Imperial College London

PROFESSOR CHARLOTTE K. WILLIAMS

Faculty of Natural SciencesDepartment of Chemistry

Visiting Professor
 
 
 
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Contact

 

+44 (0)20 7594 5790c.k.williams Website

 
 
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Location

 

317 RCS1ChemistrySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

227 results found

Lindeboom W, Deacy AC, Phanopoulos A, Buchard A, Williams CKet al., 2023, Correlating metal redox potentials to Co(III)K(I) catalyst performances in carbon dioxide and propene oxide ring opening copolymerization, Angewandte Chemie International Edition, Vol: 62, ISSN: 1433-7851

Carbon dioxide copolymerization is a front-runner CO2 utilization strategy but its viability depends on improving the catalysis. So far, catalyst structure-performance correlations have not been straightforward, limiting the ability to predict how to improve both catalytic activity and selectivity. Here, a simple measure of a catalyst ground-state parameter, metal reduction potential, directly correlates with both polymerization activity and selectivity. It is applied to compare performances of 6 new heterodinuclear Co(III)K(I) catalysts for propene oxide (PO)/CO2 ring opening copolymerization (ROCOP) producing poly(propene carbonate) (PPC). The best catalyst shows an excellent turnover frequency of 389 h−1 and high PPC selectivity of >99 % (50 °C, 20 bar, 0.025 mol% catalyst). As demonstration of its utility, neither DFT calculations nor ligand Hammett parameter analyses are viable predictors. It is proposed that the cobalt redox potential informs upon the active site electron density with a more electron rich cobalt centre showing better performances. The method may be widely applicable and is recommended to guide future catalyst discovery for other (co)polymerizations and carbon dioxide utilizations.

Journal article

McGuire TM, Buchard A, Williams C, 2023, Chemical Recycling of Commercial Poly(L-lactic acid) to L-Lactide Using a High-Performance Sn(II)/Alcohol Catalyst System, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 145, Pages: 19840-19848, ISSN: 0002-7863

Journal article

Poon KC, Gregory GL, Sulley GS, Vidal F, Williams CKet al., 2023, Toughening CO<sub>2</sub>-Derived Copolymer Elastomers Through Ionomer Networking, ADVANCED MATERIALS, Vol: 35, ISSN: 0935-9648

Journal article

Fiorentini F, Diment WTT, Deacy ACC, Kerr RWF, Faulkner S, Williams CKKet al., 2023, Understanding catalytic synergy in dinuclear polymerization catalysts for sustainable polymers, NATURE COMMUNICATIONS, Vol: 14

Journal article

Cowie BE, Häfele L, Phanopoulos A, Said SA, Lee JK, Regoutz A, Shaffer MSP, Williams CKet al., 2023, Matched ligands for small, stable colloidal nanoparticles of copper, cuprous oxide and cuprous sulfide, Chemistry: A European Journal, Vol: 29, Pages: 1-18, ISSN: 0947-6539

This work applies organometallic routes to copper(0/I) nanoparticles and describes how to match ligand chemistries with different material compositions. The syntheses involve reacting an organo-copper precursor, mesitylcopper(I) [CuMes]z (z=4, 5), at low temperatures and in organic solvents, with hydrogen, air or hydrogen sulfide to deliver Cu, Cu2 O or Cu2 S nanoparticles. Use of sub-stoichiometric quantities of protonated ligand (pro-ligand; 0.1-0.2 equivalents vs. [CuMes]z ) allows saturation of surface coordination sites but avoids excess pro-ligand contaminating the nanoparticle solutions. The pro-ligands are nonanoic acid (HO2 CR1 ), 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (HO2 CR2 ) or di(thio)nonanoic acid, (HS2 CR1 ), and are matched to the metallic, oxide or sulfide nanoparticles. Ligand exchange reactions reveal that copper(0) nanoparticles may be coordinated by carboxylate or di(thio)carboxylate ligands, but Cu2 O is preferentially coordinated by carboxylate ligands and Cu2 S by di(thio)carboxylate ligands. This work highlights the opportunities for organometallic routes to well-defined nanoparticles and the need for appropriate ligand selection.

Journal article

Vidal F, Smith S, Williams CK, 2023, Ring Opening Copolymerization of Boron-Containing Anhydride with Epoxides as a Controlled Platform to Functional Polyesters, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 145, Pages: 13888-13900, ISSN: 0002-7863

Journal article

Wilmore JTT, Tse YC, Docker A, Whitehead C, Williams CKK, Beer PDDet al., 2023, Dynamic Metalloporphyrin-Based [2]Rotaxane Molecular Shuttles Stimulated by Neutral Lewis Base and Anion Coordination, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 29, ISSN: 0947-6539

Journal article

Diment WT, Rosetto G, Ezaz-Nikpay N, Kerr RWF, Williams CKet al., 2023, A highly active, thermally robust iron(iii)/potassium(i) heterodinuclear catalyst for bio-derived epoxide/anhydride ring-opening copolymerizations, GREEN CHEMISTRY, Vol: 25, Pages: 2262-2267, ISSN: 1463-9262

Journal article

Gregory GL, Sulley GS, Kimpel J, Lagodzinska M, Hafele L, Carrodeguas LP, Williams CKet al., 2022, Block Poly(carbonate-ester) Ionomers as High-Performance and Recyclable Thermoplastic Elastomers, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 61, ISSN: 1433-7851

Journal article

Deacy AC, Phanopoulos A, Lindeboom W, Buchard A, Williams CKet al., 2022, Insights into the mechanism of carbon dioxide and propylene oxide ring-opening copolymerization using a Co(III)/K(I) heterodinuclear catalyst, Journal of the American Chemical Society, Vol: 144, Pages: 17929-17938, ISSN: 0002-7863

A combined computational and experimental investigation into the catalytic cycle of carbon dioxide and propylene oxide ring-opening copolymerization is presented using a Co(III)K(I) heterodinuclear complex (Deacy, A. C. Co(III)/Alkali-Metal(I) Heterodinuclear Catalysts for the Ring-Opening Copolymerization of CO2 and Propylene Oxide. J. Am. Chem. Soc. 2020, 142(45), 19150−19160). The complex is a rare example of a dinuclear catalyst, which is active for the copolymerization of CO2 and propylene oxide, a large-scale commercial product. Understanding the mechanisms for both product and byproduct formation is essential for rational catalyst improvements, but there are very few other mechanistic studies using these monomers. The investigation suggests that cobalt serves both to activate propylene oxide and to stabilize the catalytic intermediates, while potassium provides a transient carbonate nucleophile that ring-opens the activated propylene oxide. Density functional theory (DFT) calculations indicate that reverse roles for the metals have inaccessibly high energy barriers and are unlikely to occur under experimental conditions. The rate-determining step is calculated as the ring opening of the propylene oxide (ΔGcalc† = +22.2 kcal mol–1); consistent with experimental measurements (ΔGexp† = +22.1 kcal mol–1, 50 °C). The calculated barrier to the selectivity limiting step, i.e., backbiting from the alkoxide intermediate to form propylene carbonate (ΔGcalc† = +21.4 kcal mol–1), is competitive with the barrier to epoxide ring opening (ΔGcalc† = +22.2 kcal mol–1) implicating an equilibrium between alkoxide and carbonate intermediates. This idea is tested experimentally and is controlled by carbon dioxide pressure or temperature to moderate selectivity. The catalytic mechanism, supported by theoretical and experimental investigations, should help to guide future catalyst design and optim

Journal article

McGuire TM, Deacy AC, Buchard A, Williams CKet al., 2022, Solid-State Chemical Recycling of Polycarbonates to Epoxides and Carbon Dioxide Using a Heterodinuclear Mg(II)Co(II) Catalyst, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, ISSN: 0002-7863

Journal article

Gregory GL, Gao H, Liu B, Gao X, Rees GJ, Pasta M, Bruce PG, Williams CKet al., 2022, Buffering Volume Change in Solid-State Battery Composite Cathodes with CO<sub>2</sub>-Derived Block Polycarbonate Ethers, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, ISSN: 0002-7863

Journal article

Diment WT, Lindeboom W, Fiorentini F, Deacy AC, Williams CKet al., 2022, Synergic Heterodinuclear Catalysts for the Ring-Opening Copolymerization (ROCOP) of Epoxides, Carbon Dioxide, and Anhydrides, ACCOUNTS OF CHEMICAL RESEARCH, Vol: 55, Pages: 1997-2010, ISSN: 0001-4842

Journal article

Diment WT, Williams CK, 2022, Chain end-group selectivity using an organometallic Al(iii)/K(i) ring-opening copolymerization catalyst delivers high molar mass, monodisperse polyesters, CHEMICAL SCIENCE, Vol: 13, Pages: 8543-8549, ISSN: 2041-6520

Journal article

Singer FN, Deacy AC, McGuire TM, Williams CK, Buchard Aet al., 2022, Chemical Recycling of Poly(Cyclohexene Carbonate) Using a Di-Mg<SUP>II</SUP> Catalyst, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 61, ISSN: 1433-7851

Journal article

Kerr RWF, Williams CK, 2022, Zr(IV) Catalyst for the Ring-Opening Copolymerization of Anhydrides (A) with Epoxides (B), Oxetane (B), and Tetrahydrofurans (C) to Make ABB- and/or ABC-Poly(ester-<i>alt</i>-ethers), JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 144, Pages: 6882-6893, ISSN: 0002-7863

Journal article

Gregory GL, Williams CK, 2022, Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers, MACROMOLECULES, Vol: 55, Pages: 2290-2299, ISSN: 0024-9297

Journal article

Reis N, Deacy AC, Rosetto G, Durr CB, Williams CKet al., 2022, Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 28, ISSN: 0947-6539

Journal article

Plajer AJ, Williams CK, 2022, Heterocycle/Heteroallene Ring-Opening Copolymerization: Selective Catalysis Delivering Alternating Copolymers, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 61, ISSN: 1433-7851

Journal article

Plajer AJ, Williams CK, 2021, Heterotrinuclear Ring Opening Copolymerization Catalysis: Structure-activity Relationships, ACS CATALYSIS, Vol: 11, Pages: 14819-14828, ISSN: 2155-5435

Journal article

Diment WT, Gregory GL, Kerr RWF, Phanopoulos A, Buchard A, Williams CKet al., 2021, Catalytic Synergy Using AI(III) and Group 1 Metals to Accelerate Epoxide and Anhydride Ring-Opening Copolymerizations, ACS CATALYSIS, Vol: 11, Pages: 12532-12542, ISSN: 2155-5435

Journal article

Rosetto G, Deacy AC, Williams CK, 2021, Mg(ii) heterodinuclear catalysts delivering carbon dioxide derived multi-block polymers, CHEMICAL SCIENCE, Vol: 12, Pages: 12315-12325, ISSN: 2041-6520

Journal article

Lindeboom W, Fraser DAX, Durr CB, Williams CKet al., 2021, Heterodinuclear Zn(II), Mg(II) or Co(III) with Na(I) Catalysts for Carbon Dioxide and Cyclohexene Oxide Ring Opening Copolymerizations, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 27, Pages: 12224-12231, ISSN: 0947-6539

Journal article

Said SA, Roberts CS, Lee JK, Shaffer MSP, Williams CKet al., 2021, Direct organometallic synthesis of carboxylate intercalated layered zinc hydroxides for fully exfoliated functional nanosheets, Advanced Functional Materials, Vol: 31, Pages: 1-11, ISSN: 1616-301X

Intercalation of organic anions into 2D materials can enable exfoliation, improve dispersion stability, increase surface area, and provide useful functional groups. In layered metal hydroxides, intercalation of bulk structures is commonly achieved by cumbersome and typically incomplete anion exchange reactions. In contrast, here, a series of carboxylate-intercalated layered zinc hydroxides (LZH-R) are synthesized directly, at room temperature, by reacting an organozinc reagent with a precise sub-stoichiometric quantity of the desired carboxylic acid and water. A range of carboxylic acids are used to make new LZH-R materials which are crystalline, soluble, and functionalized, as established by X-ray diffraction, spectroscopic, and microscopy techniques. When R is an alkyl ether carboxylate, this direct synthesis method results in the spontaneous exfoliation of the LZH-R into monolayer nanosheets with high yields (70–80%) and high solubilities in alcohols and water of up to 180 mg mL−1. By altering the carboxylate ligand, functional groups suitable for post-synthetic modification or for detection by fluorescence are also introduced. These examples demonstrate a versatile synthetic route for functional exfoliated nanosheets.

Journal article

Yuntawattana N, Gregory GL, Carrodeguas LP, Williams CKet al., 2021, Switchable Polymerization Catalysis Using a Tin(II) Catalyst and Commercial Monomers to Toughen Poly(L-lactide), ACS MACRO LETTERS, Vol: 10, Pages: 774-779

Journal article

Deacy AC, Gregory GL, Sulley GS, Chen TTD, Williams CKet al., 2021, Sequence Control from Mixtures: Switchable Polymerization Catalysis and Future Materials Applications, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 143, Pages: 10021-10040, ISSN: 0002-7863

Journal article

Plajer AJ, Williams CK, 2021, Heterotrimetallic Carbon Dioxide Copolymerization and Switchable Catalysts: Sodium is the Key to High Activity and Unusual Selectivity, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 60, Pages: 13372-13379, ISSN: 1433-7851

Journal article

Deacy AC, Durr CB, Kerr RWF, Williams CKet al., 2021, Heterodinuclear catalysts Zn(ii)/M and Mg(ii)/M, where M = Na(i), Ca(ii) or Cd(ii), for phthalic anhydride/cyclohexene oxide ring opening copolymerisation, CATALYSIS SCIENCE & TECHNOLOGY, Vol: 11, Pages: 3109-3118, ISSN: 2044-4753

Journal article

Diment WT, Stosser T, Kerr RWF, Phanopoulos A, Durr CB, Williams CKet al., 2021, <i>Ortho</i>-vanillin derived Al(iii) and Co(iii) catalyst systems for switchable catalysis using ε-decalactone, phthalic anhydride and cyclohexene oxide, CATALYSIS SCIENCE & TECHNOLOGY, Vol: 11, Pages: 1737-1745, ISSN: 2044-4753

Journal article

Kerr RWF, Ewing PMDA, Raman SK, Smith AD, Williams CK, Arnold PLet al., 2021, Ultrarapid Cerium(III)-NHC Catalysts for High Molar Mass Cyclic Polylactide, ACS CATALYSIS, Vol: 11, Pages: 1563-1569, ISSN: 2155-5435

Journal article

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