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 add ed saccharides, three amphiphilic porphyrins bearing boronic acid grou ps were synthesised. 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 be en found to act as a membrane-forming amphiphile in an aqueous system. Spectroscopic (UV-Vis and CD), light-scattering, DSC and electron mic rographic studies have established that in aqueous media 4 forms stabl e fibrous aggregates only in the presence of saccharides, which are ch irally twisted by the absolute configuration of the added saccharides. This is a novel method to control the aggregate morphology by sacchar ides and well imitates the morphological functions of certain cell mem branes, the surfaces of which are covered by saccharides. (C) 1998 Els evier Science Limited.