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Ruthenium Pyrazole Complexes: A Family of Highly Active Metallodrugs for Photoactivated Chemotherapy. Inorg Chem 2024; 63:1988-1996. [PMID: 38215027 DOI: 10.1021/acs.inorgchem.3c03716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
Abstract
Ruthenium complexes bearing bis pyrazole (pzH) ligands, cis-[Ru(bpy)2(R-pzH)2]2+ (bpy = 2,2'-bipyridine, R = -H, -Cl), were examined as photoactivated anticancer prodrugs. A dicationic pyrazole complex deprotonated to give monocationic pyrazole-pyrazolate complexes, cis-[Ru(bpy)2(R-pz-)(R-pzH)]+, in an aqueous solution with pKa values of 9.5 and 7.2 for R = H and R = Cl, respectively. Upon deprotonation, relative quantum yields of photosubstitution decreased while lipophilicity of the complexes increased according to the measurements of water-octanol coefficients. The ruthenium complex with 4-chloropyrazole ligands displayed high cytotoxicity upon light irradiation (IC50 = 0.060 ± 0.016 μM) toward lung cancer cells, which was 7 times higher than that in the dark (IC50 = 0.44 ± 0.07 μM). Additional experiments for the ruthenium R-pyrazole complexes indicated that (1) selective photodissociation of the 4-chloropyrazole ligand occurs from cis-[Ru(bpy)2(4-Clpz-)(4-ClpzH)]+, (2) photoinduced ligand dissociation is dominant rather than photoinduced generation of singlet oxygen (1O2), and (3) induction of cell death occurs via the intrinsic pathway of apoptosis.
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Configurationally Nonselective Aquation of a Mononuclear Ru(II) Chloro Complex to Aquo Complex Isomers with Distinctive Aspects in Photoisomerization, Redox, and Catalytic Water Oxidation. Inorg Chem 2023; 62:17654-17667. [PMID: 37850902 DOI: 10.1021/acs.inorgchem.3c02147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
distal-[Ru(EtOtpy)(pynp)Cl]+ (d-EtO1Cl) (EtOtpy = 4'-ethoxy-2,2':6',2″-terpyridine, pynp = 2-(2-pyridyl)-1,8-naphthyridine), and distal/proximal-[Ru(EtOtpy)(pynp)OH2]2+ (d/p-EtO1H2O) complexes were newly synthesized to investigate the synergistic influence of the geometric configuration coupled with substituent introduction of an ethoxy (EtO) group on the physicochemical properties and reactions of the Ru(II) complexes. Configurationally nonselective aquation of d-EtO1Cl was uniquely observed to form d/p-EtO1H2O isomers in water, in contrast to configurationally selective aquation of distal-[Ru(tpy)(pynp)Cl]+ (d-1Cl, tpy = 2,2':6',2″-terpyridine) without the EtO group [Yamazaki, H. . J. Am. Chem. Soc. 2011, 133, 8846-8849].The kinetic profiles of the aquation reactions of d-EtO1Cl were well analyzed using a sequential reversible reaction model assuming the reversible interconversion between d/p-EtO1H2O isomers via d-EtO1Cl. The observed equilibrium constant (Kiso) of isomerization between p/d-EtO1H2O was calculated from the kinetic analysis as Kiso = 0.45, which is consistent with the final concentration ratio (1:0.43) of p/d-EtO1H2O generated in the aquation reaction of d-EtO1Cl. The irreversible photoisomerization from d-EtO1H2O to p-EtO1H2O was observed in water with an internal quantum yield (Φ) of 0.44% at 520 nm. Electrochemical measurements showed that d-EtO1H2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1.3-9.7, whereas p-EtO1H2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of 1.8-11.5. Any redox potential of d/p-EtO1H2O isomers was decreased by the electro-donating EtO substitution, compared with distal/proximal-[Ru(tpy)(pynp)OH2]2+ (d/p-1H2O). The turnover frequency (kO2 = 1.7 × 10-2 s-1) of d-EtO1H2O for water oxidation catalysis is higher than that (3.5 × 10-4 s-1) of p-EtO1H2O by a factor of 48.6. The kO2 value (1.7 × 10-2 s-1) for d-EtO1H2O is 4.5-fold higher than those of d-1H2O (3.8 × 10-3 s-1). The higher kO2 value of d-EtO1H2O compared with d-1H2O could be explained by the fast oxidation rate from RuIV═O to RuV═O involved in the rate-determining step due to the electron-donating EtO group.
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Binding of Stimuli-Responsive Ruthenium Aqua Complexes with 9-Ethylguanine. ACS OMEGA 2023; 8:37391-37401. [PMID: 37841177 PMCID: PMC10569010 DOI: 10.1021/acsomega.3c05343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 09/14/2023] [Indexed: 10/17/2023]
Abstract
Stimuli-responsive ruthenium complexes proximal- and distal-[Ru(C10tpy)(C10pyqu) OH2]2+ (proximal-1 and distal-1; C10tpy = 4'-decyloxy-2,2':6',2″-terpyridine and C10pyqu = 2-[2'-(6'-decyloxy)-pyridyl]quinoline) were experimentally studied for adduct formation with a model DNA base. At 303 K, proximal-1 exhibited 1:1 adduct formation with 9-ethylguanine (9-EtG) to yield proximal-[Ru(C10tpy)(C10pyqu)(9-EtG)]2+ (proximal-RuEtG). Rotation of the guanine ligand on the ruthenium center was sterically hindered by the presence of an adjacent quinoline moiety at 303 K. Results from 1H NMR measurements indicated that photoirradiation of a proximal-RuEtG solution caused photoisomerization to distal-RuEtG, whereas heating of proximal-RuEtG caused ligand substitution to proximal-1. The distal isomer of the aqua complex, distal-1, was observed to slowly revert to proximal-1 at 303 K. In the presence of 9-EtG, distal-1 underwent thermal back-isomerization to proximal-1 and adduct formation to distal-RuEtG. Kinetic analysis of 1H NMR measurements showed that adduct formation between proximal-1 and 9-EtG was 8-fold faster than that between distal-1 and 9-EtG. This difference may be attributed to intramolecular hydrogen bonding and steric repulsion between the aqua ligand and the pendant moiety of the bidentate ligand..
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Deep-sea in situ determination of sulfide using a sensitized chemiluminescent terbium complex. ANAL SCI 2023:10.1007/s44211-023-00323-7. [PMID: 36959381 DOI: 10.1007/s44211-023-00323-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 03/09/2023] [Indexed: 03/25/2023]
Abstract
A new chemiluminescence (CL) method based on the chemiluminescent reaction between sulfide and an acidic permanganate solution was used to quantify sulfide in seawater. A terbium-pipemidic acid complex was used as CL enhancer. The method was used to determine sulfide in the concentration range of 1-30 μmol/L in artificial seawater samples. The limit of detection of the method was 21 nmol/L sulfide. The sensitivity of the CL method was eight times higher than that of the CL method reported previously. Br- ions, which are conservative ions, interfered with sulfide. We investigated the effects of salinity, water temperature, and interfering chemicals,such asheavy-metal ions and organic matter, on the performance of the CL method. In addition, sulfite-spiked natural seawater samples were analyzed. The results demonstrate that the CL method can be used to develop a deep-sea sulfide analyzer.
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Photofunctional molecular assembly for artificial photosynthesis: Beyond a simple dye sensitization strategy. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Distinctive Aspects in Aquation, Proton-Coupled Redox, and Photoisomerization Reactions between Geometric Isomers of Mononuclear Ruthenium Complexes with a Large-π-Conjugated Tetradentate Ligand. Inorg Chem 2022; 61:13956-13967. [PMID: 36000984 DOI: 10.1021/acs.inorgchem.2c01937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Geometric isomers of mononuclear ruthenium(II) complexes, distal-/proximal-[Ru(tpy)(dpda)Cl]+ (d-/p-RuCl, tpy = 2,2':6',2″-terpyridine, dpda = 2,7-bis(2-pyridyl)-1,8-diazaanthracene), were newly synthesized to comprehensively investigate the geometric and electronic structures and distinctive aspects in various reactions between isomers. The ultraviolet (UV)-visible absorption spectra of d-/p-RuCl isomers show intense bands for metal-to-ligand charge transfer (MLCT) at close wavelengths of 576 and 573 nm, respectively. However, time-dependent density functional theory (TD-DFT) calculations suggest that the MLCT transition of d-RuCl involves mainly single transitions to the π* orbital of the dpda ligand in contrast to mixing of the π* orbitals of the dpda and tpy ligands for p-RuCl. The aquation reaction (1.5 × 10-3 s-1) of p-RuCl to yield proximal-[Ru(tpy)(dpda)(OH2)]2+ (p-RuH2O) is faster than that (5.3 × 10-6 s-1) of d-RuCl in D2O/CD3OD (4:1 v/v) by three orders of magnitude, which resulted from the longer Ru-Cl bond by 0.017 Å and the distorted angle (100.2(3)°) of Cl-Ru-N (a nitrogen of dpda, being on a tpy plane) due to the steric repulsion between Cl and dpda for p-RuCl. Electrochemical measurements showed that d-RuH2O undergoes a 2-step oxidation reaction of 1H+-coupled 1e- processes of RuII-OH2/RuIII-OH and RuIII-OH/RuIV═O at pH 1-9, whereas p-RuH2O undergoes a 1-step oxidation reaction of a 2H+-coupled 2e- process of RuII-OH2/RuIV═O in the pH range of pH 1-10. The irreversible photoisomerization from d-RuH2O to p-RuH2O was observed in aqueous solution with an internal quantum yield (Φ) of 5.4 × 10-3% at 520 nm, which is lower compared with Φ = 1.1-2.1% of mononuclear Ru(II) aquo complexes with similar bidentate ligands instead of dpda by three orders of magnitude. This is possibly ascribed to the faster nonradiative decay rate from the excited 3MLCT state to the ground state for d-RuH2O due to the lower π* level of dpda ligands according to the energy-gap law: the rate decreases exponentially with the increasing energy gap.
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A Visible-Light and Temperature Responsive Host-Guest System: Photoisomerization of a Ruthenium Complex and Inclusion Complex Formation with Cyclodextrins. Dalton Trans 2022; 51:4477-4483. [DOI: 10.1039/d1dt04003k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the present study, we investigated the visible-light- and thermal-stimuli-responsive properties of a host–guest system based on proximal- and distal-[Ru(C10tpy)(C10pyqu)OH2]2+ (proximal and distal-1, C10tpy = 4’-decyloxy-2,2’;6’,2”-terpyridine, C10pyqu = 2-[2’-(6’-decyloxy)-pyridyl]quinoline). The...
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Abstract
Photosubstitution reactions of cis-[Ru(bpy)2(MeCN)2]2+ with a pyrazole ligand (pzH) were studied under various conditions toward the development of a photochemical synthetic route to polypyridyl ruthenium complexes (bpy = 2,2'-bipyridine). In the absence of a base, light irradiation of an acetonitrile solution of pyrazole and cis-[Ru(bpy)2(MeCN)2]2+ gave a mixture of the reactant and cis-[Ru(bpy)2(pzH)(MeCN)]2+. In the presence of a mild base such as N,N-dimethylaminopyridine, a second photosubstitution from cis-[Ru(bpy)2(pzH)(MeCN)]2+ to cis-[Ru(bpy)2(pz)(pzH)]+ (1b) was greatly enhanced, as confirmed by UV-vis and 1H nuclear magnetic resonance spectroscopy. The yields of 1b were increased in solvents with moderate coordinating properties, such as acetone. The successive photosubstitution reaction was observed using a stoichiometric amount of pyrazole.
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A multi-stimuli responsive ruthenium complex for catalytic water oxidation. Chem Commun (Camb) 2020; 56:12825-12828. [PMID: 32966386 DOI: 10.1039/d0cc04940a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A ruthenium complex showing multi-stimuli-responsive isomerization was synthesized. The catalytic activity of this complex toward water oxidation showed responses to visible-light irradiation and heat due to photoisomerization and thermal back-isomerization, respectively. DFT calculations suggested that a pendant moiety in the complex was key to controlling the catalytic activity.
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Intramolecular Hydrogen Bonding: A Key Factor Controlling the Photosubstitution of Ruthenium Complexes. Inorg Chem 2020; 59:11273-11286. [PMID: 32799483 DOI: 10.1021/acs.inorgchem.0c00738] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Photosubstitution reactions of ruthenium complexes with pyrazole ligands, cis-[Ru(bpy)2(pzH)2]2+ (1a), cis-[Ru(bpy)2(pz)(pzH)]+ (1b), and cis-[Ru(bpy)2(pz)2]0 (1c) (pzH = pyrazole, bpy = 2,2'-bipyridine), were investigated. Dicationic complex 1a was deprotonated to 1b using moderate base (pKa = 15.2, MeCN), while the second deprotonation to give 1c required more severe conditions (pKa = 26.9). Monocationic complex 1b possessed an N-H···N-type intramolecular hydrogen bond between the pyrazole and pyrazolate ligands, as corroborated by the solid-state crystal structure. The photosubstitution quantum yield of 1a (Φ = 0.26) was comparable to that of cis-[Ru(bpy)2(pyridine)2]2+ (Φ = 0.24) in acetonitrile solution. In contrast, the photodissociation of a pzH ligand was strongly suppressed by the deprotonation of a pyrazole ligand N-H group. In the presence of 10 000 equiv of 4,4'-dimethylaminopyridine, the quantum yield dropped to ∼2 × 10-6 in acetonitrile. The photosubstitution quantum yield of 1b was even smaller than that of neutral complex 1c, although 1c had a smaller HOMO-LUMO energy gap than monocationic complex 1b. The small quantum yield of 1b was attributed to intramolecular hydrogen bonding between pyrazole and pyrazolate ligands. The apparent rate constants for the photosubstitution of 1b were highly solvent-dependent. The photosubstitution of 1b was suppressed in aprotic solvents, while the reaction was accelerated by 2 orders of magnitude in protic solvents with strong proton donor abilities.
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Application of electrospray spreading to a modified Langmuir–Blodgett technique for organo-clay hybrid film preparation. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.123714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Critical Hammett Electron-Donating Ability of Substituent Groups for Efficient Water Oxidation Catalysis by Mononuclear Ruthenium Aquo Complexes. Inorg Chem 2019; 58:12716-12723. [PMID: 31549813 DOI: 10.1021/acs.inorgchem.9b01623] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[Ru(Rtpy)(bpy)(H2O)]2+ (1R; bpy = 2,2'-bipyridine, and Rtpy = 2,2':6',2″-terpyridine derivatives) complexes with a variety of 4'-substituent groups on Rtpy were synthesized and characterized to reveal the effects of substituents on their structures, physicochemical properties, and catalytic activities for water oxidation. The geometric structures of 1R are not considerably influenced by the electron-donating ability of the 4'-substituent groups on Rtpy. Similar multistep proton-coupled electron transfer reactions were observed for 1R, and the redox potentials for each oxidation step tended to decrease with an increase in the electron-donating ability of the substituent, which is explained by the increased electron density on the Ru center by electron-donating groups, stabilizing the positive charge that builds up upon oxidation. This is consistent with the red-shift of the absorption bands around 480 nm assigned to the metal-to-ligand charge transfer transition for 1R due to the increased d orbital energy level of the Ru center. The turnover frequency (kO2) of 1R for water oxidation catalysis, however, depended greatly on the Rtpy ligands, varying from 0.05 × 10-2 to 44 × 10-2 s-1 (as the highest kO2 was observed for R = ethoxy) by a factor of 880. A critical electron-donating ability of the 4'-substituent groups with a narrow range of Hammett constants (σp = -0.27 to -0.24) found for the highest kO2 values is valuable for understanding the great difficulty in the search for efficient water oxidation catalysts. On another front, the kO2 values increased with a decrease in the redox potentials of RuIV═O/RuV═O for 1R, indicating that the potential of formation of RuV═O species for 1R is crucial for water oxidation catalysis under the employed conditions.
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Photoisomerization and thermal isomerization of ruthenium aqua complexes with chloro-substituted asymmetric bidentate ligands. RSC Adv 2019; 9:2002-2010. [PMID: 35516112 PMCID: PMC9059708 DOI: 10.1039/c8ra08943d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 01/04/2019] [Indexed: 12/30/2022] Open
Abstract
Introduction of a chloro substituent to the bidentate ligand of ruthenium aqua complexes enhanced photoisomerization and thermal back-isomerization.
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Molecular Mimics of Heterogeneous Metal Phosphides: Thermochemistry, Hydride‐Proton Isomerism, and HER Reactivity. Angew Chem Int Ed Engl 2018; 57:16329-16333. [DOI: 10.1002/anie.201808307] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/18/2018] [Indexed: 01/08/2023]
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Molecular Mimics of Heterogeneous Metal Phosphides: Thermochemistry, Hydride‐Proton Isomerism, and HER Reactivity. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201808307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Mechanistic Insight into Reversible Core Structural Changes of Dinuclear μ-Hydroxoruthenium(II) Complexes with a 2,8-Di-2-pyridyl-1,9,10-anthyridine Backbone Prior to Water Oxidation Catalysis. Inorg Chem 2017; 56:10235-10246. [DOI: 10.1021/acs.inorgchem.7b00978] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Photoisomerization of ruthenium(ii) aquo complexes: mechanistic insights and application development. Dalton Trans 2017; 46:3787-3799. [DOI: 10.1039/c7dt00079k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The perspective article highlights a new strategic synthesis of dinuclear ruthenium(ii) complexes acting as active water oxidation catalysts and also reports the development of unique visible-light-responsive giant vesicles, both of which are achieved based on photoisomerization.
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A mild hand cleanser, alkyl ether sulphate supplemented with alkyl ether carboxylic acid and alkyl glucoside, improves eczema on the hand and prevents the growth ofStaphylococcus aureuson the skin surface. Int J Cosmet Sci 2016; 38:599-606. [DOI: 10.1111/ics.12325] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/23/2016] [Indexed: 11/30/2022]
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Visible-Light-Induced Morphological Changes of Giant Vesicles by Photoisomerization of a Ruthenium Aqua Complex. Chemistry 2016; 22:2590-4. [DOI: 10.1002/chem.201504249] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/27/2015] [Indexed: 11/08/2022]
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Influence of chloro substituent on photoisomerization, redox reactions and water oxidation catalysis of mononuclear ruthenium complexes. J Photochem Photobiol A Chem 2015. [DOI: 10.1016/j.jphotochem.2015.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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New Series of Dinuclear Ruthenium(II) Complexes Synthesized Using Photoisomerization for Efficient Water Oxidation Catalysis. Inorg Chem 2015. [PMID: 26200106 DOI: 10.1021/acs.inorgchem.5b01264] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new series of proximal,proximal-[Ru2(tpy)2(L)XY](n+) (p,p-Ru2XY, tpy = 2,2':6',2″-terpyridine, L = 5-phenyl-2,8-di(2-pyridyl)-1,9,10-anthyridine, X and Y = other coordination sites) were synthesized using photoisomerization of a mononuclear complex. The p,p-Ru2XY complexes undergo unusual reversible bridge-exchange reactions to generate p,p-Ru2(μ-Cl), p,p-Ru2(μ-OH), and p,p-Ru2(OH)(OH2) with μ-Cl, μ-OH, as well as hydroxo and aquo ligands at X and Y sites of p,p-Ru2XY, respectively. The geometric and electronic structures of these complexes were characterized based on UV-vis and (1)H NMR spectra, X-ray crystallography, and density functional theory (DFT) calculations. (1)H NMR data showed C2 symmetry of p,p-Ru2(OH)(OH2) with the distorted L chelate and nonequivalence of two tpy ligands, in contrast to the C2v symmetry of p,p-Ru2(μ-Cl) and p,p-Ru2(μ-OH). However, irrespective of the lower symmetry, p,p-Ru2(OH)(OH2) is predominantly formed in neutral and weakly basic conditions due to the specially stabilized core structure by multiple hydrogen-bond interactions among aquo, hydroxo, and backbone L ligands. The electrochemical data suggested that p,p-Ru2(OH)(OH2) (Ru(II)-OH:Ru(II)-OH2) is oxidized to the Ru(III)-OH:Ru(III)-OH state at 0.64 V vs saturated calomel electrode (SCE) and further to Ru(IV)═O:Ru(IV)-OH at 0.79 V by successive 1-proton-coupled 2-electron processes at pH 7.0. The cyclic voltammogram data exhibited that the p,p-Ru2(OH)(OH2) complex works more efficiently for electrocatalytic water oxidation, compared with a similar mononuclear complex distal-[Ru(tpy)(L)OH2](2+) (d-RuOH2) and p,p-Ru2(μ-Cl) and p,p-Ru2(μ-OH), showing that the p,p-Ru2 core structure with aquo and hydroxo ligands is important for efficient electrocatalytic water oxidation. Bulk electrolysis of the p,p-Ru2(OH)(OH2) solution corroborated the electrocatalytic cycle involving the Ru(III)-OH:Ru(III)-OH state species as a resting state. The mechanistic insight into O-O bond formation for O2 production was provided by the isotope effect on electrocatalytic water oxidation by p,p-Ru2(OH)(OH2) and d-RuOH2 in H2O and D2O media.
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Mechanisms and Factors Controlling Photoisomerization Equilibria, Ligand Exchange, and Water Oxidation Catalysis Capabilities of Mononuclear Ruthenium(II) Complexes. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500642] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Artificial Manganese Center Models for Photosynthetic Oxygen Evolution in Photosystem II. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300683] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Mechanisms of Photoisomerization and Water-Oxidation Catalysis of Mononuclear Ruthenium(II) Monoaquo Complexes. Inorg Chem 2013; 52:6354-64. [DOI: 10.1021/ic400054k] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Synthesis, characterization and heterogeneous catalysis for water oxidation of a di-manganese complex with 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine. Polyhedron 2013. [DOI: 10.1016/j.poly.2012.08.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Arrangement effect of the di-μ-oxo dimanganese catalyst and Ru(bpy)32+ photoexcitation centers adsorbed on mica for visible-light-derived water oxidation. Catal Sci Technol 2013. [DOI: 10.1039/c3cy00010a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Syntheses, characterization, and photochemical properties of amidate-bridged Pt(bpy) dimers tethered to Ru(bpy)32+ derivatives. Dalton Trans 2011; 40:3967-78. [DOI: 10.1039/c0dt01548b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Identification of substorm onset location and preonset sequence using Reimei, THEMIS GBO, PFISR, and Geotail. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010ja015520] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Bis(2,2'-bipyridine){ethyl 4'-[N-(4-carbamoylphen-yl)carbamo-yl]-2,2'-bi-pyridine-4-carboxyl-ate}ruthenium(II) bis-[hexa-fluorido-phosphate(V)]. Acta Crystallogr Sect E Struct Rep Online 2009; 65:m228-9. [PMID: 21581819 PMCID: PMC2968400 DOI: 10.1107/s1600536809002360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Accepted: 01/19/2009] [Indexed: 11/10/2022]
Abstract
In the title compound, [Ru(C(10)H(8)N(2))(2)(C(21)H(18)N(4)O(4))](PF(6))(2), the Ru(II) complex cation reveals a slightly distorted octa-hedral coordination. The coordination bonds of the 4,4'-substituted bipyridyl donors [Ru-N = 2.038 (3) and 2.051 (3) Å] are shorter than those of the 2,2'-bipyridyl donors [Ru-N1 = 2.065 (3)-2.077 (3) Å], due to the electron-withdrawing effects of the substituents at the 4,4'-positions. The angles between the pyridyl planes of the three bipyridyl ligands are 1.5 (2), 6.3 (3) and 8.7 (2)°, respectively. The cations are connected by anions via N-H⋯F inter-actions.
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Abstract
In Earth's environment, the observed polar outflow rate for O(+) ions, the main source of oxygen above gravitational escape energy, corresponds to the loss of approximately 18% of the present-day atmospheric oxygen over 3 billion years. However, part of this apparent loss can actually be returned to the atmosphere. Examining loss rates of four escape routes with high-altitude spacecraft observations, we show that the total oxygen loss rate inferred from current knowledge is about one order of magnitude smaller than the polar O(+) outflow rate. This disagreement suggests that there may be a substantial return flux from the magnetosphere to the low-latitude ionosphere. Then the net oxygen loss over 3 billion years drops to approximately 2% of the current atmospheric oxygen content.
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Cold flowing O+beams in the lobe/mantle at Geotail: Does FAST observe the source? ACTA ACUST UNITED AC 2000. [DOI: 10.1029/1999ja900470] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
In conventional models for storing hierarchically correlated patterns, correlations between ancestors (first-level patterns) and their descendants (second-level ones) are assumed to be uniform, so that the descendants are distributed around their ancestors with equal distances. However, this assumption might be unnatural. We believe that objects are encoded into patterns by preserving the similarity between them. In this case, descendants are distributed around their ancestors with various distances, so that the assumption is invalid and the conventional models become inapplicable. To overcome this, we propose a model CASM3 for storing hierarchically correlated patterns with various correlations. In CASM3, critical load levels vary with the descendants, and become higher with increasing correlations. Increase in load level successively destroys the memories of the descendants in descending order of their correlations. The size of the basins of attraction depends on the range of the correlations, and becomes larger as the correlation range is shifted toward lower levels.
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Abstract
The introduction of a hierarchical memory structure into a cascade associative memory model for storing hierarchically correlated patterns improves the storage capacity and the size of the basins of attraction remarkably. A learning algorithm groups descendants (second-level patterns) according to their ancestors (first-level ones), and organizes the memory structure in a weight matrix where the groups are memorized separately. The weight matrix is, thus, in the form of a pile of covariance matrices, each of which is responsible for recalling only the descendants of each ancestor. Putting it simply, the model is multiplex associative memory. The recalling process proceeds as follows: the model first recalls the ancestor of a target descendant. Then, the dynamics with dynamic threshold combines the ancestor and the weight matrix to activate the covariance matrix for recalling only the descendants of the ancestor. This mechanism suppresses the cross-talk noise generated by the descendants of the other ancestors, and the recalling ability is enhanced.
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Statistical properties and possible supply mechanisms of tailward cold O+beams in the lobe/mantle regions. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/97ja02137] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cold dense ion flows with multiple components observed in the distant tail lobe by Geotail. ACTA ACUST UNITED AC 1996. [DOI: 10.1029/95ja03165] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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[Books recommended by senior nurses and by fresh nurses. Japanese classic literature]. [KANGO] JAPANESE JOURNAL OF NURSING 1993; 45:63-5. [PMID: 8107402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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A neural network model for visual motion detection that can explain psychophysical and neurophysiological phenomena. BIOLOGICAL CYBERNETICS 1993; 68:247-252. [PMID: 8452894 DOI: 10.1007/bf00224859] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This paper proposes a new neural network model for visual motion detection. The model can well explain both psychophysical findings (the changes of displacement thresholds with stimulus velocity and the perception of apparent motion) and neurophysiological findings (the selectivity for the direction and the velocity of a moving stimulus). To confirm the behavior of the model, numerical examinations were conducted. The results were consistent with both psychophysical and neurophysiological findings.
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[Nursing management of the patient after occipital artery and posterior inferior cerebral artery anastomosis]. [KANGO GIJUTSU] : [NURSING TECHNIQUE] 1983; 29:648-51. [PMID: 6554354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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[Nursing care in induced hypertension therapy for patients with cerebral vasospasm]. [KANGO GIJUTSU] : [NURSING TECHNIQUE] 1983; 29:652-6. [PMID: 6554355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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[Nursing during the post-operative acute stage in a patient with cerebral ischemia--an analysis based on the oxygen partial pressure at the internal jugular vein]. [KANGO GIJUTSU] : [NURSING TECHNIQUE] 1983; 29:77-82. [PMID: 6550652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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[Results of penetrating keratoplasty]. NIHON GANKA KIYO 1965; 16:534-8. [PMID: 5329276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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