Les Liquides Ioniques [LI] à température ambiante forment une nouvelle classe de matériaux, prometteurs dans des applications diverses. Les avantages que les LI soulèvent par rapport aux autres liquides moléculaires ou sels fondus résident dans la facilité à changer leurs propriétés intrinsèques en jouant sur la nature chimique de la combinaison [cation-anion]. Cependant, on n'est pas encore près à prédire les propriétés d'un LI en connaissant uniquement sa composition chimique. Par conséquent, nous avons fait des expériences de diffraction de rayons-x et de neutrons, complétées par une série de simulations de dynamiques moléculaires sur une famille de LI à bases de cations d'alkyl-methylimidazolium et d'anion Bromure. Ainsi, en changeant la longueur de la chaine alkyl, nous avons comparé la structure et la dynamique de trois LI de chaines ethyl, butyl et hexyl. La comparaison des résultats structuraux obtenus par la simulation avec ceux des rayons-x donnèrent complète satisfaction. Des résultats intéressants ont été obtenus, spécialement ceux issus de la comparaison de la structure et la dynamique du LI 1-ethyl-3-methylimidazolium Bromide en phase cristalline et liquide. Par ailleurs, l'hétérogénéité en phase volumique a pu être quantifiée ce qui a permis de déterminer que la ségrégation augmente avec la longueur de la chaine alkyl cationique.

Percutaneous delivery of drugs promises many advantages over oral or intravenous administration, such as a better control of blood levels, a reduced incidence of systemic toxicity, an absence of hepatic first-pass metabolism, better patient compliance, etc. However, the dermal drug transport is limited by the unsuitable physicochemical properties of most drugs and the efficient barrier function of the skin. Thus, numerous attempts have been reported to improve topical absorption of drugs, concentrating mainly on the barrier function of the stratum corneum by use of penetration enhancers and/or skin warming. An alternative and interesting possibility for improved dermal permeability is the synthesis of derivatives or analogues with the aim of changing the physicochemical properties in favour of skin permeation, efficacy and therapeutic value. Cyclizine (I) is an anti-emetic drug primarily indicated for the prophylaxis and treatment of nausea and vomiting associated with motion sickness, post operation and Meniere's disease. It acts both on the emetic trigger zone and by damping the labyrinthine sensitivity. Pharmacologically it has anti-histaminic, antiserotonergic, local anaesthetic and vagolytic actions. It is widely used and also suitable for children from six year of age. Percutaneous absorption of (I) can, among others, avoid the "first-pass" effect and the discomfort of injection. The main objective of this study was to explore the feasibility of percutaneous absorption of (I) and its alkyl analogues via physicochemical characterization and assessment of their permeation parameters. The intent was also to establish a correlation between the physicochemical properties of these compounds and their percutaneous rate of absorption. To achieve these objectives, the study was undertaken by synthesizing the alkyl analogues and determining the physicochemical parameters relevant to skin transport. Identification and level of purity for the prepared analogues were confirmed by mass spectrometry (MS), nuclear magnetic resonance (NMR) spectrometry and infrared (IR) spectrometry. Experimental aqueous solubility (25 °c & 32 °C) and partition coefficient for each compound were determined. In vitro permeation studies were performed at pH 7.4, using Franz diffusion cells with human epidermal membranes. Diffusion experiments were conducted over a period of 24 hours maintaining a constant temperature (37 DC) by means of water bath. All samples were analysed by high pressure liquid chromatography (HPLC). Cyclizine (I) has a methyl group at N-4. Increasing the alkyl chain length on N-4 of the piperazine ring resulted' in compounds with lower melting points and higher water solubility than (I). (II) exhibited 3-fold increase in water solubility, followed by (IV) with about 2.5 fold increase. The water solubility of (III) was almost the same as that of (I). Log partition coefficients increased linearly with increasing alkyl chain length. The analogues therefore, possessed more favourable physicochemical properties to be delivered percutaneously. Indeed, the in vitro skin permeation data proved that these analogues could be delivered more easily than (I) itself. The flux of (I) was 0.132 ug/cm2/h in a saturated aqueous solution. Compound (II) resulted in a 53-fold (6.952 ug/cm2/h) increase in permeation compared to (I). (III) and (IV) resulted in a 2- and 5fold enhancement of permeation respectively. Based on the results of the study, it seems that increased aqueous solubility and low level of crystallinity play a vital role in optimizing percutaneous absorption of (I) and its alkyl analogues. But the importance of the effect of increased lipophilicity cannot be ignored. The low percutaneous• absorption of (I) might be attributed to its low aqueous solubility and increased crystallinity, as is evident from the higher melting point than the analogues. From all the permeability data using aqueous solutions, it is clear that compound (II) is the best permeant of this series and in addition it is known that this compound antagonizes the effects of histamine. / Thesis (M.Sc. (Pharm.))--North-West University, Potchefstroom Campus, 2004.

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper and copper-, based alloys for more than 40 years. It has been successfully employed for the, prevention of both atmospheric corrosion and particularly for the protection of, copper under immersed conditions. Whilst BTAH is an excellent inhibitor in alkaline, solution its efficiency drops off markedly as the pH decreases. It was hypothesized, that a possible way to increase surface adsorption and subsequent better inhibition, over a wide pH range might be through the preparation of derivatives, particularly, carboxybenzotriazoles and alkyl esters of these compounds. In this work the following techniques: weight loss measurements, potentiodynamic, polarisation, SERS spectroscopy, electrochemical impedance spectroscopy and, coulometry were employed to investigate the inhibition efficiency of 4- and 5-, carboxybenzotriazole and their alkyl ester for copper corrosion. Molecular modelling, was also investigated as a tool for inhibitor design. Studies on 4- and 5- carboxybenzotriazole (CBT) showed that the inhibition, efficiency for copper corrosion in aerated acidic sulphate solution of each isomer was, pH, concentration and time dependant. At lower pH the 5-isomer is the better, inhibitor and this behaviour continues at higher pH. The anti-tarnishing test showed, that whilst both isomers exhibited these properties, 5-CBT was once again the, superior inhibitor. It was found that a commercial mixture of the octyl esters of 4- and 5-, carboxybenzotriazole inhibits copper corrosion in sulphate environments open to air., The inhibition efficiency of the ester mixture at the lx10-4 M level (pH - 0) is 98%, which compares very favourably with that for BTAH (- 50%). With respect to other, alkyl esters of 4- and 5-carboxybezotriazole, hexyl, butyl and methyl, it was found, that all of these inlibited copper corrosion in sulphate environments open to air. In, each case the inhibition efficiency is concentration, pH and time dependent. Both, coupon tests and EIS measurements indicate that inhibition efficiency depends on the, length of the alkyl chain. At pH - 0 the inhibition efficiency decreased in the order, octyl &gthexyl &gtbutyl &gtmethyl. At higher pH (- 8) the order is reversed. At the 1x104, M level (pH - 0) the inhibition efficiency of each of the alkyl esters is equal to or, better than that for BTAH. At higher pH (- 8) the inhibition efficiency in each case is, reduced in comparison to BTAH. but is still good enough for practical use ( 2 75%)., The inhibitive behaviour of the alkyl esters at low pH can be attributed to, chemisorption through an azole nitrogen of the protonated alkyl esters. The, hydrocarbon chain is also physically adsorbed and the increase in physical adsorption, as the chain is lengthened accounts for the improved inhibition efficiency. Dry films formed by immersing copper in solutions of alkyl esters of, carboxybenzotriazole also inhibit copper corrosion in both strongly acidic (pH - 0), and near neutral (pH - S) sulphate corrodents. The inhibition efficiency depends on, the solvents used to dissolve the esters, solution temperature and immersion time., Aqueous coating solutions furnish the most protective films. Films formed by, CBTAH-BU, CBTAH-HE and CBTAH-OE are more protective than that formed by, BTAH. The inhibition efficiency of the alkyl ester film increases as the alkyl chain is, made longer. Molecular modeling showed that the optimum crude binding energy (Eblnd), between each protonated ester molecule and the surface varied linearly with the alkyl, chain length. The resulting linear correlation between IE% and E bind for compounds, that are structurally similar suggested that the crude binding energy of a single, molecule with copper may be used to predict the inhibition performance of other, compounds constituting a series.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Feb. 19, 2009). Includes bibliographical references.

This dissertation presents results of a project bringing Scanning Tunneling Microscope (STM) into a regime of unlimited operational time at cryogenic conditions. Freedom from liquid helium consumption was achieved and technical characteristics of the instrument are reported, including record low noise for a scanning probe instrument coupled to a close-cycle cryostat, which allows for atomically resolved imaging, and record low thermal drift. Subsequent studies showed that the new STM opened new prospects in nanoscience research by enabling Scanning Tunneling Spectroscopic (STS) spatial mapping to reveal details of the electronic structure in real space for molecules and low-dimensional nanomaterials, for which this depth of investigation was previously prohibitively expensive. Quantum-confined electronic states were studied in single-walled carbon nanotubes (SWCNTs) deposited on the Au(111) surface. Localization on the nanometer-scale was discovered to produce a local vibronic manifold resulting from the localization-enhanced electron-vibrational coupling. STS showed the vibrational overtones, identified as D-band Kekulé vibrational modes and K-point transverse out-of plane phonons. This study experimentally connected the properties of well-defined localized electronic states to the properties of associated vibronic states. Electronic structures of alkyl-substituted oligothiophenes with different backbone lengths were studied and correlated with torsional conformations assumed on the Au(111) surface. The molecules adopted distinct planar conformations with alkyl ligands forming cis- or trans- mutual orientations and at higher coverage self-assembled into ordered structures, binding to each other via interdigitated alkyl ligands. STS maps visualized, in real space, particle-in-a-box-like molecular orbitals. Shorter quaterthiophenes have substantially varying orbital energies because of local variations in surface reactivity. Different conformers of longer oligothiophenes with significant geometrical distortions of the oligothiophene backbones surprisingly exhibited similar electronic structures, indicating insensitivity of interaction with the surface to molecular conformation. Electronic states for annealed ligand-free lead sulfide nanocrystals were investigated, as well as hydrogen-passivated silicon nanocrystals, supported on the Au(111) surface. Delocalized quantum-confined states and localized defect-related states were identified, for the first time, via STS spatial mapping. Physical mechanisms, involving surface reconstruction or single-atom defects, were proposed for surface state formation to explain the observed spatial behavior of the electronic density of states. This dissertation includes previously published co-authored material.

Surfactants from the 'Triton' range, manufactured by Rohm and Haas, Germany, were used to study the adsorptive behaviour of non-ionic surfactants (of the alkyl polyoxyethylene type) from aqueous solution onto mineral oxide surfaces. The oligomeric distributions of the surfactants were characterised using the HPLC technique. Two gradients were used: a normal phase gradient was used to study the surfactants from non-aqueous solution; an unusual gradient, which could not be definitively categorised as either normal or reversed phase and which was developed at Brunel, was used to analyse surfactants directly from aqueous solution. Quartz was used as a model mineral oxide surface. The quartz surface was characterised using a range of techniques: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, X-ray fluorescence -analysis, Fourier transform-infra red spectroscopy and BET analysis. It was found that washing the quartz with concentrated HCI removed any calcium ions present on the surface and also removed 02- ions. Calcining the sample removed carbonaceous materials from the surface and also caused a decrease in the surface area. The quartz was shown to be non-porous by SEM and BET analysis. The adsorption experiments for this study were carried out using a simple tumbling method for which known ratios of surfactant in aqueous solution and quartz silica were mixed together for a known length of time. The amounts of surfactant present were measured using ultra-violet analysis and the HPLC techniques mentioned above. It was found that the smallest oligomers were adsorbed the most. An addition of salt to the system caused an overall increase in adsorption of the bulk surfactant, and increase in temperature caused an initial decrease in adsorbed amounts before the plateau of the isotherm and a final increase in bulk adsorption at the plateau of the isotherm. The oligomeric adsorption generally appeared to mirror the behaviour of the bulk surfactant. Atomic force microscopy (AFM), dynamic light and neutron scattering studies were used to analyse the character of the adsorbed surfactant layer. It was shown that the layer reached a finite thickness that corresponded to a bilayer of adsorbed surfactant. According to AFM data, this value of thickness was not consistent over the whole of the quartz surface.

Abstract Thirty three aryl and aryl alkyl phosphane ligands were prepared and characterized for catalytic purposes. The aryl groups in both types of ligands were modified with alkyl substituents (methyl, ethyl, isopropyl, cyclohexyl, phenyl) or hetero substituents (methoxy, N,N-dimethylaniline, thiomethyl). The alkyl groups directly attached to the phosphorous atom were ethyl, isopropyl or cyclohexyl. Mono- and in some cases also dinuclear palladium (II) complexes of the ligands were prepared and characterized. The syntheses of the palladium complexes are solvent-dependent and afford either mono- or dinuclear complexes depending on the choice of the solvent. Additionally, two 2-mercaptobenzothiazole palladium complexes were synthesized and characterized. A rare distorted lantern-type structure was presented for the first time. The ligands were characterized by 1H, 13C, 31P NMR spectroscopy and mass spectrometry. The palladium complexes were characterized by 31P NMR spectroscopy, X-ray crystallography and elemental analysis. Links between the NMR data of the palladium complexes and ligands and their catalytic activity was screened and correlation found. The crystal structures of the palladium complexes were studied for possible attractive interactions between two ligands. Such interactions were found from two examples. There is an attractive interaction between the phenyl and quinolinyl moieties of 2-quinolinyldiphenyl phosphane. A similar interaction was found between the methyl substitute and phenyl ring of o-tolylphosphane. The ligands and palladium complexes presented in this thesis were prepared in hope of finding suitable catalysts for Suzuki coupling reactions of various bulky aryl halides and phenyl boronic acids to prepare sterically hindered bi- and triaryls under microwave irradiation. A selection of aryl alkyl phosphane ligands catalyzed the couplings of bulky aryl bromides and even unactivated aryl chlorides efficiently and produced high yields. The reaction conditions of a new catalyst system were optimized, and it was noticed that the addition of a small amount of water enhanced the purity and yield of the coupling products further.

The experiment in this thesis involves a study of some 1-alkyl-1,2-dihydro-3-hydroxybenzo[g]quinoxaline-5,10-diones.

At diploma thesis will be used for determination of alkyl - derivatives of mercury especially gass chromatography. At diploma thesis will be developed metod for it´s identification, quantification, standard operating procedure and validation of the method of determination of alkyl - derivatives of mercury in animal tissues. There will be evaluated level of contamination by the polutants.

Thesis advisor: X. Peter Zhang / Among recent advances in devising different strategies for stereoselective homolytic reactions, metalloradical catalysis (MRC) has emerged as a conceptually new approach for controlling stereoselectivity of radical reactions. As stable metalloradicals, cobalt(II) complexes of D₂-symmetric chiral amidoporphyrins [Co(D₂-Por)] have proven to be effective catalysts for homolytically activating a series of diazo compounds to generate α-Co(III)-alkyl radicals for various C-centered radical transformations with well-confined reactivity and selectivity. Nevertheless, the applications of donor-, donor/donor- and alkyl diazo compounds have been largely underdeveloped. This dissertation mainly focuses on how the chemistry of these types of diazo compounds was initiated by using commonly available aldehyde-derived sulfonylhydrazones as diazo surrogates. In the context of Co(II)-MRC, in situ-generated diazo compounds can be effectively activated for various asymmetric radical transformations, including intermolecular radical cyclopropanation of alkenes and intramolecular radical alkylation of C–H bonds. First, as a proof of concept, we have demonstrated the feasibility of using aryl aldehyde-derived sulfonylhydrazones as new radical precursors for diastereo- and enantioselective radical cyclopropanation of alkenes, and proven that the diazo in situ-generation protocol is well compatible with the catalytic radical process. Second, we have expanded the application of Co(II)-based MRC to a new territory by employing aliphatic diazo compounds for asymmetric cyclopropanation. The system is highlighted by the excellent enantioselectivity together with remarkable cis-selectivity. Finally, with the utilization of linear aliphatic aldehyde sulfonylhydrazones as diazo precursors, we have presented a new radical cyclization mode, involving hydrogen atom abstraction and radical substitution, for enantioselective synthesis of common five-membered rings via radical C–H alkylation. The system would offer a new retrosynthetic paradigm for construction of ring structures, where C–C bond can be disconnected as common C=O and C–H units of linear aldehydes. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.