A set of water-soluble dendronized polyfluorenes bearing peripheral charged amino groups were synthesized by two steps: (1) Suzuki polycondensation of dendritic macromonomers carrying peripheral Bocprotected amino groups with 1,4-benzenediboronic acid propanediol ester; (2) the deprotection of the resulting Boc-protected dendronized polymers with aqueous HCl. All the protected dendronized polyfluorenes displayed good solubility in common organic solvents such as THF, chloroform, and methylene chloride. After deprotection, the zero generation polymers were only partially soluble in water, but the first and the second generation dendronized polymers were fully soluble in water. The optic properties of the protected and deprotected dendronized polymers were investigated. In solution, all these polymers exhibited bright blue emission. Unlike normal watersoluble conjugated polymer, the second generation deprotected dendronized polyfluorenes exhibited a quite high quantum yield (Φ F ) 94%) in water.
A novel class of dumbbell-shaped dendritic molecules with a p-terphenylene core was synthesized, and their self-assembling properties were investigated. The incorporation of bulky dendritic wedges to the central stiff aromatic scaffolds could finely tune their solubility in many organic solvents. Unlike the self-assembly behavior of p-terphenylen-1,4"-ylenebis(dodecanamide), the p-terphenylene cored different generation dendritic molecules could form gels in several kinds of organic solvents through a cooperative effect of the pi-pi stacking, hydrogen-bonding, and van der Waals forces. Interestingly, significant fluorescence enhancement was observed after gelation. Extensive investigations with atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), theological measurements, UV-vis absorption spectroscopy, FT-IR spectroscopy, 1H NMR, and X-ray powder diffraction (XRD) revealed that these dendritic molecules self-assembled into elastically interpenetrating one-dimensional nanostructures in organogels.
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