@phdthesis{PeethambaranNairSyamala2021,
  author    = {Peethambaran Nair Syamala, Pradeep},
  title     = {Bolaamphiphilic Rylene Bisimides: Thermodynamics of Self-assembly and Stimuli-responsive Properties in Water},
  doi       = {10.25972/OPUS-21342},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213424},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The present thesis demonstrates how different thermodynamic aspects of self-assembly and stimuli-responsive properties in water can be encoded on the structure of π-amphiphiles, consisting of perylene or naphthalene bisimide cores. Initially, quantitative thermodynamic insights into the entropically-driven self-assembly was studied for a series of naphthalene bisimides with UV/Vis and ITC measurements, which demonstrated that their thermodynamic profile of aggregation is heavily influenced by the OEG side chains. Subsequently, a control over the bifurcated thermal response of entropically driven and commonly observed enthalpically driven self-assembly was achieved by the modulation of glycol chain orientation. Finally, Lower Critical Solution Temperature (LCST) phenomenon observed for these dyes was investigated as a precise control of this behavior is quintessential for self-assembly studies as well as to generate 'smart' materials. It could be shown that the onset of phase separation for these molecules can be encoded in their imide substituents, and they are primarily determined by the supramolecular packing, rather than the hydrophobicity of individual monomers.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{Kirchner2019,
  author    = {Kirchner, Eva},
  title     = {Discrete Supramolecular Stacks by Self-Assembly and Folding of Bis(merocyanine) Dyes},
  doi       = {10.25972/OPUS-15941},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159419},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {The present thesis describes the development of a strategy to create discrete finite-sized supramolecular stacks of merocyanine dyes. Thus, bichromophoric stacks of two identical or different chromophores could be realized by folding of bis(merocyanine) dyes and their optical properties were discussed in terms of exciton theory. Quantum chemical calculations revealed strong exciton coupling between the chromophores within the homo- and hetero-π-stacks and the increase of the J-band of the hetero-dimers with increasing energy difference between the excited states of the chromophores could be attributed not only to the different magnitudes of transition dipole moments of the chromophores but also to the increased localization of the excitation in the respective exciton state. Furthermore, careful selection of the length of the spacer unit that defines the interplanar distance between the tethered chromophores directed the self-assembly of the respective bis(merocyanines) into dimers, trimers and tetramers comprising large, structurally precise π-stacks of four, six or eight merocyanine chromophores. It could be demonstrated that the structure of such large supramolecular architectures can be adequately elucidated by commonly accessible analysis tools, in particular NMR techniques in combination with UV/vis measurements and mass spectrometry. Supported by TDDFT calculations, the absorption spectra of the herein investigated aggregates could be explained and a relationship between the absorption properties and the number of stacking chromophores could be established based on exciton theory.},
  subject      = {Merocyanine},
  language  = {en}
}
@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{Schmidt2011,
  author    = {Schmidt, Ralf},
  title     = {Hamilton-Receptor-Mediated Self-Assembly of Merocyanine Dyes into Supramolecular Polymers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56265},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Die Selbstorganisation von Merocyaninfarbstoffen zu supramolekularen Polymeren wurde untersucht. Dabei konnte die Anordnung der hoch dipolaren Farbstoffe durch die Verwendung von verschiedenen Kombinationen von Wasserstoffbr{\"u}ckenbindungsmotiven und dipolarer Aggregation der Chromophore gesteuert.},
  subject      = {Selbstorganisation},
  language  = {en}
}
@phdthesis{Sengupta2011,
  author    = {Sengupta, Sanchita},
  title     = {Bio-inspired Zinc Chlorin Dye Assemblies for Supramolecular Electronics},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66935},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Chlorophylls are the most important pigments owing to their involvement in photosynthesis. They perform multiple functions that arise due to their optical and redox as well as packing properties. Semisynthetic zinc chlorins investigated in this thesis are the counterparts for the natural protein-free bacteriochlorophyll (BChl) c assemblies in light-harvesting (LH) systems in bacterial chlorosomes. The major advantage of the zinc chlorin model compounds over the native BChls lies in their facile semisynthetic accessibility from chlorophyll a (Chl a), their higher chemical stability and the possibility to influence their packing by suitable chemical modifications of peripheral side chains. Whilst the favorable excitonic properties and the suitability of ZnChl and natural BChl c dye aggregates for long distance exciton transport are well documented, charge transport properties of aggregates of semisynthetic ZnChls are hitherto unexplored. The present study involves structural elucidations of aggregates of a variety of semisynthetic zinc chlorin derivatives in solution, in solid state and on surfaces by combination of spectroscopic, crystallographic and microscopic techniques, followed by investigation of charge transport properties and conductivities of these aggregates. Chart 1 shows the different ZnChls synthesized in this work that are functionalized with hydroxy or methoxy substituents at 31 position and contain different substituents at the 172-position benzyl ester functional group. The self-assembly of these dyes is strongly dependent upon their chemical structures. While ZnChls 1a, 2a, 3, which are functionalized with 31-hydroxy group bearing dodecyl and oligoethylene glycol side chains form well-soluble rod aggregates, the corresponding 31-methoxy functionalized counterparts 1b, 2b form stacks in solution and on surfaces. These supramolecular polymers have been studied in detail in Chapter 3 by UV/Vis and circular dichroism (CD) spectroscopy and dynamic light scattering (DLS). These studies provided useful insights into the aggregation process of these two types of aggregates. Whereas 31-hydroxy functionalized ZnChl 1a self-assemble into rod aggregates via an isodesmic mechanism, corresponding stack aggregates of ZnChl 1b are formed by a cooperative nucleation-elongation pathway. Detailed electron microscopic studies such as transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) provided unequivocal evidence for hollow tubular nanostructures of water-soluble 31-hydroxy zinc chlorin 3 aggregates for the first time. The measured tube diameter of ~ 5-6 nm of these aggregates is in excellent agreement with electron microscopy data of BChl c rod aggregates in chlorosomes (Chloroflexus aurantiacus, diameter ~ 5-6 nm) and thus complied with the tubular model postulated by Holzwarth and Schaffner... In concord with their highly organized structures, micrometer-scale one dimensionality, robust nature and efficient charge transport capabilities, these self-assembled ZnChl nanotubular, stack and liquid crystalline assemblies are highly promising for supramolecular electronic applications. Research efforts in utilizing these assemblies for (opto)electronic device fabrication, for instance, in organic field effect transistors, should thus be rewarding in the future...},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{SafontSempere2010,
  author    = {Safont Sempere, Marina Montserrat},
  title     = {Chiral self-sorting of atropo-enantiomeric perylene bisimide dyes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55359},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {This thesis included the synthesis of conformationally stable chiral perylene bisimide (PBI) dyes, the study of their optical properties in solution and their chiral self-sorting behaviour in nonpolar solvents in which dimerization via pi-pi-stacking takes place. Furthermore, the influence of PBI core chirality on the properties of these dyes in the condensed state has been also studied. We have demonstrated and quantified the prevalence of chiral self-recognition over self-discrimination in pi-stacking dimerization of PBIs. It has been shown that this self-recognition event is compromised by the increasing flexibility of the structures related to the size of the OEG bridging units. Moreover, the inherent chirality of these PBIs has been proven to strongly influence their condensed state properties, for which large differences between the pure enantiomers and the racemates were revealed, as well as between the different bridged macrocyclic PBIs.},
  subject      = {Farbstoff},
  language  = {en}
}
@phdthesis{Goerl2015,
  author    = {G{\"o}rl, Daniel},
  title     = {Hydrophobe Effekte bolaamphiphiler Rylenbisimide},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123172},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Die Selbstorganisation von amphiphilen Molek{\"u}len z{\"a}hlt zu den am intensivsten bearbeiteten Forschungsgebieten der Supramolekularen Chemie. Die faszinierenden supramolekularen Architekturen der Natur zeigen eindrucksvoll, wie neuartige Funktionen durch das Zusammenspiel wohl-definierter Molek{\"u}lensembles in einer w{\"a}ssrigen Umgebung entstehen. Es ist bekannt, dass der hydrophobe Effekt dabei eine entscheidende Rolle in der Selbstorganisation spielt und somit die Funktion eines Systems wesentlich bestimmt. Obwohl die Komplexit{\"a}t der bekannten Beispiele aus der Natur unerreicht ist, wurden in den letzten Jahren unz{\"a}hlige k{\"u}nstliche supramolekulare Architekturen basierend auf amphiphilen Molek{\"u}len erschaffen, mit vielf{\"a}ltigen Anwendungsm{\"o}glichkeiten an der Schnittstelle von Chemie, Biologie und Physik. Darunter er{\"o}ffnen insbesondere amphiphile π-konjugierte Systeme einen einfachen Zugang zu vielf{\"a}ltigen Strukturen, da im w{\"a}ssrigen Medium starke π-π-Wechselwirkungen als strukturbildendes Element ausgenutzt werden k{\"o}nnen. Vor allem wegen vielversprechender Anwendungsm{\"o}glichkeiten spiegelt sich die Selbstorganisation solcher Systeme in einem hohen Forschungsinteresse wider. Dennoch ist das Wirken des hydrophoben Effekts in der Selbstassemblierung amphiphiler π-konjugierter Molek{\"u}le weitgehend unverstanden. Die vorliegende Arbeit befasste sich daher mit der Frage, welche physikochemischen Grundprinzipien die Bildung von supramolekularen Polymeren basierend auf amphiphilen π-konjugierten Molek{\"u}len in Wasser steuern und wie der hydrophobe Effekt die Funktionalit{\"a}t solcher Strukturen beeinflusst. Bolaamphiphile Perylenbisimide (PBIs) und Naphthalinbisimide (NBIs) erwiesen sich dabei f{\"u}r das Molek{\"u}ldesign als besonders geeignet, weil sie vergleichsweise einfach dargestellt werden k{\"o}nnen, ihre hohe Symmetrie weniger komplexe Assoziationsprozesse begr{\"u}ndet und die Untersuchung ihrer Selbstassemblierung im w{\"a}ssrigen Medium weiterhin einen Vergleich erlaubt, wie sich der hydrophobe Effekt bez{\"u}glich unterschiedlich großen π-Systemen auswirkt. Es konnte gezeigt werden, dass OEG-basierte Rylenbisimide unter bestimmten strukturgeometrischen Voraussetzungen eine entropiegetriebene Aggregation aufweisen, wenn die Freisetzung von Wassermolek{\"u}len aus einer wohl-definierten Hydrath{\"u}lle ausreicht, um den Enthalpiegewinn aus den im w{\"a}ssrigen Medium verst{\"a}rkten Dispersionswechselwirkungen zwischen den π-Fl{\"a}chen zu {\"u}bertreffen. Im vorliegenden Fall wurde dies durch das Pinsel-Strukturmotiv der symmetrisch angebrachten Imidsubstituenten erreicht, f{\"u}r die sich damit einhergehend eine g{\"a}nzlich andere Temperaturabh{\"a}ngigkeit beobachten ließ und somit eine g{\"a}nzlich andere Funktionalit{\"a}t, als man sie aus organischen L{\"o}sungsmitteln kennt. Wasser als L{\"o}sungsmittel f{\"u}hrt also nicht nur zu einer signifikanten Bindungsverst{\"a}rkung, sondern {\"o}ffnet Zugang zu supramolekularen Systemen mit neuartigen Funktionen. Die entropiegetriebene Freisetzung von Wassermolek{\"u}len konnte daher im Rahmen dieser Arbeit ausgenutzt werden, um gleichzeitig die intrinsische Ordnung im π-Stapel von PBIs zu erh{\"o}hen, was anhand eines temperatursensorischen Hydrogels anschaulich demonstriert wurde. Dar{\"u}ber hinaus stellte sich heraus, dass Wasser ein geeignetes L{\"o}sungsmittel zur Darstellung supramolekularer Kompositmaterialien ist. Wie anhand sich instantan bildender Co-Aggregate gezeigt wurde, ist die entropiegetriebene Assemblierung der entscheidende Faktor zur Darstellung von komplexeren supramolekularen Strukturen, die {\"u}berdies einen Schritt hin zu den hochkomplexen multimolekularen Anordnungen der Natur darstellen.},
  subject      = {Selbstorganisation},
  language  = {de}
}
@phdthesis{Rehm2015,
  author    = {Rehm, Stefanie},
  title     = {Spermine-functionalized Perylene Bisimide Dyes: Synthesis and Self-assembly in Water},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123201},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {The main objective of this thesis was the design and synthesis of perylene bisimide dyes with sufficient water-solubility for the construction of self-assembled architectures in aqueous solutions. Beside these tasks another goal of this project was the control over the self-assembly process in terms of aggregate size and helicity, respectively. Within this thesis an appropriate synthesis for spermine-functionalized perylene bisimide dyes was developed and conducted successfully. The characterization of these building blocks and their course of self-assembly were investigated by NMR, UV/Vis and fluorescence spectroscopy as well as by atomic force and transmission electron microscopy. For the better understanding of the experimental results theoretical calculations were performed.},
  subject      = {Perylenderivate},
  language  = {en}
}
@phdthesis{Hecht2021,
  author    = {Hecht, Markus},
  title     = {Liquid-Crystalline Perylene Bisimide and Diketopyrrolopyrrole Assemblies},
  doi       = {10.25972/OPUS-21698},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-216987},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The research presented in this thesis illustrates that self-assembly of organic molecules guided by intermolecular forces is a versatile bottom-up approach towards functional materials. Through the specific design of the monomers, supramolecular architectures with distinct spatial arrangement of the individual building blocks can be realized. Particularly intriguing materials can be achieved when applying the supramolecular approach to molecules forming liquid-crystalline phases as these arrange in ordered, yet mobile structures. Therefore, they exhibit anisotropic properties on a macroscopic level. It is pivotal to precisely control the interchromophoric arrangement as functions originate in the complex structures that are formed upon self-assembly. Consequently, the aim of this thesis was the synthesis and characterization of liquid-crystalline phases with defined supramolecular arrangements as well as the investigation of the structure-property relationship. For this purpose, perylene bisimide and diketopyrrolopyrrole chromophores were used as they constitute ideal building blocks towards functional supramolecular materials due to their thermal stability, lightfastness, as well as excellent optical and electronic features desirable for the application in, e.g., organic electronics.},
  subject      = {Selbstorganisation},
  language  = {en}
}
@phdthesis{Shen2021,
  author    = {Shen, Chia-An},
  title     = {Dicyanomethylene Squaraines: Aggregation and G-Quadruplex Complexation},
  doi       = {10.25972/OPUS-24359},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-243599},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Squaraine dyes have attracted more attention in the past decade due to their strong and narrow absorption and fluorescence along with the easily functionalized molecular structure. One successful approach of core functionalization is to replace one oxygen of the squaric carbonyl group with a dicyanomethylene group, which shifts the absorption and emission into the near infrared (NIR) region and at the same time leads to a rigid, planar structure with C2v symmetry. However, such squaraines tend to aggregate cofacially in solution due to dispersion forces and dipole-dipole interactions, usually leading to H-type exciton coupling with undesired blue-shifted spectrum and quenched fluorescence. Therefore, the goal of my research was the design of dicyanomethylene-substituted squaraine dyes that self-assemble into extended aggregates in solution with J-type coupling, in order to retain or even enhance their outstanding optical properties. Toward this goal, bis(squaraine) dyes were envisioned with two squaraine units covalently linked to trigger a slip-stacked packing motif within the aggregates to enable J-type coupling. In my first project, bis(squaraine) dye BisSQ1 was synthesized, in which two dicyanomethylene squaraine chromophores are covalently linked. Concentration and temperature-dependent UV/Vis/NIR spectroscopy experiments reveal that BisSQ1 undergoes cooperative self-assembly resulting in J-type aggregates in a solvent mixture of toluene/1,1,2,2-tetrachloroethane (TCE) (98:2, v/v). The J type exciton coupling is evident from the significantly red shifted absorption maximum at 886 nm and the fluorescence peak at 904 nm. In conclusion, this was a first example to direct squaraine dye aggregation in solution to the more desired slip-stacked packing leading to J-type exciton coupling by simply connecting two dyes in a head-to-tail bis chromophore structure. Connecting two squaraine dyes with an additional phenylene spacer (BisSQ2) leads to two different polymorphs with very distinct absorption spectra upon cooling down a solution of BisSQ2 in a solvent mixture of toluene/TCE (98:2, v/v) with different rates. Accordingly, rapid cooling resulted in rigid helical nanorods with an absorption spectrum showing a panchromatic feature, while slow cooling led to a sheet-like structure with a significant bathochromic shift in the absorption spectrum. It was discovered that the conventional molecular exciton model failed to explain the panchromatic absorption features of the nanorods for the given packing arrangement, therefore more profound theoretical investigations based on the Essential States Model (ESM) were applied to unveil the importance of intermolecular charge transfer (ICT) to adequately describe the panchromatic absorption spectrum. Moreover, the red-shift observed in the spectrum for the sheet-like structure can be assigned to the interplay of Coulomb coupling and ICT-mediated coupling. Furthermore, the same bis-chromophore strategy was adopted for constructing an NIR-II emitter with a bathochromically-shifted spectrum. In chloroform, BisSQ3 exhibits an absorption maximum at 961 nm with a significant bathochromic shift (1020 cm-1) compared to the reference mono-squaraine SQ, indicating intramolecular J-type coupling via head-to-tail arrangement of two squaraine dyes. Moreover, BisSQ3 shows a fluorescence peak at 971 nm with a decent quantum yield of 0.33\%. In less polar toluene, BisSQ3 self-assembles into nanofibers with additional intermolecular J-type coupling, causing a pronounced bathochromic shift with absorption maximum at 1095 nm and a fluorescence peak at 1116 nm. Thus, connecting two quinoline-based squaraines in a head-to-tail fashion leads to not only intra-, but also intermolecular J-type exciton coupling, which serves as a promising strategy to shift the absorption and emission of organic fluorophores into the NIR-II window while retaining decent quantum yields. In conclusion, my research illustrates based on squaraine dyes how a simple modification of the molecular structure can significantly affect the aggregation behavior and further alter the optical properties of dye aggregates. Elongated supramolecular structures based on dicyanomethylene substituted squaraine dyes were successfully established by covalently linking two squaraine units to form a bis-chromophore structure. Then, a simple but efficient general approach was established to direct squaraine dye aggregation in solution to the more desired slip-stacked packing leading to J-type exciton coupling by directly connecting two squaraine dyes in a head-to-tail fashion without spacer units. Moreover, the additional spacer between the squaraine dyes in BisSQ2 allowed different molecular conformations, which leads to two different morphologies depending on the cooling rates for a hot solution. Hence, this is a promising strategy to realize supramolecular polymorphism. In general, it is expected that the concept of constructing J-aggregates by the bis-chromophore approach can be extended to entirely different classes of dyes since J-aggregates possess a variety of features such as spectral shifts into the NIR window, fluorescence enhancement, and light harvesting, which are commonly observed and utilized for numerous fundamental studies and applications. Moreover, the insights on short-range charge transfer coupling for squaraine dyes is considered of relevance for all materials based on alternating donor-acceptor π-systems. The panchromatic spectral feature is in particular crucial for acceptor-donor-acceptor (ADA) dyes, which are currently considered as very promising materials for the development of bulk heterojunction solar cells.},
  subject      = {Squaraine},
  language  = {en}
}