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Structure and Spectroscopy of Oxyluciferin, the Light Emitter of the Firefly Bioluminescence
Naumov, Panč,e,Ozawa, Yutaka,Ohkubo, Kei,Fukuzumi, Shunichi American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.32
<P>The crystal structures of the pure, unsubstituted firefly emitter oxyluciferin (OxyLH(2)) and its 5-methyl analogue (MOxyLH(2)) were determined for the first time to reveal that both molecules exist as pure trans-enol forms, enol-OxyLH(2) and enol-MOxyLH(2), assembled as head-to-tail hydrogen-bonded dimers. Their steady-state absorption and emission spectra (in solution and in the solid state) and nanosecond time-resolved fluorescence decays (in solution) were recorded and assigned to the six possible trans chemical forms of the emitter and its anions. The spectra of the pure emitter were compared to its bioluminescence and fluorescence spectra when it is complexed with luciferase from the Japanese firefly (Luciola cruciata) and interpreted in terms of the intermolecular interactions based on the structure of the emitter in the luciferase active site. The wavelengths of the emission spectral maxima of the six chemical forms of OxyLH(2) are generally in good agreement with the theoretically predicted energies of the S(0)-S(1) transitions and range from the blue to the red regions, while the respective absorption maxima range from the ultraviolet to the green regions. It was confirmed that both neutral forms, phenol-enol and phenol-keto, are blue emitters, whereas the phenolate-enol form is yellow-green emitter. The phenol-enolate form, which probably only exists as a mixture with other species, and the phenolate-enolate dianion are yellow or orange emitters with close position of their emission bands. The phenolate-keto form always emits in the red region. The concentration ratio of the different chemical species in solutions of OxyLH(2) is determined by several factors which affect the intricate triple chemical equilibrium, most notably the pH, solvent polarity, hydrogen bonding, presence of additional ions, and pi-pi stacking. Due to the stabilization of the enol group of the 4-hydroxythiazole ring by hydrogen bonding to the proximate adenosine monophosphate, which according to the density functional calculations is similar to that due to the dimerization of two enol molecules observed in the crystal, the phenolate ion of the enol tautomer, which is the predominant ground-state species within the narrow pH interval 7.44-8.14 in buffered aqueous solutions, is the most probable emitter of the yellow-green bioluminescence common for most wild-type luciferases. This conclusion is supported by the bioluminescence/fluorescence spectra and the NMR data, as well the crystal structures of OxyLH(2) and MOxyLH(2), where the conjugated acid (phenol) of the emitter exists as pure enol tautomer.</P>
Naumov, Nikolai G.,Tarasenko, Maria S.,Virovets, Alexander V.,Kim, Youngmee,Kim, Sung-Jin,Fedorov, Vladimir E. Wiley-VCH 2006 European journal of inorganic chemistry Vol. No.
<P>The interaction of aqueous solutions of octahedral cluster anions [Re<SUB>6</SUB>Q<SUB>8</SUB>(CN)<SUB>6</SUB>]<SUP>4–</SUP> with rare earth cations in the presence of glycerol resulted in the formation of a new family of compounds [Ln<SUB>2</SUB>(H<SUB>2</SUB>L)<SUB>2</SUB>(H<SUB>3</SUB>L)<SUB>4</SUB>][Re<SUB>6</SUB>Q<SUB>8</SUB>(CN)<SUB>6</SUB>] (where Ln = La, Nd, and Gd; Q = S, Se; H<SUB>3</SUB>L = glycerol; H<SUB>2</SUB>L<SUP>–</SUP> = glycerolate anion). All compounds are isostructural and crystallize in the P<TEX>$\bar {1}$</TEX> space group. Crystal structures are built from octahedral cluster anions [Re<SUB>6</SUB>Q<SUB>8</SUB>(CN)<SUB>6</SUB>]<SUP>4–</SUP> and centrosymmetrical dimers [Ln<SUB>2</SUB>(H<SUB>2</SUB>L)<SUB>2</SUB>(H<SUB>3</SUB>L)<SUB>4</SUB>]<SUP>4+</SUP> that have three different binding modes of glycerol. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/14341948-2006-2006-2-EJIC200500542-fig000.gif' alt='wiley_img/14341948-2006-2006-2-EJIC200500542-fig000'> </P>
Mironov, Yuri V.,Naumov, Nikolai G.,Kozlova, Svetlana G.,Kim, Sung-Jin,Fedorov, Vladimir E. WILEY-VCH Verlag 2005 Angewandte Chemie Vol.117 No.42
<B>Graphic Abstract</B> <P>Die Cyanidcluster [Re<SUB>12</SUB>CS<SUB>17</SUB>(CN)<SUB>6</SUB>]<SUP>n−</SUP> (n=8 oder 6) könnten als Bausteine für polymere Materialien dienen. Sie entstehen aus ReS<SUB>2</SUB> in geschmolzenem KCN bei 750 °C. Die Clustereinheit umfasst zwei {Re<SUB>6</SUB>}-Oktaeder, die durch drei μ<SUB>2</SUB>-S-Brücken und ein interstitielles μ<SUB>6</SUB>-C-Atom verbunden sind (siehe Bild). <img src='wiley_img/00448249-2005-117-42-ANGE200501911-content.gif' alt='wiley_img/00448249-2005-117-42-ANGE200501911-content'> </P>
Yarovoi, Spartak S.,Mironov, Yuri V.,Naumov, Dmitry Y.,Gatilov, Yuri V.,Kozlova, Svetlana G.,Kim, Sung-Jin,Fedorov, Vladimir E. WILEY-VCH Verlag 2005 European journal of inorganic chemistry Vol.2005 No.19
<P>Two novel rhenium cluster compounds, K<SUB>4</SUB>[Re<SUB>6</SUB>S<SUB>8</SUB>(OH)<SUB>6</SUB>]·8H<SUB>2</SUB>O (1) and K<SUB>4</SUB>[Re<SUB>6</SUB>Se<SUB>8</SUB>(OH)<SUB>6</SUB>]·8H<SUB>2</SUB>O (2), containing octahedral cluster chalcogenide anionic complexes [Re<SUB>6</SUB>Q<SUB>8</SUB>(OH)<SUB>6</SUB>]<SUP>4–</SUP> with terminal hydroxo ligands have been synthesized by the reaction of Re<SUB>6</SUB>Q<SUB>8</SUB>Br<SUB>2</SUB> (Q = S, Se) with molten KOH. Two chalcohalide compounds, one known (Cs<SUB>4</SUB>[Re<SUB>6</SUB>S<SUB>8</SUB>Br<SUB>6</SUB>]·2H<SUB>2</SUB>O, 3) and another new (Cs<SUB>3</SUB>[Re<SUB>6</SUB>Se<SUB>8</SUB>Cl<SUB>6</SUB>]·2H<SUB>2</SUB>O, 4), were prepared by reactions of 1 and 2 with CsX and HX (X = Br, Cl) in an aqueous solution. Compounds 1, 2, and 4 have been characterized by the single-crystal X-ray diffraction method. Compounds 1 and 2 are crystallized in triclinic space group P<TEX>$\bar {1}$</TEX> with one formula unit in the cell of dimensions a = 8.4936(8) Å, b = 8.9101(11) Å, c = 10.5940(13) Å, α = 77.935(11)°, β = 75.933(9)°, γ = 71.244(10)°, V = 728.9(1) Å<SUP>3</SUP> (compound 1) and a = 8.613(1) Å, b = 8.996(1) Å, c = 10.057(1) Å, α = 78.587(2)°, β = 77.811(2)°, γ = 71.728(2)°, V = 715.9(2) Å<SUP>3</SUP> (compound 2). Compound 4 crystallizes in the monoclinic space group P2<SUB>1</SUB>/n with two formula units in the cell of dimensions a = 9.819(3) Å, b = 12.925(4) Å, c = 11.756(4) Å, β = 113.38(3)°, V = 1369.6(8) Å<SUP>3</SUP>. Compounds 1 and 2 display luminescent properties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/14341948-2005-2005-19-EJIC200500284-fig000.gif' alt='wiley_img/14341948-2005-2005-19-EJIC200500284-fig000'> </P>
Fukuzumi, Shunichi,Morimoto, Yuma,Kotani, Hiroaki,Naumov, Pan?e,Lee, Yong-Min,Nam, Wonwoo Nature Publishing Group, a division of Macmillan P 2010 Nature chemistry Vol.2 No.9
Critical biological electron-transfer processes involving high-valent oxometal chemistry occur widely, for example in haem proteins [oxoiron(IV); Fe<SUP>IV</SUP>(O)] and in photosystem II. Photosystem II involves Ca<SUP>2+</SUP> as well as high-valent oxomanganese cluster species. However, there is no example of an interaction between metal ions and oxoiron(IV) complexes. Here, we report new findings concerning the binding of the redox-inactive metal ions Ca<SUP>2+</SUP> and Sc<SUP>3+</SUP> to a non-haem oxoiron(IV) complex, [(TMC)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP> (TMC?=?1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). As determined by X-ray diffraction analysis, an oxo-Sc<SUP>3+</SUP> interaction leads to a structural distortion of the oxoiron(IV) moiety. More importantly, this interaction facilitates a two-electron reduction by ferrocene, whereas only a one-electron reduction process occurs without the metal ions. This control of redox behaviour provides valuable mechanistic insights into oxometal redox chemistry, and suggests a possible key role that an auxiliary Lewis acid metal ion could play in nature, as in photosystem II.
Neutron dose rate analysis of the new CONSTOR® storage cask for the RBMK-1500 spent nuclear fuel
Narkunas, Ernestas,Smaizys, Arturas,Poskas, Povilas,Naumov, Valerij,Ekaterinichev, Dmitrij Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
This paper presents the neutron dose rate analysis of the new CONSTOR® RBMK-1500/M2 storage cask intended for the spent nuclear fuel storage at Ignalina Nuclear Power Plant in Lithuania. These casks are designed to be stored in a new "closed" type interim storage facility, with the capacity to store up to 202 CONSTOR® RBMK-1500/M2 casks. In 2016 y, the "hot trials" of this new facility were conducted and 10 CONSTOR® RBMK-1500/M2 casks loaded with the spent nuclear fuel were transported to the dedicated storage places in this facility. During "hot trials", the dose rate measurements of the CONSTOR® RBMK-1500/M2 casks were performed as the dose rate is one of the critical parameter to control and it must be below design (and safety) criteria. Therefore, having the actual data of the spent nuclear fuel characteristics, the neutron dose rate modeling of the CONSTOR® RBMK-1500/M2 cask loaded with this particular fuel was also performed. Neutron dose rate modeling was performed using MCNP 5 computer code with very detailed geometrical representation of the cask and the fuel. The obtained modeling results were compared with the measurement results and it was revealed, that modeling results are generally in good agreement with the measurements.
REBCO coil operation in gaseous helium and solid nitrogen
Diev, D.N.,Makarenko, M.N.,Naumov, A.V.,Polyakov, A.V.,Shcherbakov, V.I.,Shutova, D.I.,Surin, M.I. The Korea Institute of Applied Superconductivity a 2019 한국초전도저온공학회논문지 Vol.21 No.3
The paper gives the results of the experiments with a model two-section REBCO solenoid cooled by either gaseous helium (GHe) or sub-cooled/solid nitrogen (SN2) in (50-77) K temperature range. The major cooling source was a single-stage cryocooler Sumitomo CH-110 with the cooling power of 175 W and 130 W at 77 K and 50 K respectively. The coil itself was not directly conduction cooled. We compare the time taken by both coolants to obtain the temperature of the magnet of about 50 K and the homogeneity of the temperature distribution within the cryostat. Test results for the coil operation in solid nitrogen together with the comparison of its critical properties in SN2 and GHe are also presented.
REBCO coil operation in gaseous helium and solid nitrogen
D. N. Diev*,M. N. Makarenko,A. V. Naumov,A. V. Polyakov,V. I. Shcherbakov,D. I. Shutova,M. I. Surin 한국초전도.저온공학회 2019 한국초전도저온공학회논문지 Vol.21 No.3
The paper gives the results of the experiments with a model two-section REBCO solenoid cooled by either gaseous helium (GHe) or sub-cooled/solid nitrogen (SN2) in (50-77) K temperature range. The major cooling source was a single-stage cryocooler Sumitomo CH-110 with the cooling power of 175 W and 130 W at 77 K and 50 K respectively. The coil itself was not directly conduction cooled. We compare the time taken by both coolants to obtain the temperature of the magnet of about 50 K and the homogeneity of the temperature distribution within the cryostat. Test results for the coil operation in solid nitrogen together with the comparison of its critical properties in SN2 and GHe are also presented.