No description available.

Nitrous oxide is a greenhouse gas produced in large quantity by several industrial processes. Efficient means of eliminating N2O are therefore of interest. The denitrification enzyme nitrous oxide reductase (N2OR), which reduces N2O to N2 and water , has recently been shown to contain an unprecedented [Cu4-µ4S] active site. Multinuclear copper sulfide compounds are known but have not been studied in the context of modeling N2OR or as N2O reduction catalysts. The synthesis of new tetranuclear [Cu4-µ4S] compounds is proposed to model the N2OR active site.The purpose of our research is to synthesize [Cu2-µ2S] complex, which original compound of [Cu4-µ4S] complex. This can be groundwork for mimicking the copper protein active site.

Copper(I) complexes have been studied through both experimental and computational means in the presented work. Overall, the work focuses on photophysical and photochemical properties of copper(I) complexes. Photophysical and photochemical properties are found to be dependent on the geometries of the copper(I) complexes. One of the geometric properties that are important for both photochemical and photophysical properties is coordination number. Coordination numbers have been observed to be dependent on both ligand size and recrystallization conditions. The complexes geometric structure, as well as the electronic effects of the coordination ligands, is shown both computationally as well as experimentally to affect the emission energies. Two-coordinate complexes are seen to have only weak emission at liquid nitrogen temperature (77 K), while at room temperature (298 K) the two-coordinate complexes are not observed to be luminescent. Three-coordinate complexes are observed to be luminescent at liquid nitrogen temperature as well as at room temperature. The three-coordinate complexes have a Y-shaped ground (S0) state that distorts towards a T-shape upon photoexcitation to the lowest lying phosphorescent state (T1). The geometric distortion is tunable by size of the coordinating ligand. Luminescence is controllable by limiting the amount of non-radiative emission. One manner by which non-radiative emission is controlled is the amount of geometric distortion that occurs as the complex undergoes photoexcitation. Bulky ligands allow for less distortion than smaller ligands, leading to higher emission energies (blue shifted energies) with higher quantum efficiency. Tuning emission and increasing quantum efficiencies can be used to create highly efficient, white emitting materials for use in white OLEDS.

Copper is an essential trace element and required for various biological processes, but free copper is toxic. Therefore, copper is tightly regulated in living cells and disruptions in this homeostatic machinery are implicated in numerous diseases. The current understanding of copper homeostasis is substantial but incomplete, particularly in regard to storage and exchange at the subcellular level. Intracellular copper is primarily present in the monovalent oxidation state. Therefore, copper(I) selective fluorescent probes can be utilized for imaging exchangeable copper ions in live cells, but these probes are often lipophilic and hence poorly water soluble. To address this problem, water-soluble fluorescent probes with greatly improved contrast ratio and fluorescence quantum yield are characterized in this work. This work also describes a novel application of water-soluble fluorescent probes, in-gel detection of copper proteins with solvent accessible Cu(I) sites under non-denaturing conditions. Knowledge of copper(I) stability constants of proteins is important to elucidate the mechanisms of cellular copper homeostasis. Due to the high affinity of most Cu(I)-binding proteins, the stability constants cannot be determined directly by titration of the apo-protein with Cu(I). Therefore, accurate determination of Cu(I) stability constants of proteins critically depends on the Cu(I) affinity standards. However, the previously reported binding affinity values of the frequently used Cu(I) affinity standards are largely inconsistent impeding reliable data acquisition for the Cu(I) stability constants of proteins. To solve this problem, a set of water-soluble ligands are developed in this work that form colorless, air-stable copper(I)-complexes with 1:1 stoichiometry. These ligands can be applied as copper(I) buffering agents and affinity standards in order to study copper biochemistry. Copper(I) binding proteins are an integral part of the copper homeostatic machinery and they work in conjunction to regulate copper uptake, distribution, and excretion. However, available evidence indicates the existence of putative copper-binding proteins that are yet to be characterized. Therefore, several proteomics-based methods are developed in this work by employing the strategy to label Cu(I)-binding cysteines in a copper-dependent manner which lays the foundation for the identification of new copper proteins from cellular extracts.

Here we report the preparation, structure, and spectroscopic properties of an intriguing copper(I) cyclophane-like dimeric complex [Cu2(dppa)2(bpy)2][BF4]2(2)¡B[Cu2(dppa)2(mbpy)2][BF4]2(3)¡B[Cu2(dpbp)2(bpy)2][BF4]2(7)©M[Cu2(dppb)2(bpy)2] [BF4]2(8), containing phenyl phosphine bridge ligands, such as diphenylphosphino acetylene (dppa), 1,4-bis(diphenylphosphino)benzene (dppb) and 4,4'-bis(diphenyl phosphino)biphenyl (dpbp). As a building unit, the complex [Cu2(dpbp)2(NCMe)4] [BF4]2(9) containing labile acetonitrile molecules those can be easily substituted by anionic ligands, is expected to combine with suitable linkers to synthesize supramolecular arrays with shapes of polygons and polyhedra.

In science and technology there is a steadily increased demand of new materials and new materials production processes since they create new application areas as well as improved production technology and economy. This thesis includes development and studies of a chemical vapour deposition (CVD) process for growth of thin films of the metastable material copper nitride, Cu3N, which is a semiconductor and decomposes at around 300 oC. The combination of these properties opens for a variety of applications ranging from solar cells to sensor and information technology. The CVD process developed is based on a metal-organic compound copper hexafluoroacetylacetonate, Cu(hfac)2 , ammonia and water and was working at about 300 oC and  5 Torr. It was found that a small amount of water in the vapour increased the growth rate considerably and that the phase content, film texture, chemical composition and morphology were strongly dependent on the deposition conditions. In-situ oxygen doping during the CVD of Cu3N to an amount of 9 atomic % could also be accomplished by increasing the water concentration in the vapour. Oxygen doping increases the band gap of the material as well as the electrical resistivity and changes the stability. The crystal structure of Cu3N is very open and contains several sites which can be used for doping. Different spectroscopic techniques like X-ray photoelectron spectroscopy, Raman spectroscopy and near edge X-ray absorption fine structure spectroscopy were used to identify the oxygen doping site(s) in Cu3N. Besides the properties, the oxygen doping also affected the morphology and texture of the films. By combining thin layers of different materials several properties can be optimized at the same time. It has been demonstrated in this thesis that multilayers, composed of alternating Cu3N and Cu2O layers, i.e. a metastable and a stable material, could be grown by CVD technique. However, the stacking sequence affected the texture, morphology and chemical composition. The interfaces between the different layers were sharp and no signs of decomposition of the initially deposited metastable Cu3N layer could be detected.

No description available.

Dye design is one of the most important and challenging areas in dye-sensitised solar cell research. The purpose of the work in this thesis is to synthesise and characterise novel ruthenium(II) and copper(I) dyes that will provide insight into the number of binding groups required and the potential use of chromophoric ligands. A series of four simple Ru(II) dyes have been synthesised with the general formula Ru(4,4’- (R)-bipyridine)2(NCS)2 where R represents CH3 or CO2H. The study investigates the number of acid groups required to successfully bind to TiO2 whilst maintaining efficient charge injection. The series consists of one acid group, two acids, two acids on adjacent bipyridines, and three acids groups. Dye uptake was studied via optical waveguide spectroscopy, providing information on dye diffusion, adsorption and desorption kinetics, and surface coverage. Interestingly, the two acid groups on adjacent ligands suggested poor/slow binding to TiO2 surface and a high degree of dye aggregation in comparison to two acid groups on the same ligand. The dye with three binding groups showed strong adsorption to TiO2 and better dye coverage, resulting in a high efficiency. The complexes were all fully characterised by electrochemistry, photoluminescence, absorption spectroscopy, DFT calculations and solar cell performance testing. To date, there has been limited exploration of copper(I) complexes as potential alternatives to ruthenium(II) sensitisers, with even fewer publications reported for Cu(I) heteroleptic species. The neutral complexes that were synthesised are of the general formula: Cu(4,4’- (R)-6,6’-(CH3)-bipyridine)(β-diketonate) and Cu(4,4’-(R)-6,6’-(CH3)-bipyridine)(dipyrrin) where R represents CH3 or CO2Et. Additional blocking groups on the ligands are introduced to minimise structural change during oxidation or MLCT excitation. Improved stability and reproducibility have been shown for complexes containing the dipyrrin ligand, likely due to better steric constraints and better π-overlap with the bipyridine. There has also been a remarkable improvement in light absorption, from 450 nm to 600 nm. In-situ solar studies have been carried out on the Cu(4,4’-(R)-6,6’-(CH3)-bipyridine)(dipyrrin) series and a 0.41% efficiency has been achieved. Computational studies supports the experimental data in which the main transition appears to be ligand centred (dipyrrin) with a small MLCT contribution.

None.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work the synthesis and structural analysis of new copper(I) phenylchalcogenolate clusters will be presented. The reaction between sodium phenylchalcogenolate and copper(I) chloride generates a basic building block [Cu(EPh)]∞ (E= Se, Te) which reacts with N-donor bidentate ligands (bpy = 2,2 -bipyridine and phen = 1,10-phenantroline) to generate new compounds. Methodologies known in the literature include one-pot reaction of silyl-phenylchalcogenolates sources (PhESiMe3) with copper(I) salts and ancilliary phosphine ligands, as main route for synthesis of the clusters. This work will present how the formation of copper(I) phenylchalcogenolate in situ reveal itself as an alternate method for the synthesis of target compounds. Satisfactory results were obtained for [Cu6(bpy)2(μ-SePh)2(μ3-SePh)4]∙(THF) (1), {[Cu2(bpy)2(μ3-SePh)][CuCl2]}2 (2), {[Cu4(phen)3(μ-SePh)(μ3-SePh)(μ-Cl)][CuCl2]}2(PhSe)2 (3), [Cu3(bpy)3(μ4-TePh)3(CuCl)2] (4) and [Cu3(phen)3(μ3-TePh)3(CuCl)] (5). Structural analysis in solid state for these clusters were performed by X-ray diffraction. All the compounds obtained were additionally characterized by infrared spectroscopy and elemental analysis. / Neste trabalho será apresentada a síntese e análise estrutural de novos clusters derivados de fenilcalcogenolato de cobre(I). A reação da espécie fenilcalcogenolato de sódio com cloreto de cobre(I) gera um bloco de montagem básico [Cu(EPh)]∞ (E= Se, Te) que ao reagir com ligantes nitrogenados bidentados (bpy = 2,2 -bipiridina e phen= 1,10-fenantrolina) originam novos clusters. Metodologias apresentadas na literatura envolvem a reação one-pot de derivados de silil-fenilcalcogenolatos (PhESiMe3), sais de cobre(I) e ligantes fosfina auxiliares, como rota principal para obtenção de clusters. Nesse trabalho será apresentado como a formação prévia de fenilcalcogenolato de cobre(I) in situ revela-se uma fonte alternativa viável para a síntese dos compostos-alvo. Resultados satisfatórios foram obtidos para [Cu6(bpy)2(μ-SePh)2(μ3-SePh)4]∙(THF) (1), {[Cu2(bpy)2(μ3-SePh)][CuCl2]}2 (2), {[Cu4(phen)3(μ-SePh)(μ3-SePh)(μ-Cl)][CuCl2]}2(PhSe)2 (3), [Cu3(bpy)3(μ4-TePh)3(CuCl)2] (4) e [Cu3(phen)3(μ3-TePh)3(CuCl)] (5). Efetuou-se o estudo estrutural desses compostos no estado sólido, utilizando como análise principal a difração de raios-X em monocristal. Os compostos obtidos foram caracterizados por espectroscopia no infravermelho e análise elementar.