Abstract
1-(3-Methyl-1H-pyrazol-5-yl)-3-(3-nitrophenyl) urea (1) forms hydrogels in a range of acids at pH 1-2. The morphology and rheology of these gels are dependent on the identity of the anion and represent a way of tuning the gels' physical properties. The magnitude of the elastic storage modulus of the gels follows the trend according to the acid used to protonate the gelator H2SO4 > MePO3H2 > H3PO4 approximate to HBF4 approximate to HPF6 > EtPO3H2. Chloride salts do not form gels and the nitrate gels are unstable with respect to crystallisation. Salting out or addition of methanol results in the characterisation of five salts of 1 which reveals extensive solvation in the solid state and the absence of urea...urea hydrogen bonding in contrast to the well known bis(urea) gelators.
Original language | English |
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Pages (from-to) | 75-84 |
Number of pages | 10 |
Journal | Soft Matter |
Volume | 7 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2011 |
Keywords
- AMMONIUM MONOCARBOXYLATE SALTS
- AMINO-ACID DERIVATIVES
- MASS ORGANIC GELATORS
- ION-PAIR BINDING
- X-RAY CRYSTAL
- PHASE-TRANSITION
- CO-CRYSTAL
- SUPRAMOLECULAR HYDROGEL
- COMBINATORIAL LIBRARY
- HETEROCYCLIC UREAS