Modular synthesis of dendritic ionic triphiles and their behavior in three-phase liquid–liquid–liquid system

Triphilic molecules possess unique features due to the presence of chemically distinct domains − oleophilic, hydrophilic, and fluorophilic. In bulk, they can form intriguing crystal structures, while in solutions, they can act as multi-purpose emulsifiers or form assemblies such as multi-compartment micelles applicable in drug delivery. However, their chemico-physical properties are still relatively unexplored. Namely, they have never been studied in a three-phase liquid–liquid–liquid system consisting of organic and fluorous solvents and water. Here we present an adaptive, modular synthesis of a novel type of dendritic ionic triphiles and a study of their solution behavior, with a focus on a three-phase toluene/water/perfluoro(methylcyclohexane) (PMC) system. The synthesis is based on the quaternization of various alkylimidazoles by a previously published type of carbosilane dendritic wedges bearing polyfluorinated chains of varied lengths at their periphery. This approach enables the facile combination of different organic and fluorous blocks and, thus, easy tailoring of final structures according to the results of this work. The distribution of triphiles in the selected three-phase system was mapped in a ternary diagram representing the mass proportions of individual domains. The distribution between toluene and PMC changes gradually depending on the sizes of the corresponding domains and significantly differs from the distribution in a biphasic system where water is absent (i.e., the fluorous partition coefficient). However, at a certain size of the fluorous domain, the molecules completely lose their affinity to the fluorous phase and gain affinity to water even though being still partially soluble in PMC. The results can help understand the structure-affinity relationship of triphilic compounds and can help find a substance with balanced affinities to all three solvents. Moreover, some of the prepared compounds manifested interesting surface activity, namely the emulsification capability on both phase interfaces or the formation of stable nanoparticles in an aqueous environment.