Properties such as chemical robustness, potential for synthetic tunability, and superior electron-accepting character describe the chromophore perylene-3,4,9,10-tetracarboxylic diimide (PDI) and have enabled its penetration into organic photovoltaics. The ability to extend what is already a large aromatic core allows for synthesis of graphene ribbon PDI oligomers. Functionalization with polar and ionic groups leads to liquid crystalline phases or immense supramolecular architectures. Significantly, PDI dianions can survive in water for two months with no decomposition, an important property for charge storage materials. We realized the potential of PDI as an efficient negative-side material for Redox Flow Batteries (RFBs). The synthetic tunability of PDI allowed for screening of several derivatives with side chains that enhanced solubility in polar solvents. The optimized molecule, PDI[TFSI]2, dissolved in acetonitrile up to 0.5 M. For the positive-side, we synthesized the ferrocene oil [Fc4] in high yield. The large hydrodynamic radii of PDI[TFSI]2 and [Fc4] preclude their ability to cross a size exclusion membrane, which is a cheap alternative to the typical RFB membranes. We show that this cellulose-based membrane can support high voltages in excess of 3 V and extreme temperatures (−20 to 110 °C). We assembled a cell with 0.4 M electron concentration with negligible capacity loss for over 450 cycles (>74 days). Such concentration and stability are among the highest values reported in redox flow batteries with organic electrolytes. Oxidative photocyclizations of PDI onto acenes administer regiochemistry that favors helical products, albeit with a small number of overlapping π-bonded atoms. We achieved an oxidative photocyclization of PDI onto phenanthrene to form the [7]helicenes PPDHa and PPDHb with 20 overlapping π-bonded atoms, as well as a partially planar molecule 5HPP. Higher temperature increases the ratio of PPDHa:5HPP. Calculations reveal that these molecules contain ~20 kcal/mol more strain than planar analogs, and single crystals show bending of the PDI units from their favored planarity. The PPDH molecules display a new electronic transition in their UV-Vis spectra that sets them apart from monomer PDI and other PDI helicenes. Spectroelectrochemical measurements confirm that PPDHb accepts four electrons. Compared to a naphthyl-fused PDI helicene with only 10 overlapping π-bonded atoms, the PPDH molecules have a heightened ability to delocalize the first added electron.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 307-315). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Nevada, Reno, 2008. / "December of 2008." Includes bibliographical references (leaves 195-197). Online version available on the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references.

Thesis (Ph. D.)--School of Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Bredas, Jean-Luc, Committee Member ; Kippelen, Bernard, Committee Member ; Marder, Seth, Committee Chair ; Bunz, Uwe, Committee Member ; Perry, Joseph, Committee Member.

Perylene and perylene diimide (PDIs) are widely used for organic optical electronic materials due to their outstanding thermal stability, visible light absorption and high molar absorption coefficients. To tailor perylene and PDI’s optical and electronic properties for specific applications, molecular contortion and bay-functionalization have been proved as effective methods. In this thesis, these strategies will be applied to perylene and PDI to develop novel optical and electronic materials. In the first chapter, the molecular contortion strategy is applied to perylene to tune singlet and triplet energies and successfully turn on singlet fission in thin films of contorted perylene. Perylene does not undergo singlet fission in its planar form. The tuning of the energetics that control singlet fission through molecular contortion can be applied to a large repertoire of established molecular chromophores. In the second chapter, novel bay-functionalization reactions of PDI, which are base-assisted direct amination and N-heteroarylation, are discussed. The reactions are able to achieve up to 70% yield for mono N-heteroarylation. UV-Vis and EPR spectroscopy suggest that these reactions are mediated through PDI radical anions that are thermally induced by strong bases. An intriguing small-molecule white-light-emitter is constructed from this reaction. In the third chapter, contorting PDIs to form chiral helicenes for Chiral Induced Spin Selectivity (CISS) is discussed. CISS allows for selective transportation of one electron spin and filtration out of the other spin, exhibiting great potential applications in spintronics, spin-polarized light-emission, and spin-controlled catalysis. However, the mechanism of CISS remains unclear and it is necessary to develop a molecular system that allows for the investigation of CISS effect at the atomic level. PDI-based helicenes could be an ideal model system for the investigation of CISS effect due to their chiroptical properties. The chirality of PDI-based helicene dimers is resolved without chiral HPLC separation by converting helicene enantiomers into diastereomers, where Prep TLC is used to separate the helicene diastereomers at a relatively large scale.

Doctor of Philosophy / Department of Chemistry / Daniel A. Higgins / This doctoral thesis covers the synthesis, preparation, and characterization of a series of four perylene diimide derivatives, and the nanofibrous composite materials formed by these perylene diimides when complexed with oppositely charged polyelectrolytes. The perylene diimides include a symmetric dication (TAPDI2+), a symmetric dianion (PDISO32-), and two singly charged asymmetric varieties (C11OPDI+ and C7OPDI+) that contain a hydrophilic head group and hydrophobic ether tail. For all studies presented in the following chapters, poly(acrylate) (PA-) or poly(diallyldimethylammonium) chloride (PDDA+) are used as the polyelectrolytes (PEs). The patterned deposition of sheer aligned, nanofibrous material within a fluidic device is conclusively demonstrated. Thin films of the nanofibrous composite are prepared from aqueous solutions of the semiconducting perylene diimides and oppositely charged polyelectrolyte precursors. By sequentially exposing a clean glass substrate to the cationic and anionic precursor solutions, a thin film of composite material is deposited in a layer-by-layer fashion. By utilizing electrostatic self-assembly (ESA) and layer-by-layer (LbL) procedures, precise control of film thickness and optical density are obtained. The effect of perylene diimide structure and charge on resultant composite film morphology is explored. Through spectroscopic and microscopic studies of bulk perylene diimide solutions and composite thin films, it was determined that the formation of these fibrous materials is dependent on the aggregation of the PDI within the precursor solutions. The molecular orientation of the perylene diimide within the composite nanofiber was determined to be perpendicular to the fiber long axis. For the special case of C7OPDI+/PA- composite, flow induced fiber alignment was observed for both dip coated and flow coated samples. The influence of solution flow profile, PE molecular weight (MW), and PDI structure on deposition efficiency, macroscopic and microscopic morphology, and the potential for nanofiber alignment are investigated. Film formation mechanisms involving two unique routes are also presented.

This research involved the synthesis and characterisation of a range of optically active polyhedral oligomeric silsesquioxane (POSS) compounds. POSS precursor compounds containing functional groups required for subsequent attachment of the desired functional groups have been synthesised. Examples of such precursor compounds include mono-functionalised POSS compounds with periphery aldehyde, azide, amino and pyridyl functional groups. A variety of POSS compounds, functionalised with a range of optical functionalities, including optical limiters such as fulleropyrrolidine and iminofullerene, and dyes and pigments, including naphthalene, biphenyl, perylene, pyrene and porphyrin have been synthesised. The reaction of mono-functionalised POSS aldehydes with fullerene (C60) in the presence of N-methylglycine yielded the desired POSS fulleropyrrolidines, whilst reaction of mono-functionalised POSS azide with C60 yielded POSS iminofullerenes. All POSS fullerene compounds were characterised by power limiting measurements, exhibiting comparable power limiting to that of parent C60. The microwave condensation of mono-amino POSS with a range of mono- and bis-anhydrides yielded the POSS imide compounds, which were characterised by UV-Vis and fluorescence spectrophotometry. The perylene POSS imide derivative was further characterised by single crystal x-ray crystallography. The naphtha and biphenyl POSS imides exhibited extremely weak fluorescence, whilst the perylene ii POSS imide displayed particularly strong fluorescence, with a quantum yield approaching unity. The incorporation of a pyridyl group on the periphery of a mono-functionalised POSS cage allowed for the synthesis of the first porphyrin functionalised POSS compound. Mono-porphyrin POSS exhibited comparable absorption properties to other pyridyl ligated ruthenium porphyrins. Mono-functionalised pyrene POSS compounds were prepared through the reaction of 1-pyrene acid chloride with mono(3-aminopropyl)POSS. This synthetic pathway offered a convenient route to mono-functionalised pyrene POSS, in preference to the multi-substitution associated with Heck coupling. Mono-pyrene POSS was determined to be strongly fluorescent, exhibiting a high quantum yield of fluorescence

The work reported herein describes efforts to create ring-opening metathesis block copolymers and homopolymers. The block copolymers were studied to gain insight into the local nanoscale environment of a block copolymer thin film. Additionally, perylene containing homopolymers were characterized in light of their possible use as an n-type material. In the first section of the thesis, the synthesis of diblock copolymers consisting of two blocks with very different dynamics is described. The covalent attachment of a molecular rotor which is sensitive to its local environment allowed the study of the dynamics of the polymers in thin films. The emissive intensity as a function of temperature allowed us to see discontinuity in the rates of change, indicating a change in the local environment corresponding to the transition of the polymer from a glassy to rubbery state. The corresponding temperature, to this event, is known as the glass transition temperature, Tg. Additionally, a polymer featuring a covalently bound n-type molecule, perylene diimide, was synthesized. The photophysical properties, including aggregation in dilute solution, are described. The material is expected to demonstrate the ability to efficiently transport negative charge, acting as n-type material in organic electronics. / text

In Chapter 1, evidence is presented to correlate the vibronic progression in steady-state optical absorption spectra of a dimeric, organic material to its performance in field-effect transistor devices. The organic material, hPDI2, is fitted with solubilizing side chains of varying structure and length to investigate the effects that side chains have on both the optical and electronic properties of hPDI2. In solution, these side chains influence the character of aggregation and in thin films, the side chains influence film morphology. The character of aggregation in solution is determined by the change in relative peak intensities in optical absorption spectra with increasing concentration in solution. The change in relative peak intensity with increasing concentration in solution is a result of intermolecular electronic coupling, which alters the transitional symmetry of optical excitations. The character of aggregation in solution and the morphology of an organic material in thin films are akin to one another. In thin films, the intermolecular electronic coupling can facilitate the charge-transfer characteristics of an organic material in field-effect transistors. It is concluded that the structure and length of molecular side chains do indeed influence the optical and electronic properties of organic materials as a function of aggregation in solution and morphology in thin films. However, more evidence is necessary to elucidate a convincing correlation between the relative peak intensities in optical absorption spectra to the performance of the organic material in field-effect transistors. In Chapter 2, the fundamental electronic and chiroptical properties of a helical, polyaromatic molecule are demonstrated. Structurally, the organic material, NP3H, is a helix of helicenes, which generates intense circular dichroism. The circular dichroism is measured in spin-cast thin films. Electronic transfer characteristics are also presented for enantiopure NP3H as well as the racemic mixture. Upon fabricating field-effect transistors using spin-cast thin films of NP3H, the racemic mixture exhibits a marginally superior electron mobility over the enantiopure material. However, single crystals of enantiopure NP3H were grown and exhibited a two-fold increase in electron mobility when fabricated into a field-effect transistor device in comparison to its amorphous, spin-cast counterpart. It is concluded that enantiopure NP3H exhibits the necessary physical prerequisites to be useful in chiral device applications such as electron spin-filters and chiral light detectors. In Chapter 3, hPDI2 and NP3H are investigated for their ability to aggregate and form ordered films at the air-water interface of a Langmuir-Blodgett trough. Isotherms are presented and compared for each side chain derivative of hPDI2 as well as enantiopure and racemic NP3H. Additionally, an enhancement in circular dichroism is observed when a system of ordered layers of enantiopure NP3H are deposited from the Langmuir-Blodgett trough in comparison to its amorphous, spin-cast counterpart. Furthermore, ordered layers of enantiopure NP3H exhibit an enhancement in electron mobility when fabricated into field-effect transistor devices. The electron mobility is also demonstrated to enhance as the number of ordered layers that increases up to five layers. When ten ordered layers are deposited, a slight decrease is observed. Lastly, single crystals of hPDI2 were grown by solvent annealing a system of ordered layers deposited from the Langmuir-Blodgett trough, which is significant because, to the best of the author’s knowledge, a similar technique for single crystal growth of an organic material from ordered layers of Langmuir-Blodgett films has not yet been published in peer-reviewed scientific literature. It is concluded that the increased order that is induced by the Langmuir-Blodgett technique does indeed enhance the optical and electronic properties of organic materials in comparison to amorphous, spin-cast films and that this enhancement could be advantageous in device applications.