TY - THES A1 - Kaiser, Theo E. T1 - J-Aggregates of Tetraphenoxy-Substituted Perylene Bisimide Dyes T1 - J-Aggregate aus tetraphenoxy-substituierten Perylenbisimid-Farbstoffen N2 - 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 Wasserstoffbrücken und Pi-Pi-Wechselwirkungen zu begünstigen, 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 herrühren, sind vielversprechend für die Anwendung in optoelektronischen Bauteilen und für die Photovoltaik. N2 - In conclusion, the present thesis demonstrates that the highly desired J-type aggregation of functional perylene bisimide chromophores can be achieved by proper design of monomeric building blocks that direct self-assemble by mutual effects of hydrogen bonding and pi-pi interaction, and on the other hand, are prevented to assemble in columnar stacks owing to their twisted pi-conjugated core and sterically demanding substituents. Furthermore, the self-assembly studies gave new insights into the dynamic aggregation process of low-dimensional extended assemblies with strongly excitonically coupled chromophores. The relationship between commonly known cyanine dye aggregates like that of THIATS and that of the present PBI 1a was investigated by absorption and fluorescence spectroscopy at low temperatures down to 5 K. The formerly unprecedented functional properties of PBI aggregates that are expressed in J-type excitonic coupling hold promise for application in optoelectronic and photovoltaic devices. KW - Perylenbisdicarboximide KW - Synthetischer Farbstoff KW - Scheibe-Aggregat KW - Cyaninfarbstoff KW - supramolekular KW - J-Aggregat KW - Wasserstoffbrücken KW - Perylenbisimid KW - Aggregation KW - Farbstoff KW - supramolecular KW - J-aggregate KW - H-bonds KW - perylene bisimide Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-43544 ER - TY - THES A1 - Li, Xueqing T1 - Hydrogen Bond-directed Self-assembly of Perylene Bisimide Organogelators N2 - Perylene bisimide (PBI) dyes are a widely used class of industrial pigments, and currently have gained significant importance for organic-based electronic and optical devices. Structural modification at the PBI core results in changes of the optical and electronic properties, which enable tailored functions. Moreover, the aggregation behavior of PBIs is alterable and controllable to achieve new materials, among which organogels are of particular interest because of their potential for applications as supramolecular soft materials. In this work, new PBI-based organic gelators were designed, synthesized, and characterized, and the aggregation behaviors under different conditions were intensively studied by various spectroscopic and microscopic methods. In chapter 2, a brief overview is given on the structural and functional features of organogel systems. The definition, formation and reversibility of organogels are introduced. Some examples on dye based organogel are selected, among which PBI-based organogelators reported so far are especially emphasized. Some basic knowledges of supramolecular chirality are also overviewed such as characterization, amplification, and symmetry breaking of the chiral aggregates. According to our former experiences, PBIs tend to form aggregates because the planer aromatic cores interact with one another by pi-pi interaction. In chapter 3, a new PBI molecule is introduced which possesses amide groups between the conjugated core and periphery alkyl chains. It is found that well oriented aggregates are formed by hydrogen bonding and the pi-pi interaction of the cores. These interactions enable the aggregates to grow in one-dimension forming very long fibers, and these fibers further intercross to 3D network structures, e.g., organogels. In comparison to the very few PBI-based gelators reported before, one advantage of this gelator is that, it is more versatile and can gelate a wide range of organic solvents. Moreover, the well-organized fibers that are composed of extended π-stacks provide efficient pathways for n-type charge carriers. Interestingly, AFM studies reveal that the PBI molecules form well-defined helical fibers in toluene. Both left-handed (M) and right-handed (P) helicities can be observed without any preference for one handedness because the building block is intrinsically achiral. In chapter 4, we tried to influence the M/P enantiomeric ratio by applying external forces. For example, we utilized chiral solvents to generate chiral aggregates with a preferential handedness. AFM analysis of the helices showed that a enantiomeric ratio of about 60: 40 can be achieved by aggregation in chiral solvents R- or S-limonene. Moreover, the long aggregated fibres can align at macroscopic level in vortex flows upon rotary stirring In chapter 5, bulky tetra-phenoxy groups are introduced in the bay area of the PBI gelator. The conjugated core of the new molecule is now distorted because of the steric hindrance. UV/Vis studies reveal a J-type aggregation in apolar solvents like MCH due to intermolecular pi-pi-stacking and hydrogen-bonding interactions. Microscopic studies reveal formation of columnar aggregates in apolar solvent MCH, thus this molecule lacks the ability to form gels in this solvent, but form highly fluorescent lyotropic mesophases at higher concentration. On the other hand, in polar solvents like acetone and dioxane, participation of the solvent molecules in hydrogen bonding significantly reduced the aggregation propensity but enforced the gel formation. The outstanding fluorescence properties of the dye in both J-aggregated viscous lyotropic mesophases and bulk gel phases suggest very promising applications in photonics, photovoltaics, security printing, or as fluorescent sensors. In chapter 6, we did some studies on combining PBI molecules with inorganic gold nanorods. Gold nanorods were synthesized photochemically. By virtue of the thioacetate functionalized PBIs, the rods were connected end to end to form gold nanochains, which were characterized by absorption spectra and TEM measurement. Such chromophore-nanorod hybrids might be applied to guide electromagnetic radiation based on optical antenna technology. KW - Perylenderivate KW - Selbstorganisation KW - Wasserstoffbrückenbindung KW - Gelieren KW - Supramolekulare Struktur KW - organogelator KW - perylene bisimide KW - self-assembly Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-43727 ER -