ja510643b_si_001.pdf (2.05 MB)
Complex Columnar Hexagonal Polymorphism in Supramolecular Assemblies of a Semifluorinated Electron-Accepting Naphthalene Bisimide
journal contribution
posted on 2015-01-21, 00:00 authored by Yu-Chun Wu, Pawaret Leowanawat, Hao-Jan Sun, Benjamin E. Partridge, Mihai Peterca, Robert Graf, Hans W. Spiess, Xiangbing Zeng, Goran Ungar, Chain-Shu Hsu, Paul
A. Heiney, Virgil PercecSimple synthetic
methods for a strongly electron-accepting naphthalene
bisimide (NBI) derivative functionalized with a new environmentally
friendly chiral racemic semifluorinated alkyl group and with AB3 minidendrons containing the same semifluorinated group are
reported. The semifluorinated dendron was attached to the imide groups
of the NBI via one, two, and three (m = 1, 2, 3)
methylenic units. The NBI-containing semifluorinated groups and the
dendronized NBI with m = 1 and 2 self-organize into
lamellar crystals. The dendronized NBI with m = 3
self-assembles into an unprecedentedly complex and ordered column
that self-organizes in a columnar hexagonal periodic array. This array
undergoes a continuous transition to a columnar hexagonal superlattice
that does not display a first-order phase transition during analysis
by differential scanning calorimetry at heating and cooling rates
of 10 and 1 °C/min. These complex columnar hexagonal periodic
arrays with intramolecular order could be elucidated only by a combination
of powder and fiber X-ray diffraction studies and solid-state NMR
experiments. The lamellar crystals self-organized from m = 1 and the two highly ordered columnar hexagonal periodic arrays
of m = 3 are assembled via thermodynamically controlled
processes. Since strongly electron-accepting derivatives are of great
interest to replace fullerene acceptors in organic photovoltaics and
for other supramolecular electronic materials, the multitechnique
structural analysis methodology elaborated here must be taken into
consideration in all related studies.