Article
Materials Science, Biomaterials
Haifeng Wu, Shichao Xu, Peidong Du, Yuanxi Liu, Hui Li, Haijun Yang, Ting Wang, Zhen-Gang Wang
Summary: In this study, a nucleotide-Cu2+ complex capable of catalyzing ortho-hydroxylation reactions resembling those of minimalistic monooxygenases was synthesized and investigated. Experimental and theoretical findings revealed that the catalyst formed a ternary complex intermediate with H2O2 and tyramine substrates through weak interactions, leading to the ortho-hydroxylation of tyramine. Moreover, the Cu2+ bound to nucleotides or oligonucleotides exhibited thermophilic catalytic properties.
JOURNAL OF MATERIALS CHEMISTRY B
(2023)
Article
Chemistry, Multidisciplinary
Jindou Yang, Hai T. Dong, Mi Sook Seo, Virginia A. Larson, Yong-Min Lee, Jason Shearer, Nicolai Lehnert, Wonwoo Nam
Summary: This research reports the preparation, spectroscopic characterization, and reactivity studies of a Co(IV)-oxo complex with an N4-macrocyclic coligand. Experimental data show the formation of a Co(IV) intermediate and the existence of the oxo group, supported by DFT calculations and spectroscopic techniques analyzing the structure.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Fernan Saiz, Leonardo Bernasconi
Summary: In this study, a computational approach was used to investigate the oxidation of methane to methanol in a solid-state system catalyzed by Fe(iv)O moieties in the metal-organic framework MOF-74. The results show that the detachment of methanol serves as the rate-determining step in the overall oxidation process, with a free energy barrier of 95.6 kJ mol(-1, and van der Waals dispersion interactions playing a significant role in the reaction energetics.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
Article
Multidisciplinary Sciences
Pengfei Xie, Jing Ding, Zihao Yao, Tiancheng Pu, Peng Zhang, Zhennan Huang, Canhui Wang, Junlei Zhang, Noah Zecher-Freeman, Han Zong, Dashui Yuan, Shengwei Deng, Reza Shahbazian-Yassar, Chao Wang
Summary: Selective conversion of methane into value-added chemicals is a promising approach for efficient utilization of hydrocarbon sources. In this study, the authors developed dimeric copper centers supported on graphitic carbon nitride (Cu-2@C3N4) as advanced catalysts for partial oxidation of methane. The copper-dimer catalysts demonstrated high selectivity in both thermo- and photocatalytic reactions, with hydrogen peroxide and oxygen being used as the oxidizer, achieving >10% conversion and >98% selectivity toward methyl oxygenates.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Seiya Sakakura, Ryunosuke Kitamoto, Kazuki Goto, Seito Miura, Takamasa Takeda, Masaya Okamura, Arisa Fukatsu, Shinobu Itoh, Shiro Hikichi
Summary: Immobilised iron complex catalysts were constructed with hydrophobic reaction fields similar to the active sites of alkane hydroxylating enzymes. These catalysts were formed by anchoring chelating ligands to the mesopores of an SBA-15 silicate support and reacting them with fluoroalkyl and trimethylsilyl groups. The resulting catalysts showed improved activity and selectivity in cyclohexane and propane oxidation reactions, with the longest fluoroalkyl chain modification being the most reactive and stable.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Shinya Ariyasu, Kai Yonemura, Chie Kasai, Yuichiro Aiba, Hiroki Onoda, Yuma Shisaka, Hiroshi Sugimoto, Takehiko Tosha, Minoru Kubo, Takashi Kamachi, Kazunari Yoshizawa, Osami Shoji
Summary: This study reports the catalytic oxidation of methane to methanol by wild-type P450BM3 without mutagenesis. The findings have significant implications for the development of biological methane oxidation technology.
Article
Chemistry, Inorganic & Nuclear
Wenjuan Zhu, Namita Sharma, Yong-Min Lee, Mohamed E. El-Khouly, Shunichi Fukuzumi, Wonwoo Nam
Summary: This study reports a new method for generating a nonheme iron(IV)-oxo complex using singlet oxygen instead of triplet oxygen and a hydrogen atom donor with relatively strong C-H bonds.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Yasuyuki Yamada, Chee-Ming Teoh, Yuka Toyoda, Kentaro Tanaka
Summary: The study found that a specific iron phthalocyanine dimer catalyst can efficiently facilitate the hydroxylation of benzene under mild conditions in an acetonitrile solution with excess H2O2 present. Mechanistic studies indicated that the reaction was catalyzed by a high-valent iron-oxo species generated in situ, and the peripheral methyl groups of the catalyst may enhance the production rate of the iron-oxo species.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Ramona Jurgeleit, Benjamin Grimm-Lebsanft, Benedikt Maria Floeser, Melissa Teubner, Soren Buchenau, Laura Senft, Jonas Hoffmann, Maria Naumova, Christian Naether, Ivana Ivanovic-Burmazovic, Michael Ruebhausen, Felix Tuczek
Summary: The study demonstrates that low-temperature oxygenation of copper complexes results in the formation of unique tetranuclear mixed-valent peroxo compounds, which promote O-O bond homolysis and catalytic activity, showing efficient catalytic activity towards organic substrates.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Jaruwan Amtawong, Bastian Bjerkem Skjelstad, Rex C. Handford, Benjamin A. Suslick, David Balcells, T. Don Tilley
Summary: High-valent multimetallic-oxo/oxyl species have been studied as intermediates in oxidative catalysis involving PCET reactions. The mechanism of C-H oxidation by RuCo3O4 cubane complexes was investigated, revealing a barrierless radical combination step and insights into cooperative effects of multimetallic centers in tuning PCET reactivity. Tuning the electronic properties of the cubane modulates C-H activations and enables construction of structure-activity relationships.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Inorganic & Nuclear
Tsukasa Abe, Yohei Kametani, Kazunari Yoshizawa, Yoshihito Shiota
Summary: This study investigated the reduction mechanisms of NOx using a dicopper complex, finding that the presence of methane or benzene significantly lowers the activation energy of the reaction. The calculated results suggest that catalytic reduction of NOx using hydrocarbons is feasible at certain operating temperatures, providing new insights for catalyst design in NOx purification.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Physical
Hiroyasu Tabe, Yusuke Seki, Mari Yamane, Takashi Nakazono, Yusuke Yamada
Summary: A cyano-bridged heterometallic coordination polymer, [Mn-II(H2O)(8/3)](3/2)[Fe-II(CN)(5)(NH3)], forms open metal sites on both MnII and FeII ions. It exhibits high catalytic activity and selectivity for benzene oxygenation to phenol. Comparative studies show that the high activity is attributed to the high oxidation ability of FeII and the phenol adsorption ability of MnII.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Hiroyasu Tabe, Yusuke Seki, Mari Yamane, Takashi Nakazono, Yusuke Yamada
Summary: This article presents the catalytic activity and selectivity of a cyanide-bridged heterometallic coordination polymer with open metal sites. Experimental results demonstrate that FeII ions have high oxidation ability and MnII ions have strong adsorption ability towards phenol.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Energy & Fuels
Hui Liu, Jie Yu
Summary: In this study, LSCM powders and Cu-Ni/LSCM catalysts were prepared using the GNP method, and the structures and properties of the samples were investigated. The results showed that the Ni/Cu mass ratio had an impact on the methane conversion rate, with the sample Cu:Ni = 1:5 exhibiting the best catalytic performance due to its larger surface area and highest nickel content.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2022)
Article
Chemistry, Physical
Francesco Tavani, Giorgio Capocasa, Andrea Martini, Francesco Sessa, Stefano Di Stefano, Osvaldo Lanzalunga, Paola D'Angelo
Summary: The understanding of reactive processes involving organic substrates is crucial and requires multidisciplinary efforts. By applying a combined multivariate, statistical and theoretical analysis approach, detailed mechanistic information can be obtained for chemical reactions, enabling the structural determination of transient intermediate species and investigation of redox chemical transformations.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Inorganic & Nuclear
Ayaka Sato, Yuta Hori, Yasuteru Shigeta
Summary: This study characterized the geometrical and electronic structures of the [4Fe-4S] cluster in reduced HiPIP and evaluated their effects on the protein environment using density functional theory (DFT). DFT calculations showed that the asymmetry and spin delocalization between iron atoms allowed for the formation of a unique stable structure. The presence of surrounding amino acids was found to stabilize the unique geometrical and electronic structure of the [4Fe-4S] cluster in HiPIP.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Takayuki Iwata, Masato Hanada, Satoru Kumagai, Tatsuro Yoshinaga, Yoshihito Shiota, Kazunari Yoshizawa, Mitsuru Shindo
Summary: In this study, Hiyama coupling was achieved through intramolecular substituent transfer from silicon, resulting in the formation of 1,8,13-trisubstituted chiral triptycenes based on triptycene. The proximity effect of substituents on triptycene played a crucial role in the formation of the oxy-palladacycle and the activation of the silyl group for sigma-bond metathesis. After bromination and nucleophilic ring opening, a secondary intramolecular Hiyama coupling provided diverse 1,8,13-trisubstituted chiral triptycenes. Optical resolution of 1,8,13-triptycene yielded optically active forms for the first time.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Medicinal
Natsuki Watanabe, Yuta Hori, Mitsuo Shoji, Mauro Boero, Yasuteru Shigeta
Summary: This study investigates the mechanism of racemization of aspartic acid (Asp) catalyzed by salicylaldehyde and acetic acid using computational approaches. The results reveal the dehydration step and the reaction step to change the chirality of Asp as the main stages of the reaction. The calculated energy diagram demonstrates that the dehydration step has the highest energy barrier, followed by the reaction step to change the chirality of Asp.
Article
Chemistry, Inorganic & Nuclear
Keita Shichijo, Yohei Kametani, Yoshihito Shiota, Kazunari Yoshizawa, Mamoru Fujitsuka, Hisashi Shimakoshi
Summary: A dehydrocorrin complex, Co(II)-pyrocobester (P ( -Co(II) )), was semisynthesized from cyanocobalamin and its photochemical and electrochemical properties were compared to those of the cobester (C ( -Co(II) )). The UV-vis absorptions of P ( -Co(II) ) in CH2Cl2 were red-shifted due to the pi-expansion of the macrocycle in the pyrocobester. The redox couple of P ( -Co(II) ) was positively shifted compared to that of C ( -Co(II) ), coinciding with the high electronegativity of the dehydrocorrin macrocycle. The reactivity of P ( -Co(I) ) was evaluated by its reaction with methyl iodide.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Seiji Ogo, Takeshi Yatabe, Tamon Tome, Riko Takenaka, Yoshihito Shiota, Kenji Kato
Summary: In this study, a homogeneous catalyst is used to synthesize hydrogen peroxide using H2 and O2 in water, eliminating the need for flammable H2/O2 mixtures and cocatalysts. The catalyst is capable of extracting electrons from H2, storing them for the reduction of O2, and then converting the reduced oxygen to H2O2. The catalyst exhibits the highest turnover number (TON) among all homogeneous catalysts.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Shinya Sugiura, Takashi Kubo, Yohei Haketa, Yuta Hori, Yasuteru Shigeta, Hayato Sakai, Taku Hasobe, Hiromitsu Maeda
Summary: Quinoidal molecules based on dipyrrolyldiketone boron complexes (QPBs) with partially conjugated pyrrole units as spin coupler were synthesized. The introduction of a benzo unit at the pyrrole beta-positions stabilized QPB, forming a closed-shell tautomer conformation with near-infrared absorption. By adding bases, the deprotonated species monoanion QPB- and dianion QPB2- were formed, showing over 1000 nm absorption and ion pairs with countercations. Ion-pairing with pi -electronic and aliphatic cations modulated the diradical properties of QPB2-, characterized by cation-dependent hyperfine coupling constants. VT NMR, ESR, and theoretical study revealed the higher stability of the singlet diradical compared to the triplet diradical.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Inorganic & Nuclear
Yohei Kametani, Kei Ikeda, Kazunari Yoshizawa, Yoshihito Shiota
Summary: In this study, the reduction mechanism of nitrite by a copper(II) complex was investigated using density functional theory calculations. Two possible reaction pathways were proposed based on different coordination modes of nitrite to copper, and the Cu-ONO pathway was found to be energetically favorable. The involvement of different proton-coupled electron transfer modes in each pathway was revealed by intrinsic reaction coordinate and intrinsic bond orbital analyses.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Hideo Nagashima, Yoshihito Shiota, Kazunari Yoshizawa
Summary: Density functional theory calculations verified the reaction pathways of the two catalytic cycles and determined that the modified Chalk-Harrod cycle is more favorable. However, this mechanism contradicts some experimental results, which were resolved by assuming the presence of additional catalysts.
Article
Chemistry, Multidisciplinary
Machi Hata, Jin Ueno, Yutaka Hitomi, Masahito Kodera
Summary: The DNA target/ligand conjugates were synthesized with various lengths of linkers and examined for DNA binding, DNA cleavage, cellular uptake, and cytotoxicity. Short P-linkers were found to enhance the activity and cytotoxicity of the conjugates against cancer cells. Moreover, the conjugates with P-linkers showed specific DNA binding and selectivity towards cancer cells, while those with M-linkers exhibited non-specific binding. Overall, the conjugates with short P-linkers exhibited promising potential for cancer treatment.
Article
Chemistry, Multidisciplinary
Tomoya Ishizuka, Taichi Kogawa, Chisato Ogawa, Hiroaki Kotani, Yoshihito Shiota, Kazunari Yoshizawa, Takahiko Kojima
Summary: We synthesized and characterized a Ru-II-OH2 complex and studied its coordination equilibrium and oxidation reaction. The complex exhibits η6 coordination and intramolecular hydrogen bonding, which are important for catalytic oxidation reactions.
Article
Chemistry, Multidisciplinary
Naoki Tabata, Takumi Uchino, Chitoshi Kitamura, Kazunari Yoshizawa, Yoshihito Shiota, Shin-ichiro Kato
Summary: We have demonstrated site-selective radical reactions of the stable open-shell singlet diradicaloids DFTh and DFFu with HSn(n-Bu)(3) and azo-based radical initiators. Treatment with HSn(n-Bu)(3) induces hydrogenation at the five-membered ring, while treatment with AIBN induces substitution at the peripheral six-membered rings. One-pot substitution/hydrogenation reactions of DFTh/DFFu with various azo-based radical initiators and HSn(n-Bu)(3) have also been developed. Theoretical calculations reveal the mechanism of these radical reactions and the site-selectivity, which are controlled by the balance of spin density and steric hindrance.
Article
Chemistry, Physical
Natsuki Watanabe, Mitsuo Shoji, Koichi Miyagawa, Yuta Hori, Mauro Boero, Masayuki Umemura, Yasuteru Shigeta
Summary: Enantiomeric excesses (ee) of l-amino acids in meteorites are found to be higher than 10%, especially for isovaline (Iva), indicating the presence of a triggering mechanism that amplifies the ee from an initially small value. In this study, the dimeric molecular interactions of alanine (Ala) and Iva in solution were investigated at a precise first-principles level, revealing the chirality-dependent nature of Iva's dimeric interaction and providing molecular-level insights into the enantioselectivity of amino acids in solution.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Takumi Nakanishi, Yuta Hori, Yasuteru Shigeta, Hiroyasu Sato, Shu-Qi Wu, Ryoji Kiyanagi, Koji Munakata, Takashi Ohhara, Osamu Sato
Summary: The application of single-crystal neutron diffraction to observe proton-transfer phenomena in crystalline compounds has gained research interest. However, proton tautomerism, which involves different protonation states before and after proton transfer, has never been observed using this technique. In this study, we successfully observed proton tautomerism by developing an iron(ii) complex with a proton-transfer-coupled spin transition and using variable-temperature single-crystal neutron diffraction measurements.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Seiji Ogo, Takeshi Yatabe, Tamon Tome, Riko Takenaka, Yoshihito Shiota, Kenji Kato
Summary: This paper reports a method for the synthesis of H2O2 using a homogeneous catalyst in water, using only H2 and O2 without flammable mixtures or cocatalysts. The catalyst can remove electrons from H2, store them for the reduction of O2, and allow the protonation of the reduced oxygen to form H2O2. The turnover number (TON) is 910 under an H2/O2 (95/5) atmosphere (1.9 MPa) for 12 hours at 23 degrees C, which is the highest among any homogeneous catalysts. Furthermore, a reaction mechanism based on two crystal structures is proposed.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Tomonori Ida, Honoka Kojima, Yuta Hori
Summary: A learning model that combines machine learning and reaction network approaches is proposed to predict both products and reaction pathways. The model shows high accuracy in predicting the products and pathways of test reactions and can identify key fragment structures of reaction intermediates.
CHEMICAL COMMUNICATIONS
(2023)