Oriented molecular aggregates of porphyrin-based amphiphiles and their morphology control by a boronic acid-sugar interaction

Towards the morphology control of oriented porphyrin aggregates by added saccharides, three amphiphilic porphyrins bearing boronic acid groups were synthesized. Among them, an amphiphilic tetraphenylporphyrin (4) bearing two octadecyl groups at 5,10-positions and two boronic acid groups (acting as saccharide-binding sites) at 15,20-positions has been found to act as a membrane-forming amphiphile in an aqueous system. Spectroscopic (UV-Vis and CD), light-scattering, DSC and electron micrographic studies have established that in aqueous media 4 forms stable fibrous aggregates only in the presence of saccharides, which are chirally twisted by the absolute configuration of the added saccharides. This is a novel method control the aggregate morphology by saccharides and well imitates the morphological functions of certain cell membranes, the surfaces of which are covered by saccharides.