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A series of homoleptic aminoalcoholates of aluminium, gallium and indium was synthesised and characterised. The monomeric nature of all alkoxides was indicated by NMR spectroscopy in solution and was confirmed for the solid state via single-crystal XRD. These monomeric derivatives are the first structurally characterised homoleptic alkoxides of these metals, which was achieved by a combination of coordinative saturation via the amine donor functionality and steric shielding. Additionally, novel thioether functionalised gallium and indium alkoxides are presented. NMR spectroscopic investigations propose a monomeric state for these alkoxides with a weak interaction of the thioether moiety with the metal centre. In case of asymmetrically functionalised alcoholates featuring amine or ether donors alongside the thioether functionality, coordination of the latter is suppressed and only the stronger amine or ether donor interacts with the metal centre. These findings have been confirmed for the solid state via single-crystal XRD for a limited number of derivatives. Applying these thioether functionalised alkoxides in molecule-to-material conversion processes showed their potency to act as single-source precursors for the formation of oxysulphide materials, which are typically prepared via multi-step or multi-source procedures. Employing LPCVD, gallium alkoxides were converted to amorphous Ga2O3-xSx thin films with strong dependence of the sulphide content of temperature and precursor species. Sulphide contents reached a maximum of x = 1.17 at low temperatures (400 ��C) as obtained via EDX analysis. XPS measurements showed that thin films grown at low temperatures incorporated thioether fragments from incomplete decomposition. Pure sulphide containing oxide coatings could be obtained at temperatures >500 ��C with sulphide contents up to 12 at%. Impedance spectroscopy of selected thin films deposited on interdigitated electrodes showed drastically increased electrical conductivity accompanied by lower activation energy upon oxysulphide formation when compared to a Ga2O3 reference. Investigations of the mechanism of sulphide incorporation via TGA-MS revealed a strong supportive role of the amino functionality in asymmetric aminoalcoholates leading to in situ formation of H2S as a potent sulphidisation agent. Using hot-injection methods all alkoxides could be converted into oxysulphide sub-micron particles exhibiting high sulphide contents. Indium based materials showed particularly high sulphide contents with pure In2S3 phases found in XRD analysis, most likely because of lowered In-O bond strength and hence facilitated conversion to the sulphide. AACVD processes using indium based alkoxides showed the formation of sulphide rich In2O3-xSx thin films and 1D nanostructures. Lastly, a series of transition metal gallates [MIIGa2(OtBu)8] was prepared and characterised via single-crystal XRD showing the expected spirocyclic arrangement. Using them in sol-gel and LPCVD processes led to the formation of the respective MIIGa2O4 spinels for M=Co, Ni. In contrast, for M=Fe, non-stoichiometric deposits and phase separation was observed, most likely caused by susceptibility of the precursor towards oxidation. Copper gallates exhibited thermal instability and increased reactivity leading to copper deficient thin film deposits and phase separation upon sol-gel processing.

Aufgrund der potentiellen Anwendungen in optischen Bauteilen, als Biomarker oder Kontrastmittel wächst das Interesse an Ln-haltigen nanokristallinen Materialien stetig. Die vorliegende Dissertation beschäftigt sich mit neuen Konzepten zur morphologie- und phasenkontrollierten Synthese von Ln-Oxiden und Hydroxiden. Dazu wurden Ln-Alkoxide mit unterschiedlichen Liganden und Metallkombinationen synthetisiert und ihre Eignung als Vorstufen für die Materialsynthese mittels Solvothermal-, Sol-Gel- und CVD-Prozess untersucht. Insbesondere der Einfluss der Precursorchemie auf die hydrolyse- und kondensationsbestimmenden Schritte der Materialbildung wurde eingehend analysiert, wobei die strukturellen Unterschiede im Molekülaufbau unterschiedliche Tendenzen bezüglich Morphologie und Nebenphasenbildung bewirken. Die Kontrolle der Prozessparameter ermöglicht abhängig von der Precursorchemie die Synthese von Ln(OH)3, LnOOH, LnCl(OH)2 und LnOCl. Die Steuerung der Keimbildungsprozesse durch Zusatz von Additiven erlaubt verschiedene Morphologien von Stäbchen bis hin zu Partikeln. Neben monometallischen anorganischen Phasen wurden lumineszierende Komposite dargestellt, in denen optisch aktive Tb3+-Ionen in einer inaktiven Matrix eingebettet sind. In Hinblick auf eine Anwendung in der Nanomedizin wurden Gd(OH)3-Nanostrukturen bezüglich ihrer Zelltoxizität analysiert und Versuche zur Oberflächenfunktionalisierung der Nanomaterialien sowie zur Darstellung von Kern-Schale-Strukturen unternommen. Given the application potential of lanthanide-based materials in optoelectronic devices, biomarkers and contrast agents there is currently enormous interest in the controlled synthesis of nanocrystalline phases. In this work, lanthanide alkoxides with different ligands and metal combinations were synthesized and their molecular structures were determined. The suitability of the obtained compounds as precursors for material synthesis by solvothermal, sol-gel and CVD process was investigated to illustrate influence of precursor chemistry on hydrolysis and condensation reactions. Depending on precursor chemistry and process parameters, the solvothermal treatment resulted in nanocrystalline Ln(OH)3, LnOOH, LnCl(OH)2 and LnOCl. Variation of additives allowed a precise control over the morphology of Ln(OH)3 phases ranging from nanorods to nanoparticles. Besides monometallic inorganic phases, luminescent nanocomposites containing optically active Tb3+-ions in an optically silent matrix were prepared. To demonstrate their potential applications in nanomedicine, cell toxicity of Gd(OH)3 structures was investigated and first effort toward the surface functionalization of nanostructures was undertaken to fabricate core-shell-structures.

Das Ziel der vorliegenden Dissertation war die Synthese neuer Precursoren für die Abscheidung von Oxiden der Elemente Ti, Ta, Ba und Al. Die Bereitstellung von Verbindungen mit für die Verarbeitung im MOCVD Prozess günstigen physikalischen und chemischen Eigenschaften erforderte die Anpassung der jeweiligen Ligandensphäre an das Metallzentrum. Als besonders günstig erwiesen hat sich eine Kombination der 1,2-Difunktionalität der mehrzähnigen Amino-alkohole mit einem hohen sterischem Anspruch am a-C-Atom der Alkoholfunktion. Da die Verwendung der Precursoren in industrienahen MOCVD-Anlagen erfolgte, wurden die Syntheserouten auf die Herstellung im großen Maßstab optimiert. Thermochemische Charakterisierungen insbesondere der Ti- und Ta-Verbindungen wurden als Unterstützung der MOCVD-Experimente wurden ebenfalls durchgeführt. The aim of the dissertation was to synthesize new precursors for the deposition of metal oxides of Ti, Ta, Al, and Ba. In order to reach this goal the ligand spheres was individually adapted by using multi-dentate amino alcohols having sterically crowded carbon atoms in a-position to the alcohol function. Since the precursors are used in industrial size MOCVD devices the synthetic routes were optimized to a big scale preparation. Experiments for the characterization of the thermal behaviour of the compounds in the case of the Ti- and Ta-complexes were also carried out.