Synthesis of Azaylide-Based Amphiphiles by the Staudinger Reaction

Catalyst- and reagent-free reactions are powerful tools creating various functional molecules and materials. However, such chemical bonds are usually hydrolysable or require specific functional groups, which limits their use in aqueous media. Herein, we report the development of new amphiphiles through the Staudinger reaction. Simple mixing of chlorinated aryl azide with a hydrophilic moiety and various triarylphosphines (PAr3) gave rise to azaylide-based amphiphiles NPAr3, rapidly and quantitatively. The obtained NPAr3 formed ca. 2 nm-sized spherical aggregates (NPAr3)_n in water. The hydrolysis of NPAr3 was significantly suppressed as compared with those of non-chlorinated amphiphiles nNPAr3. Computational studies revealed that the stability is mainly governed by the decrease in LUMO around the phosphorus atom owing to the o-substituted halogen groups. Furthermore, hydrophobic dyes such as Nile red and BODIPY were encapsulated by the spherical aggregates (NPAr3)_n in water.