Le travail présenté dans ce mémoire de thèse concerne pour l'essentiel, l'utilisation des dialkylzincs en tant que médiateurs de réactions radicalaires. La particularité de ces organométalliques réside dans le fait qu'ils sont, d'une part, de très bons précurseurs de radicaux alkyle en présence d'oxygène, et d'autre part, qu'ils peuvent subir des réactions de substitution homolytique bimoléculaire permettant de passer au cours d'une même réaction d'une espèce radicalaire à une espèce organométallique. Ainsi, les dialkylzincs sont de très bons médiateurs de réactions radicalaires et polaires en cascade en milieu aérobie.Cette méthodologie a été appliquée à la synthèse one-pot stéréosélective de γ-lactones disubstituées et de pyrrolizidines à partir du fumarate de diéthyle. La synthèse inédite de dérivés fumariques tri- et tétrasubstitués a été réalisée, à partir de l'acétylènedicarboxylate de diéthyle. Des cétoesters ont également été préparés à partir du bromoacrylate d'éthyle et de cétones silylées. L'utilisation d'azoture d'alkyle comme accepteur de radicaux s'est révélée infructueuse mais a permis de détecter une réactivité originale des azotures d'alkyle, qui en présence d'iodure de tertiobutyle, sont convertis en iodures correspondants. Enfin, une étude fondamentale par RPE du mécanisme d'oxydation des dialkylzincs a été réalisée afin de mieux appréhender les différences de comportement observées pour les divers dialkylzincs à l'échelle préparative. / The research work reported in this thesis is essentially concerned with the use of dialkylzincs in radical reactions. The peculiar behavior of these organometallic reagents resides in the fact that they are good precursors of alkyl radicals in the presence of oxygen and that they are good partners for bimolecular homolytic substitution reactions that enable to generate polar species from radical ones. Thereby, dialkylzincs are reagents of choice to perform radical-polar cascades in aerobic medium.This methodology has been applied to the one-pot stereoselective synthesis of disubstituted γ-lactones and pyrrolizidines from diethylfumarate and to the original formation of tri- and tetrasubstituted fumaric derivatives from diethylacetylene dicarboxylate. Ketoesters have also been prepared from bromoethylacrylate and sylilated ketones. The use of alkyl azide as radical acceptor in this process failed but a new reactivity of alkyl azides was detected during this study, i.e, their original conversion into the corresponding alkyl iodides in the presence of t-BuI.Finally, mechanistic studies have been achieved to investigate the mechanism of the oxidation of dialkylzincs. EPR experiments have been performed with the aim to gain a better understanding of the behavior observed for various dialkylzincs at preparative scale.

The thesis entitled “Novel Redox Responsive Cationic Lipids, Lipopolymers, Glycolipids and Phospholipid-Cationic Lipid Mixtures: Syntheses, Aggregation and Gene Transfection Properties” elucidates the design, synthesis, aggregation and gene transfection properties of novel cholesterol based cationic lipids with ferrocene as the redox moiety, polyethylenimine based ferrocenylated lipopolymers and cholesterol based non-ionic glycolipids. The thesis also discusses the cationic phospholipid-cationic lipid mixtures as superior gene transfection agents. The work has been divided into six chapters. Chapter 1. Introduction Part A. Various Cholesterol based Systems for Applications as Biomaterials Liposomes composed of cationic lipids have become popular gene delivery vehicles. A great deal of research is being pursued to make efficient vectors by varying their molecular architecture. Cholesterol being ubiquitous component in most of the animal cell membranes is increasingly being used as a hydrophobic segment of synthetic cationic lipids. In this chapter we describe various cholesterol based cationic lipids and focus on the effect of modifying various structural segments like linker and the headgroup of the cationic lipids on gene transfection efficiency with a special emphasis on the importance of ether linkage between cholesteryl backbone and the polar headgroup. Interaction of cationic cholesteryl lipids with dipalmitylphosphatidycholine membranes is also discussed here. Apart from cholesterol being an attractive scaffold in the drug/gene delivery vehicles, certain cholesteryl derivatives have also been shown to be attractive room temperature liquid-crystalline materials. Part B. Diverse Applications of Ferrocene Derivatives This chapter gives a brief overview of ferrocene chemistry followed by description of major applications of ferrocenyl derivatives in a variety of fields like catalysis, materials chemistry, electrochemical sensors, medicinal chemistry etc. We discuss the use of ferrocene as an electrochemical and redox active switch to achieve control over supramolecular aggregation. It also reviews ferrocene based amphiphiles including surfactants, lipids and polymers with an emphasis on the role of ferrocene over aggregate formation and their utilization in biological applications. Chapter 2: Optimization of Redox Active Alkyl-Ferrocene Modified Polyethylenimines for Efficacious Gene Delivery in Serum 1a-c, n = 6, P8-C6-F1, P8-C6-F2, P8-C6-F3 2a-c, n = 11, P8-C11-F1 P8-C11-F2, P8-C11-F3 % ferrocene grafting, F1 = 15%, F2 = 25% and F3 = 50% Figure 1. Structure of the alkyl-ferrocene modified 800 Da Branched Polyethylenimine. In this chapter we present six new lipopolymers based on low molecular weight polyethylenimines (BPEI 800 Da) which are hydrophobically modified using ferrocene terminated alkyl tails of variable lengths. The effects of degree of grafting, spacer length and redox state of ferrocene in the lipopolymer on the self assembly properties were investigated in detail by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and zeta potential measurements. The assemblies displayed a redox induced increase in the size of the aggregates. The coliposomes comprising of the lipopolymer and a helper lipid 1,2-Dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) showed excellent gene delivery capability in serum containing environment in two cancer cell lines (HeLa, U251 cells). Optimized formulations showed remarkably higher transfection activity than BPEI 25 KDa and even better than commercial Lipofectamine 2000 as evidenced from luciferase activity and EGFP expression analysis. Oxidation of ferrocene in lipopolymers led to reduced levels of gene transfection which was also followed by cellular internalization of fluorescently labeled pDNA using confocal microscopy. Cytotoxicity assay revealed no obvious toxicity for the lipopolyplexes in the range of optimized transfection levels. Overall, we have exploited the redox activity of ferrocene in PEI based polymeric gene carriers for trenchant control over gene transfection potential. RLU/mg protein HeLa Cells Figure 2. Maximum transfection efficacies of optimized redox lipopolymer/DOPE formulations by (A) Luciferase Assay and (B) Flow cytometry (GFP expression). Chapter 3. Membranes derived from Redox-active Cholesterol based Cationic Lipids and their Interactions with DNA and Phospholipid Membranes Figure 3. Molecular structures of the electroactive cholesterol based monomeric and gemini lipids. This chapter describes the synthesis and aggregation properties of two series of redox-active ferrocene containing monomeric and gemini cationic lipids with cholesterol as a hydrophobic domain. These cationic lipids are modified at their headgroup region using ferrocene terminated alkyl chains of differing length. All the four cationic lipids formed stable suspensions in water. Aggregation behavior of these cationic lipids in aqueous suspensions in their unoxidized and oxidized state was studied using TEM, DLS, zeta potential measurements and XRD studies. Cationic lipids with ferrocene in natural, reduced state were found form bigger sized vesicles which upon oxidation became smaller aggregates with increased zeta potential. XRD results indicate the existence of nice lamellar arrangements of the lipid bilayers. Thermotropic phase transition behavior of DPPC membranes incorporated with cationic ferrocene lipids was also studied using differential scanning calorimetry. Finally, we assayed pDNA (plasmid DNA) binding ability of all the four cationic lipids using ethidium bromide intercalation assay where all the cationic lipid formulations showed excellent DNA binding capability. In the experiments involving SDS-induced release of DNA, we observed that redox-active monomeric lipids (3a-b) were found to be more efficient in facilitating the release of DNA from the liposome-DNA complex in the presence of negatively charged SDS micelles than their gemini counterparts (4a-b). Chapter 4. Redox-responsive Gene Delivery by Ferrocene containing Cationic Cholesteryl Lipids in Serum This chapter describes the transfection efficacy of redox-active monomeric and gemini cationic lipids with cholesterol backbone. The transfection efficiency of all the lipids could be tuned by changing the oxidation state of the ferrocene moiety. Gene transfection capability was assayed in terms of EGFP expression using pEGFP-C3 plasmid DNA in three cancer cell lines of different origin, namely Caco-2, HEK293T and HeLa in the presence of serum. Figure 4. Effect of oxidation state of ferrocene on maximum transfection efficacies of monomeric and gemini lipids in three different cell lines (Caco-2, HEK 293T and HeLa). Cationic liposomal formulations with ferrocene in its reduced state were observed to be potent transfectants reaching the EGFP expression levels even better than commercial lipofectamine 2000 in the presence of serum as evidenced by flow cytometry. EGFP expression was further substantiated using fluorescence microscopy studies. All liposomal formulations containing oxidized ferrocene displayed diminished levels of gene expression and interestingly, these results were consistent for each formulation in all the three cell lines. Assessment of EGFP expression mediated by both reduced and oxidized ferrocene containing formulations was also undertaken following cellular internalization of labelled pDNA using confocal microscopy and flow cytometry. Lipoplexes derived from different liposomal formulations with reduced and oxidized ferrocene were characterised using TEM, AFM, zeta potential and DLS measurements. Overall, we demonstrate here controlled gene transfection levels using redox driven, transfection efficient cationic monomeric and gemini lipids. Chapter 5: Synthesis of ‘Click Chemistry’ Mediated Glycolipids: Their Aggregation Properties and Interaction with DPPC Membranes This chapter describes the synthesis and aggregation properties of cholesterol based glycolipids along with their interaction with a model phosphatidylcholine membranes. Three series of non-ionic glycolipids with hydrophobic cholesterol backbone and various monosaccharide and disaccharide sugars as the hydrophilic polar domain have been synthesized. These were conjugated to the cholesteryl backbone via oligooxyethylene spacers of different lengths (n = 1, 3 and 4) using Cu (I) catalyzed Huisgen [3+2] cycloaddition, which is popularly known as „Click Chemistry‟. All the synthetic glycolipids (5a-d, 6a-d and 7a-d) formed vesicular aggregates in aqueous medium as confirmed by TEM and DLS. XRD studies with the cast films of lipids revealed that the bilayer width increased with increase in the length of oligoethylene spacer unit that has been incorporated between the hydrophobic and hydrophilic domains. Also, within the same series containing a particular oligoethylene unit, bilayer widths were found to be more for the lipids containing disaccharides as their headgroup than monosaccharides. Figure 5. Molecular structures of various cholesterol-based glycolipids. Calorimetry studies of the coaggregates containing naturally occurring 1, 2-dipalmitoylphosphatidylcholine (DPPC) and various mol-% of each of the glycolipids revealed that more than 30 mol-% of glycolipids are required to completely abolish the phase transition of DPPC membranes. These results were further supported by fluorescence anisotropy measurements of the co-aggregates using 1, 6-diphenylhexatriene (DPH) as a probe. Fluorescence anisotropy of the neat vesicles revealed that 9a and 9c were more rigid than DPPC vesicles in the solid-like gel phase, while the glycolipids with longer oxyethylene spacers (n = 3 and 4) were less rigid than the DPPC vesicles. Chapter 6. Hydrophobic Moiety Decides the Synergistic Increase in Transfection Efficiency in Cationic Phospholipid/Cationic Lipid mixtures This chapter describes the effect of inclusion of cationic lipid/cationic gemini lipids into the membranes of a cationic phospholipid on the gene delivery efficiency across HeLa and HEK293T cell lines. Although all the three cationic lipids have the same quaternary ammonium moiety as their headgroup, they differ from each other in terms of their hydrophobic moiety and in the number of cationic headgroups. Chol-N is a cholesterol based monocationic lipid, while 2C14-N and 2C14N-5-N2C14N are monomeric and gemini cationic lipids respectively with pseudoglycerol backbone consisting of tetradecyl (n-C14H29) chains. Each of the three cationic lipids under the current investigation, namely, Chol-N, 2C14-N and 2C14N-5-N2C14N were added in different ratios to EtDMoPC and the resultant mixed membranes were studied for the biophysical characterization and gene delivery efficacies. Figure 6. Molecular structures of cationic lipids used in this study. All the formulations were characterized using dynamic light scattering and zeta potential measurements to obtain their hydrodynamic diameters and surface charge properties respectively. Their DNA binding ability was also studied by measuring changes in zeta potential and gel electrophoresis of the lipoplexes formed by the coliposomal formulations and pDNA at different Lipid/DNA weight ratios. The gene delivery efficacies of various formulations were studied in terms of EGFP expression using pEGFP-C3 plasmid DNA in two different cell lines, namely HeLa and HEK293T. In the absence of serum we found that the formulation (EtDMoPC+2C14N-5-N2C14N) showed better transfection efficiency than the individual lipids. However, in the case of others, i.e., (EtDMoPC+Chol-N) and (EtDMoPC+2C14-N) formulations, there was a slight decrease in transfection efficiency compared to the individual lipids. In the presence of serum, the formulations (EtDMoPC+2C14-N) and (EtDMoPC+2C14N-5-N2C14N) showed significantly higher transfection efficacies compared to their individual lipids. Fusion assay using labelled cationic lipid formulations and unlabelled anionic liposomes revealed that lipoplexes prepared from EtDMoPC+ 2C14-N and EtDMoPC+ 2C14N-5-N2C14 exhibited much higher fusogenicity as compared to the lipoplexes prepared using EtDMoPC+Chol-N as well as the individual lipids. Thus, the liposome formulations which showed better transfection activity fused more readily with the anionic liposomes than did the formulations with poorer activity. Overall, we found that the hydrophobic domain of the cationic lipid/cationic gemini lipid that is added to cationic phospholipid has an important role on the transfection efficiency of the mixed formulations. Additionally the cytotoxicity studies revealed that each of these formulations was not significantly toxic making them viable for applications in vivo. (For structural formula pl see the abstract pdf file)

The aim of the present study was the development of analytical methods which can be used for gaining a deeper insight into the mechanisms of hair treatment with cosmetic formulations like shampoos. The efficacy of such a formulation is affected by the amount of different active agents remaining on the hair after treatment. Due to the complex composition of most of the formulations various dependencies and interactions of the ingredients are possible. Beneath that a variety of parameters of the treatment process influence the substantivity. Finally the degree of hair damage present at the treatment process is significant. So the process of hair treatment with cosmetic formulations is very complex. The understanding of this process enables a systematic development of products with better or novel effectivity. The developed analytical methods provide the possibility of a parallel determination of different active agents and their interaction of the adsorption behaviour. Furthermore the determination of influencing variables like treatment conditions or hair damage can be performed. So it is possible to generate the knowledge necessary for excellent scientific product development. The general methodology for the method development consists of an extraction from hair followed by a selective and sensitive quantitation of the active agents located in the extract using LC/MS and LC/MS/MS. Analytical methods for the determination of the complex composed surface active agents Sodium Laureth Sulfate, Cocamidopropyl Betaine and Alkyl Polyglucoside were developed. During the evaluation process it could be figured out that significant swelling of the hair fibre does not occur during a hair wash lasting 2 min or less. Hence the active agents are mainly adsorbed at the hair surface. During method development it was found that the composition of these agents is changing during hair treatment resulting in a difference of the singles substance distribution on hair and in the shampoo. Additionally an analytical method for selective and sensitive quantitation of the cationic polysaccharides Polyquaternium-10 and Guar Hydroxypropyltrimonium Chloride using LC/MS was developed. The parallel quantitation of Polyquaternium-10 and Guar Hydroxypropyltrimonium Chloride enables to study their interaction of the adsorption behaviour. Beneath that the quantitation of substances with low active contentes, like Ubiquinone 50, Piroctone Olamine and Benzophenone?4, was carried out. The extraction behaviour of these substances showed that an extraction time of 7 min assisted by an ultrasonic treatment is optimal. Longer extraction leads to a significant increase of the active hair surface due to swelling. The result is a higher adsorption capacity of the hair fibre and thus a decreased analyte concentration in the extract. The reproducibility of the using treatment protocol was approved by parallel quantitation of several active agents. Due to variation of several treatment parameters their influence on substantivity was studied: the flow rate, temperature and hardness of the water for rinsing and the time for massaging in the formulation. Furthermore, it was shown that the degree of hair damage and further shampoo ingredients influence the substantivity of active agents. Finally it was demonstrated that the adsorption behaviour can be significantly influenced by the application strategy. / Das Ziel der vorliegenden Arbeit war es, mit der Entwicklung von analytischen Methoden eine Möglichkeit zu schaffen, um die Mechanismen bei der Haarbehandlung mit kosmetischen Formulierungen, wie Shampoos besser verstehen zu können. Die Pflegeleistung einer solchen Formulierung wird unter anderem davon bestimmt, wie viel der unterschiedlichen eingesetzten Wirkstoffe nach der Behandlung auf dem Haar verbleiben. Durch die Komplexität der kosmetischen Formulierungen kommt es zu vielfältigen Abhängigkeiten und Beeinflussungen der Substantivität der einzelnen Substanzen voneinander. Darüber hinaus gibt es eine Vielzahl von Parametern bei der Haarbehandlung, die die Substantivität beeinflussen. Schließlich spielt auch der Zustand des Haares eine entscheidende Rolle. Alles in allem handelt es sich bei der Behandlung des Haares mit kosmetischen Formulierungen um sehr komplexe Prozesse. Das Verständnis dieser Prozesse ermöglicht eine gezielte Entwicklung von Produkten mit besserem und zum Teil neuartigem Leistungsspektrum. Die entwickelten Analysenmethoden erlauben die parallele Bestimmung der auf dem Haar adsorbierten Menge verschiedener Wirkstoffe. Dadurch kann die gegenseitige Beeinflussung der Wirkstoffadsorption untersucht werden. Darüber hinaus ermöglicht das Methodenspektrum eine Bestimmung der Einflussgröße äußerer Parameter, wie der Waschbedingungen und innerer Parameter, wie der Haarschädigung. Damit ist es möglich, das notwendige Wissen für eine fortschrittliche, wissenschaftliche Produktentwicklung zu gewinnen. Der allgemeine Ansatz für die Entwicklung der Methoden beinhaltet eine Extraktion der Wirkstoffe vom Haar, gefolgt von einer selektiven und empfindlichen Quantifizierung im Extrakt mittels LC-MS und LC-MS/MS. Es wurden Analysenmethoden für die komplex zusammengesetzten oberflächenaktiven Wirkstoffe Sodium Laureth Sulfate, Cocamidopropyl Betaine und Alkyl Polyglucoside entwickelt. Dabei wurde durch Untersuchungen der Extraktion vom Haar bewiesen, dass die zweiminütige Haarwäsche nicht zu einem signifikanten Aufquellen des Haares führt, so dass die Wirkstoffe hauptsächlich an der Haaroberfläche adsorbiert werden. Außerdem wurde gezeigt, dass sich die Zusammensetzung dieser Wirkstoffe während der Haarwäsche ändert, so dass sich die Einzelsubstanzverteilung auf dem Haar von der im Shampoo unterscheidet. Des Weiteren wurde die selektive und empfindliche Quantifizierung der kationischen Polymere Polyquaternium-10 und Guar Hydroxypropyltrimonium Chloride durchgeführt. Die parallele Quantifizierung beider Konditionierungsstoffe ermöglicht die Untersuchung, in welchem Umfang sich beide Polymere in ihrem Adsorptionsverhalten beeinflussen. Bei der Methodenentwicklung für die Quantifizierung der Wirkstoffe Ubiquinone, Piroctone Olamine und Benzophenone-4 zeigte sich, dass eine Extraktion über 7 min im Ultraschallbad die besten Ergebnisse brachte. Bei längerer Extraktionszeit vergrößert sich die Oberfläche des Haares durch Quellung, so dass sich der Anteil an adsorbierten Analyten wieder erhöht. Die Reproduzierbarkeit der Haarwäsche mit dem verwendeten Waschprotokoll wurde bestätigt, indem verschiedene Wirkstoffe parallel auf dem Haar quantifiziert wurden. Durch Veränderung der Waschparameter Einmassierzeit sowie Durchflussmenge, Temperatur und Härte des Spülwassers wurde der Einfluss dieser Parameter auf die Substantivität der Wirkstoffe untersucht. Darüber wurde gezeigt, dass sowohl der Schädigungsgrad des Haares als auch andere auf dem Haar befindliche Shampoo-Bestandteile einen Einfluss auf die Substantivität von Wirkstoffen haben. Schließlich wurde an einem Beispiel gezeigt, dass man die Substantivität von Wirkstoffen nicht nur durch die Zusammensetzung der kosmetischen Formulierung, sondern auch durch die Art der Anwendung entscheidend beeinflussen kann.

The theoretical part of this diploma thesis consists of current matters regarding the presence of perfluorinated organic compounds in living environment elements. The attention has been focused on perfluoroktanoic acid (PFOA), (PFOS), and (FOSA). Physical-chemical characteristics of these organic pollutants and their toxicological and environmental aspects have been described. Possible ways of the pollutants analytical determination have been specified. The experimental part has explored effects of extraction techniques (sonication, pressurized solvent extraction, solid-phase extraction) used for PFAS separation from seats of fire soil sample. Identification of the analytes have been achieved by liquid chromatography/mass spektrometry.

Imidazolium-based ionic liquids are very popular for different applications because of their low viscosity and melting point. However, the hydrogen atom at the C2 position of the imidazolium cation can easily be deprotonated by a base, resulting in a reactive carbene. If an inert ionic liquid is needed, it is necessary to introduce an unreactive alkyl or aryl group at the C2 position to prevent deprotonation. Tunable aryl alkyl ionic liquids (TAAILs) were first introduced by our group in 2009 and are characterized by a phenyl group at the N1 position, which offers the possibility to fine-tune the physicochemical properties by using different electron-donating or -withdrawing substituents. In this work, we present a new series of TAAILs where the C2 position is blocked by a methyl, propyl or phenyl group. For each of the blocking groups, the phenyl and three different phenyl derivatives (2-Me, 4-OMe, 2,4-F₂) are compared with respect to melting point, viscosity, conductivity and electrochemical window. In addition, the differences between blocked and unblocked TAAILs with regard to their electrochemical reduction potentials are investigated by quantum chemical methods.

Organic solar cells (OSCs) based on non-fullerene acceptors (NFAs) have attracted a great deal of attention in recent years due to their rapidly increasing efficiency and enormous potential. In this work, the optical and electronic properties of systems containing the very promising non-fullerene acceptor PYT have been thoroughly studied with the use of the density functional theory (DFT) and the time-dependent density functional theory (TDDFT). By changing the electron linker from thiophene to furan and selenophene, respectively, the PYT was divided into three variants, each of which was studied independently. In addition, these three systems were combined with the donor PBDB-T to generate two distinct interface conformations. The properties studied in this work include the optimized geometries, HOMO-LUMO levels, UV-Vis spectra, frontier molecular orbitals (FMOs), natural transition orbitals (NTOs), density of states (DOS), dipole moments, open-circuit voltages, exciton binding energies, and local exciton (LE) and charge transfer (CT) energies. The calculations were performed in chlorobenzene solution utilizing the polarizable continuum model (PCM). It was discovered that PBDB-T/PY-Se exhibited remarkable flatness employing the π-π stacking conformation which corresponds well with the excellent D/A compatibility observed experimentally. All interfaces displayed appropriate positioning of the HOMO-LUMO levels, with the acceptor dominating the LUMO and the donor dominating the HOMO, with HOMO-LUMO gaps ranging between 1.34 and 1.38 eV. The differences in the interchanging of the electron linker were not that significant, and neither was the change in interface conformation in terms of the HOMO-LUMO levels. This may indicate that the system can be effective even without the presence of a π-π stacking conformation. The first excited states for all interface systems were shown to be pure CT transitions, and on average, 80% of the states exhibit CT character. The remaining contributions consisted of transitions within the pure materials, with a larger contribution within the acceptor. The theoretical results of this study indicate that systems containing the novel polymer acceptor PYT and its variants PY-O and PY-Se exhibit very intriguing properties, and further development of OSCs containing these polymers might further aid in the development of high-performance OSCs. / Organiska solceller (OSC) baserade på icke-fullerenacceptorer (NFA) har väckt stor uppmärksamhet de senaste åren på grund av dess snabbt ökande effektivitet och enorma potential. I detta arbete har de optiska och elektroniska egenskaperna hos system innehållande den mycket lovande icke-fullerenacceptorn PYT studerats grundligt med användning av täthetsfunktionalteorin (DFT) och den tidsberoende täthetsfunktionalteorin (TDDFT). Genom att ändra elektronförbindelsen från tiofen till furan respektive selenofen så delades PYT upp i tre varianter som var och en studerades oberoende av varandra. Dessutom kombinerades dessa tre system med donatorn PBDB-T för att generera två distinkta gränssnittskonformationer. Egenskaperna som studeras i detta arbete inkluderar optimerade geometrier, HOMO-LUMO-nivåer, UV-vis spektra, gränsmolekylära orbitaler (FMO), naturliga övergångsorbitaler (NTO), tillståndstäthet (DOS), dipolmoment, tomgångsspänning, excitonbindningsenergi samt lokal exciton (LE) och laddningsöverförings (CT) energier. Beräkningarna utfördes i klorbensenlösning med användning av den polariserbara kontinuummodellen (PCM). I resultatet uppvisade PBDB-T/PY-Se en anmärkningsvärd planhet med användning av π-π staplingskonformationen som överensstämmer väl med den utmärkta D/A-kompatibiliteten som observerats experimentellt. Alla gränssnitt visade lämplig positionering av HOMO-LUMO-nivåerna, med acceptorn som dominerade LUMO och donatorn som dominerade HOMO, med HOMO-LUMO-gap mellan 1.34 och 1.38 eV. Skillnaderna i utbytet av elektronförbindelsen visade sig inte vara signifikanta och inte heller skillnaden i gränssnittskonformation när det gäller HOMO-LUMO-nivåerna. Detta kan indikera att systemet kan vara effektivt även utan förekomst av π-π staplingskonformation. De första exciterade tillstånden för alla gränssnittssystem visade sig vara rena CT-övergångar och i genomsnitt uppvisade 80% av tillstånden CT-karaktär. Resterande andel bestod av övergångar inom de rena materialen med en större andel inom acceptorn. De teoretiska resultaten av denna studie indikerar att system innehållande den nya polymeracceptorn PYT och dess varianter PY-O och PY-Se uppvisar mycket spännande egenskaper samt att vidareutveckling av OSC:er som innehåller dessa polymerer ytterligare kan hjälpa till i utvecklingen av högpresterande OSC:er.

A new method, probability distribution of diffusivities (time scaled square displacements between succeeding video frames), was developed to analyze single molecule tracking (SMT) experiments. This method was then applied to SMT experiments on ultrathin liquid tetrakis(2-ethylhexoxy)silane (TEHOS) films on Si wafer with 100 nm thermally grown oxide, and on thin semectic liquid crystal films. Spatial maps of diffusivities from SMT experiments on 220 nm thick semectic liquid crystal films reveal structure related dynamics. The SMT experiments on ultrathin TEHOS films were complemented by fluorescence correlation spectroscopy (FCS). The observed strongly heterogeneous single molecule dynamics within those films can be explained by a three-layer model consisting of (i) dye molecules adsorbed to the substrate, (ii) slowly diffusing molecules in the laterally heterogeneous near-surface region of 1 - 2 molecular diameters, and (iii) freely diffusing dye molecules in the upper region of the film. FCS and SMT experiments reveal a strong influence of substrate heterogeneity on SM dynamics. Thereby chemisorption to substrate surface silanols plays an important role. Vertical mean first passage times (mfpt) in those films are below 1 µs. This appears as fast component in FCS autocorrelation curves, which further contain a contribution from lateral diffusion and from adsorption events. Therefore, the FCS curves are approximated by a tri-component function, which contains an exponential term related to the mfpt, the correlation function for translational diffusion and a stretched exponential term for the broad distribution of adsorption events. Lateral diffusion coefficients obtained by FCS on 10 nm thick TEHOS films, thereby, are effective diffusion coefficients from dye transients in the focal area. They strongly depend on the substrate heterogeneity. Variation of the frame times for the acquisition of SMT experiments in steps of 20 ms from 20 ms to 200 ms revealed a strong dependence of the corresponding probability distributions of diffusivities on time, in particular in the range between 20 ms and 100 ms. This points to average dwell times of the dye molecules in at least one type of the heterogeneous regions (e.g. on and above silanol clusters) in the range of few tens of milliseconds. Furthermore, time series of SM spectra from Nile Red in 25 nm thick poly-n-alkyl-methacrylate (PnAMA) films were studied. In analogy to translational diffusion, spectral diffusion (shifts in energetic positions of SM spectra) can be studied by probability distributions of spectral diffusivities, i.e. time scaled square energetic displacements. Simulations were run and analyzed to study contributions from noise and fitting uncertainty to spectral diffusion. Furthermore the effect of spectral jumps during acquisition of a SM spectrum was investigated. Probability distributions of spectral diffusivites of Nile Red probing vitreous PnAMA films reveal a two-level system. In contrast, such probability distributions obtained from Nile Red within a 25 nm thick poly-n-butylmethacrylate film around glass transition and in the melt state, display larger spectral jumps. Moreover, for longer alkyl side chains a solvent shift to higher energies is observed, which supports the idea of nanophase separation within those polymers.

A new method, probability distribution of diffusivities (time scaled square displacements between succeeding video frames), was developed to analyze single molecule tracking (SMT) experiments. This method was then applied to SMT experiments on ultrathin liquid tetrakis(2-ethylhexoxy)silane (TEHOS) films on Si wafer with 100 nm thermally grown oxide, and on thin semectic liquid crystal films. Spatial maps of diffusivities from SMT experiments on 220 nm thick semectic liquid crystal films reveal structure related dynamics. The SMT experiments on ultrathin TEHOS films were complemented by fluorescence correlation spectroscopy (FCS). The observed strongly heterogeneous single molecule dynamics within those films can be explained by a three-layer model consisting of (i) dye molecules adsorbed to the substrate, (ii) slowly diffusing molecules in the laterally heterogeneous near-surface region of 1 - 2 molecular diameters, and (iii) freely diffusing dye molecules in the upper region of the film. FCS and SMT experiments reveal a strong influence of substrate heterogeneity on SM dynamics. Thereby chemisorption to substrate surface silanols plays an important role. Vertical mean first passage times (mfpt) in those films are below 1 µs. This appears as fast component in FCS autocorrelation curves, which further contain a contribution from lateral diffusion and from adsorption events. Therefore, the FCS curves are approximated by a tri-component function, which contains an exponential term related to the mfpt, the correlation function for translational diffusion and a stretched exponential term for the broad distribution of adsorption events. Lateral diffusion coefficients obtained by FCS on 10 nm thick TEHOS films, thereby, are effective diffusion coefficients from dye transients in the focal area. They strongly depend on the substrate heterogeneity. Variation of the frame times for the acquisition of SMT experiments in steps of 20 ms from 20 ms to 200 ms revealed a strong dependence of the corresponding probability distributions of diffusivities on time, in particular in the range between 20 ms and 100 ms. This points to average dwell times of the dye molecules in at least one type of the heterogeneous regions (e.g. on and above silanol clusters) in the range of few tens of milliseconds. Furthermore, time series of SM spectra from Nile Red in 25 nm thick poly-n-alkyl-methacrylate (PnAMA) films were studied. In analogy to translational diffusion, spectral diffusion (shifts in energetic positions of SM spectra) can be studied by probability distributions of spectral diffusivities, i.e. time scaled square energetic displacements. Simulations were run and analyzed to study contributions from noise and fitting uncertainty to spectral diffusion. Furthermore the effect of spectral jumps during acquisition of a SM spectrum was investigated. Probability distributions of spectral diffusivites of Nile Red probing vitreous PnAMA films reveal a two-level system. In contrast, such probability distributions obtained from Nile Red within a 25 nm thick poly-n-butylmethacrylate film around glass transition and in the melt state, display larger spectral jumps. Moreover, for longer alkyl side chains a solvent shift to higher energies is observed, which supports the idea of nanophase separation within those polymers.