In this work, we were able to take advantage of a deregulated wnt signaling pathway – a condition which is found in most gastrointestinal cancers, in particular in colorectal carcinomas. In order to restrict reporter gene expression to the desired cell type, we utilized the β-catenin dependent CTP4-promoter to restrict the expression of Firefly Luciferase and enhanced green fluorescent fusion protein (EGFPLuc) to cell lines with deregulated wnt signaling including SW480, LS174T, HepG2, Coga2 and Coga12. Stable cell lines containing this CTP4-driven EGFPLuc construct were established with the help of a lentiviral vector to monitor wnt activity by transgene expression. With these stably transduced cell lines, we performed a therapeutic target screen via siRNA-mediated knock-down of a number of potentially therapeutic targets within the wnt pathway – osteoprotegerin (OPG), Traf2 and Nck-interacting kinase (TNIK), SRY-related HMG-box (Sox2), protease-activated receptor 1 (PAR-1), β-catenin and transcription factor 4 (TCF4). The in vitro screening system was utilized as a prevalidation tool for therapeutically relevant targets. The degree of interference of our novel targets was determined and the search for a suitable siRNA target in colorectal cancer cells was narrowed down to β-catenin, PAR-1 and TNIK. As proof of principle the siRNA-mediated knock down of β-catenin was verified on mRNA and protein level in LS174T cells. After the initial read-out of various cell lines with different siRNAs has been established via the reduction of Luciferase expression levels, the biological effect of these targets were validated. For this purpose colony formation and cell motility/invasion assays were conducted for all relevant target cell lines. Furthermore in the in vitro experiments, the tumor-selectivtiy of the CTP4-promoter was employed in the delivery of the cytotoxic protein diphteria toxin A (DTA) in colorectal cancer target cells. Data evaluation of all in vitro assays pointed at reduced levels of proliferation, invasive behavior and aggressiveness, which yielded three candidates (PAR-1, TNIK and β-catenin) considered as viable for a treatment attempt in vivo. In the in vivo experiments, systemic delivery of siRNA against β-catenin, sticky siRNA targeting PAR-1 and plasmid DNA encoding for CTP4 controlled DTA were evaluated in a disseminated liver metastasis model of LS174T colorectal cancer. Specific knock-downs of β-catenin and PAR-1 were achieved which was confirmed via mRNA analysis. As for CTP4-DTA pDNA delivery the overall tumor load of the liver was reduced without any significant systemic toxicity, indicating specific DTA expression in tumor tissue. Also knock down of PAR1 using sticky siRNA significantly reduced tumor growth. All in all, the therapeutic effect of PAR-1 and β-catenin knock-down could be verified in various in vitro assays analyzing invasive behavior and anchorage independent growth and ultimately also in vivo. The tumor-specific expression of DTA pDNA could also be confirmed in vitro and was further investigated in an orthotopic liver dissemination model in NMRI nude mice.

Covalent Organic Frameworks (COFs) are a novel class of highly stable, purely organic crystalline frameworks made of molecular building blocks. For example, the condensation of boronic acids with appropriate polyols in principle allows the design of precisely controllable structures since their chemical and physical properties can be easily tuned through the selection of the building blocks. The young research field of COFs has attracted scientists due to their extraordinary and versatile properties, however, strategies to control the topology and the properties of the backbone as well as the inner surface are still not well established. With support of Prof. Knochel and his group, who contributed numerous new organic COF linkers, this thesis aims to extend the functionalization strategies for the design of Covalent Organic Frameworks. Investigation of the structural modification and the associated change in physical and chemical properties should lead to progress regarding the applicability of these materials.

Employing the concept of reticular chemistry in combination with High Throughput Synthesis Techniques, the formation of a very large Covalent Organic Framework BTP-COF with 4 nm open pores was successfully carried out. The solvothermal co-condensation of 1,3,5-benzenetris(4-phenylboronic acid) (BTPA) and 2,3,6,7-tetrahydroxy-9,10-dimethyl-anthracene (THDMA) was carried out using microwave irradiation instead of conventional synthesis in an oven, thus synthesis time of BTP-COF was reduced from initially 72 h to 5 min. Extending the open pore diameter of a crystalline material to 4 nm, in combination with the resulting high accessible surface area of 2000 m2/g offers great potential to exploit organic reactions in the pores and enables the incorporation of large functional guests, such as polymers or dyes. Bearing these results in mind the scope of functionalization possibilities was expanded from the geometric extension to the chemical modification of the inner surface of COFs. Decorating the organic building blocks with small functional active groups, such as methyl-, -methoxy- and hydroxy- allowed for the successful synthesis of several organic frameworks. Chemical and physical properties of the backbone and the inner surface can be precisely tailored by chemical modification of the building blocks. In order to investigate post-synthetic modification strategies, the methyl- and hydroxy-groups were used as reaction anchor points to covalently attach molecules after framework formation. The co-condensation of benzene-1,3,5-triyltriboronic acid (BTBA) and the 9,10-dimethyl-anthracene-2,3,6,7-tetraol (DMAT) succeeded in the formation of AT-COF-Me. In a radical bromination reaction the methyl groups of an anthracene linker were successfully brominated giving AT-COF-Br without degrading the crystalline framework of AT-COF-Me. The formation of the resulting benzylic bromine was monitored with IR spectroscopy and solid state NMR, respectively. Elemental analysis results correspond to the bromination of half the -CH3 groups. Reaction of (2',5'-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-diyl)diboronic acid (HTDBA) and 2,3,6,7,10,11-hexahydroxytri-phenylene (HHTP) The terphenyl-based hydroxyl substituted T-COF-OH, formed by (2',5'-dihydroxy-[1,1':4',1''-terphenyl]-4,4''-diyl)diboronic acid (HTDBA) and 2,3,6,7,10,11-hexahydroxytri-phenylene (HHTP), was tested in several nucleophilic substitution reactions. Esterification of the –OH group was achieved with either acetylchloride or in a Steglich type reaction with 4-pentynoic acid. X-ray diffraction analysis after the post-synthetic modification shows that the crystallinity of the framework was preserved. This indicates that T-COF-OH is compatible with the reaction conditions. The detection of the newly formed ester moieties in IR and in solid state NMR spectra proves the successful post-synthetic esterification of the –OH groups. Another approach to tailor functionality in COFs is to

Die Steuerung von photochemischen Reaktionen durch die gezielte Kontrolle von elektronischen Wellenpaketen mit ultrakurzen Pulsen im Femtosekunden- oder Attosekundenbereich ist Gegenstand von zahlreichen theoretischen und experimentellen Forschungsprojekten. Im ersten Teil dieser Dissertation werden drei molekulare Reaktionen theoretisch untersucht, die durch die gezielte Steuerung der Elektronendynamik kontrolliert werden. Die zeitliche Entwicklung dieser Systeme wird mit einem Ansatz zur Berechnung einer gekoppelten Kern- und Elektronendynamik beschrieben. Die Elektronenlokalisierung in den dissoziativen Ionisation der Modellsysteme D2 und CO wird durch die absolute Phase des Laserfeldes (Phase zwischen Trägerfrequenz und Einhüllenden) gesteuert. Ein Vergleich der beiden Mechanismen zeigt wesentliche Unterschiede zwischen dem homonuklearen Molekül D2 und dem heteronuklearen Molekül CO. Diese Unterschiede treten sowohl in der Präparation des elektronischen Wellenpaketes und in der Rolle der absoluten Phase des Laserfeldes in der Kontrolle, als auch im Stopp der induzierten Dynamik Elektronenbewegung zu Tage.

Durch die selektive Population von lichtbekleideten Zuständen, die durch die relative Phase zweier Pulse in einer Pulssequenz gesteuert wird, lassen sich im Kalium-Dimer zwei unterschiedliche, elektronisch angeregte Zustände kontrolliert besetzen. Diese dritte Reaktion wird zunächst mit einer Doppelpulssequenz implementiert und die Effizienz durch Variation der beiden Parameter Verzögerungszeit zwischen den beiden Subpulsen und Intensität des zweiten Hauptpulses optimiert. Für beide Zustände wurde eine maximale Effizienz von 66% erreicht. Eine Verlängerung der Verzögerungszeit zwischen den beiden Subpulsen führt zu einer signifikanten Abnahme der Effizienz. Eine Analyse dieses Effekts zeigt, dass dieser Verlust der Kontrolleffizienz durch die Kopplung zwischen Kern-- und Elektronendynamik verursacht wird. OCT-Optimierungen an diesem System führen zu einer erheblichen Steigerung der Kontrolleffizienz und erlauben den Rückschluss, dass dieser Starkfeld-Mechanismus im OCT-Suchraum liegt und somit robust und effizient ist.

Aufbauend auf diesen Untersuchungen werden die Faktoren identifiziert, welche ausschlaggebend für das optimale Zeitfenster der Kontrolle der Elektronendynamik sind. Mit diesen Erkenntnissen wird eine neue Kontrollstrategie für Photoreaktionen, die über konische Durchschneidungen verlaufen, entwickelt. Das vorgeschlagene Reaktionsschema wird an einem Modellsystem mit experimentell realisierbaren Pulsen getestet. Die kontrollierbaren Populationsverhältnisse bewegen sich in den Grenzen zwischen 24:76 und 74:26%.

Im zweiten Teil dieser Dissertation werden theoretische Methoden zur Beschreibung der Starkfeld-Ionisationen von Molekülen neu entwickelt bzw. existierende Methoden modifiziert. Die Starkfeld-Ionisation ist in vielen Experimenten der erste Teilschritt, auf dem alle folgenden aufbauen. Daher ist eine exakte Berechnung dieses Prozesses für eine genaue Beschreibung der Experimente ausschlaggebend. Der Fokus der Untersuchungen liegt vor allem auf der Winkelabhängigkeit des Ionisationsprozesses und auf dem Ionisationszeitpunkt. Für die Berechnung der winkelabhängigen Ionisationswahrscheinlichkeiten wird ein neu entwickelter, quantenmechanischer Ansatz vorgestellt und an der dissoziativen Ionisation der Moleküle D2, N2, O2 und CO getestet. Für die Berechnung des Ionisationszeitpunktes wird der Monte-Carlo-Wellenpaket-Ansatz verwendet und für die Beschreibung zweiatomiger Moleküle verallgemeinert. Sowohl die ursprüngliche Methode als auch die Erweiterung werden an der Doppelionisation des H2-Moleküls als Modellsystem getestet.