Flüssigkristalline Perylenbisimid-J-Aggregate

• Antragsteller: Professor Dr. Matthias Lehmann; Professor Dr. Frank Würthner
• Fachliche Zuordnung: Organische Molekülchemie - Synthese, Charakterisierung
• Förderung: Förderung von 2016 bis 2020
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 290315036

• Erstellungsjahr: 2020

Zusammenfassung der Projektergebnisse

The self-assembly of dye molecules into J-aggregates leads to the emergence of new useful properties in the aggregated state. The unique optical features of these J-aggregates are narrowed, bathochromically shifted absorption bands and almost resonant fluorescence with an increased radiative rate that results from the coherently coupled molecular transition dipoles arranged in a slip-stacked fashion. Taking advantage of our earlier work on the self-assembly of perylene bisimide dyes into J-aggregates by hydrogen bond-directed head-to-tail assembly of these dyes in solution, here we explored the utilization of this supramolecular concept for the design of new bulk liquid-crystalline phase materials. The chosen molecules were based on baysubstituted perylene bisimides bearing tetra-acyloxy, tetra-phenoxy and tetra-trialkoxy(oligo)thienyl-phenoxy substituents. In this project, we could show how a combination of sterical constraints and hydrogen bonding receptor sites can guide the self-assembly of PBI dyes into slip-stacked packing motifs with J-type exciton coupling. Engineering of the substituents’ steric requirements by a dendron-wedge approach afforded adjustable numbers of helical strands of PBI J-aggregates in the columnar liquid-crystalline state from two up to seven. In one specific case with the smallest dendron substituents a transition into a lamellar phase was confirmed. A second, 1,7-substituted, mesogen-jacketed PBI revealed a gradual transition from a completely nanosegregated multilayer structure, without developing a bicontinous cubic phase to a hexagonal columnar liquid crystal. A general feature of all of these columnar liquid-crystalline phases is the parallel orientation of the dyes’ transistion dipole moments and the columnar axis and the J-type coupling among the dyes. The cooperative self-assembling process is extremely robust and is the reason that cubic bicontinous LC phases could not be onserved between the lamellar and columnar LC assemblies. In addition to our elaborate studies to characterize the liquid-crystalline phases by polarized optical microscopy, differential scanning calorimetry, density studies and in particular small and wide angle X-ray diffraction (SAXS, WAXS) and supported by theoretical modeling with Materials Studio and CLEARER (fibre diffraction simulation) software, we carried out in-depth studies on the self-assembly of these molecules in solution phase. Collaborative work with spectroscopists, physicists and theoreticians provided information on functional properties originating from the specific organization of these dyes. Thus, exciton migration over distances of up to 180 nm was shown in PBI J-aggregates and applications in photonic microcavities and as photoconductive layers were demonstrated.

Projektbezogene Publikationen (Auswahl)

• Angew. Chem. 2017, 129, 2194–2197; Angew. Chem. Int. Ed. 2017, 56, 2162–2165. A Columnar Liquid-Crystal Phase Formed by Hydrogen-Bonded Perylene Bisimide J-Aggregates
  S. Herbst, B. Soberats, P. Leowanawat, M. Lehmann, F. Würthner
  
• Appl. Phys. Lett. 2017, 110, 201113-1–201113-4. Three-Dimensional Photonic Confinement in Imprinted Liquid Crystalline Pillar Microcavities
  M. Dusel, S. Betzold, S. Brodbeck, S. Herbst, F. Würthner, D. Friedrich, B. Hecht, S. Höfling, C. P. Dietrich
  
• ACS Photonics 2018, 5, 90–94. Tunable Light–Matter Hybridization in Open Organic Microcavities
  S. Betzold, S. Herbst, A. A. P. Trichet, J. M. Smith, F. Würthner, S. Höfling, C. P. Dietrich
  
• Nat. Commun. 2018, 9, 2646. Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid crystalline phases
  S. Herbst, B. Soberats, P. Leowanawat, M. Stolte, M. Lehmann, F. Würthner
  
• Angew. Chem. 2019, 131, 13113-13117; Angew. Chem. Int. Ed. 2019, 58, 12979-12983. Photoconductive Core-Shell Liquid-Crystals of a Perylene Bisimide J-Aggregate Donor-Acceptor Dyad
  M. Hecht, T. Schlossarek, M. Stolte, M. Lehmann, F. Würthner
  
• ACS Appl. Nanomaterials 2020. Multistranded Core-Shell Liquid Crystals of Perylene Bisimide J-Aggregate Donor-Acceptor Dyads: Enhanced Photoconductivity Through Macroscopic Alignment
  M. Hecht, T. Schlossarek, S. Ghosh, Y. Tsutsui, A. Schmiedel, M. Holzapfel, M. Stolte, C. Lambert, S. Seki, M. Lehmann, F. Würthner
  
• Adv. Opt. Mater. 2020, 8, 2000926 (1-8). Crystal Engineering of 1D Exciton Systems Composed of Single- and Double-Stranded Perylene Bisimide J-Aggregates
  M. Stolte, R. Hecht, Z. Xie, L. Liu, C. Kaufmann, A. Kudzus, D. Schmidt, F. Würthner
  
• Angew. Chem. 2020, 132, 17232–17238; Angew. Chem. Int. Ed. 2020, 59, 17084-17090. Self-Sorting Supramolecular Polymerization: Helical and Lamellar Aggregates of Tetra-Bay-Acyloxy Perylene Bisimide
  M. Hecht, P. Leowanawat, T. Gerlach, V. Stepanenko, M. Stolte, M. Lehmann, F. Würthner
  
• J. Phys. Chem. Lett. 2020, 11, 6612-6617. Exciton Migration in Multistranded Perylene Bisimide J-Aggregates
  C. Rehhagen, M. Stolte, S. Herbst. M. Hecht, S. Lochbrunner, F. Würthner, F. Fennel