LAUSR

Abstract Hierarchical self-assembly provides a new strategy for the bottom-up fabrication of functional materials with ordered structures. In this article, ionic self-assembly (ISA) of an anionic biological surfactant sodium deoxycholate (NaDC) and a cationic dye Rhodamine B (RhB) in NaOH solution were performed and three-dimensional spherical microcrystals consisting of symmetric nanorods which show similar architectural structure of sea urchin, were obtained. The urchin-like microcrystals possess highly ordered thermotropic liquid crystal behavior and it is interesting to find that the NaDC/RhB/NaOH microcrystals also possess highly enhanced solid emission which is in sharp contrast to nearly no photoluminescence of RhB. Moreover, they exhibited remarkably different morphologies and luminescence behaviors in mixed organic solvents which depended on the mixing ratio of the solvents, i.e., the fraction of n-propanol, due to the polarity of the solvent and the hydrophobic effect. Our NaDC/RhB/NaOH microcrystals in n-propanol show a superior fluorescent sensing capability for the detection of Fe3+ with a limit of detection (LOD) low to 4.40 μM through fluorescence quenching caused by donor–acceptor electron transfer mechanism. The supramolecular nanostructures developed herein open up new opportunities for practical applications in optoelectronics and sensors.