Assembly Structure And Optical Properties Of Several Aggregation Induced Emission Molecules

In this thesis, We investigated the optical properties and assembly of TPE-leu, TPE-Valine,TPE-2Valine,TPE-(OMe)2.and.TPE-Py-Pr.molecules.Using.fluorescence.spectrometer and circular dichroism spectrometer, we studied the AIE property induced by poor solvent of the molecules and surfactants. Using fluorescence microscope, atomic force microscope(AFM) and SEM, we also systematically studied the assemblies induced. Using LB technique, LB films of TPE-2Valine and TPE-leu were obtained at different surface pressures and the assemblies of molecules were studied with AFM.We found that TPE-2Valine formed rod-like fibers and helical structures in its good solvent; with an increase of the poor solvent percentage, it gradually formed a linear filament and spiral fiber at higher poor solvent percentage; Induced by the poor solvent of water from low percentage to high percentage, TPE-(OMe) 2 formed loose fibers, long rope tangled fibers and spherical aggregates structure, respectively; TPE-Py-Pr in the CH3 OH /H2 O volume ratio of 1: 1 formed entangled fiber aggregation.We also investigated the assembly of TPE-Valine, TPE-leu and TPE-Valine at gas-liquid interface using LB technique and AFM. We found that the first two assembled at the gas-liquid interface in a very similar way and they both formed films at low surface pressure and long fibers at high surface pressure. In contrast, TPE-2Valine formed thicker fibers, which finally transformed into dendritic fibril structures.Surfactants have considerable influence on inducing the AIE property of molecules and the influence is highly related with their concentration. Only when the concentration of the surfactant is higher than their CMC value, can the AIE property be efficiently induced. We found that in the presence of surfactant TPE-leu formed mainly filamentous fibers; Without addition of surfactant, TPE-2Valine formed granular aggregates, but formed rod-like fibers with surfactant added. This result suggested that the formation of hydrophobic micelles is pivotal for the induction of AIE property of molecules. When the concentration of the surfactants was above CMC, they formed micelles with hydrophobic internalities. The AIE molecules likely intercalated the hydrophobic internalities of the surfactant, which efficiently restricted the intramolecular rotation of the AIE molecules and induced the AIE property of the molecules.