Non-Steroidal Biphenyl Gelators: Correlation of Xerogel Structure with Solid-State Structure and Circular Dichroism Spectroscopy

Because the factors favoring the formation of well-formed single crystals are dissimilar to those conducive to gel formation, few examples of single-crystal structural characterizations of organogelators are found in the literature. A series of biphenyl methyl and ethyl diester derivatives of varying chain length were synthesized and their gelation abilities explored. X-ray diffraction of single crystals of one of the gelators reveals a columnar extended structure. Based on XRD results for xerogels obtained from the reported organogelators, the members of the series are isostructural and so also adopt a columnar superstructure. Scanning electron microscopy (SEM) was used for the investigation of the morphology of the xerogels, which display either platelet-like morphologies or more typical entangled twisted ribbon-like aggregates. The gels exhibit chirality, which depends on the sol-gel transition history, as observed by induced circular dichroism (ICD) spectroscopy.