In the 21st century the safe disposal of highly radioactive nuclear waste remains a major challenge to humanity. For the first 300 years nuclear fission products will be the main source of large amounts of the radioactivity, however, over a period of 100,000s of years most of the radiotoxicity of nuclear waste will originate from transuranium elements such as Pu, Am, and Cm. Because of the reducing conditions within a potential deep underground repository Am and Cm will exclusively – and Pu at least partially – be present in their trivalent state. For the safety case of a repository, it will be of importance to understand the mobility and retention behavior of those trivalent actinides within the host rock environment. Here, the focus is set on crystalline rock, a host rock under consideration in many countries such as Finland, Sweden, Czech Republic, and also Germany. Research in the last two decades has focused on determining the chemical speciation behavior of radionuclides on the molecular scale using primarily pure, individual mineral phases in their pulverized form. Real crystalline rock systems, on the km scale of a repository, are however much more complex, physically large and bulky, and heterogeneous. Parameters, such as heterogeneity of topography or composition, and competing surface processes have to be considered adequately in transport modelling as well as the safety assessment and thus large-scale experiments without the loss of molecular level information are needed. In this work, the focus was set on the assessment of parameters affecting chemical speciation and retention of Cm(III) and its chemical homologue Eu(III) at 5·10-7 M to 10-4 M concentrations on surfaces of crystalline rocks, relevant to potential future repositories. Correlative spectromicroscopy as a combination of spatially resolved techniques, was applied to study mineralogy, surface topography, quantitative metal ion uptake, and surface metal speciation on the same thin sections in the mm to cm scale with μm resolution. Cm(III) sorption experiments on cleaved K-feldspar crystals at pH 5.5 and 6.9 using autoradiography in conjunction with micro-focus time-resolved laser-induced fluorescence spectroscopy (μTRLFS), and vertical scanning interferometry, showed that sorption uptake and speciation is dependent on pH and surface roughness. In regions expressing a high surface roughness quantitatively more Cm(III) sorbed to the surface than in smoother regions. Further, the formed Cm(III) surface complexes are more strongly bound in regions with a high roughness, since they possess a higher number of strong sorption sites. The speciation between smooth and rough surfaces does not differ at pH 5.5. In contrast, at pH 6.9 in rougher areas, stronger species form favorably in addition to weaker surface sorption species. For comparison, Cm(III) sorption at pH 7.3 was conducted on a granodiorite crystalline rock thin section from the Grimsel Test Site, Switzerland with an inclusion of a large K-feldspar mineral grain. The spectromicroscopy approach was extended by Raman-microscopy to identify the surface mineralogy. From calibrated autoradiography of the entire thin section, it could be assessed that most sorption occurs on mica minerals rather than on feldspar. However, the K-feldspar grain was investigated in detail for a comparison of Cm(III) speciation on crystals and natural grains. On the grain, the sorption was heterogeneously distributed mainly occurring in rough surface regions. Since the overall sorption uptake was lower, the dominant species formed are bound strongly to the surface occupying strong sorption sites. Complexes were observed that were either the result of ternary complexation on the surface or incorporation. While sorption on K-feldspar crystals was higher than on the mineral grain, no ternary complexation could be observed, therefore the formation of this species is likely a result of the heterogeneous mineralogy. The formation of those complexes with carbonate is likely, whereas silicate does not seem to contribute. The exact complex structure determination will be the focus of future work. Increasing the complexity of the system, the next step was to study Cm(III) sorption at pH 8.0 on entire crystalline rock thin sections and analyzing speciation within and between different mineral gains. The focus was set on granite from Eibenstock, Germany and gneiss from Bukov, Czech Republic. On granite, sorption was highest on mica as well as feldspar and smallest on quartz as measured on the sub-mm to cm scale by quantitative autoradiography. On quartz regions, where surface roughness was higher, sorption quantities close to those on feldspar and mica could be observed. A detailed μTRLFS analysis shows highest sorption quantities on topaz, followed by feldspar, and only minor uptake was detected on quartz. Assessment of Cm(III) uptake on mica was not possible due to strong quenching of the Cm(III) luminescence through Fe as part of the mineral structure. Sorption on topaz, feldspar, and quartz occurred preferably in regions with a high surface roughness, such as surface pits, cracks, or mineral grain boundaries between the grains. Surface complexes in high roughness regions are bound more strongly than in smoother regions. A process that could either be Cm(III) ternary complexation or incorporation was exclusively observed on feldspar and quartz, likely because more sorption sites allowed for surface incorporation after which ternary complexation can occur. The experiments showed that mineralogy is the most important parameter when it comes to surface sorption, however it is closely followed by the surface roughness. On gneiss the overall mineralogy was different, which in turn affected the surface Cm(III) uptake. Combining the results from Raman microscopy and autoradiography, sorption was found almost exclusively on amphibole and mica, while little to no sorption was observed on feldspar and quartz. Due to the high Fe content of amphibole and mica, quenching hindered Cm(III) luminescence detection using μTRLFS. However, on feldspar and quartz μTRLFS allowed for uptake and speciation analysis. While no uptake was seen in smooth regions, uptake was increased in rougher regions. This highlights that in a competitive sorption environment, on low sorbing mineral phases, sorption is controlled by surface roughness. Cm(III) uptake and speciation analysis on mica using μTRLFS proved to be difficult because of luminescence quenching induced by structurally incorporated Fe in the minerals. However, to tackle this challenge, Cm(III) sorption experiments were performed on a granitic pegmatite from Olkiluoto, Finland at adjusted experimental settings, i.e., using a five times higher metal concentration than in previous experiments. Autoradiography as well as μTRLFS showed that Cm(III) sorption mainly occurred on mica, while uptake on feldspar and quartz was minor. Mica itself can be found as part of small cracks and pits, or as large grains. Inherently mica showed a high surface roughness, however Cm(III) uptake and speciation differed between the differently sized grains. On smaller grains, uptake was lower than on the larger grains, resulting in primarily stronger inner-sphere sorption species that formed. The high uptake on larger grains lead additionally to the formation of weaker inner-sphere sorption species. To compare the obtained Cm(III) results Eu(III) sorption was performed on a granite thin section. It was observed that Eu(III) uptake and speciation not only occurs heterogeneously between different minerals, but also within single grains particularly close to mineral grain boundaries. This implies that surface roughness, next to mineralogy, influences the sorption process. However, the detection of Eu(III) was hindered by surface precipitation, naturally incorporated Eu(III), and thus vague luminescence peak analysis. Spatially resolved correlative spectroscopy workflows that were further optimized in this thesis proved to be universally applicable in the range of mineral crystals to different crystalline rock thin sections and luminescent metals (Cm, Eu) and can be taken in the future as references for further studies with other luminescence metals such as Am(III) or U(VI). The derived findings show that in future assessments of the mobility of trivalent radionuclides in reactive transport modelling, parameters need to be selected carefully. Additional processes and parameters not considered before, like the surface roughness, will influence the retention of radionuclides within the geosphere. Those processes and parameters need to be quantified and implemented in the models to represent the deep repository system more reliable.

This paper deals with 3-picoline, 4-picoline, 3,4-lutidine and 3,5-lutidine complexes of copper(I) iodide (CuI(3-pic), CuI(4-pic), CuI(3,4-lut) and (CuI(3,5-lut)). The experimental investigation was divided into several parts. Firstly, the synthesis and characterization of the compounds both as powder and as thin films. Secondly, the photoluminescence study. Thirdly, the observation of ligand exchange reaction by vapor diffusion, and lastly, the determination of the lifetime by time-resolved photoluminescence of respective compound.  All studied copper(I)-iodide-substituted pyridine compounds were emissive both as powders and thin films. The synthesis of the tetranuclear cluster powders yields both cluster and polymeric forms of structure. The pXRD of the powders CuI(3-pic), CuI(4-pic), and CuI(3,5- lut) confirmed to be as polymeric structures, hence the CuI(3-pic) showed thermochromism behavior. The structure of CuI(3,4-lut) is still unconfirmed. The most effective method for the synthesis of the thin films was the SILAR method.  The photoluminescence spectra of respective thin films differ from their corresponding powders, and the structure of the compounds as thin films is yet unexplored. The emission of CuI(3-pic), CuI(4-pic), and CuI(3,4-lut) as thin films were similar 480nm, hence the emission of CuI(3,5-lut) thin film lays on 518 nm. Therefore, the ligand exchange reaction was performed on the CuI(3-pic) thin film with 3,5-lutidine as the exchanging ligand.  The ligand exchange reaction of CuI(3-pic) thin film by vapor diffusion of 3,5-lutidine results in a spectrum shift from the emission spectrum of CuI(3-pic) to the spectrum of CuI(3,5-lut). This indicates a successful ligand exchange reaction by vapor diffusion.  The lifetimes of the investigated compounds which have their best fit of mono-exponential function were between 2,2 μs and 9,52 μs. The lifetimes were determined on the thin films with time-resolved photoluminescence. The ligand exchange reaction was also observed by time- resolved photoluminescence which reveals some stable lifetimes during the reaction that can indicate the formation of intermediates. In contrast, the measured lifetimes during the ligand exchange reaction have their best fit of bi-exponential function which can be due to reaction conditions during the measurement or the homogeneity of the thin films. / Denna uppsats behandlar 3-pikolin, 4-pikolin, 3,4-lutidin och 3,5-lutidin komplex av koppar(I) jodid (CuI(3-pic), CuI(4-pic), CuI(3,4-lut) och (CuI(3,5-lut)). Den experimentella undersökningen delades in i olika delar. Först, syntesen och karakteriseringen av föreningarna både som pulver och som tunn film. Sedan studerades fotoluminiscensen av respektive förening. Därefter genomförde en ligand-utbytes-reaktion genom förgasning och slutligen bestämde livstiden av föreningarnas exciterade tillstånd.  Alla koppar(I) jodid föreningar som studerade gav upphov till emission både som pulver och som tunn film. Syntesen av tetranukleära kluster i pulverform resulterade i både kluster och polymer struktur. pXRD av pulvren CuI(3-pic), CuI(4-pic) och CuI(3,5-lut) bekräftade dess struktur som polymera strukturer. Däremot visade CuI(3-pic) termokromism. Strukturen för CuI (3,4-lut) kunde inte obekräftas. Den mest effektiva metoden för syntes av tunn film i det här fallet är med SILAR-metoden.  Fotoluminescensspektra för respektive tunn film skiljer sig från deras motsvarande pulverform och strukturen på tunn film är fortfarande outforskat. Emission av CuI(3-pic), CuI(4-pic) och CuI(3,4-lut) som tunn film var ungefär lika ~480 nm medan för CuI(3,5-lut) så var det på 518 nm. Med denna kontrast utfördes ligand-utbyte-reaktionen på tunn film av CuI(3-pic) med 3,5- lutidin.  Ligand-utbyte-reaktionen av CuI(3-pic) på tunn film via förgasning av 3,5-lutidin resulterar i en spektrumförskjutning från spektrumet av CuI(3-pic) till spektrumet av CuI(3,5-lut). Detta indikerar i en lyckad ligand-utbyte-reaktion.  Livslängderna för de undersökta föreningarna vilket har sin bästa passning i mono- exponentiell funktion var mellan 2,2 μs och 9,52 μs. Livstiderna bestämdes på de tunn film med ”time-resolved photoluminescence”. Ligand-utbyte-reaktionen observerades också med ”time- resolved photoluminescence” som avslöjar några stabila livstider under reaktionen vilket kan indikera bildning av intermedianer. De uppmätta livstiderna under ligand-utbyte-reaktionen har däremot sin bästa passning av bi-exponentiell funktion vilket kan bero på reaktionsförhållanden under mätningen och tunn filmernas homogenitet.

<p>Photodynamic therapy (PDT) is a rapidly developing clinical treatment modality involving a light-activatable photosensitizer, tissue oxygen and light of an appropriate wavelength to generate cytotoxic reactive molecular species - primarily singlet oxygen (¹O₂). Singlet oxygen readily reacts with surrounding biomolecules leading to different biological effects and subsequent therapeutic outcomes. Over the last decades, many standard PDT treatments have been approved worldwide to treat different medical conditions ranging from a variety of cancer conditions to age-related macular degeneration (AMD). Meanwhile, many active clinical trials and pre-clinical studies are underway for other clinical indications. The therapeutic outcomes of PDT are difficult to predict reliably even with many years of research. The fundamental cause for this is the inherent complexity of PDT mechanisms. As PDT involves three main components, the outcomes of PDT are determined by the combination of all components. Each component varies temporally and spatially during PDT, and the variations are mutually dependent on each other. Moreover, components such as the photosensitizer can have great variations in their initial distribution among patients even before PDT treatment. Given this, no well accepted standard PDT dose metric method has been recognized in clinics, although different approaches including explicit, implicit and direct dosimetry have been studied. To tackle the inherently complicated PDT mechanism in order to provide insights into PDT and PDT dosimetry, a theoretical one-dimensional model for aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX)-PDT of human skin was developed and is presented in this thesis. The model incorporates major photophysical and photochemical reactions in PDT, and calculated temporal and spatial distributions of PDT components as well as the detectable emission signals including both sensitizer fluorescence and singlet oxygen luminescence (SOL) using typical clinical conditions. Since singlet oxygen is considered to cause PDT outcomes, the correlations of different PDT dose metrics to average reacted (¹O₂) "dose" and "dose" at different depths were examined and compared for a wide range of varied treatment conditions. The dose metrics included absolute fluorescence bleaching metric (AFBM), fractional fluorescence bleaching metric (FFBM) and cumulative singlet oxygen luminescence (CSOL), and the varied treatment conditions took into account different treatment irradiances and wavelengths, varied initial sensitizer concentration and distribution, and a wide range of optical properties of tissue. These investigations and comparisons provide information about the complicated dynamic process of PDT such as the induction of tissue hypoxia, photosensitizer photobleaching and possible PDT-induced vascular responses. It was also found that the CSOL is the most robust and could serve as a gold standard for the testing of other techniques. In addition to these theoretical studies, recent progress on the assessment of a novel, more efficient superconducting nanowire single photon detector (SNSPD) for singlet oxygen luminescence detection will be introduced and the current photomultiplier tubes (PMT) system will be briefly described as well. The author participated in the experimental assessments of the SNSPD and analyzed the results shown in this thesis.</p> / Doctor of Philosophy (PhD)

Biogenic monoamines such as dopamine play an important role as major neurotransmitters. Simultaneous determination of the concentration changes is thus crucial to understand brain function. Additionally, quantification of pharmaceutically active compounds (PhACs) and their metabolites in biological fluids is an important issue for forensic tests, clinical toxicology and pharmaceutical analysis. We have developed two postcolumn luminescence detection methods coupled to a 2-dimensional-solid phase extraction (2D-SPE) system. The postcolumn reaction methods used in this study are the redox-dependent photoluminescence-following electron-transfer (PFET) and Fenton-based chemiluminescence techniques, for the determination of certain neurotransmitter and nonsteroidal anti-inflammatory drugs (NSAIDs). A stable [Os(tmphen)3]3+ (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline) reagent was prepared in neutral aqueous solution by oxidation of [Os(tmphen)3]2+ with lead(IV) oxide. [Os(tmphen)3]2+ and [Os(tmphen)3]3+ are characterized by absorption spectroscopy. [Os(tmphen)3]3+ stability is compared with [Ru(tmphen)3]3+ in the same pH 7 environment. The properties of Os(III) and Ru(III) complexes were investigated for use as the oxidant in a PFET system. Studies of photophysical and electrochemical properties, the stability of the Os(III) and Ru(III) complexes, and analytical application in PFET detection of oxidizable analytes are presented. The spectroscopic properties of the complexes were not very advantageous, but careful control of the detection system and reaction conditions enabled sensitive detection of the analytes. The method was fully validated and the optimized system was capable of detecting dopamine and acetaminophen at about 30.2 µg L-1 and 33.5 µg L-1, respectively. The limit of detection (LOD) was 1.5 µg L-1 for acetaminophen and 4.3 µg L-1 for dopamine. The accuracy and precision were within bioanalytical method validation limits (90.9 to 101.5 % and RSD &lt; 12.0 %, respectively). Typical analysis time was less than 15 minutes. Two Fenton-based flow-injection chemiluminescence (CL) methods were developed and validated for the determination of naproxen. Under the optimal experimental conditions the proposed methods exhibited advantages in a larger linear range from 2,760 ng mL-1 to 207,000 ng mL-1 for the first CL method and 41.4 ng mL-1 to 700.0 ng mL-1 for the second CL method. The LOD was 13.8 ng mL-1 for naproxen. The CL mechanisms for the system, H2O2-FeIIEDTA-naproxen was further studied by batch experiments, chemiluminescence spectroscopy, fluorometry, high pressure liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR). The effects of various interferences commonly found in biological and wastewater systems on the chemiluminescence intensity were also investigated. We used these methods to determine NSAIDs in commercial pharmaceutical formulations. Another application of these method was for detecting NSAIDs in biological samples. A 2x-1-Dimensional Solid Phase Extraction (2x-1D SPE) method was developed for determination of acetaminophen and naproxen in urine. This method uses both the methanol concentration and the pH advantageously to preferentially isolate analytes of interest from complex sample matrix. These methods were fully validated and had sufficient sensitivity (limit of quantification: acetaminophen; 40.41 mg L-1 - 360.0 mg L-1 and naproxen; 23.03 mg L-1 - 214.8 mg L-1) for biological matrices and applications. / Chemistry

McMaster University DOCTOR OF PHILOSOPHY (2017) Hamilton, Ontario (Engineering Physics) TITLE: Luminescent Silicon Carbonitride Thin Films Grown using ECR PECVD: Fabrication and Characterization AUTHOR: Zahra Khatami , M.A.Sc. (Shahid Behehsti University) SUPERVISOR: Professor Peter Mascher NUMBER OF PAGES: xx, 268 / Silicon, the cornerstone semiconductor of microelectronics, has seen growing interest as a low-cost material in photonics. Nanoscience has employed various strategies to overcome its fundamentally inefficient visible light emission such as developing new silicon-based nanostructures and materials. Each of the proposed materials has its own advantages and disadvantages in attempting to reach commercialization. Silicon carbonitride (SiCxNy) is a less-studied and multi-functional material with tunable optical features. Despite reports on promising mechanical properties of SiCxNy thin films, they have not yet been well explored optically. This thesis presents the first in-depth analysis of the luminescent properties of SiCxNy thin films at a broad range of compositions and temperatures. To better understand this ternary structure, the reported data of the two fairly well studied binary structures was used as a reference. Therefore, three classes of silicon-based materials were produced and explored; SiCxNy, SiNx, and SiCx. Samples were fabricated using one of the common methods in the semiconductor industry; electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR PECVD). A multitude of characterization techniques were utilized including; optical methods (ultraviolet-visible spectroscopy (UVVIS), variable angle spectroscopic ellipsometry (VASE), photoluminescence (PL)) and structural techniques (elastic recoil detection (ERD), Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM)). In view of the exploring of emission properties of SiCxNy materials, our approach was towards the enhancement of the visible emission by adjusting the film composition and subsequent thermal treatment. First, a systematic study of the influence of carbon on the optical, compositional, and structural properties of SiCxNy was carried out. This investigation was followed by an exploration of influence of growth conditions on the visible emission and its connection with the other film properties including hydrogen concentration, microstructure, and composition. In addition, hydrogen diffusion was explored and associated with two featured annealing temperatures. The key element of this thesis is the comprehensive report on the interdependency of the visible light emission and all optical, structural, and compositional features of SiCxNy structures. Unlocking the potential of this ternary and less studied material can appeal to the silicon photonics community to implement it in anti-reflection, solar cell, and sensing applications, and in particular as a substitution of SiNx used in existing microelectronic devices. / Thesis / Doctor of Philosophy (PhD)

Quorum sensing in Gram-negative bacteria is best understood in the bioluminescent marine microorganism, <i>Vibrio fischeri</i>. In <i>V. fischeri</i>, the luminescence or <i>lux</i> genes are regulated in a cell density-dependent manner by the activator LuxR in the presence of an acylated homoserine lactone autoinducer molecule (3-oxo-hexanoyl homoserine lactone). LuxR, which binds to the <i>lux</i> operon promoter at position -42.5, is thought to function as an ambidextrous activator making multiple contacts with RNA polymerase (RNAP). The specific role of the <font face = "symbol">a</font>CTD of RNAP in LuxR-dependent transcriptional activation of the <i>lux</i> operon promoter has been investigated. The effect of seventy alanine substitution variants of the <font face = "symbol">a</font> subunit was determined <i>in vivo</i> by measuring the rate of transcription of the <i>lux</i> operon via luciferase assays in recombinant <i>Escherichia coli</i>. The mutant RNAPs from strains exhibiting at least two fold increased or decreased activity in comparison to the wild-type were further examined by <i>in vitro</i> assays. Since full-length LuxR has not been purified to date, an autoinducer-independent N-terminal truncated form of LuxR, LuxR<font face = "symbol">D</font>N, was used for <i>in vitro</i> studies. Single-round transcription assays were performed using reconstituted mutant RNAPs in the presence of LuxR<font face = "symbol">D</font>N, and fourteen residues in the <font face = "symbol">a</font>CTD were identified as having negative effects on the rate of transcription from the <i>lux</i> operon promoter. Five of these fourteen residues were also involved in the mechanism of both LuxR and LuxR<font face = "symbol">D</font>N-dependent activation <i>in vivo</i> and were chosen for further analysis by DNA mobility shift assays. Results from these assays indicate that while the wild-type <font face = "symbol">a</font>CTD is capable of interacting with the <i>lux</i> DNA fragment tested, all five of the variant forms of the <font face = "symbol">a</font>CTD tested appear to be deficient in their ability to recognize and bind the DNA. These findings suggest that <font face = "symbol">a</font>CTD-DNA interactions may play a role in LuxR-dependent transcriptional activation of the <i>lux</i> operon during quorum sensing. / Master of Science

Polypyridyl transition metal complexes containing ruthenium, rhodium and iridium centers are mainly studied due to their light absorbing and emitting properties. Lanthanide oxides such as europium oxide absorb light as well and exhibit strong luminescence and long lifetimes. The optical properties of these materials were significant especially in solar energy utilization schemes and optical applications. Energy transfer across a surface is important in several applications including phosphors and biomedical applications. Excited states of metal complexes with a carboxylate-containing ligand such as deeb = diethyl-2,2'-bipyridine-4,4'-dicarboxylate were studied on nanoparticle surfaces. In this work, [Rh(deeb)2Cl2](PF6), [Ir(deeb)2Cl2](PF6) and [Ir(deeb)2(dpp)](PF6)3 were synthesized using the building block approach. The metal complexes were characterized using 1H NMR spectroscopy, mass spectrometry, electronic absorption spectroscopy and electrochemistry. The 1H NMR spectra of the complexes were consistent with those of their ruthenium analogs. Mass spectra contain fragmentation patterns of the (M-PF6)+ molecular ion for [Rh(deeb)2Cl2](PF6) and [Ir(deeb)2Cl2](PF6), and (M-3PF6)3+ molecular ions for [Ir(deeb)2(dpp)](PF6)3. The electronic absorption spectrum of [Rh(deeb)2Cl2](PF6) shows a maximum at 328 nm, which is assigned as 1π→π*transition. The electronic absorption spectrum of [Ir(deeb)2Cl2](PF6) shows maxima at 308 nm and 402 nm, which are assigned as 1π→π* and metal-to-ligand charge transfer transitions, respectively. The [Ir(deeb)2(dpp)](PF6)3 complex exhibits peaks due to 1π→π* transitions at 322 nm and 334 nm. [Rh(deeb)2Cl2](PF6) has emission maxima from the 3LF state at 680 nm and 704 nm for the solid and glassy solutions at 77 K, respectively. [Ir(deeb)2Cl2](PF6) has emission maxima from the 3MLCT state at 538 nm in acetonitrile and 567 nm in the solid state at room temperature, with lifetimes of 1.71 μs and 0.35 μs, respectively. [Ir(deeb)2Cl2](PF6) has an unusually higher quantum yield than analogous compounds. [Ir(deeb)2(dpp)](PF6)3 has emission maxima from the 3IL state at 540 nm in acetonitrile and 599 nm in the solid state at room temperature, with lifetimes of 1.23 μs and 0.14 μs, respectively. Cyclic voltammetry of [Ir(deeb)2Cl2](PF6) and [Ir(deeb)2(dpp)](PF6)3 yield reversible and quasi-reversible couples corresponding to deeb ligand and Ir3+/+reductions, respectively. Attachment of the complexes were conducted by equilibration of complex solutions in acetonitrile with europium oxide nanoparticles. Europium oxide nanoparticles, which were synthesized by gas-phase condensation, have 11-nm diameters and exhibit sharp f-based luminescence in the visible and near IR regions. EDX, TEM, IR and reflectance spectroscopy measurements indicate substantial coating through various modes of attachment of the nanoparticle surface by the metal complexes while retaining the excited state properties of the metal complexes. Surface adsorption studies indicate monolayer coverage of the nanoparticle surface by the metal complexes, consistent with limiting surface coverages of previously reported analogous systems. Eu2O3 nanoparticles modified with [Rh(deeb)2Cl2]+ exhibit minimal to no energy transfer from emission spectra, and a reduction in the lifetime at 77K could be due to the rhodium complex preventing the excitation of Eu3+. Upon attachment of the Ir complexes [Ir(deeb)2Cl2]+ and [Ir(deeb)2(dpp)]3+ on as-prepared nanoparticles, Eu3+ luminescence was observed for nanoparticles modified with iridium complexes at room temperature, which could be due to energy transfer among other possibilities. Efficiencies of 68% and 50%, and energy transfer rate constants of 1.1 x 10-5 and 1.0 x 10-5 were calculated from lifetime data for [Ir(deeb)2Cl2]+ and [Ir(deeb)2(dpp)]3+ on Eu2O3 nanoparticles, respectively. Since iridium complexes are used as components of light-emitting diodes, europium oxide nanoparticles modified with iridium complexes have potential in optical applications which make studies of these compounds interesting. / Master of Science

The mechanism of gene regulation used by Gram-negative bacteria during quorum sensing is well understood in the bioluminescent marine bacterium Vibrio fischeri. The cell-density dependent activation of the luminescence (lux) genes of V. fischeri relies on the formation of a complex between the autoinducer molecule, N-(3-oxohexanoyl) homoserine lactone, and the autoinducer-dependent transcriptional activator LuxR. LuxR, a 250 amino acid polypeptide, binds to a site known as the lux box centered at position -42.5 relative to the luxI transcriptional start site. During transcriptional activation of the lux operon, LuxR is thought to function as an ambidextrous activator capable of making multiple contacts with RNA polymerase (RNAP). The specific role of region 4 of the Escherichia coli sigma 70 subunit of RNAP in LuxR-dependent transcriptional activation of the luxI promoter has been investigated. Rich in basic amino acids, this conserved portion of sigma 70 is likely to be surface-exposed and available to interact with transcription factors bound near the -35 element. The effect of 16 single and 2 triple alanine substitution variants of sigma 70 between amino acid residues 590 and 613, was determined in vivo by measuring the rate of transcription from a luxI-lacZ translational fusion via b-galactosidase assays in recombinant E. coli. In vitro work was performed with LuxRDN, the autoinducer-independent C-terminal domain (amino acids 157 to 250) of LuxR because purified, full length LuxR is unavailable. Single-round transcription assays were performed in the presence of LuxRDN and 19 variant RNAPs, one of which contained a C-terminally truncated sigma 70 subunit devoid of region 4. Results indicate that region 4 is essential for LuxRDN-dependent luxI transcription with two specific amino acid residues, E591 and K597, having negative effects on the rate of LuxRDN-dependent luxI transcription in vivo and in vitro. None of the residues tested were identified as having any effect on LuxR-dependent luxI transcription in vivo. These findings suggest that region 4.2 is most likely to be in close proximity to LuxR when bound to the luxI promoter. However, unlike the situation found for other ambidextrous activators, no single residue within region 4.2 of sigma 70 may be critical by itself for LuxR-dependent during transcriptional activation. / Master of Science

No / This paper presents new chronological data applied to the problem of providing a date for the construction of a prehistoric building, with a case study from the Old Scatness Broch, Shetland. The innovative methodology employed utilises the combination of radiocarbon and optically stimulated luminescence (OSL) dates with the archaeological information, which includes the stratigraphic relationships of sampled deposits, context information, and evidence relating to the formation of the deposit. This paper discusses the scientific validity of the dates produced, and the advantages that the methodology employed at this site offers for archaeological interpretation. The combined dating evidence suggests that the broch at Old Scatness is earlier than the conventionally accepted dates for broch construction. More broadly it shows the value of integration of the specialists at the planning stages of the excavation. The application of a Bayesian statistical model to the sequences of dates allowed investigation of the robustness of the dates within the stratigraphic sequences, as well as increasing the resolution of the resulting chronology. In addition, the value of utilising multiple dating techniques on the same deposit was demonstrated, as this allowed different dated events to be directly compared as well as issues relating to the formation of the sampled deposit. This in turn impacted on the chronological significance of the resulting dating evidence, and therefore the confidence that could be placed in the results.

The main theme of this dissertation is the study of two racemic compounds: a bimetallic complex, [(tpy)Ru(tppz)PtCl](PF₆)₃, and a trimetallic complex, [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄, in solution and in the solid state, where tpy is 2,2':6',2''-terpyridine and tppz is 2,3,5,6-tetrakis(2-pyridyl)pyrazine. These two supramolecular assemblies display remarkably different stereochemistry, electrochemistry and photochemistry. The chapters in this document deal with a multidisciplinary project that is fundamental to the design and synthesis of similar entities with potential applications as antitumor agents. Chapter 1 gives an overview on the metal polyazine supramolecules. More specifically, the section is focused on the tridentate ruthenium and platinum metallic supramolecular assemblies with emphasis on their functionality and the methods used to study such systems. Chapter 2 describes the design and syntheses of the title complexes and their analogs using a building block strategy. The details of the experimental methods are included in this section. Chapter 3 presents the identification of the title complexes in solution and in the solid state by means of single crystal crystallography, mass spectrometry including FAB-MS and ESI-MS, and multiple NMR techniques including 1D ¹H-NMR, ¹⁹⁵Pt-NMR and 2D COSY, NOESY and ¹⁹⁵Pt-¹H HMQC, as well as dynamic ¹H-NMR at variable temperatures. The bi- and tri-metallic complexes are crystallized in the chiral space group of C2/c and P21/c as racemic compounds. The interconversion of the three steroisomers, M-M, P-P and M-P of trimetallic complexes are detected in the NMR timescale. The assignments of the atypical NMR resonance of the bi- and tri-metallic complexes are supported with the help of multidimensional NMR techniques and NMR spectroscopy of known systems. The process of assigning the NMR spectra is accomplished step by step with complexities presented by ring current effects. The 1D-fiber, 2D-plate and 3D-flowerlike topography of the trimetallic complex of [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄ was illustrated by SEM. Chapter 4 demonstrates the electrochemical and photochemical differences between the title complexes and a comparison to known systems. Electrochemically, the Ru^II,Pt^II bimetallic and trimetallic complexes display Ru^II/III oxidations at 1.63 and 1.83 V and ligand-based reduction at -0.16 and -0.03 V versus Ag/AgCl, respectively. Spectroscopically, the Ru(dπ)⟶ tppz(π*) MLCT transitions are red-shifted relative to the monometallic synthons ([(tpy)Ru(tppz)](PF₆)₂, λ_max^abs = 472 nm and [Ru(tppz)₂](PF₆)₂, λ_max^abs = 478 nm) occurring in the visible region, centered at 530 and 538 nm in CH₃CN for [(tpy)Ru(tppz)PtCl](PF₆)₃ and [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄, respectively, consistent with the bridging coordination of the tppz ligand. [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄ displays an intense emission (Φ^em = 5.4×10₄) from the Ru(dπ)⟶ tppz(π*) ³MLCT state at RT with λ_max^em = 754 nm and lifetime ofτ„ = 80 ns in CH₃CN solution. The trimetallic complex, [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄, exhibits a strong emission property in the solid state with λ_max^em = 764 nm, which was also studied by confocal laser induced emission scanning microscopy. By contrast, a barely detectable emission was observed for the bimetallic complex, [(tpy)Ru(tppz)PtCl](PF₆)₃. The redox and luminescence differences between bi- and tri-metallic complexes is the consequence of the nature of these supramolecular assemblies. All together the data suggest strong PtPt interactions in solution providing for assembly of these molecules into dimers or larger assemblies. Chapter 5 reports the applications of these complexes as bioactive species interacting with DNA. The prelimary data show the title complexes bind to DNA producing larger changes in DNA migration during gel electrophoreses than does the well-established anticancer drug, cisplatin. Preliminary study indicates trimetallic complex [ClPt(tppz)Ru(tppz)PtCl](PF₆)₄ can photochemically condenses DNA. This data could provide a form for development of a new class of photodynamic therapy agents in cancer treatment. Chapter 6 concludes with summaries of current research and perspective for further work. / Ph. D.