Mesophase characterization of some long chain vicinal multihydroxy amphiphiles [1,2]

The mesophase characterization of three stereoisomeric multihydroxy compounds, the 1,2(S),3(R),4(R)-, 1,2(R),3(S),4(R)-, and 1,2(S),3(S),4(R)-icosanetetrols, as well as of an octadecafuranose derivative has been carried out by means of polarizing microscopy, X-ray diffraction etc. The four multiols with their very long flexible alkyl chains are mono-thermomesomorphic; their single mesophases are miscible with each other, with a typical carbohydrate derivative, and are characterized by X-ray diffraction having a layer structure without order in it. The phase transition data of the three icosanetetrols are strongly dependent on their stereochemistry. The measurements of the refractive indices of one of the tetrols show a typical behaviour known for S(A) phases or for lamellar phases, i.e. the sign of the birefringence is positive.