Ornithodoros peropteryx (Acari Argasidae) in Bolivia an argasid tick with a single nymphal stage

By the end of the 1960s, the argasid tick Ornithodoros peropteryx was described from larval specimens collected from the bat Peropteryx macrotis in Colombia. Since its original description, no additional record of O. peropteryx has been reported, and its post-larval stages have remained unknown. During July 2010, 18 larvae were collected from 9 bats (Centronycteris maximiliani), resulting in a mean infestation of 2.0 ± 2.2 ticks per bat (range 1–8). These bats were captured in a farm in northeastern Bolivia close to Guapore´ River in the border with Brazil. Morphological examinations of the larvae revealed them to represent the species O. peropteryx. One engorged larva that was kept alive in the laboratory moulted to a nymph after 9 days. Fourteen days after the larval moulting, the nymph moulted to an adult female without taking any blood meal during the nymphal period. This adult female was used for a morphological description of the female stage of O. peropteryx. In addition, the larvae were used for a morphological redescription of this stage. One larva and two legs extirpated from the adult female were submitted to DNA extraction and PCR targeting a fragment of the mitochondrial 16S rDNA gene, which yielded DNA sequences at least 11 % divergent from any available argasid sequence in Genbank. We show that O. peropteryx ontogeny is characterized by a single, non-feeding, nymphal stage. This condition has never been reported for ticks.

Solución de bajo coste de captura de movimiento basada en Kinect

[ES] En este trabajo se estudia e implementa una solución de bajo coste basada en Kinect para la captura de movimiento y su integración con Blender, de manera que se cuente con una solución eficiente para la realización de captura de movimiento en animación. Dicho desarrollo está apoyado con la elaboración de un tutorial sobre el procedimiento necesario para realizar MOCAP con Kinect y Blender, facilitando así su uso con fines formativos.

Motion control and real-time systems: an approach to trajectory rebuilding in non-deterministic networks

Motion control is a sub-field of automation, in which the position and/or velocity of machines are controlled using some type of device. In motion control the position, velocity, force, pressure, etc., profiles are designed in such a way that the different mechanical parts work as an harmonious whole in which a perfect synchronization must be achieved. The real-time exchange of information in the distributed system that is nowadays an industrial plant plays an important role in order to achieve always better performance, better effectiveness and better safety. The network for connecting field devices such as sensors, actuators, field controllers such as PLCs, regulators, drive controller etc., and man-machine interfaces is commonly called fieldbus. Since the motion transmission is now task of the communication system, and not more of kinematic chains as in the past, the communication protocol must assure that the desired profiles, and their properties, are correctly transmitted to the axes then reproduced or else the synchronization among the different parts is lost with all the resulting consequences. In this thesis, the problem of trajectory reconstruction in the case of an event-triggered communication system is faced. The most important feature that a real-time communication system must have is the preservation of the following temporal and spatial properties: absolute temporal consistency, relative temporal consistency, spatial consistency. Starting from the basic system composed by one master and one slave and passing through systems made up by many slaves and one master or many masters and one slave, the problems in the profile reconstruction and temporal properties preservation, and subsequently the synchronization of different profiles in network adopting an event-triggered communication system, have been shown. These networks are characterized by the fact that a common knowledge of the global time is not available. Therefore they are non-deterministic networks. Each topology is analyzed and the proposed solution based on phase-locked loops adopted for the basic master-slave case has been improved to face with the other configurations.

Middleware per la gestione di interfacce di comunicazione e di sorgenti di contesto in ambienti wireless eterogenei

The full exploitation of multi-hop multi-path connectivity opportunities offered by heterogeneous wireless interfaces could enable innovative Always Best Served (ABS) deployment scenarios where mobile clients dynamically self-organize to offer/exploit Internet connectivity at best. Only novel middleware solutions based on heterogeneous context information can seamlessly enable this scenario: middleware solutions should i) provide a translucent access to low-level components, to achieve both fully aware and simplified pre-configured interactions, ii) permit to fully exploit communication interface capabilities, i.e., not only getting but also providing connectivity in a peer-to-peer fashion, thus relieving final users and application developers from the burden of directly managing wireless interface heterogeneity, and iii) consider user mobility as crucial context information evaluating at provision time the suitability of available Internet points of access differently when the mobile client is still or in motion. The novelty of this research work resides in three primary points. First of all, it proposes a novel model and taxonomy providing a common vocabulary to easily describe and position solutions in the area of context-aware autonomic management of preferred network opportunities. Secondly, it presents PoSIM, a context-aware middleware for the synergic exploitation and control of heterogeneous positioning systems that facilitates the development and portability of location-based services. PoSIM is translucent, i.e., it can provide application developers with differentiated visibility of data characteristics and control possibilities of available positioning solutions, thus dynamically adapting to application-specific deployment requirements and enabling cross-layer management decisions. Finally, it provides the MMHC solution for the self-organization of multi-hop multi-path heterogeneous connectivity. MMHC considers a limited set of practical indicators on node mobility and wireless network characteristics for a coarsegrained estimation of expected reliability/quality of multi-hop paths available at runtime. In particular, MMHC manages the durability/throughput-aware formation and selection of different multi-hop paths simultaneously. Furthermore, MMHC provides a novel solution based on adaptive buffers, proactively managed based on handover prediction, to support continuous services, especially by pre-fetching multimedia contents to avoid streaming interruptions.

Functional photoactive and electroactive nanodevices

Most of current ultra-miniaturized devices are obtained by the top-down approach, in which nanoscale components are fabricated by cutting down larger precursors. Since this physical-engineering method is reaching its limits, especially for components below 30 nm in size, alternative strategies are necessary. Of particular appeal to chemists is the supramolecular bottom-up approach to nanotechnology, a methodology that utilizes the principles of molecular recognition to build materials and devices from molecular components. The subject of this thesis is the photophysical and electrochemical investigation of nanodevices obtained harnessing the principles of supramolecular chemistry. These systems operate in solution-based environments and are investigated at the ensemble level. The majority of the chemical systems discussed here are based on pseudorotaxanes and catenanes. Such supramolecular systems represent prototypes of molecular machines since they are capable of performing simple controlled mechanical movements. Their properties and operation are strictly related to the supramolecular interactions between molecular components (generally photoactive or electroactive molecules) and to the possibility of modulating such interactions by means of external stimuli. The main issues addressed throughout the thesis are: (i) the analysis of the factors that can affect the architecture and perturb the stability of supramolecular systems; (ii) the possibility of controlling the direction of supramolecular motions exploiting the molecular information content; (iii) the development of switchable supramolecular polymers starting from simple host-guest complexes; (iv) the capability of some molecular machines to process information at molecular level, thus behaving as logic devices; (v) the behaviour of molecular machine components in a biological-type environment; (vi) the study of chemically functionalized metal nanoparticles by second harmonic generation spectroscopy.

Method development using ICP-MS and LA-ICP-MS and their application in environmental and material science

Within this PhD thesis several methods were developed and validated which can find applicationare suitable for environmental sample and material science and should be applicable for monitoring of particular radionuclides and the analysis of the chemical composition of construction materials in the frame of ESS project. The study demonstrated that ICP-MS is a powerful analytical technique for ultrasensitive determination of 129I, 90Sr and lanthanides in both artificial and environmental samples such as water and soil. In particular ICP-MS with collision cell allows measuring extremely low isotope ratios of iodine. It was demonstrated that isotope ratios of 129I/127I as low as 10-7 can be measured with an accuracy and precision suitable for distinguishing sample origins. ICP-MS with collision cell, in particular in combination with cool plasma conditions, reduces the influence of isobaric interferences on m/z = 90 and is therefore well-suited for 90Sr analysis in water samples. However, the applied ICP-CC-QMS in this work is limited for the measurement of 90Sr due to the tailing of 88Sr+ and in particular Daly detector noise. Hyphenation of capillary electrophoresis with ICP-MS was shown to resolve atomic ions of all lanthanides and polyatomic interferences. The elimination of polyatomic and isobaric ICP-MS interferences was accomplished without compromising the sensitivity by the use of a high resolution mode as available on ICP-SFMS. Combination of laser ablation with ICP-MS allowed direct micro and local uranium isotope ratio measurements at the ultratrace concentrations on the surface of biological samples. In particular, the application of a cooled laser ablation chamber improves the precision and accuracy of uranium isotopic ratios measurements in comparison to the non-cooled laser ablation chamber by up to one order of magnitude. In order to reduce the quantification problem, a mono gas on-line solution-based calibration was built based on the insertion of a microflow nebulizer DS-5 directly into the laser ablation chamber. A micro local method to determine the lateral element distribution on NiCrAlY-based alloy and coating after oxidation in air was tested and validated. Calibration procedures involving external calibration, quantification by relative sensitivity coefficients (RSCs) and solution-based calibration were investigated. The analytical method was validated by comparison of the LA-ICP-MS results with data acquired by EDX.

Neue 18 F-markierte Liganden zur Visualisierung des GABA A, alpha 5-Rezeptorstatus mittels PET

Die heutige Verfügbarkeit der molekularen Bildgebung ermöglicht einen signifikanten Einfluss auf die Diagnostik und die Therapiekontrolle von neurodegenerativen Erkrankungen, die unter anderem durch Fehlsteuerungen im GABAergen System auftreten können. Die Visualisierung und Quantifizierung des GABAA-alpha5-Subtyps durch PET könnte dabei zu einem besseren Verständnis von Erkrankungen wie Alzheimer und traumatischen Neurosen (emotionales Langzeitgedächtnis) beitragen. Ferner eröffnen GABAA/alpha5-subtypselektive Liganden die Möglichkeit, wesentliche Grundlagen der elementaren Vorgänge von Lernen und Erinnern zu untersuchen. 7,8,9,10-Tetrahydro-(7,10-ethan)-1,2,4-triazol[3,4-alpha]phthalazine stellen sich als vielverspre-chende Leitstrukturen zur Entwicklung neuer 18F-markierter alpha5-subtypselektiver GABAA-Rezeptorliganden für die PET dar. Um diese neuartigen Substanzen hinsichtlich ihrer Potenz als GABAA-alpha5-subtypselektive Radioliganden zu verifizieren, wurden zunächst die entsprechenden 19F-Derivate TC07-TC12 synthetisiert. Diese Referenzverbindungen wurden in Rezeptor-bindungsassays und in Autoradiographien mit [3H]Ro 15-4513 als zu verdrängender Radioligand evaluiert. In beiden Experimenten als auch in in vivo-Verdrängungsexperimenten an Ratten konnte eine hohe Affinität im nanomolaren Bereich als auch eine hohe Selektivität bezüglich der GABAA/alpha5-Untereinheit für einige der dargestellten Referenzverbindungen nachgewiesen werden. Gemäß diesen vielversprechenden Ergebnissen wurden verschiedene Markie-rungsvorläufer für eine 18F-Direktmarkierung der relevantesten Substanz TC07 in einer mehrstufigen organischen Synthese dargestellt. Die anschließende 18F-Markierung erfolgte über eine nukleophile Substitution mit [18F]Fluorid. Die Reaktionsparameter wurden hinsichtlich Reaktionstemperatur und dauer, Markierungsvorläuferkonzentration, Basenabhängigkeit und verschiedenen Markierungsmethoden optimiert. Daraus resultierend konnte [18F]TC07 mit bis zu 45 % radiochemischer Ausbeute erhalten werden. Die zerfallskorrigierte, gesamtradiochemische Ausbeute von nca [18F]TC07 in isotonischer NaCl-Lösung betrug 15 %. Basierend auf den bisher erhaltenen Ergebnissen wurde der Radioligand in in vitro-, ex vivo- und in vivo µPET-Experimenten evaluiert. Die zunächst durchgeführten in vitro-Experimente deuteten auf eine homogene Verteilung der Aktivität hin und zeigten keine spezifische Anreicherung. Diese Ergebnisse wurden sowohl in ex vivo- als auch in in vivo-µPET-Studien bestätigt. Auch hier konnte nur eine niedrige Aktivitätsanreicherung, eine homogene Verteilung im gesamten Gehirn und keine Übereinstimmung mit der bekannten GABAA/alpha5-Subtypverteilung gefunden werden. Eine im Anschluss durchgeführte Metabolismusstudie zeigte eine langsame Metabolisierungsrate des [18F]TC07 und auch eine Organverteilungsstudie zeigte keine außergewöhnlichen Anreicherungen. Aus den erhaltenen Ergebnissen kann geschlossen werden, dass der Radioligand [18F]TC07 kein geeigneter Tracer zur in vivo-Visualisierung der alpha5-Untereinheit des GABAA-Rezeptors ist.

Sequence-controlled synthesis of soluble oligo(p-benzamide)s

This work focused on the synthesis of novel monomers for the design of a series of oligo(p-benzamide)s following two approaches: iterative solution synthesis and automated solid phase protocols. These approaches present a useful method to the sequence-controlled synthesis of side-chain and main-chain functionalized oligomers for the preparation of an immense variety of nanoscaffolds. The challenge in the synthesis of such materials was their modification, while maintaining the characteristic properties (physical-chemical properties, shape persistence and anisotropy). The strategy for the preparation of predictable superstructures was devote to the selective control of noncovalent interactions, monodispersity and monomer sequence. In addition to this, the structure-properties correlation of the prepared rod-like soluble materials was pointed. The first approach involved the solution-based aramide synthesis via introduction of 2,4-dimethoxybenzyl N-amide protective group via an iterative synthetic strategy The second approach focused on the implementation of the salicylic acid scaffold to introduce substituents on the aromatic backbone for the stabilization of the OPBA-rotamers. The prepared oligomers were analyzed regarding their solubility and aggregation properties by systematically changing the degree of rotational freedom of the amide bonds, side chain polarity, monomer sequence and degree of oligomerization. The syntheses were performed on a modified commercial peptide synthesizer using a combination of fluorenylmethoxycarbonyl (Fmoc) and aramide chemistry. The automated synthesis allowed the preparation of aramides with potential applications as nanoscaffolds in supramolecular chemistry, e.g. comb-like-

Valutazione della presenza di contaminanti perfluoroalchilici in alimenti destinati al consumo umano

Le sostanze perfluoralchiliche (PFAS), composti fluorurati ampiamente utilizzati negli ultimi anni in diverse applicazioni industriali e commerciali, sono ritrovati diffusamente nell’ambiente e in diverse specie animali. Recentemente i PFAS hanno destato preoccupazione anche per la salute umana. Il rischio di esposizione è principalmente legato alla dieta (i prodotti ittici sembrano essere gli alimenti più contaminati). Lo scopo di questo lavoro è stato quello di valutare la presenza del perfluorottanosulfonato (PFOS) e dell’acido perfluorottanoico (PFOA), in diverse matrici alimentari: latte vaccino commercialmente disponibile in Italia, latte materno italiano, diverse specie di pesce commercialmente disponibili in Italia e 140 branzini di diverse aree (principalmente Mediterraneo). I campioni di latte sono stati trattati con estrazione liquido-liquido seguita da due fasi di purificazione mediante cartucce SPE prima dell’iniezione nell’UPLC-MS/MS. L’analisi del latte vaccino ha evidenziato una contaminazione diffusa di PFOS, ma a basse concentrazioni (fino a 97 ng/L), mentre il PFOA è stato ritrovato raramente. In questo studio, in grado di individuare anche i livelli delle ultra-tracce, sono state osservate nel latte materno concentrazioni di 15-288 ng/L per il PFOS e di 24-241 ng/LPFOA. Le concentrazioni e le frequenze più alte, per entrambi i PFAS, sono stati ritrovate in campioni di latte forniti da donne primipare, suggerendo un rischio di esposizione per i primogeniti. Il metodo utilizzato per i campioni di pesce era basato su un’estrazione con solvente organico seguita da due fasi di purificazione: una con i sali e una con fase solida dispersiva. L’estratto, analizzato in UPLC-MS/MS, ha confermato la contaminazione di questa matrice a livelli significativi, ma anche l’alta variabilità delle concentrazioni misurate. Il monitoraggio monospecie ha mostrato una contaminazione rilevante (PFOS 11,1- > 10000 ng/L; PFOA < 9-487 ng/L), soprattutto nei branzini pescati, rispetto a quelli allevati.

Identification of stock units of Mullus barbatus (Linnaeus, 1758) in the Italian seas: development of genomic 2b-RAD markers and biological variation analysis.

This thesis is settled within the STOCKMAPPING project, which represents one of the studies that were developed in the framework of RITMARE Flagship project. The main goals of STOCKMAPPING were the creation of a genomic mapping for stocks of demersal target species and the assembling of a database of population genomic, in order to identify stocks and stocks boundaries. The thesis focuses on three main objectives representing the core for the initial assessment of the methodologies and structure that would be applied to the entire STOCKMAPPING project: individuation of an analytical design to identify and locate stocks and stocks boundaries of Mullus barbatus, application of a multidisciplinary approach to validate biological methods and an initial assessment and improvement for the genotyping by sequencing technique utilized (2b-RAD). The first step is the individuation of an analytical design that has to take in to account the biological characteristics of red mullet and being representative for STOCKMAPPING commitments. In this framework a reduction and selection steps was needed due to budget reduction. Sampling areas were ranked according the individuation of four priorities. To guarantee a multidisciplinary approach the biological data associated to the collected samples were used to investigate differences between sampling areas and GSAs. Genomic techniques were applied to red mullet for the first time so an initial assessment of molecular protocols for DNA extraction and 2b-RAD processing were needed. At the end 192 good quality DNAs have been extracted and eight samples have been processed with 2b-RAD. Utilizing the software Stacks for sequences analyses a great number of SNPs markers among the eight samples have been identified. Several tests have been performed changing the main parameter of the Stacks pipeline in order to identify the most explicative and functional sets of parameters.

Wet chemistry synthesis towards nanostructures of thermoelectric antimonides

Die vorliegende Arbeit befasst sich mit der Synthese von nanostrukturierten Antimoniden, wobei die folgenden beiden Themen bearbeitet wurden: rnAus chemischer Sicht wurden neue Synthesewege entwickelt, um Nanopartikel der Verbindungen in den binären Systemen Zn-Sb und Fe-Sb herzustellen (Zn4Sb3, ZnSb, FeSb2, Fe1+xSb). Anders als in konventionellen Festkörperreaktionen, die auf die Synthese von Bulk-Materialien oder Einkristallen zielen, muss die Synthese von Nanopartikeln Agglomerate und Ostwald-Wachstum vermeiden. Daher benötigen annehmbare Reaktionszeiten und vergleichsweise tiefe Reaktionstemperaturen kurze Diffusionswege und tiefe Aktivierungsbarrieren. Demzufolge bedient sich die Synthese der Reaktion von Antimon-Nanopartikeln und geeigneten molekularen oder nanopartikulären Edukten der entsprechenden Übergangsmetalle. Zusätzlich wurden anisotrope ZnSb Strukturen synthetisiert, indem eine Templat-Synthese mit Hilfe von anodisierten Aluminiumoxid- oder Polycarbonat-Membranen angewandt wurde. rnDie erhaltenen Produkte wurden hauptsächlich durch Röntgen-Diffraktion und Elektronenmikroskopie untersucht. Die Auswertung der Pulver Röntgendiffraktions-Daten stellte eine Herausforderung dar, da die Nanostrukturierung und die Anwesenheit von mehreren Phasen zu verbreiterten und überlagernden Reflexen führen. Zusätzliche Fe-Mößbauer Messungen wurden im Falle der Fe-Sb Produkte vorgenommen, um detailliertere Informationen über die genaue Zusammensetzung zu erhalten. Die erstmals hergestellte Phase Zn1+xSb wurde einer detaillierten Kristallstrukturanalyse unterzogen, die mit Hilfe einer neuen Diffraktionsmethode, der automatisierten Elektronen Diffraktions Tomographie, durchgeführt wurde.rnrnAus physikalischer Sicht sind Zn4Sb3, ZnSb und FeSb2 interessante thermoelektrische Materialien, die aufgrund ihrer Fähigkeit thermische in elektrische Energie umzuwandeln, großes Interesse geweckt haben. Nanostrukturierte thermoelektrische Materialien zeigen dabei eine höhere Umwandlungseffizienz zu erhöhen, da deren thermische Leitfähigkeit herabgesetzt ist. Da thermoelektrische Bauteile aus dichten Bulk-Materialien gefertigt werden, spielte die Verfestigung der synthetisierten nanopartikulären Pulver eine große Rolle. Die als „Spark Plasma Sintering“ bezeichnete Methode wurde eingesetzt, um die Proben zu pressen. Dies ermöglicht schnelles Heizen und Abkühlen der Probe und kann so das bei klassischen Heißpress-Methoden unvermeidliche Kristallitwachstum verringern. Die optimalen Bedingungen für das Spark Plasma Sintern zu finden, ist Inhalt von bestehender und weiterführender Forschung. rnEin Problem stellt die Stabilität der Proben während des Sinterns dar. Trotz des schnellen Pressens wurde eine teilweise Zersetzung im Falle des Zn1+xSb beobachtet, wie mit Hilfe von Synchrotrondiffraktionsuntersuchungen aufgedeckt wurde. Morphologie und Dichte der verschiedenen verfestigten Materialien wurden mittels Rasterelektronenmikroskopie und Lasermikroskopie bestimmt. Die Gitterdynamik wurde mit Hilfe von Wärmekapazitätsmessungen- und inelastischer Kern-Streuung untersucht. Die Wärmeleitfähigkeit der nanostrukturierten Materialien ist im Vergleich zu den Festkörpern ist drastisch reduziert - im Falle des FeSb2 um mehr als zwei Größenordnungen. Abhängig von der Zusammensetzung und mechanischen Härte wurden für einen Teil der verfestigten Nanomaterialien die thermoelektrische Eigenschaften, wie Seebeck Koeffizient, elektrische und Wärmeleitfähigkeit, gemessen.rn

Template-assisted patterning of functional polymers

In this thesis, anodic aluminum oxide (AAO) membranes, which provide well-aligned uniform mesoscopic pores with adjustable pore parameters, were fabricated and successfully utilized as templates for the fabrication of functional organic nanowires, nanorods and the respective well-ordered arrays. The template-assisted patterning technique was successfully applied for the realization of different objectives:rnHigh-density and well-ordered arrays of hole-conducting nanorods composed of cross-linked triphenylamine (TPA) and tetraphenylbenzidine (TPD) derivatives on conductive substrates like ITO/glass have been successfully fabricated. By applying a freeze-drying technique to remove the aqueous medium after the wet-chemical etching of the template, aggregation and collapsing of the rods was prevented and macroscopic areas of perfectly freestanding nanorods were feasible. Based on the hole-conducting nanorod arrays and their subsequent embedding into an electron-conducting polymer matrix via spin-coating, a novel routine concept for the fabrication of well-ordered all-organic bulk heterojunction for organic photovoltaic applications was successfully demonstrated. The increased donor/acceptor interface of the fabricated devices resulted in a remarkable increase of the photoluminescence quenching compared to a planar bilayer morphology. Further, the fundamental working principle of the templating approach for the solution-based all-organic photovoltaic device was demonstrated for the first time.rnFurthermore, in order to broaden the applicability of patterned surfaces, which are feasible via the template-based patterning of functional materials, AAO with hierarchically branched pores were fabricated and utilized as templates. By pursuing the common templating process hierarchically polymeric replicas, which show remarkable similarities with interesting biostructures, like the surface of the lotus leaf and the feet of a gecko, were successfully prepared.rnIn contrast to the direct infiltration of organic functional materials, a novel route for the fabrication of functional nanowires via post-modification of reactive nanowires was established. Therefore, reactive nanowires based on cross-linked pentafluorophenylesters were fabricated by utilizing AAO templates. The post-modification with fluorescent dyes was demonstrated. Furthermore, reactive wires were converted into well-dispersed poly(N-isopropylacrylamide) (PNIPAM) hydrogels, which exhibit a thermal-responsive reversible phase transition. The reversible thermal-responsible swelling of the PNIPAM nanowires exhibited a more than 50 % extended length than in the collapsed PNIPAM state. rnLast but not least, the shape-anisotropic pores of AAO were utilized to uniformly align the mesogens of a nematic liquid crystalline elastomer. Liquid crystalline nanowires with a narrow size distribution and uniform orientation of the liquid crystalline material were fabricated. It was shown that during the transition from the nematic to the isotropic phase the rod’s length shortened by roughly 40 percent. As such these liquid crystalline elastomeric nanowires may find application, as wire-shaped nanoactuators in various fields of research, like lab-on-chip systems, micro fluidics and biomimetics.rn

Synthesis of polyphenylene cylinders with different sizes and connectivity patterns as well as study of their linear congeners

In dieser Arbeit wird die Synthese von Polyphenylenzylindern (PPZ) und strukturell verwandten Molekülen beschrieben, die in unterschiedlichen Größen und verschiedenartigen Bindungsmustern dargestellt wurden. Aufgrund ihres Aufbaus sind sie direkte Vorläufermoleküle von Kohlenstoffnanoröhren (CNT)s. Ziel war es, zunächst zu untersuchen, ob sich PPZs darstellen lassen. In einem anschließenden Schritt wurde die nasschemische Synthese von CNTs untersucht, die auf diesem Weg bisher noch nicht erreicht werden konnte. Die hier studierten Strukturen führten zu vielversprechenden Ergebnisse auf diesem Weg, da die oxidative Cyclodehydrierung – eine intramolekulare Anellierung – zur Bildung von ca. 50% der notwendigen Bindungen führte.

Dotierte Nanographenstreifen mit definierten Randstrukturen

Die in der vorliegenden Dissertation entwickelten organochemischen Protokolle und Konzepte erweitern die Bottom-Up-Synthese von atompräzisen Nanographenstreifen (GNR) um zwei fundamentale Bereiche. Zum einen die Dotierung der halbleitenden GNR mit Schwefel oder Stickstoffatomen und zum anderen ein Protokoll für eine lösungsbasierte Synthese von stickstoffdotierten Zickzack-Streifen.rnDie Dotierung von GNR beinhaltet die Synthese von monomeren Bausteinen bei denen, im Gegensatz zu ihren reinen Kohlenstoffhomologen, definierte Positionen am Rand mit zwei oder vier Stickstoff- beziehungsweise zwei Schwefelatomen ersetzt wurden. Die Synthese atompräziser GNR konnte mit verschiedenen experimentellen Methoden analysiert und anschaulich über STM visualisiert werden. Neben einer n-Dotierung gelang so auch erstmals eine Bottom-Up-Synthese von schwefeldotierten GNR. Eine mögliche Anwendung in der Nanoelektronik aufbauend auf dotierten GNR wurde bestätigt, indem durch Co-Polymerisation von stickstoffhaltigen mit reinen Kohlenstoffmonomeren Heteroschnittstellen zwischen dotierten und undotierten Bereichen hergestellt werden konnten. Solche Heteroschnittstellen sind fundamentale Grundlage von Dioden und damit Basis einer Vielzahl elektronischer Elemente wie Solarzellen oder Leuchtdioden.rnWährend für halbleitende GNR mit einer Armlehnen-Form ein breites Spektrum an organischen Syntheseprotokollen zur Verfügung stand, existierte zu Beginn dieser Arbeit keines für GNR mit Zickzack-Struktur. Innerhalb dieser Arbeit konnte eine Bottom-Up-Synthese zur Erschließung stickstoffdotierter GNR mit Zickzack-Randstruktur erarbeitet werden. Durch die Verwendung eines (2-Hydroxymethyl)phenylboronsäureesters werden Hydroxymethylsubsituenten entlang eines Polyphenylenrückgrats eingebaut, die nach Kondensation mit dem Stickstoffatom eine Zickzack-Kante ergeben. Innerhalb der synthetisierten Zielstrukturen kann das 9a-Azaphenalen als letztes, bislang nicht erschlossenes Isomer der Azaphenalene, als wiederkehrende Struktur, gefunden werden. Die Reaktivität der Zickzackkante konnte zudem zum Aufbau einer Vielzahl bislang unzugänglicher, polycyclischer Heteroaromaten über 1,3-dipolare Addition dieses polycyclischen Azomethin Ylides (PAMY) genutzt werden.rn

From polyarylated cycloparaphenylenes to carbon nanotube segments and metallo N 4-macrocycles as fuel cell catalysts

In this work the synthesis of polyarylated cycloparaphenylenes (CPPs) is described in order to form structurally defined carbon nanotube (CNT) segments by the Scholl reaction. Therefore, polyphenylene macrocycles in different sizes and substitution patterns were synthesized. The influence of the ring-strain on the oxidative cyclodehydrogenation of these macrocycles towards CNT segments was investigated. It was demonstrated that a selective solution based bottom-up synthesis of CNT segments could be accomplished, having polyarylated CPPs, sufficient in size and with the right substituents at the critical positions. These findings mark an important step towards the bottom-up synthesis of length- and diameter defined ultrashort CNTsrnIn the second part of this work, novel non-precious metal catalysts (NPMCs) based on phenanthroline-indole macrocycles were synthesized and their electrocatalytic performance in the cathodic oxygen reduction was investigated. It could be demonstrated that all catalysts contributed to the direct 4-electron reduction of oxygen to water in alkaline media and a superior long-term stability was observed. Since these NPMCs are not heat pre-treated, the catalytically active site was structurally well-defined, allowing the investigation of the structure-property relationship. Moreover, it could be shown that these novel NPMCs act as efficient ORR catalysts and could replace the expensive and scarce platinum in fuel cell applications.rn