Microscopic Studies of 1,3 : 2,4-Di-O-benzylidene-d-sorbitol in Ethylene Glycol

Abstract 1,3 : 2,4-Di-O-benzylidene-d-sorbitol (d-DBS) is known to be a chiral oil gelator which forms the gel state with organic solvents having a wide range of polarities. Microscopic and thermoanalytical studies on the binary system, d-DBS/ethylene glycol, were carried out. The gel of the d-DBS/ethylene glycol system showed optical anisotropy under crossed polarizers. Two kinds of mesophases have been identified in the gel state. One was the crystalline phase, by means of observing the spherulitic texture. The other was an isotropic mesophase between spherulitic textures. In the crystalline phase the supramolecular helicoidal strucrture was observed by polarized and electron microscopy. The isotropic mesophase comprized of a network-like structure. It changed to the crystalline phase below the phase transition temperature from a gel to an isotropic solution (Ti), and the crystal of d-DBS was precipitated out from ethylene glycol. It is thus concluded that the gel state of d-DBS/ethylene glycol is a metastable state and that the chirality of d-DBS affects the shape which d-DBS forms in the crystalline state.