A5021512052- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Metal-Catalyzed Oxygenation Mechanisms
- Crystallography and molecular interactions
- Porphyrin and Phthalocyanine Chemistry
- Magnetism in coordination complexes
- Catalytic Processes in Materials Science
- Metal complexes synthesis and properties
- CO2 Reduction Techniques and Catalysts
- Catalysis and Oxidation Reactions
- Lanthanide and Transition Metal Complexes
- Metal-Organic Frameworks: Synthesis and Applications
- Electrocatalysts for Energy Conversion
- Organometallic Complex Synthesis and Catalysis
- Oxidative Organic Chemistry Reactions
- Supramolecular Chemistry and Complexes
- Advanced Chemical Physics Studies
- Ammonia Synthesis and Nitrogen Reduction
- Asymmetric Hydrogenation and Catalysis
- Synthesis and Properties of Aromatic Compounds
- Metalloenzymes and iron-sulfur proteins
- Radical Photochemical Reactions
- Organoboron and organosilicon chemistry
- Luminescence and Fluorescent Materials
- Free Radicals and Antioxidants
Kyushu University
2016-2025
University of Technology, Jamaica
2024
Japan Science and Technology Agency
2018-2020
Centre de Recherche en Économie et Statistique
2017-2020
Centre for Research in Engineering Surface Technology
2017-2020
Center for Responsible Travel
2017-2020
Kyoto University
1997-2019
Kyoto Bunkyo University
2019
Kyoto University Institute for Chemical Research
2019
Graduate School USA
2017-2019
Our work reveals a high dependence on charge-transfer (CT) amounts for the optimal Hartree-Fock percentage in exchange-correlation functional of time-dependent density theory (TD-DFT) and error vertical transition energy calculated by given functional. Using these relations, zero-zero energies first singlet triplet excited states various CT compounds are accurately reproduced. (3)CT locally ((3)LE) well distinguished independently.
Metal-exchanged zeolites are known to exhibit catalytic activity in the direct conversion of methane methanol. The influence different metals on this reaction has been theoretically investigated by using density functional theory (DFT) calculations a periodic system MO+-ZSM-5 zeolite (M = Fe, Co, Ni, Cu). results indicate high dependence metals, where reactivity toward C–H bond dissociation is predicted increase order CoO+-ZSM-5 < NiO+-ZSM-5 FeO+-ZSM-5 CuO+-ZSM-5 and selectivity methanol...
Abstract Polarization change induced by directional electron transfer attracts considerable attention owing to its fast switching rate and potential light control. Here, we investigate electronic pyroelectricity in the crystal of a mononuclear complex, [Co(phendiox)( rac -cth)](ClO 4 )·0.5EtOH ( 1 ·0.5EtOH, H 2 phendiox = 9, 10-dihydroxyphenanthrene, -cth racemic 5, 7, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane), which undergoes two-step valence tautomerism (VT). Correspondingly,...
The reaction pathway and energetics for methane-to-methanol conversion by first-row transition-metal oxide ions (MO+s) are discussed from density functional theory (DFT) B3LYP calculations, where M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu. these MO+ complexes proposed to proceed in a two-step manner via two transition states: + CH4 → OM+(CH4) [TS] OH−M+−CH3 M+(CH3OH) M+ CH3OH. Both high-spin low-spin potential energy surfaces characterized detail. A crossing between the occurs once near exit...
Recent interest in Cu-exchanged zeolite catalysts for methane hydroxylation has been broadened to small-pore Cu-zeolites such as Cu-SSZ-13 (Cu-CHA), Cu-SSZ-16 (Cu-AFX), and Cu-SSZ-39 (Cu-AEI), which were reported produce more methanol per copper atom than the medium-pore Cu-ZSM-5 (Cu-MFI) large-pore Cu-mordenite (Cu-MOR) zeolites do. To elucidate nature of fascinating catalytic activities, theoretical investigations based on density functional theory (DFT) performed direct conversion by...
Copper-containing large-pore zeolites, such as Cu-mordenite (Cu-MOR) and Cu-omega (Cu-MAZ), oxidize methane to yield a high amount of methanol. Two distinct active centers in MOR zeolite, namely, [Cu2(μ-O)]2+ [Cu3(μ-O)3]2+, have been proposed debated. In particular, the species was experimentally found be formed on two different Al pair sites with reactivities toward methane. However, computational attempts based density functional theory (DFT) not able confirm them. Moreover, full cycle...
Self-assembly of artificial nanoscale units into superstructures is a prevalent topic in science. In biomimicry, scientists attempt to develop self-assembled nanoarchitectures. However, despite extensive efforts, the preparation nanoarchitectures with superior physical properties remains challenge. For example, one major topics field molecular magnetism development high-spin (HS) molecules. Here, we report cyanide-bridged magnetic nanocage composed 18 HS iron(III) ions and 24 low-spin...
ConspectusAs fossil-based energy sources become more depleted and with renewable-energy technologies still in a very early stage of development, the utilization highly abundant methane as transitional solution for current demands is important despite difficulties transport storage. Technologies enabling conversion to liquid/condensable carriers that can be easily transported integrated into existing chemical infrastructures are therefore essential. Although there commercially exists two-step...
Crossing seams between the potential energy surfaces and possible spin inversion processes for direct conversion of methane to methanol by bare FeO+ species are discussed means intrinsic reaction coordinate (IRC) approach. There three crossing sextet quartet surfaces, should occur twice in entrance exit channels; FeO+(6Σ+)+CH4(1A1)→OFe+(CH4)(6A)→TS1(4A′)→HO–Fe+–CH3(4A)→TS2(4A)→Fe+(CH3OH)(4A)→Fe+(6D)+CH3OH(1A′). The first seam exists prior TS1, a four-centered transition state cleavage C–H...
The entire reaction pathway for the gas-phase methane−methanol conversion by late transition-metal-oxide ions, MnO+, FeO+, and CoO+, is studied using an ab initio hybrid (Hartree−Fock/density-functional) method. For these oxo complexes, proposed to proceed via two transition states (TSs) in such a way MO+ + CH4 → OM+(CH4) [TS1] HO−M+−CH3 [TS2] M+(CH3OH) M+ CH3OH, where M Mn, Fe, Co. A crossing between high-spin low-spin potential energy surfaces occurs both at entrance channel exit FeO+ but...
Methane hydroxylation at the mononuclear and dinuclear copper sites of pMMO is discussed using quantum mechanical QM/MM calculations. Possible mechanisms are proposed with respect to formation reactive copper−oxo how they activate methane. Dioxygen incorporated into CuI species give a CuII−superoxo species, followed by an H-atom transfer from tyrosine residue near monocopper active site. A resultant CuII−hydroperoxo next transformed CuIII−oxo water molecule abstraction another residue. This...
The reaction pathways and the energetics for direct methane−methanol benzene−phenol conversions that occur on surface of Fe−ZSM-5 zeolite are analyzed from B3LYP DFT computations. We propose a reasonable model "α-oxygen", oxygen species responsible catalytic reactivities zeolite. Our involves an iron−oxo AlO4 site as active center source oxygen. essential features identical, especially in bonding characters. In initial stages each reaction, methane or benzene comes into contact with iron...
Water is not only the solvent but also sole oxygen source in smooth and efficient oxidation of organic compounds catalyzed by a RuII–pyridylamine–aqua complex with CeIV as oxidant. An intermediate-spin RuIV–oxo formed reactive species (see scheme; Sub=substrate). This catalytic system durable able to gain high turnover numbers for various substrates. Supporting information this article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z801170_s.pdf or from author. Please...
Mechanisms of dopamine hydroxylation by the Cu(II)−superoxo species and Cu(III)−oxo β-monooxygenase (DBM) are discussed using QM/MM calculations for a whole-enzyme model 4700 atoms. A calculated activation barrier hydrogen-atom abstraction is 23.1 kcal/mol, while that Cu(III)−oxo, which can be viewed as Cu(II)−O•, 5.4 kcal/mol. Energies optimized radical intermediate in superoxo- oxo-mediated pathways 18.4 −14.2 relative to corresponding reactant complexes, respectively. These results...
Methane hydroxylation at the dinuclear copper site of particulate methane monooxygenase (pMMO) is studied by using density functional theory (DFT) calculations. The electronic and structural properties species bis(μ-oxo)CuIICuIII CuIIICuIII are discussed with respect to C−H bond activation methane. highly reactive considered be an active for conversion methanol pMMO, whereas bis(μ-oxo)CuIIICuIII unable react as it is. If a Cu−O cleaved, resultant species, in which only one oxo ligand bridges...
Spin doctor: A mononuclear ferric complex [Fe(H-5-Br-thsa)(5-Br-thsa)]⋅H2O (1) (H2-5-Br-thsa = 5-bromo-2-hydroxybenzylidene)hydrazinecarbothioamide) was synthesized and its magnetic properties structure were investigated by DFT calculations. This shows unprecedented reversible, six/five-step spin-crossover behavior accompanied symmetry breaking. More importantly, each step in the multi-step transition successfully characterized single-crystal X-ray diffraction.
A light change: linear cyanido-bridged Fe2Co compound (see picture) exhibits a reversible, thermally induced cooperative charge transfer transition accompanying spin and polar–nonpolar transformation in the trinuclear cluster. The change magnetic properties polarity could also be by irradiation with light. Bistable materials possess two close-lying states, which can reversibly interchanged external stimuli such as temperature, light, pressure, guest molecules.1 These offer attractive...
Abstract Harnessing molecular motion to reversibly control macroscopic properties, such as shape and size, is a fascinating challenging subject in materials science. Here we design crystalline cobalt(II) complex with an n -butyl group on its ligands, which exhibits reversible crystal deformation at structural phase transition temperature. In the low-temperature phase, of freezes. On heating, rotates ca. 100° around C–C bond resulting 6–7% expansion size along packing direction. Importantly,...
Abstract A dicopper(II) complex, stabilized by the bis(tpa) ligand 1,2‐bis[2‐[bis(2‐pyridylmethyl)aminomethyl]‐6‐pyridyl]ethane (6‐hpa), [Cu 2 (μ‐OH)(6‐hpa)] 3+ , was synthesized and structurally characterized. This complex catalyzed selective hydroxylation of benzene to phenol using H O thus attaining large turnover numbers (TONs) high efficiency. The TON after 40 hours for production exceeded 12000 in MeCN at 50 °C under N highest value reported with homogeneous complexes. At 22 %...
A bis-hydroxo-bridged dinuclear CoIII-pyridylmethylamine complex (1) was synthesized and the crystal structure determined by X-ray crystallography. Complex 1 acts as a homogeneous catalyst for visible-light-driven water oxidation persulfate (S2O82–) an oxidant with [RuII(bpy)3]2+ (bpy = 2,2′-bipyridine) photosensitizer affording high quantum yield (44%) large turnover number (TON 742) O2 formation without forming catalytically active Co-oxide (CoOx) nanoparticles. In water-oxidation process,...
Abstract The hydrogen evolution reaction using semiconductor photocatalysts has been significantly improved by cocatalyst loading. However, there are still many speculations regarding the actual role of cocatalyst. Now a photocatalytic pathway is reported on site TiO 2 nanosheets doped with Rh at Ti sites as one‐atom cocatalysts. A hydride species adsorbed dopant was confirmed experimentally intermediate state for evolution, which consistent results density functional theory (DFT)...