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Design Strategies for Metal Complexes that Activate Bio-Related Small Molecules

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Inorganic Chemistry".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 17269

Special Issue Editors


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Guest Editor
1. Department of Applied Chemistry, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392, Japan
2. Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa, Nagoya 466-8555, Japan
Interests: bio-inorganic chemistry; dioxygen activation; dinitrogen activation; hydrogen activation; CO2 activation; NO sensor; siderophore chemistry; microbe sensor; molecular recognition; dye-sensitized solar cell

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Guest Editor
1. Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
2. Faculty of Science and Engineering, Meijo University, Nagoya, Aichi 468-8502, Japan
3. Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Republic of Korea
Interests: artificial photosynthesis; electron transfer chemistry; organic photocatalysis; redox catalysis; dioxygen activation

Special Issue Information

Dear Colleagues,

In living organisms, there are many metalloenzymes that activate biologically active small molecules such as hydrogen, oxygen, nitrogen, methane, and carbon dioxide. Currently, the structures and functions of many of these enzymes are being clarified by excellent structural and spectroscopic analysis methods. At the same time, research is being conducted to mimic the structure and function of these enzymes using metal complexes, and to develop catalysts that can function under environmental-friendly conditions in order to contribute to our lives in the future. In this special issue, as a message to future bioinorganic chemists and catalysis researchers, we invite papers on design strategies of metals and ligands focusing on the activation of small molecules from many researchers, in this case, oxygen and nitrogen.

Prof. Dr. Hideki Masuda
Prof. Dr. Shunichi Fukuzumi
Guest Editors

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Keywords

  • small molecule activation
  • dinitrogen activation
  • dioxygen activation
  • ligand design
  • design concept

Published Papers (11 papers)

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Research

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13 pages, 1947 KiB  
Article
Preparations of trans- and cis-μ-1,2-Peroxodiiron(III) Complexes
by Yuji Kajita, Masaki Kubo, Hidekazu Arii, Shinya Ishikawa, Yamato Saito, Yuko Wasada-Tsutsui, Yasuhiro Funahashi, Tomohiro Ozawa and Hideki Masuda
Molecules 2024, 29(1), 205; https://doi.org/10.3390/molecules29010205 - 29 Dec 2023
Viewed by 515
Abstract
The iron(II) complex with cis,cis-1,3,5-tris(benzylamino)cyclohexane (Bn3CY) (1) has been synthesized and characterized, which reacted with dioxygen to form the peroxo complex 2 in acetone at −60 °C. On the basis of spectroscopic measurements for 2, it was [...] Read more.
The iron(II) complex with cis,cis-1,3,5-tris(benzylamino)cyclohexane (Bn3CY) (1) has been synthesized and characterized, which reacted with dioxygen to form the peroxo complex 2 in acetone at −60 °C. On the basis of spectroscopic measurements for 2, it was confirmed that the peroxo complex 2 has a trans-μ-1,2 fashion. Additionally, the peroxo complex 2 was reacted with benzoate anion as a bridging agent to give a peroxo complex 3. The results of resonance Raman and 1H-NMR studies supported that the peroxo complex 3 is a cis-μ-1,2-peroxodiiron(III) complex. These spectral features were interpreted by using DFT calculations. Full article
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18 pages, 2847 KiB  
Article
Coordinatively Unsaturated Nickel Nitroxyl Complex: Structure, Physicochemical Properties, and Reactivity toward Dioxygen
by Kiyoshi Fujisawa, Taisei Kataoka, Kohei Terashima, Haruka Kurihara, Felipe de Santis Gonçalves and Nicolai Lehnert
Molecules 2023, 28(17), 6206; https://doi.org/10.3390/molecules28176206 - 23 Aug 2023
Viewed by 1155
Abstract
For its important roles in biology, nitrogen monoxide (·NO) has become one of the most studied and fascinating molecules in chemistry. ·NO itself acts as a “noninnocent” or “redox active” ligand to transition metal ions to give metal–NO (M–NO) complexes. Because of this [...] Read more.
For its important roles in biology, nitrogen monoxide (·NO) has become one of the most studied and fascinating molecules in chemistry. ·NO itself acts as a “noninnocent” or “redox active” ligand to transition metal ions to give metal–NO (M–NO) complexes. Because of this uncertainty due to redox chemistry, the real description of the electronic structure of the M–NO unit requires extensive spectroscopic and theoretical studies. We previously reported the Ni–NO complex with a hindered N3 type ligand [Ni(NO)(L3)] (L3 denotes hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate anion), which contains a high-spin (hs) nickel(II) center and a coordinated 3NO. This complex is very stable toward dioxygen due to steric protection of the nickel(II) center. Here, we report the dioxygen reactivity of a new Ni–NO complex, [Ni(NO)(I)(L1″)], with a less hindered N2 type bis(pyrazolyl)methane ligand, which creates a coordinatively unsaturated ligand environment about the nickel center. Here, L1″ denotes bis(3,5-diisopropyl-1-pyrazolyl)methane. This complex is also described as a hs-nickel(II) center with a bound 3NO, based on spectroscopic and theoretical studies. Unexpectedly, the reaction of [Ni(NO)(I)(L1″)] with O2 yielded [Ni(κ2-O2N)(L1″)2](I3), with the oxidation of both 3NO and the I ion to yield NO2 and I3. Both complexes were characterized by X-ray crystallography, IR, and UV–Vis spectroscopy and theoretical calculations. Full article
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12 pages, 2872 KiB  
Article
Selective C–H Bond Cleavage with a High-Spin FeIV–Oxido Complex
by Chen Sun, Jennifer L. Jaimes, Alec H. Follmer, Joseph W. Ziller and Andrew S. Borovik
Molecules 2023, 28(12), 4755; https://doi.org/10.3390/molecules28124755 - 14 Jun 2023
Cited by 1 | Viewed by 1063
Abstract
Non-heme Fe monooxygenases activate C–H bonds using intermediates with high-spin FeIV–oxido centers. To mimic these sites, a new tripodal ligand [pop]3− was prepared that contains three phosphoryl amido groups that are capable of stabilizing metal centers in high oxidation states. [...] Read more.
Non-heme Fe monooxygenases activate C–H bonds using intermediates with high-spin FeIV–oxido centers. To mimic these sites, a new tripodal ligand [pop]3− was prepared that contains three phosphoryl amido groups that are capable of stabilizing metal centers in high oxidation states. The ligand was used to generate [FeIVpop(O)], a new FeIV–oxido complex with an S = 2 spin ground state. Spectroscopic measurements, which included low-temperature absorption and electron paramagnetic resonance spectroscopy, supported the assignment of a high-spin FeIV center. The complex showed reactivity with benzyl alcohol as the external substrate but not with related compounds (e.g., ethyl benzene and benzyl methyl ether), suggesting the possibility that hydrogen bonding interaction(s) between the substrate and [FeIVpop(O)] was necessary for reactivity. These results exemplify the potential role of the secondary coordination sphere in metal-mediated processes. Full article
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12 pages, 1050 KiB  
Article
Electrochemical Epoxidation Catalyzed by Manganese Salen Complex and Carbonate with Boron-Doped Diamond Electrode
by Pijush Kanti Roy, Keisuke Amanai, Ryosuke Shimizu, Masahito Kodera, Takuya Kurahashi, Kenji Kitayama and Yutaka Hitomi
Molecules 2023, 28(4), 1797; https://doi.org/10.3390/molecules28041797 - 14 Feb 2023
Cited by 1 | Viewed by 1913
Abstract
Epoxides are essential precursors for epoxy resins and other chemical products. In this study, we investigated whether electrochemically oxidizing carbonate ions could produce percarbonate to promote an epoxidation reaction in the presence of appropriate metal catalysts, although Tanaka and co-workers had already completed [...] Read more.
Epoxides are essential precursors for epoxy resins and other chemical products. In this study, we investigated whether electrochemically oxidizing carbonate ions could produce percarbonate to promote an epoxidation reaction in the presence of appropriate metal catalysts, although Tanaka and co-workers had already completed a separate study in which the electrochemical oxidation of chloride ions was used to produce hypochlorite ions for electrochemical epoxidation. We found that epoxides could be obtained from styrene derivatives in the presence of metal complexes, including manganese(III) and oxidovanadium(IV) porphyrin complexes and manganese salen complexes, using a boron-doped diamond as the anode. After considering various complexes as potential catalysts, we found that manganese salen complexes showed better performance in terms of epoxide yield. Furthermore, the substituent effect of the manganese salen complex was also investigated, and it was found that the highest epoxide yields were obtained when Jacobsen’s catalyst was used. Although there is still room for improving the yields, this study has shown that the in situ electrochemical generation of percarbonate ions is a promising method for the electrochemical epoxidation of alkenes. Full article
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12 pages, 18165 KiB  
Article
Catalytic Ammonia Synthesis Mediated by Molybdenum Complexes with PN3P Pincer Ligands: Influence of P/N Substituents and Molecular Mechanism
by Katja Bedbur, Nadja Stucke, Lina Liehrs, Jan Krahmer and Felix Tuczek
Molecules 2022, 27(22), 7843; https://doi.org/10.3390/molecules27227843 - 14 Nov 2022
Cited by 4 | Viewed by 1443
Abstract
Three molybdenum trihalogenido complexes supported by different PN3P pincer ligands were synthesized and investigated regarding their activity towards catalytic N2-to-NH3 conversion. The highest yields were obtained with the H-PN3PtBu ligand. The corresponding Mo(V)-nitrido complex also [...] Read more.
Three molybdenum trihalogenido complexes supported by different PN3P pincer ligands were synthesized and investigated regarding their activity towards catalytic N2-to-NH3 conversion. The highest yields were obtained with the H-PN3PtBu ligand. The corresponding Mo(V)-nitrido complex also shows good catalytic activity. Experiments regarding the formation of the analogous Mo(IV)-nitrido complex lead to the conclusion that the mechanism of catalytic ammonia formation mediated by the title systems does not involve N-N cleavage of a dinuclear Mo-dinitrogen complex, but follows the classic Chatt cycle. Full article
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11 pages, 5115 KiB  
Article
Direct Hydroxylation of Benzene with Hydrogen Peroxide Using Fe Complexes Encapsulated into Mesoporous Y-Type Zeolite
by Syuhei Yamaguchi, Yuito Ishida, Hitomu Koga and Hidenori Yahiro
Molecules 2022, 27(20), 6852; https://doi.org/10.3390/molecules27206852 - 13 Oct 2022
Cited by 1 | Viewed by 1176
Abstract
Mesoporous Y-type zeolite (MYZ) was prepared by an acid and base treatment of commercial Y-type zeolite (YZ). The mesopore volume of MYZ was six times higher than that of YZ. [Fe(terpy)2]2+ complexes encapsulated into MYZ and YZ with different Fe [...] Read more.
Mesoporous Y-type zeolite (MYZ) was prepared by an acid and base treatment of commercial Y-type zeolite (YZ). The mesopore volume of MYZ was six times higher than that of YZ. [Fe(terpy)2]2+ complexes encapsulated into MYZ and YZ with different Fe contents (Fe(X)L-MYZ and Fe(X)L-YZ; X is the amount of Fe) were prepared and characterized. The oxidation of benzene with H2O2 using Fe(X)L-MYZ and Fe(X)L-YZ catalysts was carried out; phenol was selectively produced with all Fe-containing zeolite catalysts. As a result, the oxidation activity of benzene increased with increasing iron complex content in the Fe(X)L-MYZ and Fe(X)L-YZ catalysts. The oxidation activity of benzene using Fe(X)L-MYZ catalyst was higher than that using Fe(X)L-YZ. Furthermore, adding mesopores increased the catalytic activity of the iron complex as the iron complex content increased. Full article
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10 pages, 2560 KiB  
Article
The Conversion of Superoxide to Hydroperoxide on Cobalt(III) Depends on the Structural and Electronic Properties of Azole-Based Chelating Ligands
by Toshiki Nishiura, Takehiro Ohta, Takashi Ogura, Jun Nakazawa, Masaya Okamura and Shiro Hikichi
Molecules 2022, 27(19), 6416; https://doi.org/10.3390/molecules27196416 - 28 Sep 2022
Viewed by 1194
Abstract
Conversion from superoxide (O2) to hydroperoxide (OOH) on the metal center of oxygenases and oxidases is recognized to be a key step to generating an active species for substrate oxidation. In this study, reactivity of cobalt(III)-superoxido complexes supported [...] Read more.
Conversion from superoxide (O2) to hydroperoxide (OOH) on the metal center of oxygenases and oxidases is recognized to be a key step to generating an active species for substrate oxidation. In this study, reactivity of cobalt(III)-superoxido complexes supported by facially-capping tridentate tris(3,5-dimethyl-4-X-pyrazolyl)hydroborate ([HB(pzMe2,X)3]; TpMe2,X) and bidentate bis(1-methyl-imidazolyl)methylborate ([B(ImN-Me)2Me(Y)]; LY) ligands toward H-atom donating reagent (2-hydroxy-2-azaadamantane; AZADOL) has been explored. The oxygenation of the cobalt(II) precursors give the corresponding cobalt(III)-superoxido complexes, and the following reaction with AZADOL yield the hydroperoxido species as has been characterized by spectroscopy (UV-vis, resonance Raman, EPR). The reaction of the cobalt(III)-superoxido species and a reducing reagent ([CoII(C5H5)2]; cobaltocene) with proton (trifluoroacetic acid; TFA) also yields the corresponding cobalt(III)-hydroperoxido species. Kinetic analyses of the formation rates of the cobalt(III)-hydroperoxido complexes reveal that second-order rate constants depend on the structural and electronic properties of the cobalt-supporting chelating ligands. An electron-withdrawing ligand opposite to the superoxide accelerates the hydrogen atom transfer (HAT) reaction from AZADOL due to an increase in the electrophilicity of the superoxide ligand. Shielding the cobalt center by the alkyl group on the boron center of bis(imidazolyl)borate ligands hinders the approaching of AZADOL to the superoxide, although the steric effect is insignificant. Full article
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15 pages, 2451 KiB  
Article
The Steric Effect in Preparations of Vanadium(II)/(III) Dinitrogen Complexes of Triamidoamine Ligands Bearing Bulky Substituents
by Yoshiaki Kokubo, Itsuki Igarashi, Kenichi Nakao, Wataru Hachiya, Shinichi Kugimiya, Tomohiro Ozawa, Hideki Masuda and Yuji Kajita
Molecules 2022, 27(18), 5864; https://doi.org/10.3390/molecules27185864 - 09 Sep 2022
Viewed by 1477
Abstract
The reactions of newly designed lithiated triamidoamines Li3LR (R = iPr, Pen, and Cy2) with VCl3(THF)3 under N2 yielded dinitrogen–divanadium complexes with a μ-N2 between vanadium atoms [{V(LR)}2 [...] Read more.
The reactions of newly designed lithiated triamidoamines Li3LR (R = iPr, Pen, and Cy2) with VCl3(THF)3 under N2 yielded dinitrogen–divanadium complexes with a μ-N2 between vanadium atoms [{V(LR)}2(μ-N2)] (R = iPr (1) and Pen (2)) for the former two, while not dinitrogen–divanadium complexes but a mononuclear vanadium complex with a vacant site, [V(LCy2)] (R = Cy2 (3)), were obtained for the third ligand. The V–NN2 and N–N distances were 1.7655(18) and 1.219(4) Å for 1 and 1.7935(14) and 1.226(3) Å for 2, respectively. The ν(14N–14N) stretching vibrations of 1 and 2, as measured using resonance Raman spectroscopy, were detected at 1436 and 1412 cm–1, respectively. Complex 3 reacted with potassium metal in the presence of 18-crown-6-ether under N2 to give a hetero-dinuclear vanadium complex with μ-N2 between vanadium and potassium, [VK(LCy2)(μ-N2)(18-crown-6)] (4). The N–N distance and ν(14N–14N) stretching for 4 were 1.152(3) Å and 1818 cm−1, respectively, suggesting that 4 is more activated than complexes 1 and 2. The complexes 1, 2, 3, and 4 reacted with HOTf and K[C10H8] to give NH3 and N2H4. The yields of NH3 and N2H4 (per V atom) were 47 and 11% for 1, 38 and 16% for 2, 77 and 7% for 3, and 80 and 5% for 4, respectively, and 3 and 4, which have a ligand LCy2, showed higher reactivity than 1 and 2. Full article
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10 pages, 1232 KiB  
Article
Lewis Acid-Induced Dinitrogen Cleavage in an Anionic Side-on End-on Bound Dinitrogen Diniobium Hydride Complex
by Naofumi Suzuki, Yutaka Ishida and Hiroyuki Kawaguchi
Molecules 2022, 27(17), 5553; https://doi.org/10.3390/molecules27175553 - 29 Aug 2022
Viewed by 1297
Abstract
The side-on end-on dinitrogen hydride complex [{Na(dme)}2{(O3)Nb}2(μ-η12-N2)(μ-H)2] (3-Na, [O3]3− = [(3,5-tBu2-2-O-C6H2)3CH]3−) was [...] Read more.
The side-on end-on dinitrogen hydride complex [{Na(dme)}2{(O3)Nb}2(μ-η12-N2)(μ-H)2] (3-Na, [O3]3− = [(3,5-tBu2-2-O-C6H2)3CH]3−) was observed to undergo facile elimination of H2 and cleavage of the N–N bond in the presence of 9-borabicyclo[3.3.1]nonane (9-BBN), AlMe3, and ZnMe2. Treatment of 3-Na with 9-BBN and ZnMe2 afforded the nitride complex [{K(dme)2}2{(O3)Nb}2(μ-N)2] (2-Na). The reaction of 3-Na with AlMe3 afforded [{Na(dme)}2{(O3)AlMe}2(NbMe2)2(μ-N)2] (5). The nitride complex 2-Na was treated with 9-BBN and AlMe3 to form [{Na(dme)}2{(O3)Nb}(μ-NH)(μ-NBC8H14){Nb(O3C)}] (4) and 5, respectively. Complex 2-Na, 4, and 5 were structurally characterized. Full article
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11 pages, 10968 KiB  
Article
Synthesis and Reactivity of Manganese Complexes Bearing Anionic PNP- and PCP-Type Pincer Ligands toward Nitrogen Fixation
by Shogo Kuriyama, Shenglan Wei, Takeru Kato and Yoshiaki Nishibayashi
Molecules 2022, 27(7), 2373; https://doi.org/10.3390/molecules27072373 - 06 Apr 2022
Cited by 3 | Viewed by 2596
Abstract
A series of manganese complexes bearing an anionic pyrrole-based PNP-type pincer ligand and an anionic benzene-based PCP-type pincer ligand is synthesized and characterized. The reactivity of these complexes toward ammonia formation and silylamine formation from dinitrogen under mild conditions is evaluated to produce [...] Read more.
A series of manganese complexes bearing an anionic pyrrole-based PNP-type pincer ligand and an anionic benzene-based PCP-type pincer ligand is synthesized and characterized. The reactivity of these complexes toward ammonia formation and silylamine formation from dinitrogen under mild conditions is evaluated to produce only stoichiometric amounts of ammonia and silylamine, probably because the manganese pincer complexes are unstable under reducing conditions. Full article
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Review

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19 pages, 6107 KiB  
Review
π–π Stacking Interaction of Metal Phenoxyl Radical Complexes
by Hiromi Oshita and Yuichi Shimazaki
Molecules 2022, 27(3), 1135; https://doi.org/10.3390/molecules27031135 - 08 Feb 2022
Cited by 4 | Viewed by 2247
Abstract
π–π stacking interaction is well-known to be one of the weak interactions. Its importance in the stabilization of protein structures and functionalization has been reported for various systems. We have focused on a single copper oxidase, galactose oxidase, which has the π–π stacking [...] Read more.
π–π stacking interaction is well-known to be one of the weak interactions. Its importance in the stabilization of protein structures and functionalization has been reported for various systems. We have focused on a single copper oxidase, galactose oxidase, which has the π–π stacking interaction of the alkylthio-substituted phenoxyl radical with the indole ring of the proximal tryptophan residue and catalyzes primary alcohol oxidation to give the corresponding aldehyde. This stacking interaction has been considered to stabilize the alkylthio-phenoxyl radical, but further details of the interaction are still unclear. In this review, we discuss the effect of the π–π stacking interaction of the alkylthio-substituted phenoxyl radical with an indole ring. Full article
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