p-Phenyleneethynylene-based comb-like oligomers: the synthesis and self-assembling property

This paper describes the self-assembling property of three series of p-phenyleneethynylene based comb-like oligomers, which carry multiple peripheral side chains of different polarity. The new oligomers are prepared readily through the formation of the hydrazone bonds from the corresponding aldehyde and gallic acid-derived benzohydrazides. In polar solvents such as methanol and ethanol, the oligomers that bear n-decyl or 2-(2-(dioctylamino)-2-oxoethyl-amino)-2-oxoethoxyl unit (DOAOE) segments as the side chains are revealed to form vesicular structures, while the oligomers carrying hydrophilic oligo(ethyleneglycol) side chains do not. The structures of the vesicles are evidenced by SEM, AFM, TEM, and dye-encapsulation experiments. UV–vis absorption spectroscopic experiments suggest that the vesicles are generated through the stacking of the conjugated backbones, which is promoted by the solvophobic interaction of the peripheral side chains.