1
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Sailer R, VandeVen W, Teindl K, Chiang L. Ni II and Cu II complexes of a salen ligand bearing ferrocenes in its secondary coordination sphere. RSC Adv 2023; 13:7293-7299. [PMID: 36891492 PMCID: PMC9986886 DOI: 10.1039/d2ra07671c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/24/2023] [Indexed: 03/08/2023] Open
Abstract
Herein, we report the synthesis, spectroscopic characterization and electrochemical investigation of the NiII and CuII complexes of a novel Sal ligand bearing two ferrocene moieties attached at its diimine linker, M(Sal)Fc. The electronic spectra of M(Sal)Fc are near identical to its phenyl-substituted counterpart, M(Sal)Ph, indicating the ferrocene moieties exist in the secondary coordination sphere of M(Sal)Fc. The cyclic voltammograms of M(Sal)Fc exhibit an additional two-electron wave in comparison to M(Sal)Ph, which is assigned to the sequential oxidation of the two ferrocene moieties. The chemical oxidation of M(Sal)Fc, monitored by low temperature UV-vis spectroscopy, supports the formation of a mixed valent FeIIFeIII species followed by a bis(ferrocenium) species upon sequential addition of one and two equivalents of chemical oxidant. The addition of a third equivalent of oxidant to Ni(Sal)Fc yielded intense near-IR transitions that are indicative of the formation of a fully delocalized Sal-ligand radical (Sal˙), while the same addition to Cu(Sal)Fc yielded a species that is currently under further spectroscopic investigation. These results suggest the oxidation of the ferrocene moieties of M(Sal)Fc does not affect the electronic structure of the M(Sal) core, and these are thus in the secondary coordination sphere of the overall complex.
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Affiliation(s)
- Rachel Sailer
- Department of Chemistry, University of the Fraser Valley Abbotsford V2S 7M8 British Columbia Canada
| | - Warren VandeVen
- Department of Chemistry, Simon Fraser University Burnaby V5A 1S6 British Columbia Canada
| | - Kaeden Teindl
- Department of Chemistry, University of the Fraser Valley Abbotsford V2S 7M8 British Columbia Canada
| | - Linus Chiang
- Department of Chemistry, University of the Fraser Valley Abbotsford V2S 7M8 British Columbia Canada
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2
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Li B, Hu C, Pang X, Chen X. Valence-variable Catalysts for Redox-controlled Switchable Ring-opening Polymerization. Chem Asian J 2023; 18:e202201031. [PMID: 36321213 DOI: 10.1002/asia.202201031] [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: 10/11/2022] [Revised: 10/25/2022] [Indexed: 11/25/2022]
Abstract
As a representative class of sustainable polymer materials, biodegradable polymers have attracted increasing interest in recent years. Despite significant advance of related polymerization techniques, realizing high sequence-control and easy-handling in ring-opening (co)polymerizations still remains a central challenge. To this end, a promising solution is the development of valence-variable metal-based catalysts for redox-induced switchable polymerization of cyclic esters, cyclic ethers, epoxides, and CO2 . Through a valence-determined electron effect, the switch between different catalytically active states as well as dormant state contributes to convenient formation of polymer products with desired microstructures and various practical performances. This redox-controlled switchable strategy for controlled synthesis of polymers is overviewed in this Review with a focus on potential applications and challenges for further studies.
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Affiliation(s)
- Bokun Li
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
| | - Chenyang Hu
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China
| | - Xuan Pang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
| | - Xuesi Chen
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, P. R. China.,University of Science and Technology of China, 230026, Hefei, P. R. China
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3
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Shawver NM, Doerr AM, Long BK. A perspective on
redox‐switchable ring‐opening
polymerization. JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1002/pol.20220585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Alicia M. Doerr
- Department of Chemistry University of Tennessee Knoxville Tennessee USA
| | - Brian K. Long
- Department of Chemistry University of Tennessee Knoxville Tennessee USA
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4
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Turner ZR, Wilmore JT, Rees NH, Buffet JC. Sterically rigid bismuth pincer complexes; observation of the growing polymer chain in polar monomer polymerisation. Dalton Trans 2022; 51:3060-3074. [PMID: 35089302 DOI: 10.1039/d1dt04297a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A family of pyridine dipyrrolide bismuth complexes (Mes,PhL)MX (1-6) (M = Bi, X = O-2,6-Me-C6H3 = OXyl (1); M = Sb, X = OXyl (2); M = Bi, X = O-2,6-iPr-C6H3 = ODipp (3), O-2,6-tBu-C6H3 = OArtBu (4), OtBu (5) and OCMe2Et = OAm (6), N(SiMe3)2 = N'' (7) and CH2Ph (8)) have been prepared and investigated as initiators for the ring-opening polymerisation of lactide monomers. Bismuth lactate complexes (Mes,PhL)Bi{OC(H)(Me)C(O)OR} were prepared as models for the propagating species (R = tBu (9), Me (10), iPr (11)). The first insertion of the lactide monomer is rate limiting and the second and subsequent insertions are more rapid (kinit ≪ kLA2 < kprop), leading to a significant induction period. The sterically demanding, rigid pincer ligand affords a well-defined coordination environment at the metal centre and allows for the enchainment of two lactide monomers to be differentiated spectroscopically ((Mes,PhL)Bi{OC(H)(Me)C(O)}4OX (12-X)), with this species also implied to be the true initiator for the regime of propagation with first order kinetics. Well-controlled first order kinetic data for the polymerisation of L-, D-, rac- and meso-lactide are observed.
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Affiliation(s)
- Zoë R Turner
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
| | - Jamie T Wilmore
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
| | - Nicholas H Rees
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
| | - Jean-Charles Buffet
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
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5
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Hern ZC, Quan SM, Dai R, Lai A, Wang Y, Liu C, Diaconescu PL. ABC and ABAB Block Copolymers by Electrochemically Controlled Ring-Opening Polymerization. J Am Chem Soc 2021; 143:19802-19808. [PMID: 34792339 DOI: 10.1021/jacs.1c08648] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An electrochemically controlled synthesis of multiblock copolymers by alternating the redox states of (salfan)Zr(OtBu)2 (salfan = 1,1'-di(2-tert-butyl-6-N-methylmethylenephenoxy)ferrocene) is reported. Aided by electrochemistry with a glassy carbon working electrode, an in situ potential switch alters the catalyst's oxidation state and its subsequent monomer (l-lactide, β-butyrolactone, or cyclohexene oxide) selectivity in one pot. Various multiblock copolymers were prepared, including an ABAB tetrablock copolymer, poly(cyclohexene oxide-b-lactide-b-cyclohexene oxide-b-lactide), and an ABC triblock copolymer, poly(hydroxybutyrate-b-cyclohexene oxide-b-lactide). The polymers produced using this technique are similar to those produced via a chemical redox reagent method, displaying moderately narrow dispersities (1.1-1.5) and molecular weights ranging from 7 to 26 kDa.
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Affiliation(s)
- Zachary C Hern
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Stephanie M Quan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Ruxi Dai
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Amy Lai
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Yihang Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Chong Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Paula L Diaconescu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
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6
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Maity R, Birenheide BS, Breher F, Sarkar B. Cooperative Effects in Multimetallic Complexes Applied in Catalysis. ChemCatChem 2021. [DOI: 10.1002/cctc.202001951] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ramananda Maity
- Department of Chemistry University of Calcutta 92, A. P. C. Road Kolkata 700009 India
| | - Bernhard S. Birenheide
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstr. 15 76131 Karlsruhe Germany
| | - Frank Breher
- Institute of Inorganic Chemistry Karlsruhe Institute of Technology (KIT) Engesserstr. 15 76131 Karlsruhe Germany
| | - Biprajit Sarkar
- Lehrstuhl für Anorganische Koordinationschemie Institut für Anorganische Chemie Universität Stuttgart Pfaffenwaldring 55 D 70569 Stuttgart Germany
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7
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Deng S, Diaconescu PL. A switchable dimeric yttrium complex and its three catalytic states in ring opening polymerization. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01479f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A dimeric yttrium phenoxide complex can be oxidized in a stepwise fashion to access three oxidation states. The three states show different activity in the ring opening polymerization of cyclic esters and epoxides.
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Affiliation(s)
- Shijie Deng
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
| | - Paula L. Diaconescu
- University of California
- Los Angeles
- Department of Chemistry and Biochemistry
- Los Angeles
- USA
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8
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Wei C, Han B, Zheng D, Zheng Q, Liu S, Li Z. Aluminum Complexes Bearing Bidentate Amido–Phosphine Ligands for Ring-Opening Polymerization of ε-Caprolactone: Steric Effect on Coordination Chemistry and Reactivity. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00502] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Chuanzhi Wei
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
| | - Binghao Han
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
| | - Dejuan Zheng
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
| | - Quande Zheng
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
| | - Shaofeng Liu
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
| | - Zhibo Li
- Key Laboratory of Biobased Polymer Materials, Shandong Provincial Education Department; College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China
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9
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Lai A, Hern ZC, Diaconescu PL. Switchable Ring‐Opening Polymerization by a Ferrocene Supported Aluminum Complex. ChemCatChem 2019. [DOI: 10.1002/cctc.201900747] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Amy Lai
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
| | - Zachary C. Hern
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry University of California, Los Angeles 607 Charles E. Young Drive East Los Angeles CA 90095 USA
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10
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Palomero OE, Jones RA. 1,1′-Dicarbodiimidoferrocenes: Synthesis, Characterization, and Group IV 1,1′-Bisguanidinateferrocene Complexes. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00336] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Orhi Esarte Palomero
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712-1224, United States
| | - Richard A. Jones
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712-1224, United States
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11
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Shen Y, Shepard SM, Reed CJ, Diaconescu PL. Zirconium complexes supported by a ferrocene-based ligand as redox switches for hydroamination reactions. Chem Commun (Camb) 2019; 55:5587-5590. [PMID: 31020301 DOI: 10.1039/c9cc01076a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The synthesis of (thiolfan*)Zr(NEt2)2 (thiolfan* = 1,1'-bis(2,4-di-tert-butyl-6-thiophenoxy)ferrocene) and its catalytic activity for intramolecular hydroamination are reported. In situ oxidation and reduction of the metal complex results in reactivity towards different substrates. The reduced form of (thiolfan*)Zr(NEt2)2 catalyzes hydroamination reactions of primary aminoalkenes, whereas the oxidized form catalyzes hydroamination reactions of secondary aminoalkenes.
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Affiliation(s)
- Yi Shen
- Department of Chemistry & Biochemistry, University of California, Los Angeles, USA.
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12
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Wei J, Diaconescu PL. Redox-Switchable Ring-Opening Polymerization with Ferrocene Derivatives. Acc Chem Res 2019; 52:415-424. [PMID: 30707548 DOI: 10.1021/acs.accounts.8b00523] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Switchable catalysts incorporate stimuli-responsive features and allow synthetic tasks that are difficult or impossible to accomplish in other ways. They mimic biological processes in that they can provide both spatial and temporal control, unlike most reactions promoted by human-made catalysts that usually occur according to carefully optimized conditions. In the area of switchable catalysis, redox-switchable ring-opening polymerization (ROP) has attracted much attention, emerging as a powerful strategy for the development of environmentally friendly biodegradable copolymers, especially those containing blocks with complementary properties. Controlling the sequence and regularity of each copolymeric building block can affect the material properties significantly since they are directly related to the respective microstructures. Such control can be exerted with a well-designed redox-switchable catalyst by timing the oxidation and reduction events. In highly selective systems, one form of the catalyst reacts with a monomer until the redox state of the catalyst is altered, at which point the altered state of the catalyst reacts with another monomer. The reaction time may be varied from one cycle to another to generate various designer multiblock copolymers. The first instance of redox-mediated ROP was described by N. Long and co-workers in 2006. This example, as well as many early reported redox-switchable catalysts, could only achieve an on/off switch of activity toward a single monomer or substrate. However, our efforts brought on a general strategy for designing redox-switchable metal complexes that can catalyze different reactions in two oxidation states. In recent years, our contributions to this research field led to the synthesis of several multiblock copolymers prepared from biorenewable resources. This Account provides an overview of reported redox-switchable polymerization catalysts that allow for complementary reactivity in different oxidation states and highlights the potential of this strategy in preparing biodegradable materials. First, we define the field of redox-switchable catalysis and illustrate the design and significance of our ferrocene-chelating ligands, in which the oxidation state of iron in ferrocene can control the reactivity of the resulting metal complexes remotely. Next, we illustrate recent advances in the synthesis of new biodegradable copolymers including (1) how to tune the activity of the ROP catalysts by exploring various metal centers and ferrocene-based ligand combinations; (2) how to synthesize new multiblock copolymers of cyclic esters, epoxides, and carbonates by redox-switchable ROP; and (3) how to understand the mechanism of these reactions by discussing both experimental and theoretical investigations. By the application and development of redox-switchable strategies, various novel materials and reactions can be expected in the future.
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Affiliation(s)
- Junnian Wei
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
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13
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Dai R, Diaconescu PL. Investigation of a zirconium compound for redox switchable ring opening polymerization. Dalton Trans 2019; 48:2996-3002. [DOI: 10.1039/c9dt00212j] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Redox switchable catalysis with a ferrocene Schiff base zirconium complex allowed the synthesis of diblock and triblock copolymers.
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Affiliation(s)
- Ruxi Dai
- Department of Chemistry and Biochemistry
- University of California
- Los Angeles
- USA
| | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry
- University of California
- Los Angeles
- USA
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14
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Lai A, Clifton J, Diaconescu PL, Fey N. Computational mapping of redox-switchable metal complexes based on ferrocene derivatives. Chem Commun (Camb) 2019; 55:7021-7024. [DOI: 10.1039/c9cc01977d] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The properties of redox-switchable metal complexes have been captured with DFT-calculated parameters and processed into a map of chemical space, highlighting the effects of varying metals, donors, linkers and substituents in both accessible ferrocene oxidation states.
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Affiliation(s)
- Amy Lai
- Department of Chemistry and Biochemistry
- University of California
- Los Angeles
- USA
| | | | - Paula L. Diaconescu
- Department of Chemistry and Biochemistry
- University of California
- Los Angeles
- USA
| | - Natalie Fey
- School of Chemistry
- University of Bristol
- Bristol
- UK
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