CO2 and photo-controlled reversible conversion of supramolecular assemblies based on water soluble pillar[5]arene and coumarin-containing guest

In this communication, a new supramolecualr amphiphile was successfully constructed based on water soluble pillar[5]arene and a unique guest which contain a CO2 responsive tertiary amine unit and a UV responsive coumarin group. When guest molecule 1 dispersed in water, it self-assembled into sheet-like structures. Upon bubbling CO2, 1 transformed into 1H due to the tertiary amine unit was protonated, accompany the nano-sheets transformed into vesicles. Further irradiation of 1H with 365 nm light for 3 h, the coumarin group reacted with each other to form bola-type amphiphie 2H. In this case, vesicles collapsed and re-assembled into nano-tubes. However, when addition of WP5 into the solution of 1H, the vesicles transformed into micelles, this is due to the formation of supramolecular amphiphile WP5&1H. Upon irradiation of WP5&1H with 365 nm light for 3 h, nano-ribbons observed instead of micelles in the solution. Notably, nanotubes from 2H could also transform into nano-ribbons after adding WP5. The self-assembly process and the resultant assemblies were characterized by TEM, SEM, DLS, SAXS and NMR technologies. Due to both CO2 and light are “green” for living organisms, we anticipated our system can offer the possibilities in “on demand” drug absorption and release.