TEM and SEM observations of super-structures constructed in organogel systems from a combination of boronic-acid-appended bola-amphiphiles with chiral diols

Abstract

Two bola-amphiphilic α,ω-diboronic acids separated by a (CH₂)₁₁ or (CH₂)₁₂ group were synthesized. Complexation with chiral diols readily gave new amphiphiles end-capped with the chiral substituents. Some of these acted as good gelators of organic solvents. Transmission electron microscope and scanning electron microscope observations established that a variety of super-structures are created in the organogels, depending on the solvents and the structure of the chiral end-cap groups. In most cases, the fibrous aggregates, the network structure which is the driving-force for gelation, showed a helical higher-order structure reflecting the chirality of the end-cap groups. The results indicate that the combinatorial approach utilizing boronic acid functions and diol compounds is useful in creating a variety of new super-structures in the gel phase.