Exploring molecular recognition pathways within a family of gelators with different hydrogen bonding motifs

John G. Hardy, Andrew R. Hirst, Ian Ashworth, Colin Brennan, David K. Smith*

*Corresponding author for this work

Research output: Contribution to journalArticle

48 Citations (Scopus)
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Abstract

We report the synthesis of a family of gelators in which alkyl chains are connected to the amino groups of L-lysine methyl ester using a range of different hydrogen bonding linking groups (carbamate, amide, urea, thiourea and diacylhydrazine) using simple synthetic methodology based on isocyanate or acid chloride chemistry. The ability of these compounds to gelate organic solvents such as toluene or cyclohexane can be directly related to the ability of the linking group to form intermolecular hydrogen bonds. In general terms, the ability to structure solvents can be considered as: thiourea <carbamate <amide <urea similar to diacylhydrazine. This process has been confirmed by thermal measurements, scanning electron microscopy (SEM) and infrared and circular dichroism spectroscopies. By deprotecting the methyl ester group, we have demonstrated that a balance between hydrophobic and hydrophilic groups is essential-if the system has too much hydrophilicity (e. g., diacylhydrazine, urea) it will not form gels due to low solubility in the organic media. However, the less effective gelators based on amide and carbamate linkages are enhanced by converting the methyl ester to a carboxylic acid. Furthermore, subsequent mixing of the acid with a second component (diaminododecane) further enhances the ability to form networks, and, in the case of the amide, generates a two-component gel, which can immobilise a wide range of solvents of industrial interest including petrol and diesel (fuel oils), olive oil and sunflower oil (renewable food oils) and ethyl laurate, isopropyl myristate and isopropyl palmitate (oils used in pharmaceutical formulation). The gels are all thermoreversible, and may therefore be useful in controlled release/formulation applications.
Original languageEnglish
Pages (from-to)7397-7406
Number of pages10
JournalTetrahedron
Volume63
Issue number31
DOIs
Publication statusPublished - 30 Jul 2007

Keywords

  • GEL-PHASE MATERIALS
  • 2-COMPONENT DENDRITIC GEL
  • L-LYSINE DERIVATIVES
  • WEIGHT HYDROGELATORS
  • ORGANIC LIQUIDS
  • CONTROLLABLE NANOMATERIALS
  • SUPRAMOLECULAR GELS
  • PEPTIDIC DENDRIMERS
  • MASS GELATORS
  • ONE-COMPONENT

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science (miscellaneous)

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