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[en] Complete text of publication follows. In analytical chemistry, aqueous borane derivatization for the generation of volatile hydrides or volatile metallic species (CHG), coupled with atomic or mass spectrometry, represents one of the most powerful and widely employed analytical tool for trace and ultra trace element determination and speciation. Fundamental aspects dealing with the mechanisms involved in CHG have scarce relevance in comparison with analytical applications and developments. Moreover, the analytical community has disregarded most of the experimental evidence relating to the chemistry of borane complexes that have been reported in the fundamental chemistry literature in the past years. These are probably the reasons for which CHG is still dominated by erroneous concepts, which have been disseminated and consolidated within the analytical scientific community over the course of many years. The overall approach to CHG has thus remained completely empirical, which hinders the possibilities for further developments. This presentation reports a discussion devoted to clarification of the most controversial aspects of CHG: - Kinetic and Mechanism of hydrolysis of THB and borane complexes. - Mechanism of CHG. - Reaction model of general validity for CHG. - Mechanism of action and role played by additives. The discussion is based on the present status of knowledge, which results from the survey of fundamental chemistry literature (1950-1985) and analytical chemistry literature (1972-to date)(IUPAC Project 2007-041-1-500; ) and it includes some recent dedicated experiments (A. D'Ulivo et al., Anal.Chem. 76 (2004) 6342-6352.; A. D'Ulivo et al., Anal.Chem. 79(2007) 3008-3015.;E. Pitzalis et al., Anal.Chem. 79 (2007) 6324-6333.).
[en] Isotopically labeled compounds play an important role in chemistry, biology, and medicine. In recent years, organometallic chemistry has been utilized extensively in the development of labeled compounds. Syntheses involving the use of organoboranes have proven to be among the most versatile and effective of the new labeling methodologies. 26 refs
[en] Radioiodine-labeled pharmaceuticals have been used extensively in diagnostic nuclear medicine. We have developed a rapid and mild method for incorporating radioiodine into functionally substituted molecules. The new process involves the reaction of the radioiodide ion with organoboranes in the presence of gentle oxidizing reagents. The radioiodide is utilized nearly quantitatively in a matter of seconds. The radiochemical yields are excellent, and parallel those obtained when iodine monochloride is reacted with organoboranes
[en] Organoboranes have proven to be effective precursors for the incorporation of isotopically labeled compounds. Their value rests on the fact that they are reactive intermediates which tolerate variety of functional groups. Thus the isotopes of interest can be incorporated in the final synthetic step which maximizes the yields of desired product. (author). 34 refs
[en] The preference for icosahedral B12 amongst polyhedral boranes and elemental boron is explained based on an optimization of overlap model. The ingenious ways in which elemental boron and boron-rich solids achieve icosahedron-related structures are explained by a fragment approach. The Jemmis mno rules are used to get the electron requirements. The extra occupancies and vacancies in β-rhombohedral structures are shown to be inevitable results of electron requirements. The detailed understanding of the structure suggests ways of doping β-rhombohedral boron with metals for desired properties. Theoretical studies of model β-rhombohedral solids with metal dopings provide support for the analysis. - Graphical abstract: A short legend: Principal building blocks B12, B57, and B84 of elemental boron and boron-rich solids
[en] Electrochemical behavior of four cluster boranes and nine derivatives of ten- and eleven-vertex cluster boranes has been studied in phosphate buffers. These compounds show promising applications in biological sciences and in biomedicine and, therefore, analytical techniques developed for their determination and analysis of their bioconjugates should be compatible with aqueous media. Results presented herein show that both endo- and exo-skeletal substitutions of cluster boranes significantly influence their electrochemical responses, such as the shape of voltammetric curves, the position of the current maximum in a potential scale, and the peak current density. Selected substitutions can be utilized to tune electrochemical properties of the boron cluster compounds in order to optimize their responses for their electroanalytical determination and their usage as labels for biopolymers.
[en] The present work is structured around boron-based materials expected to be used in the field of 'energy'. We especially worked on two types of materials. (i) With the first type, solid-state hydrogen storage was targeted. Hydrazine borane N2H4BH3 was used as precursor of novel derivatives obtained by mechano-synthesis. We first made it react with lithium amide LiNH2 to obtain LiN2H3BH3.0.25NH3. Then, we considered calcium hydride CaH2; it reacted with N2H4BH3 at 67° (after ball-milling) to form a new phase, calcium hydrazinidoborane of formula Ca(N2H3BH3)2. (ii) The second type of boron-based materials we investigated is about anionic poly-boranes. They are known to be stable in aqueous solution and accordingly could be used as anodic fuel of direct liquid-fed fuel cell. We aimed at synthesizing and fully characterizing two salts: sodium closo-decaborane Na2B10H10 and sodium 1-oxa-nido-dodeca-borate NaB11H12O. Their potential for the aforementioned application was tested by cyclic voltammetry by using bulk electrodes of platinum, silver and gold. All of our results are presented, discussed in detail and put into perspective in the present thesis. (author)
[en] Complete text of publication follows. Analyte introduction via chemical vapor generation (CVG) is frequently used to increase detection power, eliminate spectroscopic interference, eliminate an intractable matrix, etc. CVG approaches have expanded in the past decade: the number of elements has increased to encompass several transition and noble metals; fundamental understanding of reduction techniques is now within reach and, once mastered, will be used to enhance analytical performance. The vast majority of applications of CVG target cold vapor production of mercury and hydride generation of Groups IIIA-VIA by derivatization with borane salts. Most recently, use of UV radiation has been explored for this purpose, i.e., photo-CVG. This technique suggests use of promising greener chemistry, with highly efficient generation of many atomic and alkylated transition, noble and semi-metals for environmental, analytical and industrial purposes. It remains to capitalize on this chemistry, construct hardware to make efficient use of its properties and explore the extent and limitations of its application. Photo-CVG may provide a powerful alternative to conventional CVG due to its simplicity, versatility and cost effectiveness. The methodology has its origins in waste-water treatment, wherein use of photocatalytic processes based on UV/vis irradiation provided for oxidation of dissolved organic matter and sterilization of bacteria. It has subsequently been found possible to achieve photo-CVG in the absence of semiconductor catalysts. Applications of photo-CVG comprise processes to pre-reduce valence states of various species prior to use of conventional chemical CVG, as for example the reduction of a number of selenium species prior to hybridization with tetrahydroborate (III), and direct photo-CVG which gives rise to synthesis of volatile metal containing species. Examples of the latter approach include direct generation of volatile selenium hydride, carbonyl or methyl- and ethylated- derivatives, depending on the selection of experimental conditions. Cold vapor generation of mercury can be conveniently achieved using photo-CVG, as can direct speciation of inorganic and methylmercury forms. This presentation will briefly review the state-of-the-art in photo-CVG techniques, summarizing its application in the areas of enhanced sample introduction efficiency for several detection modes, preconcentration techniques as well as speciation, and speculate on future developments based on work in our laboratories.