Download or read book Interactions of Immobilized Transition Metal Complexes with Electrode Surfaces and Their Implications for Catalysis written by Felix Marc Brunner and published by . This book was released on 2021 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the incorporation of more renewable electricity into the power-grid leads to surplus generation, methods to utilize electricity to drive chemical reactions are becoming more relevant. Immobilizaton of molecular electrocatalysts combines the mechanistic understanding of molecular catalysts with the advantages of heterogeneous catalysts. Electrocatalysts of the type Ni(P2N2)2 are well-understood molecular catalysts that can achieve enzyme-like activity for hydrogen evolution and oxidation in solution. This extraordinary performance is attributed to their unique structure with proton shuttles in the second coordination sphere. Previously this amine substituent was used for surface attachment to immobilize this catalyst onto electrodes. However, the mobility of this substituent is crucial to the activity of the catalyst. We evaluated possible synthetic pathways to incorporate surface attachable functionality on the phosphine substituent of these ligands. Due to the high reactivity of the phosphines involved in the synthesis, incorporation of surface attachable groups through established synthetic protocols was found to be not feasible. A synthesis based on post-synthetic modification of P[superscript ArBr]2N[superscript Ph]2 was identified as the best way to incorporate attachable surface groups. This strategy was subsequently utilized to synthesize complexes of the type Ni(P2N2)2 with unprecedented, highly functionalized, surface attachable phosphine substituents. Phosphonate modified ligands and their corresponding nickel complexes were isolated and characterized. Subsequent deprotection of the phosphonic ester derivatives provided the first Ni(P2N2)2 catalyst that can be covalently attached via pendent phosphonate groups to an electrode without the involvement of hte important pendent amine groups. Mesoporous TiO2 electrodes were surface modified by attachment of the new phosphonate functionalized complexes, and these provided electrocatalytic materials that proved to be competent and stable for sustained hydrogen evolution in aqueous solution at mild pH and low over potential. We directly compared the new ligand to a previously reported complex that utilized the amine moiety for surface attachment. Using HER as the benchmark reaction, the P-attached catalyst showed a marginally (9-14%) higher turnover frequency than its N-attached counterpart. Finally, we report the synthesis of three new iridium piano-stool complexes that are immobilized on gold surfaces through thiol groups. We characterized these molecules using surface-sensitive IR spectroscopy. Further studies with these molecules are geared towards promoting the non-faradaic electrochemical tuning of catalysts using interfacial electric fields.
Download or read book Covalent Immobilization High potential Stability and Synthetic Manipulation of Catalytically Relevant Iron Complexes at Oxide Electrodes written by Matthew Aaron Pellow and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Immobilizing transition metal complexes to electrode surfaces offers a variety of advantages for developing and characterizing new molecular architectures. The copper-catalyzed alkyne-azide cycloaddition (CuAAC) is a useful method for such covalent immobilization. This work presents a new technique for applying the CuAAC reaction to covalent surface immobilization. In this technique, a drop of an alkyne solution is enclosed between an azide-terminated electrode surface and a freshly etched copper plate, which provides the copper(I) catalyst for the cycloaddition reaction. Using this convenient benchtop procedure, a full monolayer of alkyne is covalently immobilized to an azide-terminated electrode surface in 10 seconds. Cyclic voltammetry and X-ray photoelectron spectroscopy are used to characterize both conducting and non-conducting surfaces modified in this way. This method is effective in aerobic conditions using either water or aprotic organic solvents. The copper plate and the alkyne are the only reagents required to rapidly immobilize dense coverages of alkyne-terminated molecules using the rapid, additive-free, CuAAC surface immobilization method. Electrocatalysis is an important application of immobilized metal complexes. Discrete iron complexes supported by pyridine-based ligands are promising candidates for surface-immobilized electrocatalysts. This study characterizes the stability of catalytically relevant iron complexes covalently immobilized to oxide electrodes when the eletrodes are held at high potential. Several homoleptic polypyridyl iron complexes are covalently immobilized onto electrode surfaces using the CuAAC reaction and characterized electrochemically. The decay rate of each complex is quantified using its iv faradaic wave as the electrode is posed at +1.5 V vs. NHE, mimicking the high-potential conditions relevant for substrate oxidation. Several strategies to enhance the highpotential stability of surface-bonded complexes are explored. These include higher-denticity ligands, lower electrolyte pH, and buffering the electrolyte with iron. In their oxidized (ferric) forms, the surface-bound complexes are unstable to common electrochemical buffers. Conditions that enhance stability at high potentials include acidic conditions, iron-containing electrolyte, and longer alkyl linkers between the surface and the immobilized complex. These immobilized complexes are also used to explore the synthetic opportunities of immobilization. Voltammetry of modified electrodes indicates that when a surface-immobilized Fe(terpyridine)2 complex is exposed to a solution of Fe(bipyridine)3, a new complex is generated on the electrode surface. This new species is identified by its unique reduction potential. The incorporation of a bipyridine ligand is confirmed by using a series of bipyridine derivatives and monitoring the effect on the potential of the surface complex. The new species is assigned as a heteroleptic terpyridine-bipyridine complex immobilized to the surface through the terpyridine ligand. The ability to generate a heteroleptic polypyridyl Fe complex contrasts with solution conditions, in which thermodynamic equilibria disfavor the formation of such a species. Immobilization of the complex to the electrode surface therefore facilitates the ligand exchange. The reduction potential of the new complex is altered by the choice of substituent on the bipyridine ligand introduced onto the metal center, demonstrating the ability to modulate the redox potential of an immobilized complex through convenient solution processing.
Download or read book Transition Metals in Coordination Environments written by Ewa Broclawik and published by Springer. This book was released on 2019-03-16 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the electronic properties of transition metals in coordination environments. These properties are responsible for the unique and intricate activity of transition metal sites in bio- and inorganic catalysis, but also pose challenges for both theoretical and experimental studies. Written by an international group of recognized experts, the book reviews recent advances in computational modeling and discusses their interplay using experiments. It covers a broad range of topics, including advanced computational methods for transition metal systems; spectroscopic, electrochemical and catalytic properties of transition metals in coordination environments; metalloenzymes and biomimetic compounds; and spin-related phenomena. As such, the book offers an invaluable resource for all researchers and postgraduate students interested in both fundamental and application-oriented research in the field of transition metal systems.
Download or read book Transition Metal Sulphides written by Th. Weber and published by Springer Science & Business Media. This book was released on 1998-09-30 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrotreating catalysis with transition metal sulphides is one of the most important areas of industrial heterogeneous catalysis. The present book deals with the chemical and catalytic aspects of transition metal sulphides, focusing on their use in hydrotreating catalysis. The book¿s 12 chapters present reviews of solid-state, coordination and organometallic chemistry, surface science and spectroscopic studies, quantum chemical calculations, catalytic studies with model and real catalysts, as well as refinery processes. A presentation of state-of-the-art background to pertinent work in the field. Can be used as an introduction to the chemical and catalytic properties of transition metal sulphides as well as an advanced level reference.
Download or read book Adsorption and Catalysis on Transition Metals and Their Oxides written by Vsevolod Fedorovich Kiselev and published by . This book was released on 1989 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the third in a three-volume series treating the adsorptive, catalytic and electronic properties of solid surfaces. The authors are the first to treat surface chemical bonding in compounds of transition metals from a unified viewpoint taking ideas from both physics and chemistry. This volume gives an account of active sites in complexes and on the surfaces of metals and oxides in terms of the electronic structure of transition metal atoms. Possible mechanisms of interaction of simple molecules with such active sites are also discussed. All chemists and physicists concerned with the study of catalysis, adsorption and surface phenomena should find this book useful and interesting.
Download or read book Catalysis by Polymer Immobilized Metal Complexes written by Anatoly D. Pomogailo and published by CRC Press. This book was released on 1999-01-27 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deals with a new and promising field developed during the last two decades on the boundary between homogeneous and heterogeneous catalysis. This book presents general information on catalysis for a wide range of organic reactions, e.g., hydrogenation and oxidation reactions, and polymerization transformations. Special attention is paid to electro- and photochemical stimulation of catalytic processes in the presence of immobilized metal complexes. Other topics covered are the quantitative data on the comparison of catalyses by mobile and immobilized metal complexes; main factors affecting the activity of these catalytic systems and methods of optimizing their control; and specific problems of catalysis by fixed complexes (e.g., ligand exchange and electron transfer in metal polymer systems, macromolecular effects and polyfunctional catalysis).
Download or read book Theoretical Aspects of Transition Metal Catalysis written by Gernot Frenking and published by Springer Science & Business Media. This book was released on 2005-06-23 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal catalysis belongs to the most important chemical research areas because a ubiquitous number of chemical reactions are catalyzed by transition metal compounds. Many efforts are being made by industry and academia to find new and more efficient catalysts for chemical processes. Transition metals play a prominent role in catalytic research because they have been proven to show an enormous diversity in lowering the activation barrier for chemical reactions. For many years, the search for new catalysts was carried out by trial and error, which was costly and time consuming. The understanding of the mechanism of the catalytic process is often not very advanced because it is difficult to study the elementary steps of the catalysis with experimental techniques. The development of modern quantum chemical methods for calculating possible intermediates and transition states was a breakthrough in gaining an understanding of the reaction pathways of transition metal catalyzed reactions. This volume, organized into eight chapters written by leading scientists in the field, illustrates the progress made during the last decade. The reader will obtain a deep insight into the present state of quantum chemical research in transition metal catalysis.
Download or read book Mechanical Control of Metal ligand Complexation and Catalysis Through Surface Immobilization written by Brian Jacob Smith and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogenization, or the covalent immobilization of discrete molecular species to a material surface, is a promising strategy in catalyst design to leverage high selectivity and ligand variability with the practical heterogeneous advantages of catalyst separation and recycling. Moreover, heterogenization can be used as a mechanical means to control intermolecular interactions and thereby probe reaction mechanisms in a way not achievable through purely homogeneous characterization. An ideal immobilization approach needs to be modular, with high degree of control over the total surface loading of a species and its overall surface distribution. Here we report the preparation and application of functionalized mesoporous silica SBA-15 with a silioxypropylazide incorporated through a co-condensation approach. These materials serve as the platform for the heterogenization of ethynylated organic moieties through the copper-catalyzed azide alkyne cycloaddition. Surface loading is controlled by the amount of azide incorporation during co-condensation, and the surface distribution of immobilized species correlates well with a statistically random model. Immobilized manganese complexes demonstrate rapid catalytic epoxidation and C-H hydroxylation with peracetic acid as the terminal oxidant. Through a controlled variation of the surface loading and a quantitative understanding of site-interactions, we examine the impact of multi-ligand binding and site-isolation on catalysis.
Download or read book Metal Organic Framework Composites written by Anish Khan and published by Materials Research Forum LLC. This book was released on 2019-10-25 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of their nanoporous structures and ultra-high surface areas Metal-Organic Framework Composites (MOFs) are very interesting materials. The book focusses on the following applications: gas capture and storage, especially molecular hydrogen storage; performance enhancement of Li-ion batteries; gas separation, nano-filtration, ionic sieving, water treatment, and catalysis; sustainable renewable energy resources, electrochemical capacitors, including supercapacitors, asymmetric supercapacitors and hybrid supercapacitors; biomedical disciplines including drug delivery, theranostics; biological detection and imaging; nanoparticle photosensitizers for photodynamic therapy (PDT) and photothermal therapy (PTT). Keywords: MOF Materials, Hydrogen Storage, Renewable Energy Applications, Lithium Batteries, MOF-Quantum Dots, Clean Energy, Nanoporous MOFs, Supercapacitors, Therapeutic Applications, Biosensing, Bioimaging, Phototherapy of Cancer, Gas Separation, Nano-filtration, Ionic Sieving, Water Treatment, Drug Delivery, Theranostics; Nanoparticle Photosensitizers, Photodynamic Therapy (PDT), Photothermal Therapy (PTT).
Download or read book Immobilized Transition Metal Complexes as Macromolecular Catalysts written by James Dion Barnett and published by . This book was released on 2012 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Metals in Homogeneous Catalysis written by Gerhard N. Schrauzer and published by . This book was released on 1971 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biomimetic Catalysis with Immobilized Transition Metal Complexes written by Alexander Schiller and published by . This book was released on 2006 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cage Metal Complexes written by Yan Voloshin and published by Springer. This book was released on 2017-05-11 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fundamental book presents the most comprehensive summary of the current state in chemistry of cage metal complexes. After their previous book “The Encapsulation Phenomenon” (www.springer.com/978-3-319-27737-0) the authors in this book focus on the encapsulation of metal ions by different types of three-dimensional mono- and polynucleating caging ligands. Within these cage metal complexes, (metal) ions can be isolated from external factors. The book provides both a classification of the cage compounds and summaries of synthetic approaches. On that basis the authors then describe the unique chemical and physical properties and the resulting reactivity of the cage compounds, as well as practical and potential applications as potent topological drugs and prodrugs, antifibrillogenic agents, radiodiagnostic and radiotherapeutic compounds, paramagnetic probes, single-molecule magnets, electrocatalysts for hydrogen production, (photo)electronic devices, and many more. Readers will find a well-structured and concise overview, with particular emphasis on a review of synthesis and reactivity of various cage metal complexes, summarizing over 400 literature references, clearly presented in over 300 color schemes and figures.
Download or read book Mechanistic Studies and Design of Supported Transition Metal Complexes written by Terry Zhi Hao Gani and published by . This book was released on 2020 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supported transition metal (TM) complexes are an emerging class of materials with many potential applications in the chemical industry ranging from separations to catalysis. They offer increased tunability and often also improved performance over their bulk heterogeneous counterparts. Their study and rational design is, however, accompanied by several unique considerations and challenges that we address in this thesis. The first part of the thesis broadly develops and applies computational screening strategies for supported TM complexes. First, we detail how weak C-H[superscript ...]O hydrogen bonds can be exploited to increase selectivity of ferrocenium (Fc+)-based polymer electrode materials for formate adsorption over perchlorate adsorption while maintaining reasonable desorption rates in the reduced (ferrocene, Fc) state. Through a systematic characterization of formate and perchlorate interactions with a small (ca. 40) but diverse set of functionalized Fc+ complexes, we identify and rationalize design rules for functionalizations that simultaneously increase selectivity for formate in aqueous environments while permitting rapid release from Fc. Next, we screen a larger (ca. 500) set of model Fe(II) complexes for methane hydroxylation in order to assess if linear free energy relationships (LFERs), extensively developed to reduce the computational cost of computationally screening bulk heterogeneous catalysts, can also be applied to supported single-site TM catalysts. We demonstrate that structural distortions achievable in porous frameworks and chelating ligands break these LFERs by altering relative d-orbital splittings, thereby revealing a potential strategy for improving the activity of these catalysts. Finally, to address a particularly pervasive issue in density functional theory (DFT) studies of first-row open-shell TM complexes, we investigate how the fraction of exact exchange parameterized in the functional affects computed reaction and spin-splitting energies. We rationalize this sensitivity in terms of differences in metal-ligand electron delocalization and introduce the metal-ligand bond valence as a simple, yet robust, descriptor that unifies understanding of exchange sensitivity for catalytic properties and spin-state ordering in TM complexes.
Download or read book Recent Developments in Polymer Research written by Anthony V. Hopper and published by Nova Publishers. This book was released on 2007 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers are substances containing a large number of structural units joined by the same type of linkage. These substances often form into a chain-like structure. Starch, cellulose, and rubber all possess polymeric properties. Today, the polymer industry has grown to be larger than the aluminium, copper and steel industries combined. Polymers already have a range of applications that far exceeds that of any other class of material available to man. Current applications extend from adhesives, coatings, foams, and packaging materials to textile and industrial fibres, elastomers, and structural plastics. Polymers are also used for most composites, electronic devices, biomedical devices, optical devices, and precursors for many newly developed high-tech ceramics. This book presents leading-edge research in this rapidly-changing and evolving field.
Download or read book Renewable Synthetic Fuels and Chemicals from Carbon Dioxide written by David S.A. Simakov and published by Springer. This book was released on 2017-07-24 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book outlines the most recent progress in the development of technologies for carbon dioxide utilization into renewable synthetic fuels and platform chemicals via chemical and biological routes. Various processes are discussed, including thermocatalytic, electrocatalytic, photocatalytic, and biological conversion. This SpringerBrief consists of four chapters, each chapter outlining fundamentals and catalytic mechanisms, and discussing main design considerations and major technological challenges, providing also a brief outline of the most recent progress. The book is useful for a broad community of academic and industrial researchers in the fields of chemical reaction engineering, electro- and photo-chemistry, and biochemical engineering, with specific emphasizes on heterogeneous catalysis, reactor design and process development.
Download or read book Immobilized Catalysts written by Andreas Kirschning and published by Springer Science & Business Media. This book was released on 2004-11-22 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: R. Haag, S. Roller: Polymeric Supports for the Immobilisation of Catalysts .- J. Horn, F. Michalek, C.C. Tzschucke, W. Bannwarth: Non-Covalently Solid-Phase Bound Catalysts for Organic Synthesis .- Y. Uozumi: Recent Progress in Polymeric Palladium Catalysts for Organic Synthesis .- D.E. Bergbreiter, J. Li: Applications of Catalysts on Soluble Supports .- B. Desai, C.O. Kappe: Microwave-Assisted Synthesis Involving Immobilized Catalysts .- A. Kirschning, G. Jas: Applications of Immobilized Catalysts in Continuous Flow Processes .- N. End, K.-U. Schöning: Immobilized Catalysts in Industrial Research and Application .- N. End, K.-U. Schöning: Immobilized Biocatalysts in Industrial Research and Production
