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The literature surrounding organic small-molecule donor-acceptor systems is summarised for a range of optoelectronic applications (OLEDs, OPVs, OFETs etc.). There is a focus on the key building blocks: 1,3,4-oxadiazole (OXD), diphenylamine (DPA), carbazole (Cbz) and fluorene (F). The incorporation of such moieties into various donor-acceptor systems is discussed with further reference to selected alternative organic donor and acceptor systems. The syntheses of novel bipolar molecules based on a donor-spacer-acceptor (DPA/Cbz-F-OXD) structure and the incorporation of these molecules into single-layer OLEDs is presented. It is demonstrated how the emission colour can be tuned from green to deep blue by systematic manipulation of the structure. A significant result is that high efficiency accompanied with pure, deep blue emission in single-layer OLEDs can be achieved with this structural motif. The incorporation of these materials as part of a simple two-component blend to produce white OLEDs is presented and the modification of the materials to improve electron-transport properties is discussed. The synthesis of DPA-bridge-OXD wire systems is presented with the use of oligo-p-phenyleneethynylene units as a bridge of varying length to investigate the effect on charge transfer between the donor and acceptor. Photophysical studies demonstrate the change in absorption, emission and fluorescence lifetimes as the length scale of the molecules is altered. The synthesis of a series of planarised and twisted DPA-bridge-OXD systems based upon phenylene linkers is discussed. Finally, a series of DPA-F-OXD-anchor molecules is presented for incorporation into DSSC devices. The synthesis of these materials is described and the suitability of various anchoring groups for DSSCs is analysed through photophysical and device studies.

The war between human and malaria has never stopped, and the development and application of antimalarial drugs has not eradicated this terrible disease. To fight drug-resistant malaria, many leads have been studied over the years. (1S,3R)-MMV008138 and MMV1803522 are two compounds that have been studied in the Carlier Group. My research focused on the structural variation of each of these compounds, in the hope that greater potency could be realized. Chapter 2 describes my work on (1S,3R)-MMV008138, which inhibits the enzyme PfIspD in the methylerythritol phosphate (MEP) pathway. This compound shows good in vitro potency against the drug resistant Dd2 strain of Plasmodium falciparum. However, this lead showed no activity in mouse models. This lack of activity may be due to poor metabolic stability of the compound. However, a significant increase in in vitro potency could also improve in vivo activity. Towards that end, I focused on further variation of the D-ring and A-rings. With the regard to the D-ring, we made five analogs of MMV008138 that replaced the 2,4-dichlorophenyl ring with dihalogenated thiophen-3-yl and thiophen-2-yl rings. We also explored the effect of installing a cyano group on the A-ring of MMV008138. Unfortunately, none of these new compounds were potent growth inhibitors of Dd2 strain P. falciparum. We conclude that the lead goes into a well-defined pocket within the PfIspD enzyme that only accommodates 2,4-dihalogenated phenyl D-rings. This pocket also cannot accept any substitution larger than F on the A-ring. Interestingly, the crystal structure of 5-cyano-substituted MMV008138 was obtained ((±)-2-50c). This is the first compound out of more than 100 analogs of MMV008138 family to be amenable to crystallization. The solid state conformation of the (±)-2-50c revealed that the C3-carboxyl group was in a pseudoequatorial orientation, and the C1-aryl group was thus in a pseudoaxial orientation. 1H NMR spectroscopic studies in CD3OD-D2O were carried out to determine the solution conformation. As expected from previous studies of ester derivatives of MMV008138, these studies indicated that in solution, 2-5 would adopt both the C3-carboxyl pseudoequatorial and pseudoaxial conformations. In Chapter 3, I describe the synthesis of analogs of the antimalarial drug candidate MMV1803522. This β-carboline-3-carboxamide shows good in vitro growth inhibition potency of Dd2 strain P. falciparum, operating by a still unknown mechanism. To investigate the pharmacophore of this lead, I first sought to determine whether the pyridine N (i.e. N2) of the β-carboline was important for in vitro potency. I prepared series of carbazole analogs of MMV1803522, which replace N2 with a CH. These compounds potently inhibited the growth of Dd2 strain P. falciparum. These results suggest that N2 of MMV1803522 is not involved in any energetically significant interactions with its target protein. To further identify the pharmacophore, we prepared truncated analogs lacking the A- and B- rings (biphenyl analogs), and tricyclic analogs that feature a reversed indole moiety. Unfortunately, the biphenyl analogs and reversed indole analogs show no growth inhibition at 10,000 nM the highest concentration tested. Lastly, I describe analogs of MMV1803522 in which the 3,4-dichlorophenyl ring of MMV1803522 was replaced with halogenated thiophene. This substitution was tolerated, but compounds were roughly half as potent as MMV1803522.

Mass spectrometry is one of the most powerful techniques used in analytical chemistry today. It has been utilized in a wide variety of fields, from synthesis to pharmaceuticals to analyzing medicinal samples. One of its greatest strengths is its ability to be combined with other techniques to further improve the collected data. In this work, the ability to couple mass spectrometry with electrochemistry in the dimerization of two aromatic amines, carbazole and triphenylamine, is explored, and insight into the underlying dimerization mechanism is achieved. In addition, photochemistry is also coupled with mass spectrometry, and the potential dehydrogenation of pyrrolidine is explored.

Six peripherally meso-modified Zn (II) porphyrin sensitizer dyes are designed and their J-V performance in dye sensitized solar cell (DSSC) evaluated. Electron-donating groups including phenothiazine, carbazole and pyrene are used to modify the porphyrin macrocycle at the meso-carbon position(s). To compare the effect of donor substitution on the performance of the cells in terms of short circuit current (Jsc), light harvesting efficiency (LHE) and power conversion efficiency (η), two sets of sensitizers with different degrees of substitution are synthesized. One set of dyes (mono-substituted) have one electron donor at trans-position to the acceptor, while the second set (tri-substituted) dyes have three of the same type electron donor groups at 5, 10 and 15 meso-carbon positions making all the six dyes push-pull type sensitizers incorporating 4'-carboxyphenyl as an electron-acceptor/anchor group. Different spectroscopic and electrochemical methods are used to study the photophysical and electrochemical properties of the dyes, while the photovoltaic performance of their cells under 1.5 A.M is studied using solar simulator. Meso-substitution of Zinc (II) porphyrin with these small donor molecules is shown to improve the light harvesting character of the Zinc (II) porphyrin macrocycle in the UV-Vis absorption while at same time improving its fluorescence quantum yield, excited-state life time and electron donating potential. All these factors combined make these meso-modified dyes better sensitizers with suitable Δ0 Δ0, and much improved power conversion efficiencies (PCE) compared to unsubstituted Zn (II) porphyrin. In particular, as a result of the peripheral modification, a doubling in efficiency in the mono- substituted series (RA-200-Zn; η=^M 4.2%, Jsc= -13.13 mA cm-2, Voc=0.54 ) and tripling in the tri-substituted series ( tri-phenothiazine Zn (II) Porphyrin; η= 7.3%, Jsc= -18.15 mA cm-2, Voc= 0.55 ) compared to unsubstituted Zn (II) porphyrin (η= 2.11%, Jsc= -5.7 mA cm-2, Voc= 0.53 V) has been accomplished.

Abstract: In response to an increasing global need for inexpensive, energy efficient electronics, the field of organic semiconductors has experienced tremendous growth over the last 3 decades. In addition to their low cost, and interesting electronic and optical properties, organic semiconductors offer the additional benfits of being composed largely of earth-abundant elements, having electronic properties that are easily tailored through structural modifications, and can be solution processed to form flexible films. In particular, the heterofluorene structure has become a popular structural motif in organic semiconductors as a result of their straightforward preparation, and excellent electronic properties which have made them popular materials for devices ranging from transistors to solar cells. In this thesis, I present the results of original research on the subject of heterofluorene oligomers based on two structural motifs: i) macrocyclic carbazole tetramers, and ii) linear trimers of group 14-bridged spirobifluorenes. The early chapters of this thesis outline the preparation of a family of shape persistent macrocycles based on a carbazole monomer unit through the coupling of 3,6-dibromocarbazole and a series of N-alkylated derivatives with bis-(1,5-cyclooctadiene)Nickel(0) (i.e., Ni(COD)2). The macrocycles produced using this methodology were then used as building-blocks for the preparation of soft carbon nano and micromaterials through polarity induced self-assembly in acetone/water and THF/water co-solvent mixtures. The impact of the assembly process on the optical properties of the tetramers was also studied, and revealed that the alkyl-free derivative underwent aggregation-induced emission enhancement. The substitution of the tetramers with larger N-alkyl substituents disrupted the aggregation process leading to this favourable behaviour, but allowed the preparation of a range of morphologies from twisted nanofibers through microrods, ribbons and paddlewheels, the nature of which depended on the length and steric bulk of the N-alkyl substituent. The latter work in this thesis presents the results of a theoretical investigation into a series of linear trimers based on a spirobifluorene monomer unit in which the identity of the spiro-bridging atom is varied from C, Si, Ge and Sn. The potential for spiro-conjugation based charge transfer was calculated at three levels of theory, and suggested that the carbon and silicon analogues are most appropriate for spiroconjugation-based off-chain charge transfer in these trimers. The use of long-range corrected functionals dramatically decreased the charge transfer contributions to the singlet excited states of the trimers, and increased the estimated band gaps to values that were more comparable to experimental results obtained using the carbon-bridged trimer.

The synthesis of poly(arylene ether sulfone)s, with a pendant aryl iodide, was achieved via nucleophilic aromatic substitution (NAS) polycondensation of 3-iodo-3’,5’-difluoro-diphenylsulfone. The polymer series was subjected to amino acid promoted, copper catalyzed coupling reactions with various N-heterocycles. The resulting polymers became crosslinked and insoluble in any organic solvents. The iodo monomer was then subjected to an amino acid promoted, copper catalyzed coupling reaction with carbazole. The successful synthesis of 3’-(9-carbazole) 3,5-difluorodiphenylsulfone is reported. A series of PAES containing a carbazole substituent were synthesized and characterized. The polymers were characterized by a combination of NMR spectroscopy, SEC, TGA, DSC, UV-Vis spectroscopy. NMR spectroscopy was used to confirm that the carbazole monomer was successfully polymerized. SEC was used to find polymer molecular weights and dispersity. Several polymers in the series showed high thermal stability, and formed tough flexible films when solution cast from N-methyl pyrrolidinone

This thesis examined photo-induced toxicity and toxicokinetics for acute exposure to polycyclic aromatic hydrocarbons (PAHs) in fish. Co-exposure of ultraviolet radiation (UV) and PAHs enhances the toxicity at PAH concentrations orders of magnitude below effects in the absence of UV. Because environmental exposure to PAHs is in the form of complex mixtures, this study examined both single compounds and mixtures. The sensitivity of two species of larval fish (zebrafish and sheepshead minnow) to fluoranthene was identified by derivation of acute 96hr median lethal concentrations (LC50s). Differential sensitivity was explained by differences in toxicokinetics. In the zebrafish, 96hr LC50s were derived for four additional PAHs to examine the hypothesis that phototoxic (anthracene and pyrene) and non-phototoxic (carbazole and phenanthrene) pathways could be predicted. Anthracene and pyrene were phototoxic; however, carbazole exhibited moderate and phenanthrene exhibited weak photo-induced toxicity. Individual toxicity was used to compare the toxicity of mixtures in binary, tertiary, and quaternary combinations using a Toxic Unit approach. Toxicity was predicted to be additive, regardless of the level of photo-induced toxicity. Genetic analysis of biomarkers indicative of toxicity pathway for individual exposures and mixtures was investigated. Due to limitations of the results, no final conclusions were able to be made.

Isatin-derived 1,2,4-triazines were employed as electron deficient azadienes in inverse electron demand Diels-Alder (IEDDA) chemistry with tethered alkynyl dienophiles, leading to biologically interesting heterocyclic lactam- and lactone-annulated α-carbolines in excellent yields under microwave promotion. The chemistry scope was probed using various alkynyl amines and alcohols, and the impact of the tether length between the triazines and the dienophiles was also investigated. This IEDDA methodology was subsequently applied to the synthesis of an α-carboline library, producing eighty-eight members starting with various isatin-derived triazines, indole-derivatives, and propargylamine derivatives. In a related project, a regioselective Lewis acid catalyzed amidation of dimethyl 5H-pyridazino[4,5-b]indole-1,4-dicarboxylate was established to selectively direct the amidation to occur at either the C1 or C4 ester positions. This chemistry was then applied to tether dienophiles to the pyridazinoindole ring via an amide linkage. Subsequent IEDDA cycloadditions of these pyridazinoindole/dienophile pairs afforded carbazoles in excellent yields under thermal conditions. The scope of this chemistry scope was also thoroughly probed, leading to a library of one hundred and eighty-eight members. The synthesis of a third heterocyclic scaffold using Diels-Alder chemistry was also accomplished. Asymmetric cycloadditions of anthrone with various maleimides were successfully achieved using different chiral organocatalysts. The identity of the optimal catalytic system depended upon the dienophile, with good enantioselectivities achieved (78-83% ee). This chemistry was successfully applied as the stereocontrol element in a Diels-Alder/Functional Group Transformation/retro-Diels-Alder sequence to prepare alkaloidal scaffolds in an optically enriched form.

The electronic and optical behavior of conjugated small molecules constitutes one of the most extensively studied properties of this class of organic compounds. In particular, electron donor-acceptor compounds separated by π-conjugation have attracted much research interest because of their applications as electroactive and photoactive materials in molecular electronic areas such as fluorescent technology, chemoluminescence, and photovoltaics. This work aims to demonstrate the synthesis and some of the interesting properties of new carbazole, indole, and diphenylamine donor-based donor-acceptor compounds. Basically, we have divided our compounds into two groups: (a) aromatic fumaronitrile core-based compounds and (b) 2,7-carbazole linker-based compounds. We designed and synthesized these compounds for possible applications in electroluminescent devices (such as OLEDs), organic sensors, organic nanoparticles, sensitizers in organic dye-sensitized solar cells (DSSCs), and other optoelectronic devices. Compounds containing an aromatic fumaronitrile core have attracted significant attention as candidates in electroluminescent devices because of their strong emissions in the solid state. Five different compounds with a highly fluorescent and stable carbazole, indole, 2-phenylindole, diphenylamine, or 3,6-disubstituted carbazole donor with an aromatic fumaronitrile core were synthesized and characterized. They showed absorption ranging from Amax 306 nm to 450 nm and emission ranging from λmax 360 nm to 637 nm in medium polar solvent DCM. These compounds emitted blue, green, and red light. In most of the compounds, red-shifted emission in the solid state relative to that in solution was observed. The red shift in the solid state was as high as 114 nm. These compounds showed molar extinction coefficients ranging from 20881 dm3cm-1mol-1 to 73266 dm3cm-1mol-1 in DCM, quantum yields of fluorescence (ΦF) from 0.01 up to 0.80 in solution and 0.38-0.80 in the solid state, and lifetimes of fluorescence (τF) ranging from less than 0.1 ns up to 7 ns. Some of these compounds have significant potential for use in organic light-emitting diode devices since their emission covers nearly the entire visible region of the spectrum with high quantum yields both in solution and in solid state. The correlation between functional groups and optical properties of some of the compounds has been established. The ability of some of the compounds to function as colorimetric and luminescence pH sensors is demonstrated with color change and luminescence switching upon the addition of trifluoroacetic acid. Fumaronitrile core-based compounds have a high propensity to form Fluorescent Organic Nanoparticles (FONs) in appropriate superior/inferior solvent mixtures. All of these five aromatic fumaronitrile core-based compounds formed FONs in THF/water mixtures. These FONs emit light from the visible region to the near IR region. These FONs show remarkable change in terms of intensity in both absorption and emission. Some of the nanoparticles of these compounds absorb up to 580 nm and emit from 350 nm up to the near infrared (NIR) region. This is the first example that NIR emission was achievable upon the formation of nanoparticles from pure organic compounds. In some compounds, the emission intensity of nanoparticles is increased by 19 fold, and in some of the nanoparticles the emission is red shifted by 256 nm. A new class of 15 different organic donor-acceptor compounds with a 3,6-disubstituted carbazole or diphenylamine donor, 2,7-functionalized N-substituted carbazole linker and either (i) an aldehyde, (ii) cyanoacetic acid, (iii) malononitrile acceptors or (iv) diphenylamino or 3,6-disubstituted carbazolyl donors—all with or without phenylethynyl extenders—has been synthesized. The effect on the photophysical properties of these compounds caused by changing acceptors while keeping the donor and linker constant has been studied. These compounds, also, absorb from the UV into the visible region and emit intensely from blue to green. A study of the solvent effects of some of these compounds on their photophysical properties has shown that an increase in polarity of the solvent causes a reduction of fluorescence quantum yields. Solid state fluorescence quantum yields are generally greater than those in DCM. The compounds having a cyano group in the acceptor formed fluorescent nanoparticles in THF/water mixtures. The properties of these 2,7-functionalized N-substituted carbazole linker-based compounds were also investigated using a combination of conventional steady-state absorption spectroscopy and tools of computational photochemistry. Time-dependent density functional theory calculations provide a deep insight into the photochemistry of these compounds in terms of molecular orbitals and the changes in electron density accompanying low-lying electronic transitions. One noticeable difference is that in the absence of phenylethynyl linker extenders, delocalization along the π-framework is generally more effective. These findings point out that less efficient electronic communication between the donor and acceptor is achieved when the phenylethynyl extender is inserted by design. Compounds having cyanoacrylic acid as an acceptor have potential as sensitizers in organic DSSCs; thus, we have fabricated them into devices and obtained the power conversion efficiency of 2.7% in the blue region of the spectrum. All these data indicate that these compounds and their nanoparticles can be utilized in different applications such as photonics, electronics, sensors, and organic DSSCs.

The present manuscript describes the synthesis and photophysical properties ofsix carbazole-based ambipolar compounds with donor-acceptor-donor (hereafterD-A-D) configuration in C2v symmetric arrangement. Three acceptor units were chosenbased on their known optical properties, symmetry and planarity: fluorenone (FO),fluoren-9-ylidene malononitrile (FM), and dibenz[a,c]phenazine (Pz). Such units wereconnected through a phenylacetylene (PA) bridge (B) to favor structural rigidity and keepD-A distances fairly constant. The acceptor unit was functionalized through theircommon biphenylene skeleton via 3,3' and 4,4' substitutions (in the manuscript theyadopt the numerology from fluorene). The triads B-A-B were also synthesized forcomparison purposes. The photophysical properties have been investigated by means ofsteady state and time resolved UV-Vis absorption and photoluminescence, plus cyclicvoltammetry. Computational methods such as density functional theory (DFT) and postself-consistent field (SCF) (i.e. complete active space SCF, or CASSCF) were utilized tomap the electronic properties of the derivatives and perform a first survey of the possiblenon-radiative relaxation mechanism of their S1 state. The focus of these studies wasbased on the structure-activity relationship between the pattern of substitution and theelectronic properties of the bulk. This helped establishing design patterns for the nextgeneration of chromophores to be utilized in organic electronics applications such asthin-film transistors and photovoltaics, based on these D and A units.

Two structures of dyes were designed for dye sensitized solar cells. Both compounds were synthesized and spectroscopically characterized. It was found that they meet major requirements for devices implication. The role of phenylacetylene bridge linker was studied.

Carbazole is a heterocyclic tricyclic aromatic organic compound consisting of two six-membered benzene rings fused on either side of a five-membered nitrogen-containing ring. A large number of carbazole derivatives have been designed and synthesized and organic electronic devices based on these derivatives such as organic light emitting diodes (OLEDs), have been investigated. Ever since Tang and VanSlyke constructed electroluminescent (EL) devices using organic materials as emitters, development of efficient and stable EL materials has taken good momentum. Carbazole derivatives are widely used as materials for EL and hole-transporting layers of OLEDs which use their high charge mobility. The optical and electrical properties of carbazoles are affected by substitution on the 2-, 3-, 6-, 7- and 9H-positions. Many carbazole derivatives have sufficiently high triplet energy to make them an efficient host where they can serve as red, green, or blue triplet emitters. Highly fluorescent and stable carbazole-based compounds were synthesized and characterized. Substitution of carbazoles at 3- and 6- position by tert-butyl group enhanced the solubility. They showed high extinction coefficients of absorption (Amax 328-353 nm) and quantum yields of fluorescence ( max 386-437 nm; FF 0.72-0.89; F 2.09-3.91 ns) in dichloromethane. The quantum yields of fluorescence of these compounds in the solid state were also high ( max 385-422 nm; FF 0.40-0.85). Simple synthetic procedures were developed to prepare other stable carbazoles. These compounds emit blue, green, and orange-red light. The red-shifted emission in the solid state which can be as much as 120nm relative to that in solution is highly dependent on the nature and positions of the substituents.. The presence of a carbaldehyde or malononitrile on the carbazole moiety quenches fluorescence severely in solution and in the solid state. However, the effect is not the same for the fluorescence lifetime. Lowering the temperature from 25 0C to -10 0C causes a small but distinct red-shift in the emissions and a systematic increase in the FF values of blue and green emitters. A considerable edge excitation red shift was observed for some of these compounds. The emission of some of these compounds in solution showed both specific and general solvent effects. Nanoparticle research is currently an area of intense scientific work, due to the wide variety of potential applications in biomedical, optical, and electronic fields. Today nanotechnology has been used in various fields ranging from optoelectronic devices to sensors, in biological imaging as well as in third-order non-linear optics. A nanoparticle is a small object, sized between 1 and 100 nanometers, that behaves as a single whole in terms of its transport and properties. Suitably susbtituted carbazoles form highly stable fluorescent organic nanoparticles. The emission of these nanoparticles was reversibly switched on/off in the blue-green and orange-red regions from a change in the ratio of the tetrahydrofuran/water system used in their preparation. The size of the nanoparticles was depends on the solvent ratio and the emissions were significantly red shifted compared to those of dilute solutions in tetrahydrofuran. Similarly, highly stable composite fluorescent organic nanoparticles (CFONs) were prepared by co-reprecipitation of blue and red emitting carbazole-based organic compounds from water/tetrahydrofuran mixtures. SEM images showed diversity in particle size. Emission spectra of CFONs prepared from different ratios of red and blue emitters covered the entire visible region from 400 to 700 nm. Confocal microscopy measurements revealed composite organic nanoparticles emitting a white light. CIE coordinates of these CFONs demonstrated high color purity (CIE X, Y: 0.34, 0.35).These data indicate that these compounds and their nanoparticles have potentials as emitting materials in organic light-emitting diodes (OLEDs).

Aqueous fractions produced from mixing coal oil with water, simulating a spill, have been shown to be acutely and chronically toxic to several aquatic organisms. Identification of the chemical components of these solutions and studies of their behavior and persistence in aquatic systems are needed. The processes of oil/water partitioning and photodegradation, which are of particular importance to the aquatic fate of coal-oil components, were studied here. Analytical techniques were developed and used for the measurement of coal-oil components in both oil and aqueous phases for the determination of distribution coefficients (K(,D)s). It was observed that the addition of a ring carbon or alkyl group increased logK(,D) by 0.31 and 0.45, respectively. Projected aqueous concentrations of four- and five-ring polynuclear aromatic hydrocarbons (PAH) based on estimated K(,D)s were in the low ng/L range. In addition, aqueous concentrations can be predicted for related coal-conversion materials. To study photolytic behavior, aqueous coal-oil solutions were exposed to sunlight for up to 3 hr. The photolysis rate constants in pure water for pyrene (0.82 hr('-1)), benz(a)anthracene (1.0 hr('-1)), and benzo(a)pyrene (1.4 hr('-1)), were reduced 6-9 fold in the aqueous coal-oil matrix as determined using isotope dilution gas chromatography/mass spectrometry. The rate for fluoranthene (0.07 hr('-1)) was basically unchanged in the matrix. Bulk components of the acid, base and aromatic hydrocarbon fractions screened by gas chromatography were not photodegraded detectably in the 3-hr exposure. Minimum half-lives ranged from 5-290 hr. Indoles and carbazoles were found to photodegrade with half-lives of 2-19 hr. Autoxidation was observed for several indoles exposed to sunlight individually. In the aqueous coal-oil matrix it appears that indoles undergo sensitized photolysis. Carbazole (pure water rate, 0.51 hr('-1)) behaved similar to PAH (2.2 fold reduction). Indoles had very high quantum yields, approaching unity, due possibly to contributions from autoxidation. Products of indole photodegradation isolated from the aqueous coal oil appear to be o-acylamino-ketones. Products were also detected in the acid and base fractions spectrophotometrically. The measurement of K(,D)s and the photolytic studies performed here will contribute significantly to the understanding of the behavior of aqueous coal-oil solutions, and to the evaluation of the hazards associated with these materials.