Synthesis And Self-Assembly Properties Of Novel Amphiphilic Boron-Dipyrromethene Dyes

Recently, the nanostructure and thermodynamic of molecular assemblies have been widely investigated. In this paper, five new amphiphilic boron-dipyrromethene(BODIPY) dyes bearing different hydrophobic wedges at the meso-position and two hydrophilic cationic moieties at boron were synthesized and characterized. The self-assembly properties of one of these dyes(4, 4-bis-(3-trimethylaminoiodine-1-propynyl)-1, 3, 5, 7-tetramethyl-8-(3, 4, 5-tris(dodecyloxy))-BODIPY) were studied in detail. The spectroscopic data analysis using two different models(developed by Van der Schoot et al. and Goldstein et al. respectively) for cooperative supramolecular polymerization indicates unambiguously a nucleation-growth process of the aggregation of the molecule and the nucleus size(ca. 12-18 molecules) could be derived. Furthermore, the morphology of the dye aggregates was observed by transmission electron microscopy and X-ray diffraction, showing us a vesicular of the aggregates with multilamellar wall structure. Meanwhile, this dye vesicles exhibit unique J-aggregates characteristics, i.e. red-shifted sharp absorption band, narrowed emission linewidth, and higher fluorescence quantum yield, as compared with the monomeric dye.