Erscheinungsdatum: 31.05.2019, Medium: Buch, Einband: Gebunden, Titel: Photophysical Studies of Pi-conjugated Oligomers and Polymers That Incorporate Inorganic MLCT Chromophores, Autor: Walters, Keith, Verlag: Dissertation Discovery Company, Sprache: Englisch, Schlagworte: SCIENCE // Chemistry // General, Rubrik: Chemie // Allgemeines, Lexika, Seiten: 272, Informationen: HC gerader Rücken kaschiert, Gewicht: 954 gr, Verkäufer: averdo
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Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Water of crystallization is water that occurs in crystals but is not covalently bonded to a host molecule or ion. The term is archaic and predates modern structural inorganic chemistry, coming from an era when the relationships between stoichiometry and structure were poorly understood. Nonetheless, the concept is pervasive, and, when employed precisely, the term can be useful. Upon crystallization from water or moist solvents, many compounds incorporate water molecules in their crystalline frameworks. Often, in fact, the species of interest cannot be crystallized in the absence of water, even though no strong bonds to the "guest" water molecules may be apparent. Classically, "water of crystallization" refers to water that is found in a crystalline framework of a metal complex but that is not directly bonded to the metal ion.
Macrocyclic ligands that can incorporate two or more metal ions giving homo- or hetero-dinuclear complexes are of considerable interest. Some of these hetero-dinuclear complexes are interesting as they mimic the active sites of metalloenzymes, such as cytochrome-c oxidase and bovine erythrocyte superoxide dismutase. Such systems are very helpful in investigating mutual influences of the two metal centers on electronic, magnetic, and electrochemical properties. Therefore, such types of system are very helpful in biological diagnostic applications. Research in inorganic chemistry has expanded in recent years by exploiting a variety of chelating ligands to modify and control the characteristics of metal ions in biological systems. Macrocyclic ligands offer the benefit of high stability complex formation and, through functionalization, the opportunity to modify the coordination environment. The pharmaceutical and bio-medical industry has yet to appreciate the impact coordination chemistry can have on the design of novel medicines. This may change the future as skilled multi-disciplinary experts may develop their investigation using a strategic approach to complex design.
Over the last decade our view of chemistry has evolved substantially. Whereas individual researchers previously focused on specific areas of chemistry, such as inorganic, organic, etc. we now take a more holistic approach. Effective and efficient research projects now incorporate whatever aspects of the chemistry subdisciplines that are needed to complete the intended work. The main group elements have always been used in this manner. Depending on the use of the elements, the resulting work can be described under any heading of chemistry. The group 13 elements have been special in this regard due to the very unique characters of the constituent elements. Thus, there is a dramatic change in the properties of the elements when proceeding through the series, B, A1, Ga, In, T1. This difference is one of the main reasons why these elements have seen, and continue to see, such widespread usage in such disparate applications as organic synthesis, electronic and structural materials, and catalysis, to name but a few.
Interest in lanthanide (Ln) coordination chemistry has increased significantly over the past few years, in particular as a result of their intriguing spectral and magnetic properties. LnIII ions are “hard acids” and generally prefer to coordinate with “hard bases” such as O- and F-donor ligands. Their coordination geometries are usually determined by ligand steric factors rather than crystal field effects. The research described in this dissertation mainly focuses on the interaction of LnIII ions with O-donor ligands such as carboxylates and polyols, while aiming to synthesize Ln-based polynuclear coordination compounds having interesting magnetic properties. Moreover, investigation of the influence of ligand back-bone on the magneto-structural properties of the resulting compounds was explored. Consequently some novel and efficient one-pot synthetic methodologies have been successfully developed to prepare Ln-based polynuclear clusters as well as networks of various dimensionalities, displaying exciting magnetic properties. Also correlations between structural parameters and magnetic properties have been established. The resulting compounds were characterized in detail using analytical methods like FT-IR, elemental analysis, single crystal XRD, powder XRD, and magnetic SQUID measurements.The first approach, based upon a systematic study of Ln-carboxylate chemistry, has led to the isolation of two 1D chains possessing single chain magnet (SCM) properties, a 2D honeycomb network, two chiral metal-organic frameworks (MOFs) and one porous MOF showing slow relaxation of the magnetisation. This study has increased the understanding of the self-assembly processes of LnIII ions under the influence of various aliphatic as well as aromatic carboxylate ligands. The second approach relies upon introducing an additional polyol ligand into the Lncarboxylate system, in order to investigate further the magneto-structural variations of the binary ligand system. This led to a variety of discrete molecular clusters ranging in nuclearity from 3 to 26, exhibiting SMM behavior. In addition to this, two 1D polymers with the highest energy barriers to reversal of the magnetization found for 4f-based single chain magnets reported so far and a 2D honeycomb network showing slow relaxation of its magnetization have been characterized. The third approach aimed to incorporate an additional metal ion, such as MnII, into the Ln-polyol-carboxylate system, thereby synthesizing heterometallic complexes with interesting magnetic properties. This resulted in a series of mixed-valent heterometallic decanuclear clusters exhibiting SMM behavior. Finally, the organic polyol ligand was replaced with a purely inorganic polyoxometalate anion, in order to synthesize some organic/inorganic hybrid materials with novel magnetic properties. This resulted in a series of polynuclear aggregates some of which show SMM behavior.
According to many textbooks, carbohydrates are the photosynthesis and mitochondrial respiration fluctuate in a circadian manner in almost every unique final products of plant photosynthesis. However, the photoautotrophic production of organic organism studied. In addition, external triggers and environmental influences necessitate precise and nitrogenous compounds may be just as old, in appropriate re-adjustment of relative flux rates, to evolutionary terms, as carbohydrate synthesis. In the algae and plants of today, the light-driven assimilation prevent excessive swings in energy/resource provision of nitrogen remains a key function, operating and use. This requires integrated control of the alongside and intermeshing with photosynthesis and expression and activity of numerous key enzymes in respiration. Photosynthetic production of reduced photosynthetic and respiratory pathways, in order to carbon and its reoxidation in respiration are necessary co-ordinate carbon partioning and nitrogen assim- ation. to produce both the energy and the carbon skeletons required for the incorporation of inorganic nitrogen This volume has two principal aims. The first is to into amino acids. Conversely, nitrogen assimilation provide a comprehensive account of the very latest developments in our understanding of how green is required to sustain the output of organic carbon cells reductively incorporate nitrate and ammonium and nitrogen. Together, the sugars and amino acids into the organic compounds required for growth.