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

5 years ago

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

Rajkamal, Navendu P. Pathak, Somnath Yadav, Shubhajit Dhara, Tanmoy Halder

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. Minimal protection: Structurally simple partially acetylated or benzoylated arabinose derivatives are reported as gelators (see figure). The reasons for the greater mechanical robustness of the benzoylated derivatives than that of the acetylated derivatives have been investigated and are reported.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201701669