Spectroscopic Characterization and Properties of Some Bioactive- Peroxovanadium Complexes in Aqueous Solution

1　ＩＮＴＲＯＤＵＣＴＩＯＮＰｅｒｏｘｏｖａｎａｄｉｕｍ ( ｐＶ )ｃｏｍｐｌｅｘｅｓａｒｅ ｐｏｔｅｎｔｐｒｏｔｅｉｎｔｙｒｏｓｉｎｅｐｈｏｓｐｈａｔａｓｅｉｎ ｈｉｂｉｔｏｒｓｗｉｔｈｉｎｓｕｌｉｎ ｍｉｍｅｓｉｓｐｒｏｐｅｒｔｉｅｓａｎｄｃｏｕｌｄｐｏｓｓｉｂｌｙｂｅｄｅｖｅｌｏｐｅｄｉｎｔｏａｎｅｗｋｉｎｄｏｆｏｒａｌｄｒｕｇｆｏｒｔｈｅｔｒｅａｔｍｅｎｔｏｆｄｉａｂｅｔｅｓ[1～ 3].Ｒｅｃｅｎｔｌｙ ,ｔｈｉｓｋｉｎｄｏｆｃｏｍｐｏｕｎｄｈａｓｒｅｃｅｉｖｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔ…     

Acidity and Structure of Isosaccharinate in Aqueous Solution: A Nuclear Magnetic Resonance Study

Dilute aqueous solutions of the calcium and sodium salts of -d-isosaccharinate (ISA) have been analyzed by ¹³C and ¹H NMR spectroscopy. The positions of the six ¹³C ISA NMR lines show a pH dependence that can be used to infer that the most acidic proton is the one associated with the carboxylate group, with an aver- age log k⁰ of –3.27 for the reaction H(ISA) H⁺ + ISA^– in solutions made with the sodium salt. In acidic solutions (pH < 4),=" nmr=" signals=" were=" found=" that=" could=" be=" assigned=" to=">-d-isosaccharinate-1,4-lactone (ISL), formed from the dehydration of H(ISA). The pH dependence of the H(ISA) ¹³C line positions, furthermore, reveals that the deprotonated H(ISA) at neutral to high pH assumes a conformation with the carboxylate anion hydrogen-bonded to the secondary alcohol and the cation (Na⁺ or Ca²⁺) interacting with the tertiary alcohol.     

Some Nuclear Magnetic Resonance Studies on Triethylenetetraminehexaacetic Acid in Aqueous Solutions

Abstract

Aqueous solutions of triethylenetetraminehexaacetic acid (TTHA) in the pH range 4 to 11 have been studied by NMR. Chemical shifts as a function of pH are reported and a structure proposed for TTHA on the basis of these data. The influence of complex formation of metal ions with TTHA, in varying ratios, on NMR spectra is discussed.     

含有机配体的活性双过氧钒配合物与组氨酸的相互作用研究

在合成和表征了4种具有较强生物活性双过氧钒配合物K_3[VO(O_2)_2(ox)]· 2H_2O，Na[VO(O_2)_2(bipy)]·5H_2O，K[VO(O_2)_2(phen)]·3H_2O和K_2[VO (O_2)_2(pic)]·2H_2O[分别缩写为pV(ox)，pV(bipy)，pV(phen)和pV(pic)，其中 ox为草酸根，bipy为2,2'-联吡啶，phen为邻菲咯啉，pic为2-羧酸吡啶负离子]的 基础上，利用多种NMR技术和电喷雾质谱（ESI-MS）研究了这4种含有机配体双过氧 钒酸合物与组氨酸（His）在溶液中的相互作用以及反应物浓度、时间、pH等对相 互作用体系的影响。~(51)V NMR跟踪监测的结果表明：双过氧钒配合物pV(ox)和 pV(pic)与His在中性水溶液中存在强配位相互作用，而pV(bipy)和pV(phen)与His 在中性水溶液中无明显作用。我们还利用谱学方法确定了pV(ox)和His相互作用后 所生成产物是pV(ox)分别与His在中性水溶液中无明显作用。我们还利用谱学方法 确定了pV(ox)和His相互作用后所生成产物是pV(ox)分别与His咪唑基上的3-N和1- N配位的一对异构体。     

含有机配体的活性双过氧钒配合物与组氨酸的相互作用研究

在合成和表征了4种具有较强生物活性双过氧钒配合物K_3[VO(O_2)_2(ox)]· 2H_2O,Na[VO(O_2)_2(bipy)]·5H_2O,K[VO(O_2)_2(phen)]·3H_2O和K_2[VO (O_2)_2(pic)]·2H_2O[分别缩写为pV(ox),pV(bipy),pV(phen)和pV(pic),其中 ox为草酸根,bipy为2,2'-联吡啶,phen为邻菲咯啉,pic为2-羧酸吡啶负离子]的 基础上,利用多种NMR技术和电喷雾质谱（ESI-MS）研究了这4种含有机配体双过氧 钒酸合物与组氨酸（His）在溶液中的相互作用以及反应物浓度、时间、pH等对相 互作用体系的影响。~(51)V NMR跟踪监测的结果表明：双过氧钒配合物pV(ox)和 pV(pic)与His在中性水溶液中存在强配位相互作用,而pV(bipy)和pV(phen)与His 在中性水溶液中无明显作用。我们还利用谱学方法确定了pV(ox)和His相互作用后 所生成产物是pV(ox)分别与His在中性水溶液中无明显作用。我们还利用谱学方法 确定了pV(ox)和His相互作用后所生成产物是pV(ox)分别与His咪唑基上的3-N和1- N配位的一对异构体。     

过氧钒配合物的合成、结构及模拟过氧化酶催化溴化动力学

根据模拟钒卤代过氧化物酶(V-HPOs)活性中心的配位环境,设计并合成了2种新型过氧钒配合物：Na[VO(O2)2(C10H8N2)]·8H2O(1)和K3H[(VO)2(O2)4(μ2-O)]·H2O(2),通过元素分析、红外光谱和紫外光谱对其进行了表征,并通过X射线单晶衍射方法确定了其结构。 配合物1晶体属于三斜晶系,空间群：P-1,a=0.7213(2) nm,b=1.1269(4) nm,c=1.3728(4) nm,α=68.349(4)°,β=89.178(4)°,γ=88.050(4)°,V=1.0365(6) nm3。 配合物2的晶体属于单斜晶系,空间群：P21/c,a=0.67047(12) nm,b=0.99503(18) nm,c=1.5817(3) nm,α=γ=90°,β=93.739(2)°,V=1.0530(3) nm3。 配合物1和2分别是五角双锥和八面体配位构型。 通过催化溴化反应活性研究发现,2种配合物均可作为潜在的钒卤代过氧化物酶模拟物。     

几种硅烷及其氟取代衍生物的质子核磁共振

属于H_mF_2-mSi(CH₂CH₅)_n(CHCH₂)_2-n型的九个化合物可以系统地合成出来。本文报导它们的质子核磁共振谱。     

cAMP及其衍生物金属离子铬合物的核磁共振研究

本文报导用核磁共振谱研究了有重要生理意义的二价金属离子与cAMP及其衍生物双丁酰cAMP的相互作用,比较了环苷酸与金属络合时各谱线的化学位移值和谱线宽度。     

Magnetic Resonance of Paramagnetic Complexes

The line width of the ESR and NMR signals of paramagnetic transition metal complexes is determined mainly by the electron spin-lattice relaxation time τ_e. Values of τ_e greater than 10^?9 lead to ESR spectra that are readily resolved, while values smaller than 10^?11 give NMR spectra having small line widths. Since fast relaxation processes are effective in nearly all transition metal complexes with several unpaired electrons and in all complexes having an orbitally degenerate ground state, the NMR method has a wider scope. The sign and magnitude of the electron-nucleus coupling can be determined with great sensitivity from the NMR spectra, whereas only the magnitude of this interaction can be determined from the ESR spectra. Free spin densities can be found very accurately from the NMR shifts, and the method can therefore be advantageously applied to kinetic measurements, e.g. on short-lived contact complexes.     

水解聚合铝阳离子Al13和Al30的27Al核磁共振定量研究

采用不同磁场强度的NMR谱仪和不同测试温度,对水解聚合铝溶液中Keggin结构的聚合铝阳离子形态的定量分析方法进行了研究。检测结果表明,高场27A l NMR分析技术不仅能精确定量地检测出水解聚合铝溶液中具有Keggin结构的[A lO4A l12(OH)24(H2O)12]7 (简称A l13)聚合阳离子,而且还能定量地检测出[(A lO4)2A l28(OH)56(H2O)26]18 (简称A l30)聚合阳离子。提高测试温度,有利于降低A l30共振峰的线宽,增强其分辨率。在70℃测试温度下,采用高场27A lNMR分别对8种中、高浓度(0.1~2.0 mol/L)水解聚合铝溶液中的A l13和A l30形态分布进行了定量研究,证实了A l30形态是高浓度水解聚合铝溶液中的一种优势聚合形态。     

Dynamics of Bacteriorhodopsin in the Dark-Adapted State from Solution Nuclear Magnetic Resonance Spectroscopy

To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR.     

Ferric Chloride Complexes in Aqueous Solution: An EXAFS Study

A series of concentrated aqueous solutions of ferric chloride with different chloride:iron(III) ratios has been studied by means of EXAFS to determine the structure around the iron(III) ion of the dominating species in such solutions. The dominating species in dilute acidic aqueous solution of ferric chloride, at less than 1 mmol·dm^?3, are the hydrated iron(III) and chloride ions, while in concentrated aqueous solution and in solutions with an excess of chloride ions, up to 1.0 mol·dm^?3, it is the trans-[FeCl₂(H₂O)₄]⁺ complex. Possible higher chloroferrate(III) or dimeric [Fe₂Cl₆] complexes at room temperature, as proposed in the literature, were not observed in any of the studied solutions in spite of an excess of chloride ions of 1 mol·dm^?3.     

水溶液中质子核磁共振(PMR)消除水峰及应用

WATR方法是通过在稀水溶液中加入质子交换试剂(NH_4Cl,NH_2OH·HCl,(H_2N)_2CNH·HCl)或驰豫试剂(M_nCl_2)缩短水质子T_2,采用CPMG脉冲序列进行PMR谱图的测定,从而达到消除水峰的目的。本文使用AM-300超导核磁共振波谱仪,研究了溶液的pH、温度及各种试剂对WATR方法最佳使用条件的影响,并对WATR方法的原理及应用实例进行了讨论。使用相应改进后的脉冲序列,可得到完全消失水峰的同核20-J分解谱和相应继相关谱。     

Nuclear Magnetic Resonance and X-Ray Study of a Rectangular Phase

The rectangular phase in the lyotropic system sodium decyl sulphate (SdS)–decanol–water was studied by²H NMR and small-angle X-ray scattering. To investigate the variation in unit cell dimensions, the shape of the ribbons, and molecular segregation within the ribbons with composition, nine samples were prepared. The aspect ratio of the ribbon cross section was found to be independent of composition, ρ = 1.42 ± 0.02, whereas the aspect ratio of the unit cell varied with composition,b/a= 2.7–3.0. In general, the molecular distribution of SdS and decanol is highly nonuniform; the decanol concentration is 2.5 to 3.0 times higher in the central lamellar region of the ribbons than in their curved edges, while SdS accumulates in the curved regions. On addition of SdS, a vertical compression of the unit cell occurs (adecreases andbremains unchanged). However, the absolute dimensions of the ribbons remain constant and the added SdS accumulates in the central lamellar region of the ribbons. Addition of decanol yields horizontal expansion of the unit cell (adecreases andbincreases) and the absolute dimensions of the ribbon cross section increase slightly. The added decanol distributes evenly in the aggregate.     

Nuclear Magnetic Resonance in Solid-State Chemistry

Various problems of solid-state chemistry can be solved by spectroscopic investigation of the nuclear magnetic resonance (NMR and NQR methods). This progress report presents a survey of the nature of the interactions in the crystal that underlie such measurements, of the observations in the spectrum, and of the information obtainable from it. The field of application of the methods covers both static and dynamic properties of solids.     

Solution Conformation of Gramicidin S Determined by Nuclear Magnetic Resonance and Distance Geometry Calculation

The solution conformation of the homodetic decapeptide antibiotic Gramicidin S has been determined by two-dimensional ¹H NMR spectroscopy and distance geometry followed by energy minimization. All structures corresponding to energy minima have four intramolecular hydrogen bonds between Leu and Val residues.     

Electron Paramagnetic Resonance and Proton Nuclear Magnetic Resonance Relaxations in Polyanilines

Magnetic resonance measurements, including nuclear magnetic resonance T₁ and T₁ and electron paramagnetic resonance T₁ and T_2e relaxation times are presented for polyanilines prepared according to a modification of the conventional synthesis and doping methods, showing a conductivity higher than that of standard HCl-polyaniline polymers. The results, obtained as a function of the doping rate, are interpreted in terms of one-dimensional diffusive motions of spin and charge carriers. High anisotropy in the spin diffusion rate is found. In the framework of the model of single metallic polymer chains, this leads to the conclusion that in our polyanilines the mechanism of conduction is more markedly one-dimensional. © 1997 John Wiley & Sons, Ltd.