1
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Zhang X, Li Z, Wang L, Yu J, Liu Y, Song P. Selective Copolymerization from Mixed Monomers of Phthalic Anhydride, Propylene Oxide and Lactide Using Nano-Sized Zinc Glutarate. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1535. [PMID: 39330691 PMCID: PMC11434771 DOI: 10.3390/nano14181535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 09/09/2024] [Accepted: 09/10/2024] [Indexed: 09/28/2024]
Abstract
Selective polymerization with heterogeneous catalysts from mixed monomers remains a challenge in polymer synthesis. Herein, we describe that nano-sized zinc glutarate (ZnGA) can serve as a catalyst for the selective copolymerization of phthalic anhydride (PA), propylene oxide (PO) and lactide (LA). It was found that the ring-opening copolymerization (ROCOP) of PA with PO occurs firstly in the multicomponent polymerization. After the complete consumption of PA, the ring-opening polymerization (ROP) of LA turns into the formation of block polyester. In the process, the formation of zinc-alkoxide bonds on the surface of ZnGA accounts for the selective copolymerization from ROCOP to ROP. These results facilitate the understanding of the heterogeneous catalytic process and offer a new platform for selective polymerization from monomer mixtures.
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Affiliation(s)
- Xiaoting Zhang
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
| | - Zhidong Li
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
| | - Liyan Wang
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
| | - Jingjing Yu
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
| | - Yefan Liu
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
| | - Pengfei Song
- College of Chemistry and Chemical Engineering, Key Laboratory of Eco-Functional Polymer Materials of the Ministry of Education, Key Laboratory of Eco-Environmental Polymer Materials of Gansu Province, Gansu International Scientific and Technological Cooperation Base of Water-Retention Chemical Functional Materials, Northwest Normal University, Lanzhou 730070, China
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2
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Fiorentini F, Eisenhardt KHS, Deacy AC, Williams CK. Synergic Catalysis: the Importance of Intermetallic Separation in Co(III)K(I) Catalysts for Ring Opening Copolymerizations. J Am Chem Soc 2024; 146:23517-23528. [PMID: 39120158 PMCID: PMC11345820 DOI: 10.1021/jacs.4c07405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 08/10/2024]
Abstract
Dinuclear polymerization catalysts can show high activity and control. Understanding how to design for synergy between the metals is important to improving catalytic performances. Three heterodinuclear Co(III)K(I) catalysts, featuring very similar coordination chemistries, are prepared with different intermetallic separations. The catalysts are compared for the ring-opening copolymerization (ROCOP) of propene oxide (PO) with CO2 or with phthalic anhydride (PA). The catalyst with a fixed, wide intermetallic separation, LwideCoK(OAc)2 (Co-K = 8.06 Å), shows very high activity for PO/PA ROCOP, but is inactive for PO/CO2 ROCOP. On the other hand, the catalyst with a fixed, narrow intermetallic separation, LshortCoK(OAc)2 (Co-K, 3.59 Å), shows high activity for PO/CO2 ROCOP, but is much less active for PO/PA ROCOP. A bicomponent catalyst system, comprising a monometallic complex LmonoCoOAc used with an equivalent of KOAc[18-crown-6], shows high activity for both PO/CO2 and PO/PA ROCOP, provided the catalyst concentration is sufficiently high, but underperforms at low catalyst loadings. It is proposed that the two lead catalysts, LwideCoK(OAc)2 and LshortCoK(OAc)2, operate by different mechanisms for PO/PA and PO/CO2 ROCOP. The new wide separation catalyst, LwideCoK(OAc)2, shows some of the best performances yet reported for PO/PA ROCOP, and suggests other catalysts featuring larger intermetallic separations should be targeted for epoxide/anhydride copolymerizations.
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Affiliation(s)
| | | | - Arron C. Deacy
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, United Kingdom
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3
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Xie T, Chen SS, Li YY, Chen DF. Leveraging Electron Push-Pull Effect for Catalytic Polymerization and Degradation of a Cyclobutane Monomer System. Angew Chem Int Ed Engl 2024; 63:e202405408. [PMID: 38728168 DOI: 10.1002/anie.202405408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/26/2024] [Accepted: 05/09/2024] [Indexed: 05/12/2024]
Abstract
Ring-opening polymerization (ROP) offers a striking solution to solve problems encountered in step-growth condensation polymerization, including precise control over molecular weight, molecular weight distribution, and topology. This has inspired our interest in ROP of cycloalkanes with an ultimate goal to rethink polyolefins, which clearly poses a number of challenges. Practicality of ROP of cycloalkanes is actually limited by their low polymerizability and elusive mechanisms which arise from significantly varied ring size and non-polar C-C bonds in monomers. In this work, by using Lewis acid/Brønsted base/C(sp3)-H initiator system previously developed in our laboratory, we focus on cyclobutanes and explore the positional and electronic effects of substituents on the ring, namely electron push-pull effect, in promoting controlled polymerization to afford densely functionalized poly(cyclobutanes), as well as catalytic degradation of obtained polymers for upcycling. More importantly, experiments and DFT calculations unveil considerable population of Lewis-acid-induced thermostabilized 1,4-zwitterions, which distinguish cyclobutanes from cyclopropanes and others. All these findings would shed light on catalytic synthesis and degradation of saturated all-carbon main-chain polymers, as well as small molecule transformations of cyclobutanes.
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Affiliation(s)
- Teng Xie
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Shu-Sen Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yang-Yang Li
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Dian-Feng Chen
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
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4
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Fornacon-Wood C, Stühler MR, Millanvois A, Steiner L, Weimann C, Silbernagl D, Sturm H, Paulus B, Plajer AJ. Fluoride recovery in degradable fluorinated polyesters. Chem Commun (Camb) 2024; 60:7479-7482. [PMID: 38939919 DOI: 10.1039/d4cc02513j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
We report a new class of degradable fluorinated polymers through the copolymerization of tetrafluorophthalic anhydride and propylene oxide or trifluoropropylene oxide which show up to 20 times quicker degradation than the non-fluorinated equivalents and allow for fluoride recovery.
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Affiliation(s)
- Christoph Fornacon-Wood
- Makromolekulare Chemie 1, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
| | - Merlin R Stühler
- Institut für Chemie und Biochemie, Freie Universität Berlin, Arminallee 22, 14195 Berlin, Germany
| | - Alexandre Millanvois
- Institut für Chemie und Biochemie, Freie Universität Berlin, Arminallee 22, 14195 Berlin, Germany
| | - Luca Steiner
- Institut für Chemie und Biochemie, Freie Universität Berlin, Arminallee 22, 14195 Berlin, Germany
| | - Christiane Weimann
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
| | - Dorothee Silbernagl
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
| | - Heinz Sturm
- Bundesanstalt für Materialforschung und -Prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
| | - Beate Paulus
- Institut für Chemie und Biochemie, Freie Universität Berlin, Arminallee 22, 14195 Berlin, Germany
| | - Alex J Plajer
- Makromolekulare Chemie 1, Universität Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
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5
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Xie R, Wang Y, Li S, Li B, Xu J, Liu J, He Y, Yang GW, Wu GP. Insights into the Distinct Behaviors between Bifunctional and Binary Organoborane Catalysts through Terpolymerization of Epoxide, CO 2, and Anhydride. Angew Chem Int Ed Engl 2024; 63:e202404207. [PMID: 38647637 DOI: 10.1002/anie.202404207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/01/2024] [Accepted: 04/22/2024] [Indexed: 04/25/2024]
Abstract
Alkyl borane compounds-mediated polymerizations have expanded to Lewis pair polymerization, free radical polymerization, ionic ring-opening polymerization, and polyhomologation. The bifunctional organoborane catalysts that contain the Lewis acid and ammonium or phosphonium salt in one molecule have demonstrated superior catalytic performance for ring-opening polymerization of epoxides and ring-opening copolymerization of epoxides and CO2 than their two-component analogues, i.e., the blend of organoborane and ammonium or phosphonium salt. To explore the origin of the differences of the one-component and two-component organoborane catalysts, here we conducted a systematic investigation on the catalytic performances of these two kinds of organoborane catalysts via terpolymerization of epoxide, carbon dioxide and anhydride. The resultant terpolymers produced independently by bifunctional and binary organoborane catalyst exhibited distinct microstructures, where a series of gradient polyester-polycarbonate terpolymers with varying polyester content were afforded using the bifunctional catalyst, while tapering diblock terpolymers were obtained using the binary system. The bifunctional catalyst enhances the competitiveness of CO2 insertion than anhydride, which leads to the premature incorporation of CO2 into the polymer chains and ultimately results in the formation of gradient terpolymers. DFT calculations revealed the role of electrostatic interaction and charge distribution caused by intramolecular synergistic effect for bifunctional organoborane catalyst.
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Affiliation(s)
- Rui Xie
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, P. R. China
| | - Yuhui Wang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, P. R. China
| | - Shuai Li
- College of Material Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, P. R. China
| | - Bo Li
- College of Material Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, P. R. China
| | - Jie Xu
- Shaanxi Coal Chemical Industry Technology Research Institute Co., Ltd., Xi'an, 710100, Shaanxi, P. R. China
| | - Jinqian Liu
- Shaanxi Coal Chemical Industry Technology Research Institute Co., Ltd., Xi'an, 710100, Shaanxi, P. R. China
| | - Yuchen He
- Shaanxi Coal Chemical Industry Technology Research Institute Co., Ltd., Xi'an, 710100, Shaanxi, P. R. China
| | - Guan-Wen Yang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, P. R. China
| | - Guang-Peng Wu
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Key Laboratory of Adsorption and Separation Materials & Technologies of Zhejiang Province, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, P. R. China
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6
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Karnes JP, Kumar A, Hopkins Leseberg JA, Day VW, Blakemore JD. Trivalent Cations Slow Electron Transfer to Macrocyclic Heterobimetallic Complexes. Inorg Chem 2024; 63:8710-8729. [PMID: 38669449 DOI: 10.1021/acs.inorgchem.4c00230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Incorporation of secondary redox-inactive cations into heterobimetallic complexes is an attractive strategy for modulation of metal-centered redox chemistry, but quantification of the consequences of incorporating strongly Lewis acidic trivalent cations has received little attention. Here, a family of seven heterobimetallic complexes that pair a redox-active nickel center with La3+, Y3+, Lu3+, Sr2+, Ca2+, K+, and Na+ (in the form of their triflate salts) have been prepared on a heteroditopic ligand platform to understand how chemical behavior varies across the comprehensive series. Structural data from X-ray diffraction analysis demonstrate that the positions adopted by the secondary cations in the crown-ether-like site of the ligand relative to nickel are dependent primarily on the secondary cations' ionic radii and that the triflate counteranions are bound to the cations in all cases. Electrochemical data, in concert with electron paramagnetic resonance studies, show that nickel(II)/nickel(I) redox is modulated by the secondary metals; the heterogeneous electron-transfer rate is diminished for the derivatives incorporating trivalent metals, an effect that is dependent on steric crowding about the nickel metal center and that was quantified here with a topographical free-volume analysis. As related analyses carried out here on previously reported systems bear out similar relationships, we conclude that the placement and identity of both the secondary metal cations and their associated counteranions can afford unique changes in the (electro)chemical behavior of heterobimetallic species.
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Affiliation(s)
- Joseph P Karnes
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Amit Kumar
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Julie A Hopkins Leseberg
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Victor W Day
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - James D Blakemore
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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7
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Eisenhardt KS, Fiorentini F, Lindeboom W, Williams CK. Quantifying CO 2 Insertion Equilibria for Low-Pressure Propene Oxide and Carbon Dioxide Ring Opening Copolymerization Catalysts. J Am Chem Soc 2024; 146:10451-10464. [PMID: 38589774 PMCID: PMC11027146 DOI: 10.1021/jacs.3c13959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/10/2024]
Abstract
While outstanding catalysts are known for the ring-opening copolymerization (ROCOP) of CO2 and propene oxide (PO), few are reported at low CO2 pressure. Here, a new series of Co(III)M(I) heterodinuclear catalysts are compared. The Co(III)K(I) complex shows the best activity (TOF = 1728 h-1) and selectivity (>90% polymer, >99% CO2) and is highly effective at low pressures (<10 bar). CO2 insertion is a prerate determining chemical equilibrium step. At low pressures, the concentration of the active catalyst depends on CO2 pressure; above 12 bar, its concentration is saturated, and rates are independent of pressure, allowing the equilibrium constant to be quantified for the first time (Keq = 1.27 M-1). A unified rate law, applicable under all operating conditions, is presented. As proof of potential, published data for leading literature catalysts are reinterpreted and the CO2 equilibrium constants estimated, showing that this unified rate law applies to other systems.
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Affiliation(s)
- Katharina
H. S. Eisenhardt
- Department Chemistry, University
of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Francesca Fiorentini
- Department Chemistry, University
of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Wouter Lindeboom
- Department Chemistry, University
of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Charlotte K. Williams
- Department Chemistry, University
of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford OX1 3TA, U.K.
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8
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Seo YH, Lee MR, Lee DY, Park JH, Seo HJ, Park SU, Kim H, Kim SJ, Lee BY. Preparation of Well-Defined Double-Metal Cyanide Catalysts for Propylene Oxide Polymerization and CO 2 Copolymerization. Inorg Chem 2024; 63:1414-1426. [PMID: 38166391 DOI: 10.1021/acs.inorgchem.3c03957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Reevaluating the composition of the double metal cyanide catalyst (DMC) as a salt of (NC)6Co3- anions with 1:1 Zn2+/(X)Zn+ cations (X = Cl, RO, AcO), we prepared a series of well-defined DMCs, [ClZn+][Zn2+][(NC)6Co3-][ROH], [(RO)Zn+][Zn2+][(NC)6Co3-], [(AcO)Zn+][Zn2+][(NC)6Co3-], [(RO)Zn+]p[ClZn+](1-p)[Zn2+][(NC)6Co3-], [(AcO)Zn+]p[(tBuO)Zn+]q[Zn2+][(NC)6Co3-], and [(AcO)Zn+]p[(tBuO)Zn+]q[ClZn+]r[Zn2+][(NC)6Co3-]. The structure of [(MeOC3H6O)Zn+][Zn2+][(NC)6Co3-] was precisely determined at the atomic level through Rietveld refinement of the synchrotron X-ray powder diffraction data. By evaluating the catalyst's performance in both propylene oxide (PO) polymerization and PO/CO2 copolymerization, a correlation between structure and performance was established on various aspects including activity, dispersity, unsaturation level, and carbonate fraction in the resulting polyols. Ultimately, our study identified highly efficient catalysts that outperformed the state-of-the-art benchmark DMC not only in PO polymerization [DMC-(OAc/OtBu/Cl)(0.59/0.38/0.15)] but also in PO/CO2 copolymerization [DMC-(OAc/OtBu)(0.95/0.08)].
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Affiliation(s)
- Yeong Hyun Seo
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Mi Ryu Lee
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Da-Young Lee
- Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Jun Hyeong Park
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Hyeon Jeong Seo
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Sang Uk Park
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Hyunjin Kim
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Seung-Joo Kim
- Department of Energy Systems Research, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Bun Yeoul Lee
- Department of Molecular Science and Technology, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
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9
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Navarro M, González-Lizana D, Sánchez-Barba LF, Garcés A, Fernández I, Lara-Sánchez A, Rodríguez AM. Development of Heterobimetallic Al/Mg Complexes for the Very Rapid Ring-Opening Polymerization of Lactides. Inorg Chem 2023; 62:14833-14837. [PMID: 37676111 PMCID: PMC10521010 DOI: 10.1021/acs.inorgchem.3c02410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Indexed: 09/08/2023]
Abstract
The successful architecture of active catalytic species with enhanced efficiencies is critical for the optimal exploitation of sustainable resources in industrially demanded processes. In this work, we describe the preparation of novel helical heterobimetallic Al/Mg-based complexes of the type [AlMe2(pbpamd-)MgR{κ1-O-(OC4H8O)}] [R = Et (1a), tBu (2a)] as potential catalysts. The design was performed through the sequential addition of the Al fragment to the ligand, followed by the Mg platform, resulting in a planar π-C2N2(sp2)-Al/Mg bridging core between metals. The new heterobimetallic species have been unambiguously characterized by single-crystal X-ray analysis. NOESY, DOSY, and EXSY NMR studies as well as density functional theory calculations corroborate both a rearrangement in solution to scorpionate complexes containing an unprecedented apical carbanion with a direct σ-C(sp3)-Al covalent bond named [{Mg(R)(pbpamd-) Al(Me)2}] [R = Et (1b), tBu (2b)] and an interconversion equilibrium between both isomers. We verified their utility and high efficiency as catalysts in the well-controlled ring-opening polymerization of the biorenewable l- and rac-lactide (LA) at 23 °C, reaching a remarkable turnover frequency value close to 25000 h-1 for rac-LA at this temperature and exerting a significant level of heteroselectivity (Pr = 0.80). Very interestingly, the kinetics demonstrate apparent first-order with respect to the catalyst and LA, which supports a synergic intramolecular cooperation between centers with electronic modulation among them.
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Affiliation(s)
- Marta Navarro
- Departamento
de Biología y Geología, Física y Química
Inorgánica, Universidad Rey Juan
Carlos, 28933 Móstoles, Madrid, Spain
- Departamento
de Química Inorgánica, Orgánica y Bioquímica,
Centro de Innovación en Química Avanzada (ORFEO-CINQA),
Campus Universitario, Universidad de Castilla—La
Mancha, 13071 Ciudad Real, Spain
| | - David González-Lizana
- Departamento
de Biología y Geología, Física y Química
Inorgánica, Universidad Rey Juan
Carlos, 28933 Móstoles, Madrid, Spain
| | - Luis F. Sánchez-Barba
- Departamento
de Biología y Geología, Física y Química
Inorgánica, Universidad Rey Juan
Carlos, 28933 Móstoles, Madrid, Spain
| | - Andrés Garcés
- Departamento
de Biología y Geología, Física y Química
Inorgánica, Universidad Rey Juan
Carlos, 28933 Móstoles, Madrid, Spain
| | - Israel Fernández
- Departamento
de Química Orgánica I and Centro de Innovación
en Química Avanzada (ORFEO-CINQA), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Agustín Lara-Sánchez
- Departamento
de Química Inorgánica, Orgánica y Bioquímica,
Centro de Innovación en Química Avanzada (ORFEO-CINQA),
Campus Universitario, Universidad de Castilla—La
Mancha, 13071 Ciudad Real, Spain
| | - Ana M. Rodríguez
- Departamento
de Química Inorgánica, Orgánica y Bioquímica,
Centro de Innovación en Química Avanzada (ORFEO-CINQA),
Campus Universitario, Universidad de Castilla—La
Mancha, 13071 Ciudad Real, Spain
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