Isomerism and C-H, C-C, O-O, C-O bond activation studies by transition metals

Aquesta tesi és el reflex que de la cooperació entre grups experimentals i grups teòrics s'aconsegueix l'assoliment d'objectius inassolibles de forma individual. A partir de la DFT s'expliquen processos inorgànics i organometàl·lics de gran valor biològic i/o industrial. La tesi està enfocada especialment a l'estudi de complexos mononuclears i binuclears de coure, on té lloc l'activació d'enllaços C-H, C-C, i O-O. L'estudi de complexos octaèdrics de ruteni ha permès dur a terme extensos estudis isomèrics i racionalitzar les propietats espectroscòpiques dels mateixos. A més a més, estudis més puntuals respecte clusters de coure, l'estudi de la reacció de Pawson-Khand, l'estudi d'enllaços Pt-Pt en complexos trimèrics de platí, a més a més de l'estudi de la isomeria de complexos de Ni i Pt.

Feature-point detection using distance transforms: Application to tracking tropical convective complexes

The identification, tracking, and statistical analysis of tropical convective complexes using satellite imagery is explored in the context of identifying feature points suitable for tracking. The feature points are determined based on the shape of complexes using the distance transform technique. This approach has been applied to the determination feature points for tropical convective complexes identified in a time series of global cloud imagery. The feature points are used to track the complexes, and from the tracks statistical diagnostic fields are computed. This approach allows the nature and distribution of organized deep convection in the Tropics to be explored.

Common black coatings - reflectance and ageing characteristics in the 0.32-14.3 mu m wavelength range

The diffuse and regular reflectances of five optically absorbing coatings frequently used in optical systems, were measured over the 0.32-14.3 mu m wavelength range, before and after exposure to heat and intense optical radiation. The measured coatings included Nextel Velvet Black, an anodised coating and NPL Super Black. The anodised coating exhibited substantial variations in its diffuse and regular reflectance values after thermal and simulated solar ageing. Solar and thermal ageing of the Nextel Velvet Black resulted in increases of its reflectance. However, thermal ageing tended to decrease the reflectance of the other paint samples examined. Thermal and solar ageing of the NPL Super Black resulted in only minor changes in its reflectance characteristics. All measurements are traceable to the UK National Standards.

The fall speeds of sub-100 mu m ice crystals

Estimates for the sedimentation rate of realistic ice crystals at sizes smaller than 100 µm are presented. These calculations, which exploit new results for the capacitance of ice crystals, are compared with laboratory studies and found to be in good agreement. The results highlight a weakness in contemporary ice particle fall speed parametrizations for very small crystals, which can lead to sedimentation rates being overestimated by a factor of two. The theoretical approach applied here may also be useful for calculating the sedimentation rate and mobility of non-spherical aerosol particles.

Hydrogen-bonded interpolymer complexes. Formation, structure and applications

Noncovalent interactions play key roles in many natural processes leading to the self-assembly of molecules with the formation of supramolecular structures. One of the most important forces responsible for self-assembly is hydrogen bonding, which also plays an important role in the self-assembly of synthetic polymers in aqueous solutions. Proton-accepting polymers can associate with proton-donating polymers via hydrogen bonding in aqueous solutions and form polymer-polymer or interpolymer complexes. There has been an increased interest among researchers in hydrogen-bonded interpolymer complexes since the first pioneering papers were published in the early 1960s. Several hundred research papers have been published on various aspects of complex formation reactions in solutions and interfaces, properties of interpolymer complexes and their potential applications. This book focuses on the latest developments in the area of interpolymer complexation via hydrogen bonding. It represents a collection of original and review articles written by recognized experts from Germany, Greece, Kazakhstan, Poland, Romania, Russia, UK, Ukraine, and the USA. It highlights many important applications of interpolymer complexes, including the stabilization of colloidal systems, pharmaceuticals, and nanomaterials.

Solvent Effects on the Formation of Nanoparticles and Multilayered Coatings Based on Hydrogen-Bonded Interpolymer Complexes of Poly(acrylic acid) with Homo- and Copolymers of N-Vinyl Pyrrolidone

The formation of hydrogen-bonded interpolymer complexes between poly(acrylic acid) and poly(N-vinyl pyrrolidone) as well as amphiphilic copolymers of N-vinyl pyrrolidone with vinyl propyl ether has been studied in aqueous and organic solutions. It was demonstrated that introduction of vinyl propyl ether units into the macromolecules of the nonionic polymer enhances their ability to form complexes in aqueous solutions due to more significant contribution of hydrophobic effects. The complexation was found to be a multistage process that involves the formation of primary polycomplex particles, which further aggregate to form spherical nanoparticles. Depending on the environmental factors (pH, solvent nature), these nanoparticles may either form stable colloidal solutions or undergo further aggregation, resulting in precipitation of interpolymer complexes. In organic solvents, the intensity of complex formation increases in the following order: methanol < ethanol < isopropanol < dioxane. The multilayered coatings were developed using layer-by-layer deposition of interpolymer complexes on glass surfaces. It was demonstrated that the solvent nature affects the efficiency of coating deposition.

Synthesis and evaluation of novel boron-containing complexes of potential use for the selective treatment of malignant melanoma

Boron-containing complexes that have the potential to irreversibly accumulate in melanoma cells have been prepared by reaction of amino acids with 9-methoxy-9-borabicyclo[3.3.1]nonane. The ability of each complex to act as a substrate for tyrosinase has been probed by oximetry. Increased uptake of the lead candidate in a tyrosinase-rich cell line, compared with a tyrosinase-absent cell line, is reported, with results correlating well with that for a drug currently approved for BNCT.

Proliferative and anti-proliferative effects of titanium- and iron-based metallocene anti-cancer drugs

In previous work we have found that Cp2TiCl2 and its corresponding deriv. of tamoxifen, Titanocene tamoxifen, show an unexpected proliferative effect on hormone dependent breast cancer cells MCF-7. In order to check if this behavior is a general trend for titanocene derivs. we have tested two other titanocene derivs., Titanocene Y and Titanocene K, on this cell line. Interestingly, these two titanocene complexes behave in a totally different manner. Titanocene K is highly proliferative on MCF-7 cells even at low concns. (0.5 .mu.M), thus behave almost similarly to Cp2TiCl2. This proliferative effect is also obsd. in the presence of bovine serum albumin (BSA). In contrast, Titanocene Y alone has almost no effect on MCF-7 at a concn. of 10 .mu.M, but exhibits a significant dose dependent cytotoxic effect of up to 50% when incubated with BSA (20-50 .mu.g/mL). This confirms the crucial role played by the binding to serum proteins in the expression of the in vivo, cytotoxicity of the titanocene complexes. From the hydridolithiation reaction of 6-p-anisylfulvene with LiBEt3H followed by transmetallation with iron dichloride [bis-[(p-methoxy-benzyl)cyclopentadienyl]iron(II)] (Ferrocene Y) was synthesized. This complex, which was characterized by single crystal X-ray diffraction, contains the robust ferrocenyl unit instead of Ti assocd. with easily leaving groups such as chlorine and shows only a modest cytotoxicity against MCF-7 or MDA-MB-231 cells.

The vibrational spectra of natural and perdeuterated monochlorogallane, H2Ga([mu]-Cl)2GaH2, and an empirical harmonic potential function

The infrared and Raman spectra of monochlorogallane and its fully deuterated isotopomer are recorded and assigned on the basis of the dimeric structures. H2Ga(μ-Cl)2GaH2 and D2Ga(μ-Cl)2GaD2, conforming to D2 symmetry. The observed frequencies are corrected for anharmonicity and fitted to a potential function in which 19 of the 33 independent force constants are refined.

The synthesis of chiral N-heterocyclic carbene–borane and –diorganoborane complexes and their use in the asymmetric reduction of ketones

Chiral N-heterocyclic carbene–borane complexes have been synthesised, and have been shown to reduce ketones with Lewis acid promotion. Chiral N-heterocyclic carbene–borane and –diorganoborane complexes can reduce ketones with enantioselectivities up to 75% and 85% ee, respectively.

Spatiotemporal modelling of CheY complexes in Escherichia coli chemotaxis

The chemotaxis pathway of Escherichia coli is one of the best studied and modelled biological signalling pathways. Here we extend existing modelling approaches by explicitly including a description of the formation and subcellular localization of intermediary complexes in the phosphotransfer pathway. The inclusion of these complexes shows that only about 60% of the total output response regulator (CheY) is uncomplexed at any moment and hence free to interact with its target, the flagellar motor. A clear strength of this model is its ability to predict the experimentally observable subcellular localization of CheY throughout a chemotactic response. We have found good agreement between the model output and experimentally determined CheY localization patterns. (C) 2009 Elsevier Ltd. All rights reserved.