Notre société s'est considérablement développée grâce à l'utilisation des ressources fossiles. L'utilisation de ces ressources, dans le domaine de l'énergie ou de l'industrie chimique, provoque un dérèglement du cycle naturel du carbone par l'accumulation dans l'atmosphère d'un CO2 anthropogénique. Pour pallier ces difficultés, une des solutions envisagées consiste à abandonner progressivement les hydrocarbures fossiles au profit de ressources carbonées renouvelables telles que le CO2 pour le stockage des énergies renouvelables et/ou comme sources de produits chimiques. Les premières briques obtenues grâce au CO2 sont des molécules comportant un seul atome de carbone, rassemblées dans la classe de composés C1. Elle comprend le méthane (CH4), le monoxyde de carbone (CO), le méthanol (CH3OH), l'acide formique (HCOOH). Ces réactions ne sont pas idéales, limitées par leur praticité, leur rendement ou par leur sélectivité. Dans ce contexte, le présent travail doctoral a exploré des chemins alternatifs permettant d'interconvertir ces composés pour offrir des voies de valorisation du CO2. En premier lieu, l'utilisation de HCOOH sera proposé comme vecteur de CO. Cette thématique est née de l'intérêt grandissant pour le secteur de la chimie organique d'obtenir des sources liquides ou solides de CO. Dans un second temps, il a été développé une nouvelle stratégie de dismutation pour accéder au CH3OH à partir de dérivés de HCOOH, les formiates de silicium. Ces réactifs permettent de s'affranchir de la limitation thermodynamique dont souffre la dismutation de HCOOH. Cette transformation a été assurée en maîtrisant le recyclage des coproduits silylés. Une nouvelle voie de production de CH4 a également été développée à partir du CH3OH, en utilisant HCOOH comme réducteur. Enfin, les connaissances acquises sur l'activiation et la réactivité du CO2 ont permis, par analogie, de transposer ces connaissances à l'étude d'autres molécules iso-électroniques, telles que les carbodiimides et leur transformation en isourées dans des conditions organocatalytiques.

There has been enormous progress in our understanding of molybdenum and tungsten enzymes and relevant inorganic complexes of molybdenum and tungsten over the past twenty years. This set of three books provides a timely and comprehensive overview of the field and documents the latest research. Building on the first and second volumes that focussed on biochemistry and bioinorganic chemistry aspects, the third volume focusses on spectroscopic and computational methods that have been applied to both enzymes and model compounds. A particular emphasis is placed on how these important studies have been used to reveal critical components of enzyme mechanisms. This text will be a valuable reference to workers both inside and outside the field, including graduate students and young investigators interested in developing new research programs in this area.

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This book covers the recent NMR studies with the application of gaseous molecules. Among the comprehensively discussed aspects of the area it includes in particular: new multinuclear experiments that deliver spectral parameters of isolated molecules and provide the most accurate values of nuclear magnetic shielding, isotropic spin–spin coupling and relaxation times; advanced, precise and correct theoretical descriptions of spectral parameters of molecules as well as the application of gas-phase NMR measurements to chemical analysis and medicine. The progress of research in these fields is enormous and has rapidly changed our knowledge and understanding of molecular parameters in NMR spectroscopy. For example, accurate studies of the shielding for isolated molecules allow the exact determination of nuclear magnetic dipole moments, the calculated values of spectral parameters can be verified by precise gas-phase NMR measurements, and the application of hyperpolarized noble gases provides excellent MRI pictures of lungs. Aimed at graduates and researchers in spectroscopy, analytical chemistry and those researching the applications of NMR in medicine, this book presents the connections between sophisticated experiments, the theory of magnetic parameters and the exploration of new methods in practice.

Soil and Sediment Remediation discusses in detail a whole set of remediative technologies currently available to minimise their impact. Technologies for the treatment of soils and sediments in-situ (landfarming, bioscreens, bioventing, nutrient injection, phytoremediation) and ex-situ (landfarming, bio-heap treatment, soil suspension reactor) will be discussed. The microbiological, process technological and socio-economical aspects of these technologies will be addressed. Special attention will be given to novel biotechnological processes that utilise sulfur cycle conversions, e.g. sulfur and heavy metal removal from soils. Also the potential of phytoremediation will be highlighted. In addition, treatment schemes for the clean-up of polluted megasites, e.g. harbours and Manufactured Gaswork Plants (MGP), will be elaborated. The aim of Soil and Sediment Remediation is to introduce the reader in: the biogeochemical characteristics of soil and sediments- new techniques to study soil/sediment processes (molecular probes, microelectrodes, NMR) clean up technologies for soils polluted with organic (PAH, NAPL, solvents) or inorganic (heavy metals) pollutants- preventative and remediative strategies and technologies available in environmental engineering novel process applications and bioreactor designs for bioremediation the impact of soil pollution on society and its economic importance.

Environmental nanotechnology is considered to play a key role in shaping of current environmental engineering and science practices. This book titled "Environmental Nanotechnology" covers the advanced materials, devices, and system development for use in the environmental protection. The development of nano-based materials, understanding their chemistry and characterization using techniques like X- Ray diffraction, FT-IR, EDX, scanning electron microscope (SEM), transmission electron microscope (TEM), high resolution-TEM, etc is included. It also highlights the scope for their applications in environmental protection, environmental remediation and environmental biosensors for detection, monitoring and assessment. Key Features: Covers basic to advanced Nano-based materials, their synthesis, development, characterization and applications and all the updated information related to environmental nanotechnology. Discusses implications of nanomaterials on the environment and applications of nanotechnology to protect the environment. Illustrates specific topics such as ethics of nanotechnology development, Nano-biotechnology, and application in wastewater technology. Includes applications of nanomaterials for combating global climate change and carbon sequestration. Gives examples of field applications of environmental nanotechnology. This book covers advanced materials, devices, and system developments for use in environmental protection. The development of nano-based materials, understanding its chemistry and characterization by the use of X-Ray diffraction, FT-IR, EDX, scanning electron microscope (SEM), transmission electron microscope (TEM), and high resolution-TEM give the scope for their application in environmental protection, environmental remediation, and environmental biosensors for detection, monitoring, and assessment. The green chemistry based on nano-based materials prevents pollution and controls environmental contaminants.