Ionic self-assembly of ammonium-based amphiphiles and negatively charged bodipy and porphyrin luminophores

This paper describes the synthesis of wedge-sbaped, charged amphiphilic molecules bearing an ammonium group at the tip that are able to organize negatively charged luminophores through an ionic self-assembly (ISA) process into discotic liquid-crystalline materials. For this purpose, two negatively charged luminescent molecules, 4,4-difluoro-1,3,5,7,8-pentamethyl-2,6-disulfonato-4-bora-3a,4a-diaza-s-indacene (sulfobodipy(2-)) and tetrakis(4-sulfonatophenyl)porphyrin (TPpS(4-)), were tested. The neutral luminescent complexes obtained through ISA form columnar mesophases that display hexagonal symmetry. Molecular modeling provides a structural description of the discotic mesophases in which the anionic luminophores are stacked in the middle of the disks. The key role of the amide linkage in the stabilization of the columnar architecture was probed by using infrared spectroscopy. Fluorescence microscopy has been used to show that the complexes are luminescent in both the solid and mesomorphic states.