Both series of monoglyceride gels samples with different monoglyceride concentration of two monoglycerides C14 and C16/18 and series of water-in-oil emulsions that differ from flocculation, water concentration and biopolymer have been investigated by means of PFG NMR. Aim of the measurements was to determine microstructural parameters characterising such heterogenous systems. For the monoglyceride gels a return-to-the-origin probability, the average surface-to-volume ratio of the pore space as well as the tortuosity and dimensionality of the network could be calculated on the basis of echo attenuation and diffusion curves. Additionally pore size distributions have been determined for the monoglyceride gels. The results verify a postulated crystallisation process for monoglyceride gels and were validated by CryoSEM images and image analysis. The PFG NMR findings of the water-in-oil emulsions have been fitted with four various models which were developed in the context of this thesis and assume different diffusion behaviour of the water molecules. All models show individual deficits as the real movement of water molecules in the water-in-oil emulsions is more complex than assumed. Non flocculated and flocculated emulsions could be characterised and the droplet and aggregate size as well as the effective diffusion coefficient could be calculated. The results have been corroborated by CSLM images and image analysis.

The electrocatalytic characteristics of N4-chelatele electrodes is well known for several redox reactions. The N4-chelate can function thereby according to the principle of the heterogeneous redox catalysis as an intermediate fixed at the electrode surface. The main problem is the limited service life of such electrodes which prohibits the practical application in organic electrosyntheses. The electrochemical properties of N4-chelate electrodes and specially of copper phthalocyanine electrodes were investigated using several electrochemical methods. The results of these measurements lead into a significant refinement of the models of heterogenous redox reaction at N4-chelates. Furthermore models for the degradation process of N4-chelate electrodes could be derived. Finally, quite stable electodes were produced and tested.

The central topic if this work was the comparative assessment of two analytical techniques: Pulsed Field Gradient Nuclear Magnetic Resonance (PFG-NMR) Spectroscopy and the Dynamic Nanosizing Microscopy (DNM). They are focused on the same physical parameter: the self diffusion, for determination of diffusion coefficients and particle sizes. With the methods introduced above nanocapsule dispersions are investigated with regard to their use in pharmaceutical applications. In this work especially the long time stability of dispersions, the dynamic of molecules like surfactants, oil and ethanol as well as the molecular exchange between the capsules and the environment were studied.

Within this thesis, instruments and methods were developed for sampling devices and chemical analysis of PM 10 and PM 2.5. These two particle size fractions are European standards for air quality monitoring since 1999. A specially designed "ambient air sampling system" for the direct collection of PM 10, PM 2.5 and PM 1 on TXRF-sample carriers for subsequent analysis by Total-Reflection X-Ray Fluorescence Analysis (TXRF) was constructed and calibrated in the laboratory. Additionally, a PM 1-Inlet for a High-Volume-Sampler was developed. As a result, the determination of mass concentrations as well as important chemical constituents (anions and cations, elemental and organic carbon, heavy metals, polycyclic aromatic hydrocarbons) is possible for the fine particle fraction PM 1. The newly developed instruments were used together with commercially available PM 10- and PM 2.5-samplers for a field campaign at a traffic-related measurement site. Data analyses showed good results concerning quality assurance and dem onstrated the complementarities of the different sampling systems. A detailed characterization of the ambient aerosols was obtained and a first source apportionment could be conducted. However, the results also showed that for an efficient air pollution reduction strategy, particle size fractionated emission measurements are necessary as well. Therefore, a PM 10/PM 2.5 in-stack cascade impactor was designed and calibrated. During measurements at various industrial plants, the newly developed instrument showed good results concerning reproducibility and plausible data in comparison with mass concentrations obtained with the plane filter device for the determination of total suspended particulates (TSP). A chemical characterization similar to the ambient air particles was conducted with TXRF for some of the samples. The results showed that size fractionated particle sampling together with multielemental analyses give characteristic patterns ("fingerprints") of emissions. In a next step, the information can be used for source apportionment by fingerprintmodelling and the quantification of the contribution of different sources to ambient air particle concentrations.

During the irradiation of 1-acetylnaphthaline in the presence of c,d-substituted olefines with a cyclic amine as a donor different products were generated. The reaction pathways were monitored by NMR-spectroscopy and it was proved that the main products were generated by a Photo-Diels-Alder-reaction. The c,d-olefines are added head-to-tail with the donor substituent in endo-position to the remaining aromatic system. Their structures could unambiguously be proven by single crystal x-ray structure analysis. Furthermore their thermal and photochemical properties were investigated: the activation enthalpies and activation entropies for their thermal decompositions were investigated and during their irradiation in solution with light of 254 nm a Di-<font face="Symbol">p</font>-methane-rearrangement could be observed.

Reactions of photoexcited 1,2-dicarbonyl compounds with chirally labelled and unlabelled captodative alkenes have been investigated, with special emphasis on their diastereoselection in cycloadditions. Irradiation of methyl phenylglyoxylate in presence of unlabelled alkenes yields to the corresponding rel-(2R, 3R)-head-to-head-oxetanes. Using the chirally labelled (S)-(methoxymethylpiperidinyl)propenenitrile gives rise to two oxetanes, one of which was isolated and identified as (2R, 3R)-head-to-head-oxetane by X-ray cristallography. Additionally, the photoreduction product meso-dimethyl-2,3-diphenyltartrate of the ester was formed in all reactions. The photoreactions of benziles with chirally labelled c,d-alkenes give rise to oxetanes in low yields, in these cases the products of Norrish type I reactions become competitive.

The thesis describes the investigation of high-resolution MQ MAS NMR in rigid spin-1/2 systems. Formerly, MQC techniques were mainly applied to systems of small molecules, the newly developed MQC technique in this thesis, the 1H-MQC-filtered-MAS-NMR method, can be well applied to study the heterogeneity of inorganic and organic materials, such as silica gel, homopolymers, copolymers and their blends. In this thesis two multiple-pulse sequences were adopted: the three-pulse and the time-reversible eight-pulse sequence. The former has the advantage that the cycle time, i.e. the excitation time can be adjusted to arbitrary values, therefore it can be used to generate 1H MQC in coupled spin-1/2 systems for a wide range of dipolar interactions, especially to pump 1H MQC from a rigid system, such as the crystalline phase of polymers. But it has disadvantages: it is sensitive to chemical shifts and resonance offsets, and has low efficiency in exciting higher order coherences. The latter has higher efficiency in exciing higher order coherences and is not sensitive to chemical shifts and resonance offsets, but it has a long cycle time, so it is only effective when the dipolar interactions are not strong such as in the amorphous phase of polymers

Im Rahmen dieser Arbeit wurden die Metallzentren der Cytochrom-c-Oxidasen (CCO) aus Thermus thermophilus (T.t.), aus Paracoccus denitrificans (P.d.) und dreier mit gentechnischen Methoden erzeugten Proteine (M227I, C216S, SU II) mit Hilfe der EXAFS-Spektroskopie untersucht. Die EXAFS-Messungen an der löslichen Domäne der Untereinheit II der CCO aus P.d. exprimiert in E. coli (SU II) ermöglichten erstmals die Untersuchung eines CuA-Zentrums mit EXAFS ohne die Überlagerung durch Signale von CuB. Das CuA-Zentrum ist ein zweikerniges Zentrum mit sehr kurzem Cu-Cu-Abstand dessen Kupfer-Atome von zwei (mü)2-Schwefel-Liganden verbrückt werden. Terminal an die beiden Cu-Atome koordiniert jeweils ein Histidin. Es kann nicht ausgeschlossen werden, daß die in verschiedenen Arbeiten als schwach koordinierend diskutierten Methionin- und Glutamat-Backbone-Liganden maskiert und damit nicht zu detektieren sind. Somit ist eine CuA-Zentrum. Am CuB koordinieren drei Histidinliganden. Der mittlere Fe-Cu-Abstand im Fea3/CuB-Zentrum beträgt 3,99 Å. Die beiden Eisenatome des Enzyms sind durch je einen Porphyrin-Ring koordiniert. Das Feb-Zentrum vervollständigt seine Koordination durch zwei axial zum Ring gebundene Histidin-Reste, das Fea3 durch einen axial gebundenen Histidin-Rest. Der Vergleich der EXAFS-Messungen an der CCO aus P.d. mit denen für die CCO aus T.t. zeigt, daß die Metallzentren der beiden Enzyme bis auf Details identisch sind. Das Kupfer-EXAFS der Mutante M227I der CCO aus P.d. zeigt eine Erhöhung der mittleren Koordinationszahl der Kupfer-Atome im mutierten CuA-Zentrum auf vier. Die daraus resultierende strukturelle Änderung bedingt eine Spin-Lokalisation im nativ Spin-delokalisierten Zentrum. Offensichtlich ist das in CCO hochkonservierte Methionin 227 erforderlich, um die einzigartige geometrische und elektronische Struktur des CuA-Zentrums zu stabilisieren. Die spektroskopischen Untersuchungen an der Mutante C216S der CCO aus P.d. zeigen statt des CuA-Zentrums ein einkerniges Kupfer-Zentrum an der Bindungsstelle des dem konservierten Methionin 227 zugewandten Kupferatoms des CuA-Zentrums. Das Zentrum wird durch ein Histidin, ein Cystein, ein Methionin und einen weiteren Liganden (S/Cl) tetraedrisch koordiniert. Es wird deutlich, daß das im CuA verbrückend koordinierende Cystein 216 essentiell zur Bildung eines homodinuklearen Zentrums ist. Ausserdem wurde eine optimierte Meßstrategie entworfen, mit der die zur Verfügung stehende Meßzeit zugunsten der kritischen Bereiche des Spektrums teilweise umverteilt wird. Es wurde eine neuartige Methode zur quantitativen Bestimmung der statistischen Qualität von EXAFS-Spektren entwickelt. Mit Hilfe dieser Methode konnte ein neuartiges dynamisch-adaptives Verfahren zur Glättung von Spektren entwickelt und programmiert werden. Es wurden zusätzlich Erweiterungen zur Standardsoftware Cerius2 entwickelt. Die Erweiterungen ergänzen die Funktion und die Oberfläche des Programms.

This thesis describes the measurement of xenon diffusion coefficients in porous media via Pulsed Field Gradient (PFG) NMR spectroscopy. The thesis includes the characterization of a phase seperated polymer blend (PP/EPDM) in comparison to the pure components, the characterization of a number of commercially available semi-crystalline polymers and the characterization of a new microporous solid catalyst (silconimidonitride) with three different pore sizes by the diffusional behaviour of xenon in these materials. In addition to that a new theory is described which correlates the chemical shift of 129Xe NMR adsorption resonances with the corresponding xenon diffusion coefficients.

Reactions of photoexcited coumarins and their thia analogues with captodative alkenes have been investigated, with special emphasis on the nature of the excited states and the specific influence of the substrates on regio- and stereoselectivity of the observed [2+2]-photocycloadditions. Aside of two coumarin thiones all coumarins investigated regioselectively add captodative alkenes at the pyranone moeity giving rise to head-to-tail [2+2]-photocycloadducts with donor-endo adducts as prevailing isomers. The observed regio- and stereoselectivities can be best explained if a 1,4-biradical is assumed as intermediate in the photocycloaddition.