Article
Polymer Science
Sentaro Okamoto, Takeshi Yamada, Takaya Uchida, Nana Kikuta, Yu-ya Kimura
Summary: This article discusses the application of a low-valent titanium reagent in the McMurry coupling polymerization and [2+2+2] cycloaddition polymerization of aryl dialdehyde and aromatic diyne monomers. Additionally, a low-valent titanium mediated dual-mode coupling copolymerization of aryl dialdehyde and alkynylaldehyde monomers via concurrent McMurry olefination and alkyne cyclotrimerization reactions is proposed.
Article
Polymer Science
Nana Kikuta, Takahiro Shindo, Yu-ki Sugiyama, Takeshi Yamada, Sentaro Okamoto
Summary: The novel synthetic method for hyperbranched polymers utilizes a cobalt catalyst to promote the successful polymerization of aromatic diynes with internal alkynes, resulting in soluble polymers without the production of insoluble materials. The resulting polymer's molecular weight and degree of branching can be controlled by selecting the internal alkyne monomer and adjusting its loading amount.
Article
Chemistry, Multidisciplinary
Itay Raz, Roman Dobrovetsky
Summary: The synthesis of a dicationic Zn+2-based complex with a tripodal tris(2-pyridylmethyl)amine (TPA) ligand is reported, which serves as a highly chemoselective catalyst for hydrosilylation reactions of alkynes. Unlike typical Zn-catalyzed hydrosilylation reactions, this system activates C equivalent to C triple bonds instead of Si-H bonds, which explains its high chemoselectivity.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Lukas Tendera, Moritz Helm, Mirjam J. Krahfuss, Maximilian W. Kuntze-Fechner, Udo Radius
Summary: This study investigates the effects of two different NHC ligands in complexes [Ni(NHC)(2)] and their behavior towards alkynes. Complex 2 demonstrated efficient catalytic activity for the cyclotrimerization of various alkynes at ambient conditions, while complex 1(Me) showed lower catalytic performance. The higher stability of N-alkyl substituted NHC complex is attributed to better electron transfer and enhanced backbonding.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Materials Science, Multidisciplinary
Bartlomiej Hrapkowicz, Sabina Lesz, Malgorzata Karolus, Dariusz Garbiec, Jakub Wisniewski, Rafal Rubach, Klaudiusz Golombek, Marek Kremzer, Julia Popis
Summary: This research investigates the effect of milling time on the properties of Mg-Zn-Ca-Pr alloy through high energy mechanical alloying and spark plasma sintering. The results demonstrate the capability of mechanical alloying to produce amorphous and crystalline materials, and the impact of milling time on their microstructure and properties.
Article
Chemistry, Multidisciplinary
Ming-xing Zhang, Chen-guang Zhu, Xiao Xie, Si-yu Liu
Summary: Using 7:3 Zn-Mg alloy powder to make pyrolants can produce stable combustion, satisfactory smoke, and light signals, while using 8:2 Zn-Mg alloy powder cannot achieve these effects. The 7:3 Zn-Mg alloy powder is an ideal ingredient for pyrotechnic compositions.
Article
Nanoscience & Nanotechnology
Yi-dan Fan, Kun-kun Deng, Cui-ju Wang, Kai-bo Nie, Quan-xin Shi
Summary: Pure titanium particles reinforced Mg-6Zn-0.2Ca magnesium matrix composites were successfully fabricated and their mechanical properties were studied. The results showed that the titanium particles promoted dynamic recrystallization of the matrix alloy, refining the size of MgZn2 phases and resulting in high yield strength and ultimate tensile strength in the composite. However, the work hardening rate of the composite decreased during plastic deformation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Biomaterials
Yue He, Mengyu Yao, Jielong Zhou, Juning Xie, Changxiang Liang, Dong Yin, Shuaihao Huang, Yu Zhang, Feng Peng, Shi Cheng
Summary: This study investigates the effects of nano-structure combined with bioactive ions release on macrophage polarization, osteogenesis, and angiogenesis. The results show that the nano-Mg(OH)(2) film coated Ti surface is more favorable for macrophages polarizing to tissue healing M2 phenotype. In vivo experiments also confirm that the nano-Mg(OH)(2) film induces milder inflammation and thinner fibrous layer compared to untreated Ti. Moreover, the macrophages-conditioned culture medium collected from the nano-Mg(OH)(2) coated Ti group enhances the osteogenic and angiogenic behaviors of bone marrow stem cells and human umbilical vein endothelial cells.
REGENERATIVE BIOMATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Rita N. Kadikova, Ilfir R. Ramazanov, Azat M. Gabdullin, Oleg S. Mozgovoj, Usein M. Dzhemilev
Summary: This study compares the catalytic effects of NbCl5 and Cp2ZrCl2 on the reaction pathway of N,N-disubstituted 2-alkynylamines with Et2Zn, revealing the differences in the formation of (2Z)-alkenylamines and their dideuterated and diiodinated derivatives.
Article
Chemistry, Inorganic & Nuclear
Xiaomeng Liu, Pifu Gong, Zheshuai Lin
Summary: Two new Zn-based cyanurate crystals were synthesized, with Zn-5(OH)(4)(C3N3O3)2 showing three different coordinating environments for the d(10) Zn2+ cations, which has never been observed in cyanurates. These compounds exhibit wide band gaps (around 5 eV) and large birefringence (about 0.32 at 400 nm), suggesting their potential as ultraviolet birefringence crystals.
INORGANIC CHEMISTRY
(2021)
Article
Materials Science, Multidisciplinary
Mikolaj Kozlowski, Grzegorz Adamek, Piotr Siwak, Jaroslaw Jakubowicz
Summary: The goal of this study was to develop poreless titanium alloys with nanocrystalline structure. The effects of Ta, Mg, and Zn content on the properties of Ti alloys were investigated. Nanocrystalline powders of TixTayMg and TixTayZn were prepared using mechanical alloying, followed by hot-pressing to consolidate the powders. The alloys with Mg showed improved mechanical properties and a more hydrophobic surface, while all new alloys exhibited non-toxic properties. The Ti40Ta5Mg alloy had the most promising properties for biomedical applications, with a high Ti-beta phase content, low porosity, low Young modulus and low surface free energy.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2023)
Article
Engineering, Environmental
Chen Chen, Xiaowen Zhang, Tianjiao Jiang, Mi Li, Ying Peng, Xudong Liu, Jian Ye, Yilong Hua
Summary: By successfully coating Mg(OH)(2) onto the surface of nZVI, the removal efficiency and stability of nZVI have been improved, enhancing the removal performance of U(VI). nZVI@Mg(OH)(2) is expected to play an important role in the in-situ remediation of U(VI).
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2021)
Article
Engineering, Biomedical
Mengyu Yao, Shi Cheng, Guoqing Zhong, Jielong Zhou, Hongwei Shao, Limin Ma, Chang Du, Feng Peng, Yu Zhang
Summary: Bioactive Mg(OH)(2) films developed on titanium surfaces through hydrothermal treatment can improve osteointegration of implants and promote osteogenesis. These films function as platforms for releasing Mg ions, creating nanostructures and weakly alkaline microenvironments, leading to better in vitro and in vivo osteogenesis. Nano-Mg(OH)(2) coated titanium outperforms traditional implants in promoting bone cell biology, showing potential for orthopedic applications.
BIOACTIVE MATERIALS
(2021)
Article
Metallurgy & Metallurgical Engineering
Jin-Kai Zhang, Cui-Ju Wang, Yi-Dan Fan, Chao Xu, Kai-Bo Nie, Kun-Kun Deng
Summary: The -Ti-p/ZX60 composites with different -Ti-p contents were prepared and analyzed for their microstructure, work hardening, and softening behavior. The addition of -Ti-p promoted the nucleation and refinement of dynamic recrystallized grains. The strength and elongation of the composites were improved with increasing -Ti-p content, but the elongation decreased sharply when the -Ti-p content reached 15 vol.%. The work hardening rate increased with increasing -Ti-p content, while the softening rate did not show the same trend.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2023)
Article
Chemistry, Physical
B. Bondzior, T. H. Q. Vu, D. Stefanska, M. J. Winiarski, P. J. Deren
Summary: Four tungstate double-perovskite materials were synthesized using co-precipitation method, exhibiting blue emission under UV excitation. The energy levels of different centers can be altered by substitutions at the A and B sites, influencing the luminescent properties. This ability to control emission wavelength and thermal stability is important for designing novel luminescent thermometers.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Suchithra Madhavan, Sentaro Okamoto
Article
Polymer Science
Sentaro Okamoto, Takeshi Yamada, Takaya Uchida, Nana Kikuta, Yu-ya Kimura
Summary: This article discusses the application of a low-valent titanium reagent in the McMurry coupling polymerization and [2+2+2] cycloaddition polymerization of aryl dialdehyde and aromatic diyne monomers. Additionally, a low-valent titanium mediated dual-mode coupling copolymerization of aryl dialdehyde and alkynylaldehyde monomers via concurrent McMurry olefination and alkyne cyclotrimerization reactions is proposed.
Article
Polymer Science
Sentaro Okamoto, Yusuke Naito, Ryosuke Nomura
Summary: A series of polymers P1-P4, synthesized via Suzuki-Miyaura coupling polymerization, predominantly exist in their folded H-stacking form in solution and film, as confirmed by ultraviolet absorption, fluorescent behavior, and X-ray diffraction analysis. The morphology of the polymers in solid states depends on the structure of the Z group present. The conductive nature of P1-P4 was demonstrated on hole-only devices, with P4 showing relatively higher conductivity due to its structure containing cross-conjugated pi units.
Article
Chemistry, Multidisciplinary
Takeshi Yamada, Kazuki Arai, Rie Kikuchi, Sentaro Okamoto
Summary: This study introduces a practical and facile synthesis method for deuterium-labeled indoles via acid-catalyzed hydrogen-deuterium exchange. Different substituted indoles can be efficiently deuterated, enabling large-scale and low-cost synthesis of plant auxins.
Article
Chemistry, Applied
Yu-ki Sugiyama, Masaki Amo, Kouta Ibe, Sentaro Okamoto
Summary: The reactivity of nitriles in a CoCl2-6H(2)O/dppe/Zn-catalyzed diyne-nitrile cycloaddition was studied. It was found that cyanamides are good substrates and result in the formation of 2-aminopyridines. Notably, N-unsubstituted cyanamide (H2N-CN) can react with 1,6-diynes to produce N-unsubstituted 2-aminopyridines, which cannot be obtained through other catalytic reactions and serve as versatile intermediates for further transformations.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Takeshi Yamada, Sentaro Okamoto
Summary: The interrupted Passerini reaction of 3-(2-isocyanoethyl)-indole catalysed by 3,5,6-trifluoro-2-pyridone was studied. The reaction afforded a diastereoselective tetracyclic furolindoline, which showed good reactivity in the Joullie-Ugi reaction. Therefore, one-pot sequential Passerini/Joullie-Ugi reactions were performed to rapidly obtain versatile and highly functionalised furoindolines from 3-(2-isocyanoethyl)-indole.
CHEMICAL COMMUNICATIONS
(2022)
Article
Polymer Science
Yuhsaku Okabe, Takeshi Yamada, Sentaro Okamoto
Summary: This study demonstrates that nickel complexes with sterically demanding ligands can catalyze the cycloaddition oligomerization of 1,6-heptadiynes to selectively produce medium-size cyclic polyenes with narrow molecular dispersity and minimal side reactions. The resulting cyclic polyenes exhibit non-conjugated behavior, while thermally isomerized cyclic polyenes show conjugated behavior. The oligomerization reaction has wide functional group compatibility, allowing for the production of medium-size cyclic polyenes with various functional groups. A plausible reaction mechanism explaining the narrow polydispersity is proposed.
Article
Chemistry, Multidisciplinary
Takeshi Yamada, Yusuke Watanabe, Sentaro Okamoto
Summary: The research found that 6-halo-2-pyridones could catalyze ester aminolysis, allowing both reactive aryl esters and less reactive methyl and benzyl esters to be used as substrates. The reaction could be carried out without strict dry and anaerobic conditions, and the 6-chloro-2-pyridone catalyst could be quantitatively recovered after the reaction. The proposed mechanism involved dual activation of ester and amine substrates through hydrogen bonding between the catalyst and substrates, with 6-halo-2-pyridones acting as a bifunctional Bronsted acid/base catalyst.
Article
Chemistry, Organic
Kouta Ibe, Takeshi Yamada, Sentaro Okamoto
ORGANIC & BIOMOLECULAR CHEMISTRY
(2019)
