Kapoor, Iti and Schoen, Eva-Maria and Bachl, Jourgen and Kuehbeck, Dennis and Cativiela, Carlos and Saha, Subhadeep and Banerjee, Rahul and Roelens, Stefano and Marrero-Tellado, Jose and Diaz Diaz, David (2012) Competition between gelation and crystallisation of a peculiar multicomponent liquid system based on ammonium salts. SOFT MATTER, 8 (12). pp. 3446-3456. ISSN 1744-683X,
Full text not available from this repository. (Request a copy)Abstract
An exemplar competition between gelation and crystallisation phenomena was examined with an unusual synergistic multicomponent (organo) gelator solution (MGS), which consists of a well-defined methanolic solution of (1R, 2R)-1,2-diaminocyclohexane L-tartrate containing 2.4 equiv. of concentrated hydrochloric acid. The optimal composition of the MGS was determined through meticulous solubility, gelation and structural studies, which support a transient gelation mechanism based on the kinetic self-assembly of the tartrate salt driven by hydrogen-bonding interactions, involving ammonium nitrogen donors and hydroxyl oxygen acceptors, and electrostatic interactions. The hydrochloric acid is involved in the solubilisation of the salt through an ionic dissociation-exchange process, which ends up with the formation-precipitation of (1R, 2R)-1,2-diaminocyclohexane dihydrochloride. As a consequence, an irreversible destruction of the gel takes place, which indicates the metastable nature of this phase that cannot be accessed from the thermodynamically equilibrated state. Gelation of a variety of oxygenated and nitrogenated solvents with moderate polarity occurred efficiently using extremely low MGS concentrations at low temperatures, and the gel phase was confirmed by dynamic rheological measurements. Several features make the described MGS unique: (1) it is a multicomponent solution where each component and its stoichiometry play a key role in the reproducible formation and stabilization of the gels; (2) it is formed by simple, small, and commercially available chiral building blocks (dissolved in a well-defined solvent system), which are easily amenable for further modifications; (3) the gelation phenomenon takes place efficiently at low temperature upon warming up the isotropic solution, conversely to the typical gel preparation protocol; and (4) the formed organogels are not thermoreversible despite the non-covalent interactions that characterize the 3D-network.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | MASS ORGANIC GELATORS; SUPRAMOLECULAR CHEMISTRY; FIBRILLAR NETWORKS; CRYSTAL-GROWTH; GELS; ORGANOGELS; TRANSITION; SOLVENT; TEMPERATURE; RECOGNITION; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Arbeitskreis Prof. Dr. David Díaz Díaz |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 25 May 2020 07:54 |
| Last Modified: | 25 May 2020 07:54 |
| URI: | https://pred.uni-regensburg.de/id/eprint/19538 |
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