Understanding the gelation properties of the fluorophenyl glycosides of arabinoside gelators: experimental and theoretical studies.

In supramolecular gelation, fluorinated gelators are important due to the unique properties displayed by these compounds that arise out of the presence of fluorine atoms. Generally, incorporation of fluorine leads to higher mechanical strength of the gels compared to their non-fluorinated counterparts and this property is enhanced with increasing the number of fluorine atoms. Herein, we show that the incorporation of fluorine into the phenyl ring of phenyl arabinoside allows the molecule to act as a gelator, unlike the non-fluorinated compound. We also show that the mechanical strength and stiffness of the gels is not only dependent on the positions of the fluorine atoms but also guided by their number. Detailed experimental studies, supported by computational studies, allowed us to rationalize the observed supramolecular interactions and propose reasons based on the conformational preferences of these compounds that allow additional hydrogen bonds and π-π interactions which guide the self-assembly, in addition to the primary H-bonding interactions. This, in turn, affects the mechanical behavior of these gels.

A gelator-starch blend for dry powder based instant solidification of crude oil at room temperature.

Immobilization of crude oil via solidification is a technique that allows for the control and remediation of oil spills. Gelation using supramolecular gelators is a powerful method for the solidification of crude oil. However, this method suffers from the limitation that the gelator has to be dispersed over the crude oil as a solution in environmentally harmful and volatile carrier solvents. Compared to this, the solid dispersal of the dry powder solidifier offers a very attractive solution to the problem but has rarely been reported with very limited success. Herein, we report a previously untested method for the dispersal of the solid gelator as a gelator-natural polymer blend that allows the uniform dispersion of the gelator over a wider bulk of the crude oil, resulting in its ultrafast gelation in less than 30 s at ambient temperature. Also, the technique is successful at low loadings of the composite material that contains the gelator at very low concentrations (0.34%, w/v).

Partially Acetylated or Benzoylated Arabinose Derivatives as Structurally Simple Organogelators: Effect of the Ester Protecting Group on Gel Properties.

Sugar-based low-molecular-weight gelators (LMWGs) have been used for various applications for a long time. Herein, structurally simple, ester-protected arabinosides are reported as low-molecular-weight organogelators (LMOGs) that are able to gel aromatic solvents, as well as petrol and diesel. Studies on the mechanical strength of the gels, through detailed rheological experiments, indicate that gels from the 1,2-dibenzoylated arabinose gelator possess better mechanical properties than those from the 1,2-diacetylated gelator. These results are interpreted in terms of the tendency of the former to form fibers with comparatively lower diameter than those of the latter, based on detailed field-emission SEM and AFM studies. Investigations of the interactions responsible for the self-assembly of gelators through IR spectroscopy and wide-angle X-ray scattering reveal that the primary interactions responsible are hydrogen bonds between the hydroxyl groups and ester C=O, which is absent in the solid state of the gelators. In addition, π interactions present in the 1,2-dibenzoylated derivative result in a more regular arrangement, which, in turn, leads to better mechanical properties of the gels compared with those of the 1,2-diacetylated gelator.