posted on 2004-05-26, 00:00authored byYong-Sik Yoo, Jin-Ho Choi, Ji-Ho Song, Nam-Keun Oh, Wang-Cheol Zin, Soojin Park, Taihyun Chang, Myongsoo Lee
Tree-shaped molecules consisting of octa-p-phenylene as a stem segment and oligoether
dendrons as a flexible head were synthesized and characterized. The molecular tree based on a small
flexible head self-assembles into a lamellar structure, whereas the molecule based on a larger headgroup
self-assembles into a discrete heptameric bundle that organizes into a 3-D primitive orthorhombic
supercrystals, as confirmed by X-ray scatterings and transmission electron microscopic (TEM) observations.
Optical studies revealed that the absorption and emission maxima and absorption edge of the 3-D structure
shift to higher energy compared to those of the lamellar structure. The molecules in dilute solution (THF/water = 1:10 v/v) were observed to self-assemble into capsule-like hollow aggregates, as confirmed by
dynamic and static light scatterings, scanning electron microscopy (SEM), and TEM investigations. These
results demonstrate that tree-shaped molecules are capable of packing into organized discrete nanocrystals
with parallel arrangement as well as hollow nanocapsules with radial arrangement, depending on the
presence of selective solvents for flexible headgroup.