripheral groups. The ligands bearing either chiral or meso-bipyrrolidine cores led to single diastereomeric complexes, whereas the ligands bearing a diaminoethane core led to diastereomer mixtures. All {ONNN}Mg-X complexes [X=Cl, HMDS (hexamethyldisilazide)] led to highly active and isoselective catalysts. The complexes bearing the chiral bipyrrolidine core exhibited the highest activities (full consumption of 5000 equiv. of rac-LA at RT within 5 min) and highest isoselectivities (Pm =0.91), as well as a living character. The complexes of the meso-bipyrrolidine based ligands were almost as active and slightly less stereoselective, while those of the diaminoethane based ligands exhibited reduced activities and isoselectivities.
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Affiliation(s)
- Tomer Rosen
- School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv, 6997801, Israel
| | | | - Sophia Lipstman
- School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv, 6997801, Israel
| | - Vincenzo Venditto
- Department of Chemistry and Biology A. Zambelli, INSTM Research Unit, University of Salerno, Via Giovanni Paolo II 132, 84084, Fisciano, SA, Italy
| | - Moshe Kol
- School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv, 6997801, Israel
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Platel RH, Hurst AR. Precise Microstructure Control in Poly(hydroxybutyrate- co-lactic Acid) Copolymers Prepared by an Yttrium Amine Bis(phenolate) Complex. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Rachel H. Platel
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, U.K
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21
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New way of anionic ring-opening copolymerization of β-butyrolactone and ε-caprolactone: determination of the reaction course. JOURNAL OF POLYMER RESEARCH 2020. [DOI: 10.1007/s10965-020-02333-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractPoly(ε-caprolactone)-block-poly(β-butyrolactone) copolymers were prepared in two-step synthesis. Firstly, poly(ε-caprolactone) (PCL) was obtained by anionic ring-opening polymerization of CL initiated with anhydrous KOH activated 12-crown-4 cation complexing agent. Reaction was carried out in tetrahydrofuran solution and argon atmosphere at room temperature. Then, β-butyrolactone (BL) and 18-crown-6 were added to the system, resulting in PCL-block-PBL copolymer, which contains after methylation hydroxyl starting group and methyl ester end group. The main product was contaminated with PCL and PBL homopolymers formed in a side reactions. 13C NMR technique was used for determination of chemical structure of polymers obtained. The course of the studied processes was proposed. MALDI-TOF technique was used to reveal the macromolecules’ architecture where several series were found. The identified series shown that mainly copolymeric macromolecules were formed with scare contribution of homopolymeric polybutyrolactone with trans-crotonate starting groups and polycaprolactone, which is congruent with the proposed reaction mechanism. Moreover, critical approach concerning previously reported PCL-block-PBL copolymer synthesis by use of NaH as initiator was also presented.
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Gruszka W, Lykkeberg A, Nichol GS, Shaver MP, Buchard A, Garden JA. Combining alkali metals and zinc to harness heterometallic cooperativity in cyclic ester ring-opening polymerisation. Chem Sci 2020; 11:11785-11790. [PMID: 34123205 PMCID: PMC8162475 DOI: 10.1039/d0sc04705h] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Heterometallic cooperativity is an emerging strategy to elevate polymerisation catalyst performance. Here, we report the first heterotrimetallic Na/Zn2 and K/Zn2 complexes supported by a ProPhenol ligand, which deliver “best of both” in cyclic ester ring-opening polymerisation, combining the outstanding activity (Na/K) and good control (Zn2) of homometallic analogues. Detailed NMR studies and density-functional theory calculations suggest that the Na/Zn2 and K/Zn2 complexes retain their heterometallic structures in the solution-state. To the best of our knowledge, the K/Zn2 analogue is the most active heterometallic catalyst reported for rac-lactide polymerisation (kobs = 1.7 × 10−2 s−1), giving activities five times faster than the Na/Zn2 complex. These versatile catalysts also display outstanding performance in ε-caprolatone and δ-valerolactone ring-opening polymerisation. These studies provide underpinning methodologies for future heterometallic polymerisation catalyst design, both in cyclic ester polymerisation and other ring-opening (co)polymerisation reactions. Cooperative heterotrimetallic Na/Zn2 and K/Zn2 complexes combine the excellent activities and control of the homometallic analogues, giving “best of both” in cyclic ester ring-opening polymerisation.![]()
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Affiliation(s)
- Weronika Gruszka
- EaStCHEM School of Chemistry, University of Edinburgh Edinburgh EH9 3FJ UK
| | - Anna Lykkeberg
- EaStCHEM School of Chemistry, University of Edinburgh Edinburgh EH9 3FJ UK
| | - Gary S Nichol
- EaStCHEM School of Chemistry, University of Edinburgh Edinburgh EH9 3FJ UK
| | - Michael P Shaver
- School of Natural Sciences, Department of Materials, Henry Royce Institute, University of Manchester Manchester M13 9PL UK
| | - Antoine Buchard
- Department of Chemistry, University of Bath Claverton Down Bath BA2 7AY UK
| | - Jennifer A Garden
- EaStCHEM School of Chemistry, University of Edinburgh Edinburgh EH9 3FJ UK
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