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4. Conformational control of bis-urea self-assembled supramolecular pH switchable low-molecular-weight hydrogelators

Author

O'Donnell, Adam, Gavriel, Alex, Christie, William, Chippindale, Ann, German, Ian, and Hayes, Wayne

Abstract

We report the synthesis and investigation into the structure-property relationships of eight different low molecular weight hydrogelators based on a bisaromatic urea core unit, all of which form gels as the pH of the solution is lowered. The low molecular weight hydrogelators are functionalized with carboxylic acid moieties on one aromatic ring, and the other aromatic ring features a nitro functional group either in the meta- or para-position relative to the urea linkage. Ortho-methyl substituents were installed on the aromatic rings to enforce a non-coplanar arrangement between the phenyl and urea moieties. Gel formation was triggered by the addition of a mineral acid or the ring-opening hydrolysis of glucono-δ-lactone. The low molecular weight hydrogelators were studied by a variety of analytical techniques, including NMR spectroscopy and rheology. In addition, their ability to uptake a dye, methylene blue, was determined by UV-vis spectroscopy.

Published
2021

10. Halomethyl-cobalt(bis-acetylacetonate) for the controlled synthesis of functional polymers

Author

UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Demarteau, Jérémy, Kermagoret, Anthony, German, Ian, Cordella, Daniela, Robeyns, Koen, De Winter, Julien, Gerbaux, Pascal, Jerôme, Christine, Debuigne, Antoine, Detrembleur , Christophe, UCL - SST/IMCN/MOST - Molecules, Solids and Reactivity, Demarteau, Jérémy, Kermagoret, Anthony, German, Ian, Cordella, Daniela, Robeyns, Koen, De Winter, Julien, Gerbaux, Pascal, Jerôme, Christine, Debuigne, Antoine, and Detrembleur , Christophe

Abstract

Novel organocobalt complexes featuring weak C–CoL2 bonds (L = acetylacetonate) are prepared and used as sources of halomethyl radicals. They permit the precision synthesis of a-halide functionalized and telechelic polymers in organic media or in water. Substitution of halide by azide allows derivatization of polymers using the CuAAC click reaction.

Published
2015

15. Completely Miscible Polyethylene Nanocomposites

Author

Bieligmeyer, Matthias, primary, Taheri, Sara Mehdizadeh, additional, German, Ian, additional, Boisson, Christophe, additional, Probst, Christian, additional, Milius, Wolfgang, additional, Altstädt, Volker, additional, Breu, Josef, additional, Schmidt, Hans-Werner, additional, D’Agosto, Franck, additional, and Förster, Stephan, additional

Published
2012
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16. A New, Flexible N,N,N‐Tripodal Facially Capping Ligand System: Synthesis and Structural Characterization of β‐Triketimines and Their M(CO)3 Complexes (M = Cr, Mo, W)

Author

Barnes, Donna, primary, Brown, Gemma L., additional, Brownhill, Martyn, additional, German, Ian, additional, Herbert, Christopher J., additional, Jolleys, Andrew, additional, Kennedy, Alan R., additional, Liu, Boyang, additional, McBride, Katy, additional, Mair, Francis S., additional, Pritchard, Robin G., additional, Sanders, Arron, additional, and Warren, John E., additional

Published
2009
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17. A New, Flexible N,N,NTripodal Facially Capping Ligand System: Synthesis and Structural Characterization of βTriketimines and Their MCO3Complexes M = Cr, Mo, WDedicated to the memory of Swiatoslaw Jerry TrofimenkoPioneer of scorpionate chemistry

Author

Barnes, Donna, Brown, Gemma L., Brownhill, Martyn, German, Ian, Herbert, Christopher J., Jolleys, Andrew, Kennedy, Alan R., Liu, Boyang, McBride, Katy, Mair, Francis S., Pritchard, Robin G., Sanders, Arron, and Warren, John E.

Abstract

Reaction of imidoyl chlorides ArN=CClR Ar = 2iPrC6H4, 2,6iPr2C6H3, 2MeOC6H4; R = Me, Ph, tBu with [Linacnac] [nacnac = ArNCMe2CH] gives βtriketimines L, most of which exist in solution in equilibrium with their imineenamine tautomers. The route is highly modular, allowing independent variation of at least five parameters. The solution equilibria are very sensitive to such substituent pattern variation. Singlecrystal Xray diffraction analyses of examples of both tautomers and a geometric isomer in the solid state are presented, alongside solution NMR studies of the tautomerism. All examples revert exclusively to the βtriimine form on complexation with MCO3fragments M = Cr, Mo, W. Facial isomers result. The ligands are weak σdonors, as adjudged by CO IR stretching frequencies in [LMCO3]. Crystalstructure determination on the isostructural pair [HC2iPrC6H4N=CMe3MCO3] M = Cr, Mo revealed a hexagonal packing arrangement composed of aryl–aryl and carbonyl CO–H–C interactions which generates pseudocylindrical voids accounting for 6–9  of the crystal volume. In only one case were these occupied by solvent molecules. This family of facially capping N,N,Nligands with finely tunable bulk have wide potential in coordination chemistry.© WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Published
2009
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18. Healable Supramolecular Polyurethane Elastomers Possessing Pendant Bis-Aromatic Urea Recognition Units for Use in Repairable Coatings.

Author

O'Donnell AD, Hyder M, Chippindale AM, Harries JL, German IM, and Hayes W

Abstract

This paper describes the synthesis, characterization, and supramolecular assembly of polyurethane elastomers. Bis-aromatic urea hydrogen-bonding motifs have been used to promote the self-assembly of the materials. The materials described comprise a soft block, namely, polytetramethylene ether glycol (PTMG), as a telechelic diol and hard crystalline domains that feature a bis-aromatic urea hydrogen bonding motif as a chain extender. Two diols were polymerized (one featuring the bis-aromatic urea hydrogen bonding motif) with a PTMG diisocyanate prepolymer to yield supramolecular polyurethanes with molecular weights ca . 185000 with polydispersities ca . 2.0. The mechanical properties and processing temperatures of the polyurethanes were shown to be tunable by controlling the feed ratio of the supramolecular chain extenders. These supramolecular polyurethanes were found to be healable in nature, offering a useful property for use of these elastomers in applications such as cable coatings., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Published
2024
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