Synthesis and Reactivity of Cobalt, Zinc, Copper and Iron Dimetallic Complexes Using Bis(carboxylate) and 1,8-napthyridine-based Dinucleating Ligands PDF Download
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Author: Chuan He
Publisher:
ISBN:
Category :
Languages : en
Pages : 300
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Author: Chuan He
Publisher:
ISBN:
Category :
Languages : en
Pages : 300
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Author: Daniel David LeCloux
Publisher:
ISBN:
Category :
Languages : en
Pages : 568
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Author: Brandon Fitchett
Publisher:
ISBN:
Category :
Languages : en
Pages :
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The use of rare and expensive noble metals in the chemical industry as organometallic catalysts has grown exponentially in the past few decades due to their high activity, selectivity and their ability to catalyze a wide range of reactions. With this growth in use has also come a proportional growth in concern as these toxic metals inevitably leach into the environment and their negative effects on public health and our ecosystems are becoming better understood. First-row transition metal catalysts provide both environmental and economic benefits as alternatives to these noble metals due to their lower toxicity and cheaper costs. The two-electron chemistry that makes the noble metals so attractive however, is more challenging to accomplish with first-row transition metals. Intelligently designing the ligand scaffold which surrounds the metal can mitigate or even eliminate some of the shortfalls of these first-row metals. Some key features that should be considered when designing a ligand are: 1) a strong chelating ability so the ligand can stay attached to the metal, 2) incorporation of strong donors to favour low-spin complexes, 3) inclusion of hemilabile groups to allow for substrate activation and metal stabilization throughout various oxidation states, 4) redox activity to be able to donate or accept electrons, and 5) inclusion of Lewis base functionalities which are able to assist the substrate activation. Ligands which incorporate these features are known as bifunctional ligands as they can accomplish more than one function in the catalytic cycle. Developing first-row transition metal complexes containing these ligands may enable these species to replicate the reactivity and selectivity generally associated with the precious metals. Being able to replace the noble metals used in industry with these catalysts would have tremendous environmental and economic benefits. The objective of this thesis is to advance the field of bifunctional catalysis by examining the behaviour of two sterically svelte, tridentate SNS ligands containing hard nitrogen and soft sulphur donors when bonded to cobalt. Previous work with iron provides a template of the ligand behaviour to which cobalt can be compared, allowing us to contrast the effects exerted by the different metals. After an introduction to bifunctional catalysis in Chapter 1, Chapter 2 describes the reactivity of the amido ligand, SMeNHSMe, with precursors ranging from Co(I) to Co(III), all of which yielded the 19e- pseudooctahedral cobalt(II) bis-amido complex, Co(SMeN-SMe)2 characterized by 1H NMR spectroscopy, single-crystal X-ray crystallography and cyclic voltammetry. Although this complex has a similar structure as the Fe analogue, the cobalt bis-amido complex did not exhibit the same hemilabile behaviour that allowed for simple ligand substitution of one of the thioether groups. Instead it reacted reversibly with 2,2'-bipyridine while 1,2-bis(dimethylphosphino)ethane (DMPE) and 2,6-dimethylphenyl isocyanide both triggered additional redox chemistry accompanied by the loss of protonated SMeNHSMe. In contrast, protonation gave the cobalt(II) amido-amine cation, [Co(SMeNSMe)(SMeNHSMe)](NTf2), which allowed for substitution of the protonated ligand by acetonitrile, triphenylphosphine and 2,2'-bipyridine based on 1H NMR evidence. The ability of Co(SMeNSMe)2 to act as a precatalyst for ammonia-borane dehydrogenation was also probed, revealing that it was unstable under these conditions. Addition of one equivalent of DMPE per cobalt, however, resulted in better activity with a preference for linear aminoborane oligomers using ammonia-borane and, surprisingly, to a change in selectivity to prefer cyclic products when moving to methylamine-borane. Chapter 3 delves into the chemistry of the thiolate ligand, SMeNHS, which formed a new 18e- cobalt(III) pseudooctahedral complex, Co(S-NC-)(SMe)(DEPE), from oxidative addition of the Caryl-SMe bond. Scaling up this reaction resulted instead in formation of an imine-coupled [Co(N2S2)]- anion which was characterized by 1H NMR/EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and DFT studies. The latter revealed an interesting electronic structure with two electrons delocalized in the ligand, demonstrating the non-innocent nature of the N2S2 ligand. While the analogous iron complex proved to be an effective pre-catalyst for the hydroboration of aldehydes with selectivity against ketones, this behaviour was not observed with [Co(N2S2)]- which gave a slower rate and less selectivity. The knowledge acquired from this thesis work has advanced the field of bifunctional catalysis by extending the application of these two SNS ligands from iron to cobalt, revealing unpredictable differences in reactivity between the metals. By comparing the behaviour of these ligands with iron and cobalt, we gain a better understanding of the chemistry that is accessible by these ligands and the applications for which they may be used. This increased knowledge contributes to our long-term goal of replacing expensive and toxic noble metals with more benign first-row transition metals, improving the sustainability of the chemical industry.
Author: Xuliang Dai
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 512
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Author: John R. Matachek
Publisher:
ISBN:
Category :
Languages : en
Pages : 286
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Author: Andrew C. Lane
Publisher:
ISBN:
Category :
Languages : en
Pages : 87
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Group 11 transition metals are used daily throughout our bodies and as additives in many common products. One biological function of copper, a group 11 metal, is its use in the Cu A site of cytochrome c oxidase, an enzyme found in the last step of cellular respiration. To model this active site, three formamidinate ligands have been examined: 2,6-dimethylphenyl, 2,6- diisopropylphenyl, and 2,4,6-trimethylphenyl. The synthesis and structural characterization of these dinuclear Cu(I) complexes is described as well as their redox chemistry with I 2 to afford complexes of mixed-valence which is the normal resting state of the Cu A site. Using EPR spectroscopy and DFT calculations on the iodine oxidized products, different electronic structures base d on the formamidinate was found. Additionally, insertion of CS 2 into the copper-nitrogen bonds of the copper(I) formamidinate complexes produces tetra- and hexanuclear clusters based on the steric properties of the ligand
Author: Jeffrey W. Kelly
Publisher: Springer Science & Business Media
ISBN: 1475792352
Category : Science
Languages : en
Pages : 312
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The Industry-University Cooperative Chemistry Program (IUCCP) has sponsored eight previous international symposia covering a range of topics of interest to industrial and academic chemists. The ninth IUCCP Symposium, held March 18-21, 1991 at Texas A&M University was the second in a two part series focusing on Biotechnology. The title for this Symposium "Applications of Enzyme Biotechnology" was by design a rather all encompassing title, similar in some respects to the discipline. Biotechnology refers to the application of biochemistry for the development of a commercial product. Persons employed in or interested in biotechnology may be chemists, molecular biologists, biophysicists, or physicians. The breadth of biotech research projects requires close collaboration between scientists of a variety of backgrounds, prejudices, and interests. Biotechnology is a comparatively new discipline closely tied to new developments in the fields of chemistry, biochemistry, molecular biology and medicine. The primary function of Texas A&M University is to educate students who will be appropriately trained to carry out the mission of biotechnology. The IUCCP Symposium serves as an important forum for fostering closer ties between academia and industry and exchanging ideas so important to this evolving area.
Author: Astrid Sigel
Publisher: Walter de Gruyter GmbH & Co KG
ISBN: 311047073X
Category : Science
Languages : en
Pages : 588
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Volume 18, entitled Metallo-Drugs: Development and Action of Anticancer Agents of the series Metal Ions in Life Sciences centers on biological, medicinal inorganic chemistry. The serendipitous discovery of the antitumor activity of cis-diamminodichloroplatinum(II) (cisplatin) by Barnett Rosenberg in the 1960s is a landmark in metallodrug-based chemotherapy. The success of cisplatin in the clinic, followed by oxaliplatin and carboplatin, along with their drawbacks relating mainly to resistance development and severe toxicity, initiated research on polynuclear platinum complexes and on Pt(IV) complexes as prodrugs. Furthermore, the indicated shortcomings led to the exploration of other transition and main group metal ions, among them Ru(II/III), Au(I/III), Ti(IV), V(IV/V), and Ga(III) including also the essential metal ions Fe(II/III), Cu(I/II), and Zn(II). Ionic as well as covalent and non-covalent interactions between structurally very different complexes and biomolecules like nucleic acids, proteins, and carbohydrates are studied and discussed with regard to their possible anticancer actions. Hence, MILS-18 summarizes the research at the forefront of medicinal inorganic chemistry, including studies on the next-generation, tailor-made anticancer drugs. All this and more is treated in an authoritative and timely manner in the 17 stimulating chapters of this book, written by 39 internationally recognized experts from 10 nations (from the US via Europe to China and Australia). The impact of this vibrant research area is manifested by more than 2700 references, nearly 150 illustrations (more than half in color) and several comprehensive tables. Metallo-Drugs: Development and Action of Anticancer Agents is an essential resource for scientists working in the wide range from enzymology, material sciences, analytical, organic, and inorganic biochemistry all the way through to medicine including the clinic ... not forgetting that it also provides excellent information for teaching.
Author: Bernhard Lippert
Publisher: John Wiley & Sons
ISBN: 9783906390208
Category : Medical
Languages : en
Pages : 628
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Book Description
30 years after its discovery as an antitumor agent, cisplatin represents today one of the most successful drugs in chemotherapy. This book is intended to reminisce this event, to take inventory, and to point out new lines of development in this field. Divided in 6 sections and 22 chapters, the book provides an up-to-date account on topics such as - the chemistry and biochemistry of cisplatin, - the clinical status of Pt anticancer drugs, - the impact of cisplatin on inorganic and coordination chemistry, - new developments in drug design, testing and delivery. It also includes a chapter describing the historical development of the discovery of cisplatin. The ultimate question - How does cisplatin kill a cell? - is yet to be answered, but there are now new links suggesting how Pt binding to DNA may trigger a cascade of cellular reactions that eventually result in apoptosis. p53 and a series of damage recognition proteins of the HMG-domain family appear to be involved. The book addresses the problem of mutagenicity of Pt drugs and raises the question of the possible relevance of the minor DNA adducts, e.g. of interstrand cross-links, and the possible use of trans-(NH3)2Pt(II)-modified oligonucleotides in antisense and antigene strategies. Our present understanding of reactions of cisplatin with DNA is based upon numerous model studies (from isolated model nucleobases to short DNA fragments) and application of a large body of spectroscopic and other physico-chemical techniques. Thanks to these efforts there is presently no other metal ion whose reactions with nucleic acids are better understood than Pt. In a series of chapters, basic studies on the interactions of Pt electrophiles with nucleobases, oligonucleotides, DNA, amino acids, peptides and proteins are reported, which use, among others, sophisticated NMR techniques or X-ray crystallography, to get remarkable understanding of details on such reactions. Reactivity of cisplatin, once bound to DNA and formerly believed to be inert enough to stay, is an emerging phenomenon. It has (not yet) widely been studied but is potentially extremely important. Medicinal bioinorganic chemistry - the role of metal compounds in medicine - has received an enormous boost from cisplatin, and so has bioinorganic chemistry as a whole. There is hardly a better example than cisplatin to demonstrate what bioinorganic chemistry is all about: The marriage between classic inorganic (coordination) chemistry and the other life sciences - medicine, pharmacy, biology, biochemistry. Cisplatin has left its mark also on areas that are generally considered largely inorganic. The subject of mixed-valance Pt compounds is an example: From the sleeping beauty it made its way to the headlines of scientific journals, thanks to a class of novel Pt antitumor agents, the so-called "platinum pyrimidine blues". In the aftermath diplatinum (III) compounds were recognized and studies in large numbers, and now an organometalic chemistry of these diplatinum (III) species is beginning to emerge. The final section of the book is concerned with new developments such as novel di- and trinuclear Pt(II) drugs with DNA binding properties different from those of cisplatin, with orally active Pt(IV) drugs which are presently in clinical studies, and with attempts to modify combinatorial chemistry in such a way that it may become applicable to fast screening of Pt antitumor drugs. The potential of including computational methods in solving questions of Pt-DNA interactions is critically dealt with in the concluding chapter.
Author: Jonathan L. Sessler
Publisher:
ISBN:
Category : Medical
Languages : en
Pages : 480
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Book Description
This book reviews the current diagnostic and therapeutic uses of metal-containing compounds in medicine, as well as the role of metals in disease.
