@phdthesis{Dehm2010,
  author    = {Dehm, Volker Christoph},
  title     = {Synthesis and Characterization of an Oligo(Phenylene Ethynylene)-Based Perylene Bisimide Foldamer},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53211},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {The present work is part of the currently only rudimentary understanding of the structure-property relationships in the self-assembly of pi-conjugated organic molecules. Such structures may reveal favorable photophysical and semiconducting properties due to the weak non-covalent pi-pi interactions between the monomer units. The specific mutual orientation of the dyes is known to evoke individual functional properties for the condensed matter, however, the related electronic processes are still not well-understood and further enhancements of functional properties are seldom triggered by rational design. The pi-pi self-assembly structures of perylene bisimide (PBI) dyes are promising, versatile materials for organic electronic devices and have been elected for this thesis as an archetype aggregate system to investigate the dye-dye interactions in more detail. In cooperation with experts in the field of spectroscopy and theory the development of reliable routines towards a better understanding of the origins of the functional properties may be feasible, and, on a longer time-line, such knowledge may enable optimization of functional organic materials. Having designed such structures entailed the challenge of developing feasible synthesis strategies, and to actually generate the targeted molecules by synthesis. Several synthesis approaches were conducted until finally a perylene bisimide foldamer was obtained based on a Sonogashira co-polymerization reaction. After purification and enrichment of the larger-sized species by means of semi-preparative gel permeation chromatography (GPC) the average size of an octamer (8500 Da) species was determined by analytical GPC. The low polydispersity index (PD) of 1.1 is indicative of a sharp size distribution of the oligomers. This average size was confirmed by performing diffusion ordered NMR spectroscopy (DOSY). Furthermore, MALDI-TOF mass analysis substantiated the structural integrity of the co-polymerization product. Solvent-dependent UV/vis spectroscopic investigations demonstrated that intramolecular PBI  aggregates are reversibly formed, indicating that this oligomer is able to fold and unfold in the intended manner upon changing external conditions. In the unfolded states, the PBI moieties are closely arranged due to the short OPE bridges (< 2.4 nm), which is expressed by an exciton coupling interaction of the dyes and therefore the characteristic monomer absorption pattern of the PBI chromophore cannot be obtained in the unfolded states. More interestingly, the folded state revealed a pronounced aggregate spectrum of the PBIs, however, striking differences in the shape of the absorption spectrum compared to our previously investigated PBI self-assembly were obtained.},
  subject      = {Perylenbisdicarboximide <Perylen-3},
  language  = {en}
}
@phdthesis{Kaiser2009,
  author    = {Kaiser, Theo E.},
  title     = {J-Aggregates of Tetraphenoxy-Substituted Perylene Bisimide Dyes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-43544},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {In dieser Doktorarbeit wurde gezeigt, dass die sehr begehrte J-Aggregation funktionaler Perylenbisimid-Chromophore durch geeignetes Design der monomeren Bausteine erreicht werden kann. Hierzu war einerseits die Selbstanordnung durch ein Zusammenwirken von Wasserstoffbr{\"u}cken und Pi-Pi-Wechselwirkungen zu beg{\"u}nstigen, und andererseits eine Anordnung in kolumnaren Stapeln zu verhindern, was durch Kern-Verdrillung mittels sterisch anspruchsvollen Substituenten gelang. Desweiteren gaben Selbstanordnungsstudien neue Einblicke in den dynamischen Aggregationsprozess niedrigdimensionaler langgestreckter Aggregate mit stark exzitonisch gekoppelten Chromophoren. Die Beziehung zwischen bekannten Cyaninfarbstoffen, wie der von THIATS mit dem vorliegenden PBI 1a wurde durch Absorptions- und Fluoreszenzspektroskopie bei Tieftemperaturen von 5 K bis Raumtemperatur untersucht. Die vormals beispiellosen funktionalen Eigenschaften der PBI-Aggregate, welche aus der J-artigen exzitonischen Kopplung herr{\"u}hren, sind vielversprechend f{\"u}r die Anwendung in optoelektronischen Bauteilen und f{\"u}r die Photovoltaik.},
  subject      = {Perylenbisdicarboximide <Perylen-3},
  language  = {en}
}