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New Peptide Type Tripodal Ligands And Their Metal Complexes
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Book Synopsis New Peptide-type Tripodal Ligands and Their Metal Complexes by : Ágnes Dancs
Download or read book New Peptide-type Tripodal Ligands and Their Metal Complexes written by Ágnes Dancs and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most important directions of modern bioinorganic research is the development of artificial enzymes. One pathway of enzyme modeling strategy is the study of amino acid sequences present in the active centers of metalloenzymes. Linear peptides, however, have their limitations in reconstituting the active centers of metalloenzymes, since they do not possess the well-defined three dimensional structure, therefore their structure is vulnerable towards amide nitrogen coordination/hydrolysis. Improvement of metal binding capabilities of linear peptides can be obtained by e.g. their functionalization with tripodal ligands. Tripodal compounds may provide a rigid, less flexible platform for the coordinating amino acid side chains, creating pre-organized metal binding sites. In my thesis, I present synthesis and characterization of histidine containing tripodal peptide ligands and their complex formation in presence of copper(II) and zinc(II). Solution equilibrium was studied with pH potentiometric measurements, and several spectroscopic methods were used for structural characterization (UV-Vis, CD, ESR, NMR and MS methods). Beside thermodynamic and structural characterization, enzyme mimicking catalytical properties of the complexes have also been investigated (catechol oxidation, superoxide dismutation). Our results demonstrated that tripodal peptide ligands are capable of enhancing the stability of metal-peptide complexes, and they may provide convenient structures to efficiently mimic the catalytic functions of enzymes. With thorough and systematical solution equilibrium and spectroscopic studies, we uncovered the driving forces of metal coordination, and established the impact of the tripodal structure in stability, structure and catalytic properties of the forming complexes. Our findings confirm the beneficial effect of tripodal scaffolds in peptide-type ligand-metal complexes, and emphasize the possibilities lying within tripodal peptides in the field of enzyme mimicking.
Book Synopsis Main Group and Transition Metal Complexes Supported by Multidentate Tripodal Ligands that Feature Nitrogen, Oxygen and Sulfur Donors by :
Download or read book Main Group and Transition Metal Complexes Supported by Multidentate Tripodal Ligands that Feature Nitrogen, Oxygen and Sulfur Donors written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 5 describes two multidentate, L3X type ligands, which feature [CN3] and [CNO2] donors, namely tris(2 pyridylseleno)methane, [Tpsem]H, and bis(2-pyridonyl)(pyridin-2-yloxy)methane, [O-poBpom]H. They have been synthesized, characterized, and employed in the synthesis of zinc and cadmium complexes. Chapter 6 describes the synthesis and structural characterization of a new [Tp] ligand featuring an allyl substituent on the central boron atom, namely [allylTpBut]Li is reported. The compound reacts steadily with CH3CH2SH under 350 nm UV light via a thiol-ene click reaction. The resulting [CH3CH2S(CH2)3TpBut]Li complex can further react with metal halide. For example, the reaction of [CH3CH2S(CH2)3TpBut]Li with ZnI2 produced [CH3CH2S(CH2)3TpBut]ZnI at room temperature. This study provides a simple model on the immobilization of [Tp] metal complexes to the polymer chains with -SH terminals.
Book Synopsis Monometallic and Bimetallic Complexes with Sulfonamido-Based Tripodal Ligands by : Nathanael Lau
Download or read book Monometallic and Bimetallic Complexes with Sulfonamido-Based Tripodal Ligands written by Nathanael Lau and published by . This book was released on 2017 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: A central tenet of chemistry is the importance of the local environments that surround molecules. Rules for how such local environments control molecular properties have been developed and form the basis for coordination chemistry, an area of chemistry devoted to the study of molecules containing metal ions. Within this context, the volume of space surrounding metal ions is divided into two regions, referred to as the primary and secondary coordination spheres. The primary coordination sphere involves covalent interactions between atoms on ligands that are directly bound to the metal center. The secondary coordination sphere, which involves non-covalent interactions, is part of the volume of space around the metal center and often interacts with the ligands of the primary coordination sphere. Together, the coordination spheres define the physical properties and reactivity of a metal ion. The importance of modulating both is seen within the active sites of metalloproteins, in which the interplay between the two coordination spheres allow these proteins to catalyze difficult reactions under ambient conditions, with selectivities and efficiencies that are currently unattainable in synthetic systems.One approach towards understanding how the two coordination spheres affect function involves specially designed ligands that account for effects in both coordination spheres. The aim of this dissertation is to study synthetic metal complexes that incorporate these types of ligands, and explore their fundamental physical, structural, and chemical properties. The ligands used are based on the tripodal sulfonamido-based ligand N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]tris(2,4,6-trimethylbenzenesulfonamido) ([MST]3--). This ligand contains a tris(2-aminoethyl)amine (tren) backbone that allows for the preparation of four- or five-coordinate metal complexes with local C3 symmetry to control the primary coordination sphere. The trigonal environment leads to high-spin metal complexes, and the presence of three anionic nitrogen donors helps to stabilize relatively high oxidation states. Secondary coordination sphere effects are modulated through the sulfonamido moieties. The [MST]3-- ligand can support monometallic metal complexes with terminal hydroxido, aqua, or ammine ligands, as the sulfonamido moieties can accept H-bonds from H-atom containing exogenous ligands. Additionally, the sulfonamido O-atoms can serve as a secondary metal binding site, allowing discrete bimetallic complexes to be prepared with [MST] 3--.In this dissertation, new monometallic and bimetallic complexes with sulfonamido-based tripodal ligands were prepared, with the goal of understanding how the choice of ligands influences the properties of metal complexes. The first study investigated the effect of ligand modification on the physical properties of a series of FeII--OH2 complexes supported by ligands related to [MST]3--. The aryl groups of the five new N,N',N"-[2,2',2"-nitrilotris(ethane-2,1-diyl)]-tris-({R-Ph}-sulfonamido)) ([RST]3--) ligands had para-substituents of varying electron-withdrawing and donating strengths. The physical properties of the subsequent Fe II--OH2 complexes were probed by various characterization methods, which revealed that the greatest impact of the ligand modification occurred in the metal complexes' electrochemical properties.Monometallic Ni complexes with [MST]3-- and a related urea-based ligand, [H3buea]3--, were then studied. The solid-state structures of these compounds showed that these ligands allowed for the preparation of NiII complexes with terminal aqua or hydroxido ligands in distorted trigonal bipyramidal geometries. Additionally, the oxidation chemistry of both NiII compounds was investigated, allowing for the preparation and characterization of uncommon NiII I complexes.Bimetallic complexes with [MST]3-- are prepared by treating a solution of a monometallic [MST]3-- complex, secondary metal salt, and secondary multidentate ligand with O2. The secondary ligand serves to "cap" the secondary metal center, resulting in discretely bimetallic units. A new series of bimetallic complexes with FeII(OH)FeIII, CoII(OH)Fe III, and NiII(OH)FeIII cores was prepared, using the bidentate capping ligand tetramethylethylenediamine (TMEDA). Previously, all other capping ligands used in this system had denticities of three and above. The bidentate capping ligand TMEDA allows the previously outer-sphere trifluoromethansulfonate (OTf--) counter anion to become inner-sphere, occupying the sixth coordination site of the second metal center.
Book Synopsis Metal Complexes of a New Tripodal Multidentate Ligand by : Getinet Tamiru Tigineh
Download or read book Metal Complexes of a New Tripodal Multidentate Ligand written by Getinet Tamiru Tigineh and published by LAP Lambert Academic Publishing. This book was released on 2012-03-01 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal complexes are species consisting of metal coordinated with one or more ligands, they are important in catalysis, materials synthesis, photochemistry, biological Systems and so on .Moreover these metal complexes display diverse chemical, optical and magnetic properties which are significant for different applications. This monograph contains an attempt has been made to synthesize a new tipodal multidentae ligand containing S-Triazine function capable of holding metal ions through possible coordination center with alternative path of preparation and to search metal ions which are capable of coordinated in these available sites. Based on the analytical, spectral (i.e NMR, IR, UV), magnetic susceptibility and conductance data it is proposed that the ligand employs one or more ONN sequence in metal binding process. Precisely, the Ni(II) complex involves bonding through one ONN sequence and the Zn(II) complex has bonding through three such sequences. As such TSHSTZ behaves as a dibasic ONN donor towards Ni(II) and tri basic tris-ONN donor towards Zn(II) with the preference of Octahedral and Tetrahedral geometries respectively.
Book Synopsis New Tripodal Ligands for Novel Transition Metals Complexes by : David James Harding
Download or read book New Tripodal Ligands for Novel Transition Metals Complexes written by David James Harding and published by . This book was released on 2005 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies on New Diiminodiphosphine Type Ligands and Their Metal Complexes by : Ino C. Vei
Download or read book Studies on New Diiminodiphosphine Type Ligands and Their Metal Complexes written by Ino C. Vei and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Divalent Metal Complexes of Novel Tripodal Ligands by : Magdalena M. Makowska-Grzyska
Download or read book Divalent Metal Complexes of Novel Tripodal Ligands written by Magdalena M. Makowska-Grzyska and published by . This book was released on 2003 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Amino Acids, Peptides and Proteins by : Maxim Ryadnov
Download or read book Amino Acids, Peptides and Proteins written by Maxim Ryadnov and published by Royal Society of Chemistry. This book was released on 2014-12-01 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amino Acids, Peptides and Proteins comprises a comprehensive and critical review of significant developments at this biology/chemistry interface. Each volume of this Specialist Periodical Report opens with an overview of amino acids and their applications. Each chapter incorporates current trends of the reviewed topic and the author’s outlook of future perspectives. This is to facilitate the monitoring of the covered area and their potential expansion with the inclusion of other specialist reports in subsequent volumes. All chapters are compiled by leading researchers in their subject areas, which presents this series as an appealing source of information for the research community in both academia and industry.
Book Synopsis Synthesis and Reactivity of Metal Complexes Supported by Kläui's Oxygen Tripodal Ligand by : Ho Fai Ip
Download or read book Synthesis and Reactivity of Metal Complexes Supported by Kläui's Oxygen Tripodal Ligand written by Ho Fai Ip and published by . This book was released on 2010 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modulating the Secondary Coordination Sphere Around Metal Complexes with Hybrid Tripodal Ligands by : Jason R. Jones
Download or read book Modulating the Secondary Coordination Sphere Around Metal Complexes with Hybrid Tripodal Ligands written by Jason R. Jones and published by . This book was released on 2017 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: In biological systems, metalloproteins have evolved to carry out difficult chemical transformations with high activity and selectivity through control of the primary and secondary coordination spheres. Inorganic chemists have developed organic ligand scaffolds to prepare small-molecule model complexes with similar coordination environments to active sites of metalloproteins. However, the resulting complexes are often unable to carry out the same reactivity as their metalloprotein counterparts because they lack the precise control of the secondary coordination sphere.The most common secondary coordination sphere interaction in metalloproteins is hydrogen bonds (H-bonds). Our group has shown that intramolecular H-bonds can be incorporated into rigid ligand scaffolds to facilitate the activation of small molecules. This has been demonstrated through the use of tetradentate, anionic, and C3 symmetric ligand scaffolds, which when bound to a metal ion have one open coordination site available for binding of small molecules. Intramolecular H-bonds have been incorporated through the introduction of sulfonamido, urea and amido groups, which can serve as H-bond donors or acceptors. This dissertation focuses on ligand design that systematically changes the H-bonding network in the secondary coordination sphere around M--O and M--OH units.The first study investigates the effect of having intramolecular H-bond donors and acceptors in the same ligand by developing new ligands based upon the symmetrical sulfonamido tripodal ligand [MST]3-- and the symmetrical urea tripodal ligand [H3buea]3--. Two new hybrid ligand systems ([H1tol] 3-- and [H22tol]3--) having varying numbers of urea and sulfonamido groups were synthesized. These four ligands were used to synthesize a series of CoII/III--OH complexes with varying numbers of intramolecular H-bonds. These complexes allowed for the study of the structural and physical properties arising from modification of the H-bonding network about a Co--OH unit.The remainder of the dissertation focuses on the development of new hybrid urea tripodal ligands ([H33R]3--) based upon [H3buea]3--. These ligands were developed to maintain a constant primary coordination sphere, while modifying the properties of only one H-bond donor. This is accomplished through attaching a substituted phenyl ring with electron-withdrawing groups on only one of the urea units, which modulates the acidity of this urea NH. These ligands were used to synthesize a series of M--O(H) (M = Mn III/IV/V and FeIII) complexes, which showed that their properties are highly dependent on changes to only one H-bond.
Book Synopsis Metal Complexes of Tripodal N-heterocyclic Carbene Ligands by : Xile Hu
Download or read book Metal Complexes of Tripodal N-heterocyclic Carbene Ligands written by Xile Hu and published by . This book was released on 2004 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis C3-symmetric Tripodal Ligands by : Brian Scott Hammes
Download or read book C3-symmetric Tripodal Ligands written by Brian Scott Hammes and published by . This book was released on 1998 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Metal-Ligand Multiple Bonds by : William A. Nugent
Download or read book Metal-Ligand Multiple Bonds written by William A. Nugent and published by Wiley-Interscience. This book was released on 1988-11-14 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only comprehensive one-volume text/reference on metal-ligand multiple bonds. Stresses the unified nature of the field and includes handy new tabulations of data. The flow within each subtopic is oxygen to nitrogen to carbon. Coverage is up-to-date--virtually every subtopic leads to interesting questions for future research. Presents information otherwise scattered through hundreds of publications.
Book Synopsis Amino Acids, Peptides and Proteins by : G C Barrett
Download or read book Amino Acids, Peptides and Proteins written by G C Barrett and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an ever-increasing domain of activity Amino Acids Peptides and Proteins provides an annual compilation of the world's research effort into this important area of biological chemistry. Volume 33 provides a review of literature published during 2000. Comprising a comprehensive review of significant developments at this biology/chemistry interface each volume opens with an overview of amino acids and their applications. Work on peptides is reviewed over several chapters ranging from current trends in their synthesis and conformational and structural analysis to peptidomimetics and the discovery of peptide-related molecules in nature. The application of advanced techniques in structural elucidation is incorporated into all chapters whilst periodic chapters on metal complexes of amino acids peptides and beta-lactams extend the scope of coverage. Efficient searching of specialist topics is facilitated by the sub-division of chapters into discrete subject areas allowing annual trends to be monitored. All researchers in the pharmaceutical and allied industries and at the biology/chemistry interface in academia will find this an indispensable reference source.
Book Synopsis Molecular Technology, Volume 1 by : Hisashi Yamamoto
Download or read book Molecular Technology, Volume 1 written by Hisashi Yamamoto and published by John Wiley & Sons. This book was released on 2018-10-22 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Edited by foremost leaders in chemical research together with a number of distinguished international authors, this first of four volumes summarizes the most important and promising recent chemical developments in energy science all in one book. Interdisciplinary and application-oriented, this ready reference focuses on chemical methods that deliver practical solutions for energy problems, covering new developments in advanced materials for energy conversion, semiconductors and much more besides. Of great interest to chemists as well as researchers in the fields of energy science in academia and industry.
Book Synopsis Late Transition Metal Complexes of Mixed NHC/Phenolate Tripodal Ligands for Small Molecule Activation by : Martina Käß
Download or read book Late Transition Metal Complexes of Mixed NHC/Phenolate Tripodal Ligands for Small Molecule Activation written by Martina Käß and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multidentate Phosphino-alkene Ligands and Their Late Transition Metal Complexes by : Amanda G. Jarvis
Download or read book Multidentate Phosphino-alkene Ligands and Their Late Transition Metal Complexes written by Amanda G. Jarvis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and characterisation of a new class of multidentate conformationally flexible phosphino-alkene ligands, called dbaPHOS (127) and monodbaPHOS (128), are described is this PhD thesis. The related phosphine sulphide ligands, namely dbaTHIOPHOS (137) and monodbaTHIOPHOS (149), have also been prepared. The coordination chemistry of the novel ligands was investigated with a variety of late-transition metals, including Cu, Rh, Pd and Pt. X-ray crystal structure determination of the complexes containing these ligands highlights the multiple coordination modes and versatility of each ligand system. The ability of the 1,4-dien-3-one backbone to adopt different conformational geometries around metal centers is of particular note. DbaPHOS (127) was found to act as a cis- and trans-chelating bisphosphine in both square planar PdII and PtII complexes. The 1,4-dien-3-one motif is hemilabile; exchange between coordinated and non-coordinated alkenes is observed in both the Pd0 complex, 167, and the related cationic CuI complex, 193. An investigation into the CuI complexes' activity in the cyclopropanation of styrene, as catalysts, showed that they are commensurate with other recently reported systems. In addition to the coordination chemistry of the novel ligand systems, some interesting findings emerged in the ligand synthesis and characterisation studies. For example, monodbaTHIOPHOS (149) undergoes an interesting solid-state [2+2] intramolecular cycloaddition transformation, giving cycloadduct, 206. Furthermore, 2-hydroperoxytetrahydrofuran was found to be an impurity in the microwave-assisted Horner-Wadsworth-Emmons reaction of 2-(diphenylthiophosphine)benzaldehyde (136) with 1,3-bis-(ethoxyphosphonato)-acetone (130) to give of dbaTHIOPHOS (137) and an unexpected THF insertion product, 138. The latter is explained by a side reaction involving the reduced compound, tetrahydrofuran-2-ol, derived from 2-hydroperoxytetrahydrofuran.
