@phdthesis{Voelker2014,
  author    = {V{\"o}lker, Sebastian},
  title     = {Synthesis, Spectroscopic and Electrochemical Properties of Squaraine Polymers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-101638},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {In this work the synthesis, the spectroscopic and electrochemical investigation as well as some applications of a broad diversity of indolenine squaraine dyes were presented. This diversity was based on two parent squaraine dyes, one standard trans-configured compound (M1) and one in which one central oxygen atom was replaced by a dicyanomethylene moiety (M2), which increased the acceptor strength and induced a cis-configuration. The variety of synthesised dyes included functionalised squaraine monomers, donor- and acceptor-substituted monomeric model squaraines, donor- and acceptor-squaraine copolymers, pure squaraine homopolymers, a squaraine-squaraine copolymer, as well as some conjugated cyclic oligomers. In order to be able to synthesise all these different kinds of dyes, several bromine and boronic ester derivatives were synthesised, which enabled the use of the Suzuki cross coupling reaction, to generate model dyes and copolymers. In addition, the bromine derivatives were used to carry out the Yamamoto homocoupling reaction to the respective homopolymers and macrocycles. The absorption maximum of unsubstituted reference dye M1 was found at ~ 15500 cm-1, while that of M2 was red-shifted to ~ 14300 cm-1 due to the increased acceptor strength of the central unit. The extinction coefficients were in the order of ~ 300000 M-1 cm-1 and ~ 200000 M-1 cm-1, respectively. It was found that the implementation of functional groups (M3-M9), additional electron donors (M10-M19) or acceptors (M20-M22) at the periphery lead to bathochromic shifts of the absorption depending on the strength of either - and/or -donating properties of the substituents. For the bis- and triarylamine substituted dyes M10-M13 and the dibrominated dyes M5 and M7 the electronic structure of the mono- and diradical (di)cations was explored using the interplay of cyclic voltammetry, spectroelectrochemistry, and DFT calculations. It was demonstrated that the monoradical cations still show a cyanine-like character and are delocalised Robin-Day class III species due to the low redox potential of the squaraine bridge between the additional amine redox centres. To the best of my knowledge, this made M13+∙, with an N-N-distance of 26 bonds between the additional redox centres to the longest bis(triarylamine) radical cation that is completely delocalised. For the diradical dications, the situation was of larger complexity. The computed most stable energetic state of the dianisylamine-substituted dyes turned out to be a broken-symmetry state with almost equal contributions of an open-shell singlet and triplet state. In addition, it was shown that the HOMO-1→HOMO transition dominated the absorption spectra of the diradical dications where the trans-/cis-configuration of the squaraines had a direct impact due to symmetry reasons. Based on the donor-squaraine model compounds M10-M19, a series of donor-squaraine copolymers was synthesised (P7-P12) in order to further red shift and broaden the low energy absorption band. However, these effects were only of marginal extent. Both the optical and the electrochemical derived band gaps were barely lowered compared to the respective monomeric model dyes. This was assigned to an increased squaraine-squaraine distance and resulting lower exciton coupling between the squaraine chromophores due to the bridging units. In addition, according to semiempirical calculations the bridges were twisted out of the squaraine plane what reduced conjugational effects between the chromophores. To sum up, the idea to insert additional electron rich bridging units in order to create copolymers with broad and red-shifted absorption did not fully work out for the presented systems. The addition of strong electron accepting NDI units at the periphery resulted in M21, the most unique monomeric model squaraine in this work. The common picture of a sharp low energy squaraine absorption completely altered due to the addition of the NDIs and a rather broad and solvent dependent low energy absorption was found. Spectroelectrochemical experiments and semiempirical calculations showed that this band is a superposition of the common squaraine HOMO→LUMO transition and a partial squaraine→NDI charge transfer transition. The latter was lost upon oxidation of the squaraine and the absorption spectrum of the monocation of M21 was found to be nearly a 1:1 image of a pure squaraine monocation. Both the monomeric model M21 and the respective copolymer P13 showed low electrochemically obtained band gaps of 1.05-1.20 eV, which were the lowest of all squaraines in this work. For both dyes, transient absorption measurements in the fs-time regime revealed the ultrafast formation of a CS state via an intermediate CT state within a few ps. Besides, charge recombination to the ground state also occured within a few ps. In the polymer, there was barely any further energy or charge transfer within the excited state lifetime and therefore the CS state was confined on adjacent squaraine-NDI pairs and did not further travel along the polymer strand. The Ni-mediated Yamamoto homocoupling reaction was applied for the synthesis of the homopolymers (P1-P5). In contrast to the donor-squaraine copolymers, those polymers revealed strongly red-shifted and broad absorption in the red to NIR region in addition to a sharp fluorescence. These features could be explained to originate mainly from the exciton coupling of localised excited states and the presence of different superstructures in solution. For the polymers P1 and P2, an elongated J-type polymer chain caused the strong lowest energy absorption band whereas a zig-zag type arrangement of the single chromophores lead to transitions into both low and high energy excited states of the excitonic manifold. For the polymers P3 and P4, several polymer fractions of different size were investigated. Here, also an elongated chain with J-type character induced the lowest energy absorption band whereas a helical H-type arrangement caused transitions to higher energies of the excitonic manifold. The fractions to which these structures were formed depended on the chain length and the solvent. In thin film measurements, it was shown that the initially in solution formed superstructures were partly retained in the thin film but could be altered by annealing procedures. A control of the superstructures should enable the controlled tuning of the optical properties. Despite the strong interaction of the chromophores in the excited state, the redox potentials of the homopolymers barely differed to those of the respective reference dyes, indicating negligible electronic interaction in the ground state. In addition squaraine-squaraine copolymer P6, consisting of alternating parent dyes M1 and M2, was synthesised. Likewise to the homopolymers, a broad and red-shifted absorption was observed. This was explained by exciton coupling theory, which was extended to also suit alternating copolymers. In toluene, an extraordinary narrow and intense lowest energy absorption band was observed. This exchange narrowing might be a result of a highly ordered J-type structure of the polymer especially in this solvent because it was not found in others. The features of the polymer may be compared to typical J-aggregates formed from monomeric cyanine molecules for example and the polymer used as model for excitonic interactions in an alternating copolymer. Transient absorption measurements revealed a strong energy dependence of the decay traces of the copolymer, most strikingly at early decay times. This was assigned to the occurrence of multiple excitations of one polymer strand (due to the large extinction coefficients of the polymer) and resulting exciton-exciton annihilation. Due to the large exciton diffusion constants that were estimated, the static exciton-exciton annihilation was the rate limiting process of the decay, in contrast to other conjugated polymers, where in thin film measurements the decay was diffusion controlled. To sum up, for the polymers consisting of exclusively squaraine chromophores, it was shown that the exciton coupling of single chromophores with strong transition dipole moments was a fruitful way to tune the absorption spectra. As a side product of some of the polycondensation reactions, unprecedented cyclic conjugated oligomers such as the triarylamine-bridged dimer Dim1, the cyclic homotrimers Tri1-Tri3, and the tetramer Tet1 were obtained by recycling GPC in low yields. Especially the cyclic trimers showed unusual absorption and even more extraordinary fluorescence properties. They showed multiple fluorescence bands in the NIR that covered a range from ~ 8000-12500 cm-1 (800-1250 nm). First hints from theoretical calculations indicated that the trimer was not fully planar but comprised a mixture of both planar and bent single squaraine chromophores. However, final results of the calculations were still missing at the time of writing. In the last part of this work, the application of some monomeric and polymeric squaraines in binary and ternary bulk heterojunction solar cells was demonstrated. Also the utilisation as a dopant in a polymer matrix in an OLED device was shown. The homopolymers P1-P4 were tested in the binary BHJ solar cells revealing poor performances and especially very low short circuit currents. The utilisation of the polymers P3 and P4 that carried the dicyanomethylene group resulted in higher open circuit voltages due to the lower LUMO energy levels but still an overall poor performance. Neither for the different alkyl chains nor for the size of the polymers was a trend observed. In the ternary BHJ solar cells, small amounts of either monomer M14 or polymers P1A, P4-1 or P13 were added to a P3HT/PCBM system in order to generate an additional pathway for charge or energy transfer that should result in a better device performance. However, for none of the tested squaraines, improved solar cells could be built. In similarity to the binary solar cells, the short circuit currents were lower compared to a P3HT/PCBM reference device. These low short circuit currents indicated that the morphology of the squaraine dyes was the major limitation in those devices. It is possible that the dimethyl groups at the indolenine hindered a favoured alignment of the compounds that would allow decent charge transport. In the squaraine doped OLED the squaraine M6 worked rather well as an NIR emitter. Already at low dye loads the fluorescence of the host polymer SY-PPV was completely quenchend and emission from the squaraine was observed. For electroluminescence measurements, a lower dye load (0.5 wt.\%) compared to the photoluminescence measurements was sufficient, indicating that apart from FRET additional quenching mechanisms were at work in the electrically driven devices such as charge carrier dynamics.},
  subject      = {Squaraine},
  language  = {en}
}
@phdthesis{Grzeszkiewicz2014,
  author    = {Grzeszkiewicz, Charlotte},
  title     = {Synthese, Charakterisierung und Aggregationsstudien von amphiphilen Perylen- und Zinkchlorinfarbstoffen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-98777},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Der erste Teil dieser Arbeit besch{\"a}ftigte sich mit dem Ziel, amphiphile Oligoethylenglykol-funktionalisierte Perylenmonoimiddiester und Dicarbons{\"a}ure- bzw. Amino-funktionalisierte Perylenbisimide zu synthetisieren. Weiterhin wurden die optischen Eigenschaften in L{\"o}sung und das Aggregationsverhalten der Ester-, Dicarbons{\"a}ure- und der Amino-funktionalisierten Perylenfarbstoffe untersucht. (...) Der zweite Teil dieser Arbeit widmete sich dem Ziel, die amphiphilen Oligoethylenglykol-funktionalisierten Zinkchlorine, 31-Hydroxy-Zinkchlorin (ZnChl-OH) und 31-Methoxy-Zinkchlorin (ZnChl-OCH3), herzustellen und desweiteren deren Aggregationsverhalten in w{\"a}ssriger L{\"o}sung vergleichend zu studieren, um den Einfluss der L{\"o}sungsmittel und des Substituenten in 31-Position auf die thermodynamischen und kinetischen Eigenschaften und auf die Aggregatstruktur zu bestimmen. (...)},
  subject      = {Amphiphile Verbindungen},
  language  = {de}
}
@phdthesis{Schlosser2012,
  author    = {Schlosser, Felix},
  title     = {Synthese und Charakterisierung kovalent gebundener Perylenbisimid-Makrozyklen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-71811},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Eine Reihe von Acetylen-verkn{\"u}pften Perylenbisimid(PBI)-Makrozyklen mit unterschiedlicher Ringgr{\"o}ße wurde durch Palladium-katalysierte Homokupplung synthetisiert und mit Hilfe von Recycling-GPC getrennt. Diese Makrozyklen wurden durch NMR-Spektroskopie und Massenspektrometrie charakterisiert und weiterhin die photophysikalischen Eigenschaften durch UV/Vis-Absorptions- und Fluoreszenzemissions-Messungen untersucht. Die Selbstorganisation dieser PBI-Makrozyklen zu hochgeordneten Nanostrukturen auf HOPG-Oberfl{\"a}chen wurde mittels Rasterkraftmikroskopie untersucht.},
  subject      = {Makrocyclische Verbindungen},
  language  = {de}
}
@phdthesis{Wolf2021,
  author    = {Wolf, Natalia},
  title     = {Synthese multifunktionaler Farbstoffe und Linker zur Visualisierung biologischer Strukturen},
  doi       = {10.25972/OPUS-20531},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-205312},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Durch stetige Entwicklung der Mikroskopiemethoden in den letzten Jahrzehnten ist es nun m{\"o}glich Strukturen und Abl{\"a}ufe in biologischen Systemen detaillierter darzustellen als mit der von Abbe entdeckten maximalen Aufl{\"o}sungsgrenze. Oft werden dabei Fluoreszenzmarker benutzt, welche die unsichtbare Welt der Mikrobiologie und deren biochemische Prozesse illuminieren. Diese werden entweder durch Expression, wie z.B. das gr{\"u}n fluoreszierende Protein (GFP), in das zu untersuchende Objekt eingebracht oder durch klassische Markierungsmethoden mithilfe von fluoreszierenden Immunkonjugaten installiert. Jedoch gewinnt eine alternative Strategie, die von der interdisziplin{\"a}ren Zusammenarbeit zwischen Chemikern, Physikern und Biologen profitiert, immer mehr an Bedeutung - die bioorthogonale Click-Chemie. Sie erm{\"o}glicht eine effiziente Fluoreszenzmarkierung der biologischen Strukturen unter minimalem Eingriff in die Abl{\"a}ufe der Zelle. Dazu m{\"u}ssen allerdings sowohl Farbstoffe als auch die biologisch aktiven Substanzen chemisch modifiziert werden, da nur dadurch die Bioorthogonalit{\"a}t gew{\"a}hrleistet werden kann. Mittlerweile existiert eine breite Palette an fluoreszierenden Farbstoffen, die das komplette sichtbare Spektrum abdecken und sich f{\"u}r diverse Mikroskopiemethoden eignen. Allerdings gibt es zwei Farbstoffklassen, die sich aus der gesamten F{\"u}lle abheben und sich f{\"u}r hochaufl{\"o}sende bildgebende Experimente auf Einzelmolek{\"u}lebene eignen. Zum einen ist es die Farbstofffamilie der Cyanine und insbesondere der wasserl{\"o}slichen Pentamethincyanine, die reversibel und kontrolliert zum Photoschalten animiert werden k{\"o}nnen und in der stochastisch optischen Rekonstruktionsmikroskopie Anwendung finden. Zum anderen ist es die Gruppe, der Rhodamine und Fluoresceine, die zu Xanthenfarbstoffen geh{\"o}ren und sich durch gute photophysikalische Eigenschaften auszeichnen. Trotz der Beliebtheit stellt ihre Darstellung immer noch eine Herausforderung dar und limitiert deren Einsatz. Deshalb war es notwendig im Rahmen der vorliegenden Arbeit M{\"o}glichkeiten zur Syntheseoptimierung beider Farbstoffklassen zu finden, damit diese im Folgenden weiterentwickelt und an die biologische Fragestellung angepasst werden k{\"o}nnen. Die Arbeit unterteilt sich deshalb in Relation an die oben genannten Farbstoffklassen in zwei Bereiche. Im ersten Teil wurden Projekte basierend auf den wasserl{\"o}slichen Pentamethincyaninen behandelt. Im zweiten Teil besch{\"a}ftigte sich die Arbeit mit Projekten, die auf Xanthen-Farbstoffen aufbauen.},
  subject      = {Farbstoff},
  language  = {de}
}
@phdthesis{Lohr2008,
  author    = {Lohr, Andreas},
  title     = {Self-Assembly of Merocyanines : Thermodynamic and Kinetic Insights into the Formation of Well-Defined Dye Aggregates},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28964},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {The present thesis demonstrates the potential of dipolar aggregation of merocyanine dyes as novel directional and specific supramolecular binding motif for the creation of more elaborate supramolecular architectures beyond simple dimers. Furthermore, the self-assembly studies into bis(merocyanine) nanorods gave new insights into the kinetics of morphogenesis in supramolecular aggregates.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{Huber2007,
  author    = {Huber, Valerie},
  title     = {Selbstorganisation von semisynthetischen Zinkchlorinen zu biomimetischen Lichtsammelsystemen und definierten Nanostrukturen},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-24517},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2007},
  abstract  = {Diese Arbeit besch{\"a}ftigt sich mit der Selbstorganisation von Zinkchlorin-Farbstoffen, welche sich strukturell von Chlorophyllen ableiten. Im Gegensatz zu allen anderen bakteriellen und pflanzlichen Lichtsammelpigmenten ist es den Bakteriochlorophyllen c, d und e der Lichtsammelsysteme gr{\"u}ner phototropher Bakterien m{\"o}glich, allein durch nichtkovalente Wechselwirkungen zwischen den Farbstoff-Molek{\"u}len, ohne die Beteiligung von Proteinen, r{\"o}hrenf{\"o}rmige Antennensysteme auszubilden, welche die am dichtest gepackten und effizientesten Lichtsammelsysteme in der Natur darstellen. Um einen Betrag zur Aufkl{\"a}rung dieser biologisch wichtigen Aggregate zu leisten, wurden im ersten Teil dieser Arbeit Zinkchlorine als Modellverbindungen f{\"u}r BChl c hergestellt. Mit den neu synthetisierten Zinkchlorinen ist es gelungen, Modellsysteme der nat{\"u}rlichen BChl-Selbstorganisate herzustellen, welche sich im Gegensatz zu den bisher in der Literatur beschriebenen Zinkchlorin-Aggregaten durch eine gute und dauerhafte L{\"o}slichkeit auszeichnen. Diese Eigenschaft erlaubte es sowohl spektroskopische als auch mikroskopische Untersuchungen zur Aufkl{\"a}rung der Aggregatstruktur durchzuf{\"u}hren. Durch Rasterkraftmikroskopie an den Zinkchlorin Aggregaten konnte erstmals ein mikroskopischer Beweis der stabf{\"o}rmigen Struktur von Aggregaten dieser Substanzklasse erhalten werden. Der zweite Teil dieser Arbeit besch{\"a}ftigt sich mit Zinkchlorinen, denen aufgrund einer methylierten 31-Hydroxy-Gruppe die F{\"a}higkeit zur R{\"o}hrenbildung fehlt, die aber durch Koordinationsbindungen und p-p-Wechselwirkungen weiterhin Stapel bilden k{\"o}nnen. Temperaturabh{\"a}ngige UV/Vis- und CD-spektroskopische Studien offenbarten die reversible Bildung von l{\"o}slichen, chiralen Zinkchlorin-Stapelaggregaten. Rasterkraft- und rastertunnelmikroskopische Untersuchungen zeigen die Bildung von zwei Typen p-gestapelter Aggregate auf hoch geordnetem Graphit.},
  subject      = {Farbstoff},
  language  = {de}
}
@phdthesis{Schulze2016,
  author    = {Schulze, Marcus},
  title     = {Ruthenium Complexes as Water Oxidation Catalysts and Photosensitizers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142454},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2016},
  abstract  = {In der vorliegenden Arbeit werden Aspekte der photokatalytischen Wasseroxidationsreaktion behandelt. Der erste Themenschwerpunkt der Dissertation besch{\"a}ftigt sich mit einem supramolekularen Makrozyklus, der drei Rutheniummetallzentren enth{\"a}lt. Dieser neuartige Katalysator zeigt eine sehr hohe katalytische Aktivit{\"a}t und gew{\"a}hrt neue Einblicke in den Mechanismus der Wasseroxidationsreaktion. Des Weiteren wird auf die mit Licht interagierenden Komponenten der photokatalytischen Wasseroxidation eingegangen. Hierbei haben sich azabenz-anellierte Perylenderivate als vielseitige Farbstoffklasse herausgestellt. Die Kombination dieser Farbstoffe mit Metallkomplexen liefert metallorganische Verbindungen, die als Photosensibilisatoren eingesetzt werden k{\"o}nnen.},
  subject      = {Farbstoff},
  language  = {en}
}
@phdthesis{Shao2012,
  author    = {Shao, Changzhun},
  title     = {Programming Self-assembly: Formation of Discrete Perylene Bisimide Aggregates},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69298},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {The objective of this thesis focuses on the development of strategies for precise control of perylene bisimide (PBI) self-assembly and the in-depth elucidation of structural and optical features of discrete PBI aggregates by means of NMR and UV/Vis spectroscopy. The strategy for discrete dimer formation of PBIs is based on delicate steric control that distinguishes the two facets of the central perylene surface. The strategy applied in this thesis for accessing discrete PBI quadruple and further oligomeric stacks relies on backbone-directed PBI self-assembly. For this purpose, two tweezer-like PBI dyads bearing the respective rigid backbones, diphenylacetylene (DPA) and diphenylbutydiyne (DPB), were synthesized. The distinct aggregation behavior of these structurally similar PBI dyads can be ascribed to the intramolecular distance between the two PBI chromophores imparted by the DPA and DPB spacers.},
  subject      = {Farbstoff},
  language  = {en}
}
@phdthesis{Mahl2023,
  author    = {Mahl, Magnus},
  title     = {Polycyclic Aromatic Dicarboximides as NIR Chromophores, Solid-State Emitters and Supramolecular Host Platforms},
  doi       = {10.25972/OPUS-23462},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-234623},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {The present thesis introduce different synthetic strategies towards a variety of polycyclic aromatic dicarboximides (PADIs) with highly interesting and diverse properties. This included tetrachlorinated, tetraaryloxy- and tetraaryl-substituted dicarboximides, fused acceptor‒donor(‒acceptor) structures as well as sterically shielded rylene and nanographene dicarboximides. The properties and thus the disclosure of structure‒property relationships of the resulting dyes were investigated in detail among others with UV‒vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry and single crystal X-ray analysis. For instance, some of the fused and substituted PADIs offer strong absorption of visible and near infrared (NIR) light, NIR emission and low-lying LUMO levels. On the contrary, intriguing optical features in the solid-state characterize the rylene dicarboximides with their bulky N-substituents, while the devised sterically enwrapped nanographene host offered remarkable complexation capabilities in solution.},
  subject      = {Organische Chemie},
  language  = {en}
}
@phdthesis{Chen2006,
  author    = {Chen, Zhijian},
  title     = {pi-Stacks Based on Self-Assembled Perylene Bisimides : Structural, Optical, and Electronic Properties},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-19940},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {As a traditional industrial pigment, perylene bisimide (PBI) dyes have found wide-spread applications. In addition, PBI dyes have been considered as versatile and promising functional materials for organic-based electronic and optic devices, such as transistors and solar cells. For these novel demands, the control of self-organization of this type of dye and the investigation of the relationship between the supramolecular structure and the relevant optical and electronic properties is of great importance. The objective of this thesis focuses on gaining a better understanding of structural and functional properties of pi-stacks based on self-assembling PBIs. Studies include the synthesis and characterization of new functional PBI dyes, their aggregation in solution, in liquid crystalline state and on surfaces, and their fluorescence and charge transport properties. An overview of the formation, thermodynamics and structures of pi-stacks of functional pi- conjugated molecules in solution and in liquid crystalline phases is given in Chapter 2. Chapters 3 and 4 deal with the pi-pi aggregates of new, highly fluorescent PBIs without core-substituents. In Chapter 3, the self-assembly of a PBI with tridodecylphenyl substituents at imide N atoms both in solution and condensed phase has been studied in great detail. In condensed state, the dye exhibits a hexagonal columnar liquid crystalline (LC) phase as confirmed by DSC, OPM and X-ray diffraction analysis. The columnar stacking of this dye has been further confirmed by atomic force microscopy (AFM) where single columns could be well resolved The charge transport properties this dye have been investigated by pulse radiolysis-time resolved microwave conductivity (PR-TRMC) measurements. To shed more light on the nature of the pi-pi interaction of the unsubstituted PBIs, solvent depend aggregation properties have been investigated in Chapter 4. The studies are further extended from core-unsubstituted PBIs to core-substituted ones (Chapter 5 and 6). In Chapter 5, a series of highly soluble and fluorescent core-twisted PBIs that bear the same trialkylphenyl groups at the imide positions but different bay-substituents and were synthesized. These compounds are characterized by distortions of the perylene planes with dihedral angles in the range of 15-37° according to crystallographic data and molecular modeling studies. In contrast to the extended oligomeric aggregates formed for planar unsubstituted PBIs, this family of dyes formed discrete pi-pi-stacked dimers in apolar methylcyclohexane as concentration-dependent UV/Vis measurements and VPO analysis revealed. The Gibbs free energy of dimerization can be correlated with the twist angles of the dyes linearly. In condensed state, several of these PBIs form luminescent rectangular or hexagonal columnar liquid crystalline phases with low isotropization temperatures. The core-twisting effect on semiconducting properties has been examined in Chapter 6. In this chapter, a comparative study of the electrochemical and the charge transport properties of a series of non-substituted and chlorine-functionalized PBIs was performed. While Chapters 3-6 focus on one-component dye systems, Chapter 7 explored the possibility of a supramolecular engineering of co-aggregates formed by hydrogen-bonded 2:1 and 1:1 complex of oligo(p-phenylene vinylene)s (OPVs) and PBIs. Covalently linked donor-acceptor dye arrays have been prepared for comparison. Concentration and temperature-dependent UV/Vis spectroscopy revealed all hydrogen-bonded and covalent systems form well-ordered J-type aggregates in methylcyclohexane. With these hydrogen-bonded OPV-PBI complexes, fibers containing p-type and n-type molecules can be prepared on the nano-scale (1-20 nm). For the 2:1 OPV-PBI hydrogenbonded arrays hierarchically assembled chiral superstructures consisting of left-handed helical pi-pi co-aggregates (CD spectroscopy) of the two dyes that further assemble into right-handed nanometer-scale supercoils in the solid state (AFM study) have been observed. All of these well-defined OPV-PBI assemblies presented here exhibit photoinduced electron transfer on sub-ps timescale, while the electron recombination differs for different systems.Thus, it was suggested that such assemblies of p- and n-type semiconductors might serve as valuable nanoscopic functional units for organic electronics.},
  subject      = {Perylenderivate},
  language  = {en}
}