München, Techn. Univ., Diss., 2000.

Techn. University, Diss., 2005--Chemnitz.

X-ray crystallography is an important analytical method for the characterisation of materials in the solid state. During the last decade, it has become important as a tool in the new field of photocrystallography. This combines both crystallography and photochemistry and is used to monitor the formation of light-induced metastable and transient species, so that structural information can be obtained during the change of a material. This is an important area of research as solid state chemistry can display new phenomena and reveal properties that are not possible in solution. Chapter 1 of this thesis commences with a brief introduction to the different methods used to achieve and measure the excitation within crystalline compounds, while Chapter 2 contains an introduction into diffraction methods. In Chapters 3-5 new photocrystallographic studies were performed on two series of compounds. The first one consists of a systematic study on metal complexes with different pyridylethylene ligands. The focus was to align complexes in the solid state so that they can undergo photo induced cycloaddition reactions. These solid state reactions are important as they present “green synthetic chemistry”. The second study involves the photoinduced linkage isomerisation of [Ni(L)2(NO2)2] complexes. Structural characterisation shows that the NO2 ligands change their coordination mode when irradiated with light of different wavelengths. Conditions for the metastable isomerisation were optimised by altering temperature and wavelengths. In Chapters 6 and 7 a systematic study of structural changes in a series of lanthanide complexes and their use as triboluminescence materials, is described. The proposed mechanism of triboluminescence for these complexes is discussed. To summarise, in this thesis, systematic investigations have been carried out in different aspects of crystallography using appropriate series of compounds. The nature of and the conditions required for the change to occur within the solid state have been established.

In highly polarized cells like neurons, cytoskeleton dynamics play a crucial role in establishing neuronal connections during development and are required for adult plasticity. Actin turnover is particularly important for neurite growth, axon path finding, branching and synaptogenesis. Motoneurons establish several thousand branches that innervate neuromuscular synapses (NMJs). Axonal branching and terminal arborization are fundamental events during the establishment of synapses in motor endplates. Branching process is triggered by the assembly of actin filaments along the axon shaft giving rise to filopodia formation. The unique contribution of the three actin isoforms, α-, β- and γ-actin, in filopodia stability and dynamics during this process is not well characterized. Here, we performed high resolution in situ hybridization and qRT-PCR and showed that in primary mouse motoneurons α-, β- and γ-actin isoforms are expressed and their transcripts are translocated into axons. Using FRAP experiments, we showed that transcripts for α-, β- and γ-actin become locally translated in axonal growth cones and translation hot spots of the axonal branch points. Using live cell imaging, we showed that shRNA depletion of α-actin reduces dynamics of axonal filopodia which correlates with reduced number of collateral branches and impairs axon elongation. Depletion of β-actin correlates with reduced dynamics of growth cone filopoida, disturbs axon elongation and impairs presynaptic differentiation. Also, depletion of γ-actin impairs axonal growth and decreases axonal filopodia dynamics. These findings implicate that actin isoforms accomplish unique functions during development of motor axons. Depletions of β- and γ-actin lead to compensatory upregulation of other two isoforms. Consistent with this, total actin levels remain unaltered and F-actin polymerization capacity is preserved. After the knockdown of either α- or γ-actin, the levels of β-actin increase in the G-actin pool indicating that polymerization and stability of β-actin filaments depend on α- or γ-actin. This study provides evidence both for unique and overlapping function of actin isoforms in motoneuron growth and differentiation. In the soma of developing motoneurons, actin isoforms act redundantly and thus could compensate for each other’s loss. In the axon, α-, β- and γ-actin accomplish specific functions, i.e. β-actin regulates axon elongation and plasticity and α- and γ-actin regulate axonal branching. Furthermore, we show that both axonal transport and local translation of α-, β- and γ-actin isoforms are impaired in Smn knockout motoneurons, indicating a role for Smn protein in RNA granule assembly and local translation of these actin isoforms in primary mouse motoneurons. / In stark polaren Zellen wie den Neuronen ist die Etablierung neuronaler Netzwerke ein entscheidender Faktor bei der Entwicklung des zentralen Nervensystems und spielt für die adulte Plastizität eine wesentliche Rolle. Besonders die Aktindynamik ist wichtig für das Neuritenwachstum, die axonale Wegfindung und Verzweigung, sowie die Synaptogenese. Motoneurone bilden mehrere tausend terminale Verzweigungen aus, um neuromuskuläre Endplatten (NMJ) zu innervieren. Die axonale Verzweigung ist ein fundamentales Ereignis bei Ausbildung synaptischer Verbindungen zwischen Motoneuron und innerviertem Muskel. Die Axonverzweigung geschieht durch die Polymerisierung von Aktin entlang des Axonschafts, was zur Entstehung von Filopodien und Lamellopodien führt. Allerdings ist die genaue Funktion der drei Aktin-Isoformen (α-, β- and γ-Actin), im Zusammenhang mit der Regulation der Filopodienstabilität und deren Dynamik, noch weitestgehend unbekannt. Somit konnten wir in dieser Arbeit mit Hilfe hoch sensitiver in situ Hybridisierungs- und qRT PCR Techniken zeigen, dass in primären Mausmotoneuronen alle drei Aktinisoformen (α-, β- und γ) exprimiert, und deren Transkripte entlang des axonalen Kompartiments transportiert werden. Unsere FRAP Daten weisen darauf hin, dass α-, β- und γ-Aktin sowohl im Wachstumskegel als auch an sogenannten „Translation Hot Spots“ innerhalb axonaler Verzweigungspunkte lokal synthetisiert werden. Anhand von „Live Cell Imaging“ Experimenten konnten wir dann zeigen, dass ein α-Aktin Knockdown die Dynamik axonaler Filopodien stark reduziert, und als Folge, die Anzahl von axonalen Verzweigungen und die Axonlänge verringert ist. Hingegen geht ein β-Aktin Knockdown mit reduzierter Filopodiendynamik im Wachstumskegel und betroffener Differenzierung präsynaptischer Strukturen einher. Veränderungen des axonalen Wachstum und der Filopodiendynamik sind ebenfalls bei einem γ-Aktin Knockdown zu beobachten. Diese Daten weisen darauf hin, dass die drei Aktinisoformen unterschiedliche Funktionen bei der Entwicklung von Motoraxonen haben. Darüber hinaus zeigen unsere Daten, dass die Herunterregulation einer Aktinisoform durch eine erhöhte Expression der beiden anderen Isoformen kompensiert wird. Dieser Kompensationsmechanismus erlaubt es, die gesamte Aktinmenge und somit die F-Aktin-Polymerisation in der Zelle aufrechtzuerhalten. Sehr interessant dabei ist die Beobachtung, dass nach einem α- oder γ-Actin Knockdown das G/F-Verhältnis verändert ist, so dass die Menge an β-Aktin im G-Aktin Pool steigt und im F-Aktin Pool abnimmt. Daher beruhen Polymerisation und Stabilität von β-Aktin auf den α-, und γ-Aktinisoformen. Zusammenfassend lässt sich sagen, dass alle drei Aktinisoformen übergreifende Funktionen während Wachstum und Differenzierung von Motoneuronen haben. Im Zellkörper von sich entwickelnden Motoneuronen übernehmen sie ähnliche Aufgaben und können sich somit gegenseitig kompensieren. Im Gegensatz dazu sind die Funktionen im axonalen Kompartiment wesentlich spezifischer. Hier reguliert β-Aktin axonales Wachstum und Plastizität, während α- und γ-Aktin eine entscheidende Rolle bei der Ausbildung axonaler Verzweigungen haben. Unsere Arbeit lässt nun Rückschlüsse über mögliche Funktionen des SMN Proteins beim Aufbau der sogenannten „RNA Granules“ und lokaler Proteinbiosynthese der verschiedenen Aktinisoformen in primären Mausmotoneuronen zu.

Turning back to look Kaohsiung city¡¦s development and history of exploitation, both of them had a close relationship with the Love River and Chianjen River. Along the rivers, there are numerous industrial estates and large population. The basin of the rivers is important in politics and economy to Kaohsiung. However, the development of Kaohsiung also causes organic pollution, such as polycyclic aromatic hydrocarbon (PAHs), released to water system. Furthermore, some of these pollutants are carcinogenic, so that this topic is quite important. This study investigates PAHs concentrations and seasonal variations in sediments and suspended solids of these two rivers. Total PAHs concentrations varied from 110 to 4300(ng g-1 dry wt) in sediments and 1500 to 7000(ng g-1 dry wt) in suspended solids of the Love River. Total PAHs concentrations of sediments and suspended solids of the Chianjen River exhibited in the range of 230-3900 (ng g-1 dry wt) and 490-9200 (ng g-1 dry wt), respectively. The average PAHs concentration during rain/ dry season of the Chianjen River is significantly higher than those of the Love River. Compared with global data in literature, level of total PAHs concentrations in sediments and suspended solids of the Love River and Chianjen River belongs to moderate pollution. Total PAHs and total organic carbon (TOC) is significantly related except suspended solids of the Chianjen River. However, the relationship between total PAHs concentrations and mean particle size is not significant because of inequilibrium resulted from different sources. Referring to Sediment quality guidelines (SQGs), most of stations are in safe range, only total PAHs concentrations at station L8 in rainy season is significantly higher than the standard ERL value. For each individual compound, the concentrations of many low-molecular-weight PAHs are higher than their standard ERL¡BLET and LAET values. The result of HCA shows that in both dry and rain season, these two rivers¡¦ sediments and suspended solids are separated into upstream and downstream groups. It is believed that the existence of an intercept device set up in midstream of both rivers is the reason. The PAHs in sediments of the Love River is mainly contributed from automobile exhaustion, while suspended solids in the Love River is mainly contributed from petrogenic source. However, both sediments and suspended solids in the Chianjen River are mainly contributed from combustion pollution.

The two-photon decay in nuclei has been formally theorized for many years and attempted to be measured on numerous occasions. The special case of a 0 + → 0 + transition in nuclei was examined for certain isotopes, and a branching ratio for the two-photon decay determined for each isotopes. Measurements of the branching ratio in nuclei other than this special case had so far proven unsuccessful. Motivated to find the two-photon branching ratio in a case where the transition competes with the single photon transition, we study the 11/2 − 137 Ba isomer. The experiment was performed at the Technische Universität Darmstadt using the available LaBr 3 scintillation detectors. We first study the absorption of various gamma energies by lead and compare the resulting values to a GEANT4 simulation. With an ideal value for lead shield thickness, the experimental setup is built in order to obtain a high two-photon count rate, while suppressing direct Compton scattering between detector pairs and suppressing other background interference. In order to suppress the background, plastic scintillators were placed atop the experimental setup. To treat the daunting level of random coincidences measured with this setup, fine energy and time gates were placed on the processed events in order to limit observation to the region of interest. Throughout the experiment, three different detector pair angles were successfully examined: 72 ◦ , 120 ◦ , and 144 ◦ . With these three angles a partial representation of the angular distribution of the two-photon decay is observed. The branching ratios were measured to be 1.56(23)·10 −6 , 0.55(22)·10 −6 , and 0.70(18)·10 −6 for the angles of 72 ◦ , 120 ◦ , and 144 ◦ respectively, with the values of 72 ◦ and 144 ◦ recorded in Ref.[1]. This experiment therefore shows it is possible to obtain a value for the two-photon branching ratio in the 11/2 − excited state of 137 Ba . A precise determination of this value, and for that of other nuclei, might contribute to solve current fundamental open problems such as restricting the parameters of the equation of state, or accurately determining neutron skin thickness.

Thesis advisor: Shih-Yuan Liu / This dissertation describes the utility of 1,2-azaborine motif as a 4C+1B+1N synthon in organic synthesis, especially for the preparation of densely functionalized cyclobutanes based on the framework of the 1,2-azaborine photoisomerization. The substitution of a CC unit with a BN unit in benzenes significantly modifies the properties of classic benzenoid compounds, leading to new reactivities and functionalities. In this vein, Chapter 1 discloses photoisomerization of 1,2-azaborines to selectively form BN-analogues of the Dewar benzene. Three applications of the Dewar photoisomers are described herein: 1) a rhodium-catalyzed ring-opening reaction to form 1,2-azaborines; 2) furnishing cis aminoborylated cyclobutanes with the boron unit as a further functionalization handle; 3) a stereospecific ring-opening reaction to afford diene which can engage in Diels-Alder reaction. Chapter 2 elaborates on a modular and stereoselective strategy to access a variety of cyclobutane β-amino alcohols. Discussed herein are regioselective functionalizations and di-functionalizations of the 1,2-azaborine core and a tandem photoisomerization-hydrogenation-oxidation protocol to translate the functionalized azaborine core to cyclobutane amino alcohols. Also examined herein are the scope of azaborine photoisomerization and Dewar hydrogenation. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

In this study, we investigated the molecular characteristics of hydrates which were synthesized from gas mixtures containing the two isomers of butane, or the pentane isomers neopentane and isopentane, in excess methane. Thereto various techniques, including Raman spectroscopy, powder and single crystal X-ray diffraction and 13C NMR spectroscopy were employed. It turned out that shape and conformation of the guest molecule and hydrate structure both influence each other. In case of the mixed butane hydrate it could be confirmed that n-butane is enclathrated in its gauche conformation. This was verified by Raman spectroscopy, single crystal X-ray diffraction and calculated data. While isopentane is known as a structure H former, our results from powder X-ray diffraction, 13C NMR and ab initio calculations show that it can be also incorporated into structure II when the hydrate is formed from a neopentane/isopentane/methane gas mixture.

Fluorescent imaging technologies that offer new ways to visualise and quantify fluorescently labelled molecules are increasing, necessitating the development of fluorescent molecules that can efficiently and specifically label targets in vitro and in vivo. The first aim of this thesis was the study of human neutrophil elastase. Human neutrophil elastase is an important enzyme in the regulation of inflammation but if over expressed can become part of the cause of inflammation itself. To elucidate this dual function and have a greater understanding of this enzyme, an imaging probe for neutrophil elastase was designed. Firstly, the syntheses of fluorescently labelled three branched dendron core structures were optimised, and studied in neutrophils. The selected core structure was functionalised with an elastase specific peptide sequence and fluorescently labelled. The probe was specifically cleaved by neutrophil elastase in an enzymatic assay and in the presence of activated neutrophils (Chapter 1). Fluorescein and rhodamine are dyes that are readily available, are affordable and have convenient wavelengths for microscopy and flow cytometry. Carboxyfluorescein diacetate N-succinimidyl ester (CFDA-SE) is a commonly used fluorescein derivative, widely used in cell proliferation assay. It is mainly used as a mixture of isomers and its synthesis is not reported. Herein a short and simple synthesis of the two individual isomers of carboxyfluorescein diacetate N-succinimidyl ester as well as the equivalent rhodamine variation (carboxytetraethylrhodamine N-succinimidyl ester) is reported (Chapter 2). The labelling properties of these probes were studied in proliferation assays on mouse and human T lymphocytes. Finally, the nuclear penetration of the dendron structure combined with nuclear localisation sequences (NLS) was investigated. Attachment of nuclear localisation sequences to the probe in the presence of fluorescein demonstrated successful entry into the nucleus in human alveolar adenocarcinoma cell line (A549) (Chapter 3).

A new approach for predicting octanol-water partition coefficients (Log P) of linear perfluorinated compounds, making use of the limited experimental data available, previous observations and the consistent similarities observed between the experimental and calculated (with electronic structure methods and using EPI suite) slopes of the linear plots of Log P values with the number of carbon atoms (N = 2 to 11) is described here. Eight families of linear organic compounds were investigated: carboxylic acids, perfluorinated carboxylic acids, sulfonic acids and perfluorinated sulfonic acids, together with their corresponding conjugate bases. To the best of our knowledge, this work reports the first application of density functional theory methods to the calculation of Log P values of perfluorinated compounds. A second part of the thesis, describes the study of the thermodynamic stability of the PFOA family of 39 structural isomers with the M06-2X, LC-ωPBE, B97D and B3LYP functionals and with the PM6 method. The PM6 results closely resemble the M06-2X results for neutral PFOAs, but greatly disagree regarding anions. The four functionals applied behave similarly from a qualitative point of view, but quantitatively speaking, the LC-ωPBE and B97D results are between the M06-2X and B3LYP stability results. M06-2X ranks highly substituted isomers as more stable than did B3LYP, and ranks less-branched isomers quite low in relative stability compared to B3LYP. Various similarities with a former PFOSs study applying the M06-2X and B3LYP functionals have been identified. The degree of branching within structural isomers cannot always be precisely determined, and is not the only aspect that determines thermodynamic stability; the pattern of substitution seems to also play a significant role. / Graduate