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CO2 and photo-controlled reversible conversion of supramolecular assemblies based on water soluble pillar[5]arene and coumarin-containing guest
摘要： 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.
关键词： Reversible conversion,Coumarin,Supramolecular assemblies,Amphiphiles,Pillar[5]arene
更新于2025-09-23 15:19:57
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Visualizing the Initial Step of Self-Assembly and the Phase Transition by Stereogenic Amphiphiles with Aggregation-Induced Emission
摘要： Many highly ordered structures with smart functions are generated by self-assembly with stimuli responsiveness. Despite the electron microscopes enable us to directly observe the end products, they are hard to visualize the initial step and the kinetic stimuli-responsive behavior of self-assembly. Here, we report the design and synthesis of stereogenic amphiphiles, namely (Z)-TPE-OEG and (E)-TPE-OEG, with aggregation-induced emission (AIE) characteristics from the hydrophobic tetraphenylethene core and thermoresponsive behavior from the hydrophilic oligoethylene glycol monomethyl ether chain. The two isomers can be easily isolated by high-performance liquid chromatography and characterized by 2D NMR spectroscopy. While (Z)-TPE-OEG self-assembles into vesicles, its (E)-cousin forms micelles in water. The initial step of their self-assembly processes can be visualized based on AIE characteristics, with the sensitivity much higher than the method based on transmittance measurement. The entrapment and release capabilities of the (Z)-stereogenic amphiphile are demonstrated by employing pyrene as a guest. The thermoresponsive behavior of the (Z)-amphiphile results in its continuous phase transition from microscopic self-assembly to macroscopic aggregation, which is successfully visualized in-situ by confocal laser scanning microscopy accompanied with AIE technique. Such kinetic process shows different stages according to the microscopic visualization and these stages have never been monitored through roughly observing the appearance of precipitates. It is anticipated that this study can deepen the understanding of the self-assembly processes for better monitoring and controlling them in different systems.
关键词： phase transition,aggregation-induced emission,self-assembly,amphiphiles,microscopic visualization
更新于2025-09-04 15:30:14