The Gelling Ability of Some Diimidazolium Salts: Effect of Isomeric Substitution of the Cation and Anion
- Autori: D'Anna, F.; Vitale, P.; Ferrante, F.; Marullo, S.; Noto, R.
- Anno di pubblicazione: 2013
- Tipologia: Articolo in rivista (Articolo in rivista)
- OA Link: http://hdl.handle.net/10447/72103
The gelling ability of some geminal imidazolium salts was investigated both in organic solvents and in water solution. Organic salts differing either in the cation or anion structure were taken into account. In particular, the effects on the gelphase formation of isomeric substitution on the cation or anion as well as of the use of mono- or dianions were evaluated. As far as the cation structure is concerned, isomeric cations, such as 3,3’-di-n-octyl-1,1’-(1,4-phenylenedimethylene)diimidazolium and 3,3’-di-n-octyl-1,1’-(1,3-phenylenedimethylene) diimidazolium, were used. On the other hand, in addition to the bromide anion, isomeric dianions, such as the 1,5- and 2,6-naphthalenedisulfonate anions, were also examined. After preliminary gelation tests, different factors affecting the obtained gel phases, such as the nature of the solvent, organogelator concentrations, and action of external stimuli, were analyzed. The gel-phase formation was also studied as a function of time, by using resonance light scattering measurements. Gel morphologies were analyzed by scanning electron microscopy. To further support the understanding of the different behavior shown by the isomeric cations, some representative ion pairs were analyzed by DFT-based investigations. The collected data underline the significant role played by isomeric substitution of both cation and anion structures in determining the gelling capability of the investigated salts, as well as the properties of the gel phases. Finally, DFT investigations were helpful in the identification of the structural features affecting the self-assembly.