title: Complex columnar hexagonal polymorphism in supramolecular assemblies of a semifluorinated electron-accepting naphthalene bisimide.
abstract: Simple 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.
authors.affiliation: Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States.
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Wu
authors.forename: Pawaret
authors.initials: P
authors.lastname: Leowanawat
authors.forename: Hao-Jan
authors.initials: HJ
authors.lastname: Sun
authors.forename: Benjamin E
authors.initials: BE
authors.lastname: Partridge
authors.forename: Mihai
authors.initials: M
authors.lastname: Peterca
authors.forename: Robert
authors.initials: R
authors.lastname: Graf
authors.forename: Hans W
authors.initials: HW
authors.lastname: Spiess
authors.forename: Xiangbing
authors.initials: X
authors.lastname: Zeng
authors.forename: Goran
authors.initials: G
authors.lastname: Ungar
authors.forename: Chain-Shu
authors.initials: CS
authors.lastname: Hsu
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heiney
authors.forename: Virgil
authors.initials: V
authors.lastname: Percec
mesh_terms: D004579:Electron Transport; D055772:Green Chemistry Technology; D054879:Halogenation; D007094:Imides / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009281:Naphthalenes / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D007094:Imides; D009281:Naphthalenes; C031721:naphthalene