Готові списки джерел за темами / Transition Metal Catalyst - Coordination Sites

Добірка наукової літератури з теми "Transition Metal Catalyst - Coordination Sites"

Автор: Grafiati

Опубліковано: 7 вересня 2023

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Статті в журналах з теми "Transition Metal Catalyst - Coordination Sites"

Díaz, Urbano, Mercedes Boronat, and Avelino Corma. "Hybrid organic–inorganic structured materials as single-site heterogeneous catalysts." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, no. 2143 (March 14, 2012): 1927–54. http://dx.doi.org/10.1098/rspa.2012.0066.

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Catalyst selectivity is associated with well-defined homogeneous active sites. Transition metal complexes and organocatalysts are highly active and selective in the homogeneous phase, and their heterogenization by incorporating them into inorganic solid materials allows combining their excellent catalytic activity with improved separation, recovering and recycling properties. In this article, we present the structural characteristics and catalytic properties of hybrid organic–inorganic materials in which the molecular catalysts are part of the inorganic structure, emphasizing the possibilities of periodic mesoporous hybrid materials and coordination polymers as single-site solid catalysts.

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Shen, Siqi, Yuanyuan Sun, Hao Sun, Yuepeng Pang, Shuixin Xia, Taiqiang Chen, Shiyou Zheng, and Tao Yuan. "Research Progress in ZIF-8 Derived Single Atomic Catalysts for Oxygen Reduction Reaction." Catalysts 12, no. 5 (May 7, 2022): 525. http://dx.doi.org/10.3390/catal12050525.

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Transition metal (TM) single atomic catalysts (MSAC-N-C) derived from doped zeolite imidazolate frameworks (ZIF-8) are considered attractive oxygen reduction reaction (ORR) catalysts for fuel cells and metal-air batteries due to their advantages of high specific surface area, more active catalytic sites, adjustable pore size, and coordination topology features. This review provides an updated overview of the latest advances of MSAC-N-C catalysts derived from ZIF-8 precursors in ORR electrocatalysis. Particularly, some key challenges, including coordination environments regulation of catalysis center in MSAC-N-C, the active sites loading optimization and synergistic effects between TM nanoclusters/nanoparticles and the single atoms on MSAC-N-C catalysis activity, as well as their adaptability in various devices, are summarized for improving future development and application of MSAC-N-C catalysts. In addition, this review puts forward future research directions, making it play a better role in ORR catalysis for fuel cells and metal air batteries.

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Li, Zhen, Zhen Wang, Nikita Chekshin, Shaoqun Qian, Jennifer X. Qiao, Peter T. Cheng, Kap-Sun Yeung, William R. Ewing, and Jin-Quan Yu. "A tautomeric ligand enables directed C‒H hydroxylation with molecular oxygen." Science 372, no. 6549 (June 24, 2021): 1452–57. http://dx.doi.org/10.1126/science.abg2362.

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Hydroxylation of aryl carbon–hydrogen bonds with transition metal catalysts has proven challenging when oxygen is used as the oxidant. Here, we report a palladium complex bearing a bidentate pyridine/pyridone ligand that efficiently catalyzes this reaction at ring positions adjacent to carboxylic acids. Infrared, x-ray, and computational analysis support a possible role of ligand tautomerization from mono-anionic (L,X) to neutral (L,L) coordination in the catalytic cycle of aerobic carbon–hydrogen hydroxylation reaction. The conventional site selectivity dictated by heterocycles is overturned by this catalyst, thus allowing late-stage modification of compounds of pharmaceutical interest at previously inaccessible sites.

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Gao, Guoping, Steven Bottle, and Aijun Du. "Understanding the activity and selectivity of single atom catalysts for hydrogen and oxygen evolution via ab initial study." Catalysis Science & Technology 8, no. 4 (2018): 996–1001. http://dx.doi.org/10.1039/c7cy02463k.

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To identify the specific activity sites for both the HER and OER in experimental realized single transition-metal atom decorated graphene sheets, we assume the number of metal–C bonds (coordination) determines the adsorption strength of reaction intermediates on the metal atom sites.

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Al-Riyahee, Ali A. A. "First Row Transition Metal Complexes Derived from N, Nʹ-Substituted Thiourea: Synthesis, Geometrical Structures and Cyclic Voltammetry Probe: A Review". BASRA JOURNAL OF SCIENCE 39, № 1 (1 січня 2021): 96–118. http://dx.doi.org/10.29072/basjs.202117.

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Thioureas or thiourea derivatives as organosulfur compounds are one of the most widely used ligands in different applications as we are going to discuss it extensively such as in coordination chemistry by involving them to rich sources of N, O and S atoms coordinating through S atom, S and O atoms in benzoyl derivatives or S, O and N atoms in pyridyl hetrocylic benzoyl derivatives. These hard and soft donor sites facilitate the bonding between thiourea free ligand and metal ion through one or more to make ligands behave as mono, bi or multidentate ligands to form huge and stable series of the metal complexes. The tautomerism (thiol↔thione) inside the thiourea derivatives is responsible on their flexibility which make them easy capable to coordinate in different modes. Thiourea derivatives and their metal complexes are known in biological area by possess them antibacterial, antifungal, antimalarial, antitubercular, antithyroid and insecticidal activity features. Thioureas used as vital reagent to separate metal ions, catalyst to synthesize organic compounds or as starting material to form different hetrocyclic compounds. The wide range applications of thioureas and their metal complexes has motivated specialized researchers to search new applications for these compounds and to create a novel derivatives. The goal of this article is to present historical survey of thioureas and their metal complexes focusing on: firstly, the development of their synthetic routes by explore reactants, products, catalysis and the conditions of reactions. Secondly: investigation of the geometrical shapes of the produced complexes are reviewed as well as to the coordinated sites with metal centers. Lastly, the electrochemical manners have been lighted by employing cyclic voltammetry (CV) to study the electrochemical behavior of free ligands and their complexes to confirm the oxidation state of the metal ion in its complexes.

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Rao, C. N. R., P. Vishnu Kamath, K. Prabhakaran, and M. S. Hegde. "Adsorption of carbon monoxide on the surfaces of polycrystalline transition metals and alloys: electron energy loss and ultraviolet photoelectron spectral studies." Canadian Journal of Chemistry 63, no. 7 (July 1, 1985): 1780–87. http://dx.doi.org/10.1139/v85-298.

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Adsorption of CO has been investigated on the surfaces of polycrystalline transition metals as well as alloys by employing electron energy loss spectroscopy (eels) and ultraviolet photoelectron spectroscopy (ups). CO adsorbs on polycrystalline transition metal surfaces with a multiplicity of sites, each being associated with a characteristic CO stretching frequency; the relative intensities vary with temperature as well as coverage. Whilst at low temperatures (80–120 K), low coordination sites are stabilized, the higher coordination sites are stabilized at higher temperatures (270–300 K). Adsorption on surfaces of polycrystalline alloys gives characteristic stretching frequencies due to the constituent metal sites. Alloying, however, causes a shift in the stretching frequencies, indicating the effect of the band structure on the nature of adsorption. The up spectra provide confirmatory evidence for the existence of separate metal sites in the alloys as well as for the high-temperature and low-temperature phases of adsorbed CO.

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Zeng, Xianshi, Chuncai Xiao, Luliang Liao, Zongxing Tu, Zhangli Lai, Kai Xiong, and Yufeng Wen. "Two-Dimensional (2D) TM-Tetrahydroxyquinone Metal–Organic Framework for Selective CO2 Electrocatalysis: A DFT Investigation." Nanomaterials 12, no. 22 (November 17, 2022): 4049. http://dx.doi.org/10.3390/nano12224049.

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The resource utilization of CO2 is one of the essential avenues to realize the goal of “double carbon”. The metal–organic framework (MOF) has shown promising applications in CO2 catalytic reduction reactions due to its sufficient pore structure, abundant active sites and functionalizability. In this paper, we investigated the electrocatalytic carbon dioxide reduction reactions of single-atom catalysts created by MOF two-dimensional coordination network materials constructed from transition metal-tetrahydroxybenzoquinone using density function theory calculations. The results indicate that for 10 transition metals, TM-THQ single levels ranging from Sc to Zn, the metal atom binding energy to the THQ is large enough to allow the metal atoms to be stably dispersed in the THQ monolayer. The Ni-THQ catalyst does not compete with the HER reaction in an electrocatalytic CO2 reduction. The primary product of reduction for Sc-THQ is HCOOH, but the major product of Co-THQ is HCHO. The main product of Cu-THQ is CO, while the main product of six catalysts, Ti, V, Cr, Mn, Fe, and Zn, is CH4. The limit potential and overpotential of Ti-THQ are the highest, 1.043 V and 1.212 V, respectively. The overpotentials of the other monolayer catalysts ranged from 0.172 to 0.952 V, and they were all relatively low. Therefore, we forecast that the TM-HQ monolayer will show powerful activity in electrocatalytic carbon dioxide reduction, making it a prospective electrocatalyst for carbon dioxide reduction.

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Kopchuk, Dmitry S., Grigory A. Kim, Igor S. Kovalev, Sougata Santra, Grigory V. Zyryanov, Adinath Majee, Vladimir L. Rusinov, and Oleg N. Chupakhin. "Tripod-type 2,2′-bipyridine ligand for lanthanide cations: synthesis and photophysical studies on coordination to transition metal cations." Canadian Journal of Chemistry 96, no. 4 (April 2018): 419–24. http://dx.doi.org/10.1139/cjc-2017-0485.

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New tripod-type 2,2′-bipyridine ligand consisting of a central polyaminocarboxylic moiety for the coordination to lanthanide cations and three appended 5-phenyl-2,2′-bipyridine fragments for the coordination to various transition metal cations have been prepared. A europium complex of this ligand was prepared, and its photophysical properties and a luminescent response towards transition metal salts (particularly, CdI2, Cd(OAc)2, Zn(ClO4)2, Cu(OAc)2, and HgCl2) have been studied. Europium cation luminescence quenching in the presence of transition metal salts in solution was observed in all cases. In addition, it was observed that the fluorescent response of the europium complex was quite individual depending on the type of the metal salt. The obtained data were compared with the earlier published data for some lanthanide complexes bearing additional sites for the chelation of transition metal cations.

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Hsieh, Meng-Chi, Ranganathan Krishnan, and Ming-Kang Tsai. "Formic Acid Generation from CO2 Reduction by MOF-253 Coordinated Transition Metal Complexes: A Computational Chemistry Perspective." Catalysts 12, no. 8 (August 12, 2022): 890. http://dx.doi.org/10.3390/catal12080890.

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The inclusion of transition metal elements within metal–organic frameworks (MOFs) is considered one of the most promising approaches for enhancing the catalytic capability of MOFs. In this study, MOF-253 containing bipyridine coordination sites is investigated for possible transition metal chelation, and a consequent possible CO2 reduction mechanism in the formation of formic acid. All transition metal elements of the third, fourth and fifth periods except hafnium and the lanthanide series are considered using density functional theory calculations. Two distinct types of CO2 reduction mechanisms are identified: (1) the five-coordination Pd center, which promotes formic acid generation via an intramolecular proton transfer pathway; (2) several four-coordination metal centers, including Mn, Pd, and Pt, which generate formic acid by means of heterolytic hydrogen activation. The MOF-253 environment is found to promote beneficial steric hindrance, and to constrain metal–ligand orientation, which consequently facilitates the formation of formic acid, particularly with the tetrahedral Mn center at high-spin electronic state.

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Nizameev, Irek R., Danis M. Kadirov, Guliya R. Nizameeva, Aigul’ F. Sabirova, Kirill V. Kholin, Mikhail V. Morozov, Lyubov’ G. Mironova, et al. "Complexes of Sodium Pectate with Nickel for Hydrogen Oxidation and Oxygen Reduction in Proton-Exchange Membrane Fuel Cells." International Journal of Molecular Sciences 23, no. 22 (November 17, 2022): 14247. http://dx.doi.org/10.3390/ijms232214247.

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A number of nickel complexes of sodium pectate with varied Ni2+ content have been synthesized and characterized. The presence of the proton conductivity, the possibility of the formation of a dense spatial network of transition metals in these coordination biopolymers, and the immobilization of transition ions in the catalytic sites of this class of compounds make them promising for proton-exchange membrane fuel cells. It has been established that the catalytic system composed of a coordination biopolymer with 20% substitution of sodium ions for divalent nickel ions, Ni (20%)-NaPG, is the leading catalyst in the series of 5, 15, 20, 25, 35% substituted pectates. Among the possible reasons for the improvement in performance the larger specific surface area of this sample compared to the other studied materials and the narrowest distribution of the vertical size of metal arrays were registered. The highest activity during CV and proximity to four-electron transfer during the catalytic cycle have also been observed for this compound.

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Більше джерел

Частини книг з теми "Transition Metal Catalyst - Coordination Sites"

Farrell, Kevin, and Martin Albrecht. "Late Transition Metal Complexes with Pincer Ligands that Comprise N-Heterocyclic Carbene Donor Sites." In The Privileged Pincer-Metal Platform: Coordination Chemistry & Applications, 45–91. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/3418_2015_127.

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Тези доповідей конференцій з теми "Transition Metal Catalyst - Coordination Sites"

Hui, K. S., Christopher Y. H. Chao, C. W. Kwong, and M. P. Wan. "Performance of Transition Metal Ions Exchanged Zeolite 13X in Greenhouse Gas Reduction." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41360.

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This study investigated the performance of multi-transition metal (Cu, Cr, Ni and Co) ions exchanged zeolite 13X catalysts on methane emission abatement, especially at methane level of the exhaust from natural gas fueled vehicles. Catalytic activity of methane combustion using multi-ions exchanged catalyst was studied under different parameters: mole % of metal loading, inlet velocity and inlet methane concentration at atmospheric pressure and 500 °C. Performance of the catalysts was investigated and explained in terms of the apparent activation energy, number of active sites and BET surface area of the catalyst. This study showed that the multi-ions exchanged catalyst outperformed the single-ions exchanged and the acidified 13X catalysts. Lengthening the residence time could also lead to higher methane conversion %. Catalytic activity of the catalysts was influenced by the mole % of metal loading which played important roles in affecting the apparent activation energy of methane combustion, active sites and also the BET surface area of the catalyst. Increasing mole % of metal loading in the catalyst decreased the apparent activation energy for methane combustion and also the BET surface area of the catalyst. In view of these, there existed an optimized mole % of metal loading where the highest catalytic activity was observed.

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