Cryo-tem, X-ray diffraction and modeling of an organic hydrogel

A more detailed picture of the molecular organization in a molecular gel will assist in efforts to rationally design low molecular mass organic gelators (LMOGs) of both organic and aqueous solvents. There is also increasing interest in being able to control the morphology of the resulting self-assembled fibrillar network (SAFIN) which will only be possible when we understand the connection between the molecular and the nano/micro structure of a given gelator [1]. The molecular recognition events leading to gelation are still poorly understood and there is a paucity of techniques with molecular level resolution that are adaptable to the analysis of gels. This chapter discusses how experimental data from complementary techniques can be used to develop models of gel structure at several levels of resolution. Using a case study of an organic hydrogelator [2, 3], we demonstrate how data obtained from vitrified ice cryo-transmission electron microscopy (cryo-TEM) (see Chapter 9) and X-ray diffraction (XRD) (see Chapter 11) can be used to develop a model of the molecular assembly processes that lead ultimately to gelation by small organic molecules.