Igor V. Koptyug

Bio: Igor V. Koptyug is an academic researcher from Novosibirsk State University. The author has contributed to research in topics: Hyperpolarization (physics) & Catalysis. The author has an hindex of 41, co-authored 235 publications receiving 5568 citations. Previous affiliations of Igor V. Koptyug include University of California, Santa Barbara & Utrecht University.

NMR Imaging of Catalytic Hydrogenation in Microreactors with the Use of para-Hydrogen

Abstract: Catalysis is vital to industrial chemistry, and the optimization of catalytic reactors attracts considerable resources. It has proven challenging to correlate the active regions in heterogeneous catalyst beds with morphology and to monitor multistep reactions within the bed. We demonstrate techniques, using magnetic resonance imaging and para-hydrogen (p-H2) polarization, that allow direct visualization of gas-phase flow and the density of active catalyst in a packed-bed microreactor, as well as control over the dynamics of the polarized state in space and time to facilitate the study of subsequent reactions. These procedures are suitable for characterizing reactors and reactions in microfluidic devices where low sensitivity of conventional magnetic resonance would otherwise be the limiting factor.

Development of new methods in modern selective organic synthesis: preparation of functionalized molecules with atomic precision

Abstract: The challenges of the modern society and the growing demand of high-technology sectors of industrial production bring about a new phase in the development of organic synthesis. A cutting edge of modern synthetic methods is introduction of functional groups and more complex structural units into organic molecules with unprecedented control over the course of chemical transformation. Analysis of the state-of-the-art achievements in selective organic synthesis indicates the appearance of a new trend — the synthesis of organic molecules, biologically active compounds, pharmaceutical substances and smart materials with absolute selectivity. Most advanced approaches to organic synthesis anticipated in the near future can be defined as 'atomic precision' in chemical reactions. The present review considers selective methods of organic synthesis suitable for transformation of complex functionalized molecules under mild conditions. Selected key trends in the modern organic synthesis are considered including the preparation of organofluorine compounds, catalytic cross-coupling and oxidative cross-coupling reactions, atom-economic addition reactions, methathesis processes, oxidation and reduction reactions, synthesis of heterocyclic compounds, design of new homogeneous and heterogeneous catalytic systems, application of photocatalysis, scaling up synthetic procedures to industrial level and development of new approaches to investigation of mechanisms of catalytic reactions. The bibliography includes 840 references.

Observation of Parahydrogen‐Induced Polarization in Heterogeneous Hydrogenation on Supported Metal Catalysts

Abstract: For homogeneous hydrogenation reactions catalyzed by transition-metal complexes in solution, utilization of the nuclear spin isomers of molecular hydrogen has become an established tool for studies on reaction mechanisms and kinetics. Parahydrogen-induced polarization (PHIP) can enhance the NMR spectroscopy signals of reaction intermediates and products by several orders of magnitude and provides the high sensitivity essential for such studies. It was demonstrated recently that PHIP effects can also be observed in hydrogenation reactions catalyzed by metal complexes immobilized on a solid support. Industrial hydrogenation processes are predominantly heterogeneous and utilize supported metal catalysts. Such catalysts are not expected to produce PHIP effects, since the reaction mechanism involved should destroy the original correlation of the two nuclear spins of parahydrogen. Herein we demonstrate for the first time that, contrary to these expectations, supported metal catalysts such as Pt/Al2O3 and Pd/ Al2O3 do exhibit PHIP effects. This fact can be used for the production of spin-polarized fluids for MRI applications and for developing new research tools for mechanistic and kinetic studies on heterogeneous hydrogenation processes. Homogeneous hydrogenation of unsaturated compounds in solution is often performed with transition metal complexes (e.g., Wilkinson2s catalyst, [RhCl(PPh3)3]). [6] The detailed mechanism of the reaction is fairly well understood. The catalytic cycle (Scheme S1 in the Supporting Information) starts with oxidative addition of an H2 molecule to the metal center to give a metal dihydride species and ends with reductive elimination of the product. Molecular hydrogen is known to be a mixture of two nuclear spin isomers: orthohydrogen with a total nuclear spin of I= 1, and parahydrogen with I= 0. If one of them (usually para-H2) is used in the hydrogenation reaction, pairwise addition of the two hydrogen atoms from the same H2 molecule, ensured by the reaction mechanism, preserves their correlated nuclear spin state. Furthermore, this correlation can strongly enhance NMR signals of the reaction intermediates and products. If hydrogenation is performed in the probe of an NMR spectrometer (i.e., in the high magnetic field of the NMR instrument), two strongly enhanced antiphase multiplets are commonly observed in the H NMR spectrum of the reaction product (Figure S1a). This experimental scheme is known as PASADENA (parahydrogen and synthesis allow dramatic enhancement of nuclear alignment). If hydrogenation is carried out in a low magnetic field and the reaction products are then adiabatically transferred to the NMR magnet for detection, the two multiplets show net signal enhancement of the opposite sign (Figure S1b). This experimental scheme is termed ALTADENA (adiabatic longitudinal transport after dissociation engenders net alignment). The observation of both ALTADENA and PASADENA requires that the two H atoms from the same para-H2 molecule travel as a pair throughout the entire catalytic cycle all the way to the product, and that the time elapsed between initial dissociation of the H2 molecule and formation of the product molecule is not much longer than the nuclear spin relaxation time of the intermediates involved. All this is favored by the fact that all processes take place on a single metal atom of the complex in solution. Since the NMR spectroscopy signal-enhancement factors observed can be as large as several orders of magnitude, hydrogenation with parahydrogen has become a powerful tool for studying the mechanisms and kinetics of homogeneous hydrogenation reactions. Heterogeneous hydrogenation processes often use highly dispersed supported metals (e.g., Pt/Al2O3, Pd/Al2O3) as catalysts. Unlike homogeneous hydrogenation, which takes place on a well-defined single metal center, heterogeneous hydrogenation proceeds over a vast surface of a metal cluster. This gives rise to a large number of interaction possibilities and a variety of relevant and irrelevant species present on the surface during the reaction. As a result, despite a great deal of effort devoted to studying the mechanisms of heterogeneous hydrogenation of simple alkenes such as ethylene, conclusions regarding the reaction mechanism are still controversial. By combining the use of parahydrogen with heterogeneous hydrogenation processes, it may be possible to develop new fundamental and practical applications which rely on the substantial amplification of the NMR signals, such as mechanistic studies of heterogeneous hydrogenation and production of polarized fluids for advanced MRI studies. However, the use of parahydrogen in combination with supported metal catalysts has been postulated to be pointless, [*] K. V. Kovtunov, Prof. Dr. I. V. Koptyug International Tomography Center SB RAS 3A Institutskaya St., Novosibirsk 630090 (Russia) Fax: (+7)383-333-1399 E-mail: koptyug@tomo.nsc.ru

Hyperpolarized NMR Spectroscopy: d-DNP, PHIP, and SABRE Techniques.

Abstract: Dynamic nuclear polarization (DNP) can boost sensitivity in nuclear magnetic resonance (NMR) experiments by several orders of magnitude. This review illustrates how the coupling of DNP with both liquid-and solid-state NMR spectroscopy has the potential to considerably extend the range of applications of NMR in analytical chemistry.

para-Hydrogen-induced polarization in heterogeneous hydrogenation reactions.

Abstract: We demonstrate the creation and observation of para-hydrogen-induced polarization in heterogeneous hydrogenation reactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on either modified silica gel or a polymer, is shown to hydrogenate styrene into ethylbenzene and to produce enhanced spin polarizations, observed through NMR, when the reaction was performed with H2 gas enriched in the para spin isomer. Furthermore, gaseous phase para-hydrogenation of propylene to propane with two catalysts, the Wilkinson's catalyst supported on modified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene; sulfos = -O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstrates heterogeneous catalytic conversion resulting in large spin polarizations. These experiments serve as a direct verification of the mechanism of heterogeneous hydrogenation reactions involving immobilized metal complexes and can be potentially developed into a practical tool for producing catalyst-free fluids with highly polarized nuclear spins...

Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles.

Abstract: Metal species with different size (single atoms, nanoclusters, and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that many factors including the particle size, shape, chemical composition, metal–support interaction, and metal–reactant/solvent interaction can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow one to correlate the relationships at the molecular level. In this Review, the electronic and geometric structures of single atoms, nanoclusters, and nanoparticles will be discussed. Furthermore, we will summarize the catalytic applications of single atoms, nanoclusters, and nanoparticles for different types of reactions, including CO oxidation, selective oxidation, selective hydrogenation, organic reactions, electrocatalytic, and photocatalytic reactions. We will compare the results o...

Metal–organic frameworks: versatile heterogeneous catalysts for efficient catalytic organic transformations

Abstract: Novel catalytic materials are highly demanded to perform a variety of catalytic organic reactions. MOFs combine the benefits of heterogeneous catalysis like easy post reaction separation, catalyst reusability, high stability and homogeneous catalysis such as high efficiency, selectivity, controllability and mild reaction conditions. The possible organization of active centers like metallic nodes, organic linkers, and their chemical synthetic functionalization on the nanoscale shows potential to build up MOFs particularly modified for catalytic challenges. In this review, we have summarized the recent research progress in heterogeneous catalysis by MOFs and their catalytic behavior in various organic reactions, highlighting the key features of MOFs as catalysts based on the active sites in the framework. Examples of their post functionalization, inclusion of active guest species and metal nanoparticles have been discussed. Finally, the use of MOFs as catalysts for asymmetric heterogeneous catalysis and stability of MOFs has been presented as separate sections.

Supported metal nanoparticles on porous materials. Methods and applications.

Abstract: Nanoparticles are regarded as a major step forward to achieving the miniaturisation and nanoscaling effects and properties that have been utilised by nature for millions of years. The chemist is no longer observing and describing the behaviour of matter but is now able to manipulate and produce new types of materials with specific desired physicochemical characteristics. Such materials are receiving extensive attention across a broad range of research disciplines. The fusion between nanoparticle and nanoporous materials technology represents one of the most interesting of these rapidly expanding areas. The harnessing of nanoscale activity and selectivity, potentially provides extremely efficient catalytic materials for the production of commodity chemicals, and energy needed for a future sustainable society. In this tutorial review, we present an introduction to the field of supported metal nanoparticles (SMNPs) on porous materials, focusing on their preparation and applications in different areas.