肽—银（Ⅰ）相互作用的NMR研究

用ＮＭＲ谱研究了银（Ⅰ）离子与肽－Ｇｌｙ－Ｇｌｙ、Ｇｌｙ－Ｇｌｙ－Ｇｌｙ、Ｇｌｙ－Ｌｅｕ、Ｇｌｙ－Ｔｙｒ、Ｎ－Ａｃｅ－Ｇｌｙ的相互作用。在所研究和配合物中,肽是螯合配体,其配位原子包括羧基的Ｏ原子和氨基的Ｎ原子。结果表明,氨基和羧基和Ａｇ（Ⅰ）离子的相互作用是有利的,将决定肽的取向和构象。     

Electron absorption spectra of univalent copper-, silver-, and gold-thiourea complexes in aqueous solutions

Using data on the stability of complex forms, electron absorption spectra of copper (I)-, silver (I)-, and gold (I)—thiourea complexes in an aqueous solution M_itu_j (Ag: i=1, 2, j=1–3; Cu: j=1, 2; Au: j=2) are calculated from the spectra of solutions of a known analytical composition. Parameters of particular bands of the absorption spectra of these complexes are given. It is found that the integral intensity of the spectra of the solutions is proportional to the concentration of thiourea in the solution with high accuracy. The same is also valid for the spectra in solutions that contain mercury (II) and thiourea. The total intensity of longwave bands in the spectra of the complexes is proportional to the number of ligands in a molecule of the complex. Institute of Ionorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, 3, Lavrent’ev Ave., 630090, Novosibirsk-90, Russia, Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 458–462, July–August, 1997.     

稀土(铕-铽)-18冠6-对苯二甲酸配合物的荧光性能

以对苯二甲酸(L′)为桥联配体,18冠6(L)为配体,稀土(Eu Tb)为中心离子,合成了一系列超分子化合物,对其进行了元素分析,红外光谱及荧光性能测量。确定了配合物的组成为(Eu1-xTbx)2L2L′(ClO4)4·H2O(6+3x);推测出Eu3+离子直接与冠醚氧原子配位,而较小半径的Tb3+与18冠6则通过H2O配位。H2O分子与冠醚氧原子以氢键形式连结,对苯二甲酸以双齿形式桥联两个稀土离子冠醚配合物,形成双核结构单元;在此配合物中,Tb3+离子对Eu3+离子的发光有一定的敏化作用,而Eu3+离子对Tb3+离子的荧光却有强的猝灭作用。     

The Vibrational Spectra of Complexes with Planar Monothiooxamides. IV. The Copper(II) and Copper(I) Complexes of Neutral Monothiooxamides

The new complexes CuX₂(LH₂), CuX₂ (SH₃) (X = Cl, Br), CuX(LH₂), CuX(SH₃) (X = Cl, Br, I), CuX(H₄MTO)₂ (X = Cl, Br), Cul(H₄MTO) and CuX(H₃MMTO)₂ (X = Cl, Br, I), where LH₂ = N.N′-dimethyl-monothiooxamide, SH₃ = N(s)-methylmonothiooxamide, H₄MTO = monothiooxamide and H₃MMTO = N_(o)-methylmonothiooxamide, have been prepared. The complexes were characterized by elemental analyses, conductivity measurements, magnetic moments and spectroscopic (UV/VIS, FT-IR, Laser-Raman) studies. The vibrational analysis of the complexes has been given using NH/ND, CH₃/CD₃ and ⁶³cu/⁶⁵cu isotopic substitutions. The neutral monothiooxamides behave as monodentate ligands in the Cu(I) complexes coordinating through their thioamide sulfur atom. The ligands LH2 and SH₃ act as bidentate chelating agents in the Cu(II) complexes with ligated atoms being the thioamide sulfur and the amide oxygen.     

Polyelectrolyte Complexes of Homo- and Copolymers of Vinyl Ether of Monoethanolamine with Poly(Acrylic Acid) in Aqueous Solutions

The complexation of homo- and copolymers of vinyl ether of monoethanolamine with poly(acrylic acid) has been studied in aqueous solutions. The effect of pH on the complexation has been shown. In acidic media (pH 2.4), the polyelectrolyte complex is enriched by anionic polymer units. In weakly acidic media (pH 4–6), the formation of stoichiometric polyelectrolyte complex is observed. In higher pH media (pH 6–8), the polycomplex contains an excessive amount of cationic polymer. The stability of the polyelectrolyte complexes is affected by the addition of inorganic salts and dimethylformamide.     

IR- and UV-Spectral Study of Palladium(II) Complexes with 2-Aminopyridine Obtained in Sulphuric Acid and Alkaline Solutions

When obtained in sulphuric acid medium sulphato-2-aminopyridine-palladium (II) complex has a polynuclear structure, with a bridging coordination of both the sulphato-group and 2-aminopyridine. The complex keeps its polynuclear structure in alkaline solution, in which the substitution of sulphato ions by hydroxylic groups yields hydroxo-2-aminopyridine-palladium (II). The compounds discussed are the main components of activators used in currentless metallization of nonconducting surfaces.     

Novel green-emitting copper(I) complexes with electron donors incorporated ligands: Synthesis, photophysical properties, and electroluminescence performances

In this paper, we explore a diimine ligand of 2-thiazol-4-yl-1H-benzoimidazole (TB) with strong electron donors in its molecule. In addition, an excess electron-donor moiety of carbazole is incorporated through an inert alkyl chain to form another diimine ligand of 1-(4-carbazolylbutyl)-2-thiazol-4-yl-1H-benzoimidazole (CTB). Their corresponding Cu(I) complexes are synthesized as well. Experimental data confirm that both the Cu(I) complexes are high-energy-emitting ones. What is more, it is found that the emitter’s photoluminescent and thermal performances can be greatly improved when active hydrogen is eliminated. Using the CTB-based Cu(I) complex as a dopant, we realize green-emitting devices with a maximum brightness of 1500 cd/m² peaking at 525 nm, and the device efficiency roll-off in these devices is largely depressed due to the shield provided by carbazole moiety.     

非水体系中吡啶和乙腈在铂电极上竞争吸附的表面增强拉曼光谱研究

继非水体系中CO在过渡金属表面吸附的表面增强拉曼光谱（SERS）研究之后，本文是又一篇关于非水体系中过渡金属表面SERS研究的文章。从拉曼谱峰的变化结果发现，吡啶在Pt电极表面是强烈的化学吸附，并且由于其吸附的量和吸附取向随电位在不断地变化，与水体系中吡啶（Py)在Pt电极表面的吸附相比较，SERS谱峰除了强度较低之外，在可研究的电位区间、谱峰位置以及其随电位变化等方面都存在着不同，这缘于结构较为复杂的有机溶剂分子在电极表面组成了更为复杂的界面结构，造成固／液界面的电迁移等电极动力学过程发生了变化，为了说明这一现象，文中还采用强吸附离子I^-进行研究，得到相似的结果。     

Spectroscopic Characterization of Eu(III) Complexes with New Monophosphorus Acid Derivatives of H<Subscript>4</Subscript>dota

The luminescence lifetimes of europium(III) complexes with new monophosphorus acid derivatives of H₄dota were measured by means of time-resolved laser-induced luminescence spectroscopy in H₂O and D₂O. The hydration numbers of these complexes were estimated using different empirical equations [Horrocks and Sudnick (1979) J. Am. Chem. Soc. 101 (1979) 334; Choppin and Barthelemy(1989) Inorg. Chem. 28, 3354–3357; Choppin and Bünzli Lanthanide probes in life, chemical and earth sciences. Theory and practice (1989); Kimura and Kato J. Alloys Comp. 275–277 (1998) 806; Parker (1999) J. Chem. Soc., Perkin Trans. 2, 493–503; Supkowski and Horroks (2002) Inorg. Chim. Acta. 340, 44–48]. It was shown that all the relationships gave similar results with a satisfactory precision. The hydration numbers of complexes of H₃do3a and H₄dota agreed with the literature values. One water molecule is coordinated in complexes of the new ligands. The results showed that the Choppin formula based on measurements only in H₂O can be satisfactorily used for estimation of the hydration numbers.     

A Study on the Spectra Characterization of Ruthenium(Ii) Complexes

Abstract

A series of Ru(II) complexes have been synthesized, and their electronic spectra and NMR spectroscopy properties were characterized. the chemical shifts of aromatic protons of [Ru(bpy)₃] (PF₆)₂, [Ru(phen)₃](ClO₄)₂ and [Ru(bqdi)₃](PF₆) move downfield, but the resonance peaks of cis-Ru(bpy)₂Cl₂ shift upfield. Within the visible spectra of the ruthenium(II) complexes appear a relatively high oscillator strength which is referred to as the π(Ru)→? (ligands) transition.     

Luminescence and OSL study of the inorganic compounds Tl-doped (NH4)2BeF4 and (NH4)2SiF6

The search of materials with efficient optically stimulated luminescence (OSL) properties and a high hydrogen content for fast neutron dosimetry has led to the development of Tl⁺-doped ammonium salts (NH₄)₂SiF₆ and (NH₄)₂BeF₄. Preliminary OSL studies have shown that the OSL in (NH₄)₂SiF₆:Tl⁺ and (NH₄)₂BeF₄:Tl⁺is efficient. In order to optimise the OSL emission and its detection, the identification of the luminescent centres in the OSL process is necessary. This study focuses on the identification of the luminescent centres associated with Tl⁺ based on optical studies in the vacuum UV (VUV) at different temperatures.     

A series of copper(I) complexes with electron donor/acceptor embedded ligands: Synthesis, photophysical and electroluminescent properties

In this paper, we report the synthesis of four diimine ligands incorporated with an electron donor/acceptor, as well as their corresponding Cu(I) complexes with bis(2-(diphenylphosphanyl)phenyl) ether as an ancillary ligand, resulting in four phosphorescent Cu(I) complexes. Their crystal structures as well as photophysical and thermal properties are discussed in detail. Experimental data and theoretical calculations confirm that electron donor moieties and limited conjugation system may self-restrict geometry relaxation in excited states, leading to narrowed and blue-shifted emission bands. On the other hand, electron acceptor moieties and large coplanar conjugation system are ineffective in restricting geometry relaxation, leading to broadened and red-shifted emission bands. However, the introduction of electron donors compromises thermal stability of Cu(I) complexes. We also explore one of the Cu(I) complexes as a dopant for electroluminescence application, and a maximum luminance of 680 cd/m² peaking at 620 nm is achieved.     

Quantitative elucidation of macrocyclic effect on extraction-ability and -selectivity. Benzo-18-crown-6 and its open-ring analog 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene–alkali metal picrate systems

The constants of overall extraction equilibrium (K_ex) and partition (K_D,MLA) for various diluents and aqueous ion-pair formation (K_MLA) of alkali metal (Li–Cs) picrate (MA) 1:1:1 complexes (MLA) with benzo-18-crown-6 (B18C6) and its open-ring analogue 1,2-bis[2-(2-methoxyethoxy)ethoxy]benzene (AC·B18C6) were determined at 25 °C, L being B18C6 or AC·B18C6; the distribution constants of AC·B18C6 were measured at 25 °C. The partition behavior of AC·B18C6 and the MLA complexes closely obeys regular solution theory, omitting chloroform; the molar volumes and the solubility parameters of AC·B18C6 and the MLA complexes were determined. The extraction selectivities of AC·B18C6 and B18C6 for the alkali metal picrates increase in the order Li < Na < Cs < K or Rb < or ≈ Rb or K and Li  Na < Cs < Rb < K, respectively. The extraction selectivity of B18C6 for neighboring alkali metal ions in the periodic table is superior to that of AC·B18C6. The macrocyclic effect on the extraction-ability and -selectivity was quantitatively elucidated by the four fundamental equilibrium constants.     

超声浸提-No Gas-电感耦合等离子体质谱法测定工作场所空气中铊及其化合物

铊(Thallium,Tl)是一种有毒的金属元素,主要用于半导体、电子设备、农药和灭鼠剂的生产,会对职业人群的身体健康造成潜在的威胁,工作场所空气中铊及其化合物浓度的测定对保证职业人群的健康具有重要意义.虽然工作场所空气中痕量铊的毒性高于其他有毒金属元素,但对其研究却很少.目前工作场所空气中铊及其化合物浓度检测方法主要...     

Spectroscopic Study of the Interaction of Mitoxantrone with Copper(I), Copper(II), and Neocuproine

Both reductive and oxidatlve mode of metabolism have been hypothesized for the antitumor agent mitoxantrone. This work aims to better understand the redox properties of mitoxantrone in the presence of the physiological redox couple, copper(I)/copper(II), by means of polarograpy and spectrophotometry. The first quasi-reversible one-electron reduction of mitoxantrone to the semiquinone and the second reduction to the hydroquinone have been shown to be considerably affected by copper. Visible spectra of mitoxantrone-copper mixtures in nitrogen and oxygen purged solutions taken in a one-week period exhibit varying degrees of complexation and oxido-reduction.

When copper(II), neocuprolne and mitoxantrone are mixed in a certain ratio in pH 7. 4 phosphate buffer solution, two new peaks at 584 and 632 nm emerge in the spectra indicating a ternary charge transfer complex. The complex atoichiometry was established as Cu(IT): neocuproine: tritoxan-trone = 2:4:1 by Job's method of continuous variations. The ternary complex is sensitive to the relative concentrations of mitoxantrone and copper(II), an excess of the latter giving rise to complete red ox products. This complex may be important in modeling the drug's oxidative mode of ant tumor action.     

Variational transition state theory with multidimensional tunnelling and kinetic isotope effects in the reactions of C2H6, C2H5D and C2D6 with .CCl3 to produce CHCl3 and CDCl3

ABSTRACT

Rate constants for the reactions of C₂H₆, C₂H₅D and C₂D₆ with .CCl₃. for the production of CHCl₃ and CDCl₃ (k₁, k₂, k₃ and k₄) were computed using variational transition state theory coupled with hybrid-meta density functional theory (MPWB1K) over the temperature range of 200–2900 K. The ground-state vibrational adiabatic potential was plotted for all channels. Small- and large-curvature tunnelling were determined to include quantum effects in the calculation of rate constants. Harmonic vibrational frequencies along the reaction path were calculated in curvilinear coordinates with scaled frequencies. Anharmonicity was included in the lowest-frequency torsion. The position of formation and dissociation of bonds was specified using the variation in harmonic vibrational frequencies along the reaction path. Representative tunnelling energy and the thermally averaged transmission probability at 298 K (P(E)exp?( ? ΔE/RT)) were determined for the reactions in which tunnelling is important. The kinetic isotope effect was used to calculate the considerable contributions of tunnelling and vibration. The expressions for rate constants were determined using nonlinear least-square fitting over the temperature range of 200–2900 K.     

四卤化锡混合物中受扩散控制的卤原子交换动力学研究

以¹¹⁹Sn NMR 方法研究了四氯化锡和四溴化锡混合物（1∶1, 摩尔比）交换体系在不同条件下的动力学性质. 测定了在不同浓度的氘代氯仿溶液中5个交换组份的表观纵向弛豫时间（T¹）及5个组份相互间的交换速率常数（k）,结果表明交换速率常数与表观纵向弛豫速率成正比关系;同时,根据¹¹⁹Sn 1D NMR信号的线宽估测了有效横向弛豫时间（T^*₂）,并由T₁/T^*₂推断在所研究的体系中分子的运动属NMR慢运动极限. 从实验结果可推断在所研究的复杂交换体系中5个组份间的交换与分子自扩散运动有关,即化学交换与交换主体的扩散运动有必然的联系.     

Selection Rules for Multiple Quantum NMR Excitation in Solids: Derivation from Time-Reversal Symmetry and Comparison with Simulations and C NMR Experiments

New derivations of selection rules for excitation and detection of multiple quantum coherences in coupled spin-1/2 systems are presented. The selection rules apply to experiments in which the effective coupling Hamiltonian used for multiple quantum excitation is both time-reversal invariant and time-reversible by a phase shift of the radiofrequency pulse sequence that generates the effective couplings. The selection rules are shown to be consequences of time-reversal invariance and time-reversibility and otherwise independent of the specific form of the effective coupling Hamiltonian. Numerical simulations of multiple quantum NMR signal amplitudes and experimental multiple quantum excitation spectra are presented for the case of a multiply ¹³C-labeled helical polypeptide. The simulations and experiments confirm the selection rules and demonstrate their impact on multiple quantum ¹³C NMR spectra in this biochemically relevant case.     

过氧化氢酶同银(I)离子作用的研究

用FT－IR、Raman和UV／Vis光谱法考察了过氧化氢酶同银（I）离子的相互作用。结果表明，过氧化氢酶可与Ag（I）离子反应生成棕黄色的物种，其特征吸收带在酰胺带Ⅰ、Ⅱ、Ⅲ和υc-s区域，且反应性随温度的升高而加强，当反应温度固定时，则随反应时间的增加而加强。在碱性介质中比在酸性介质中反应更加强烈。对反应原始状态的分析表明，过氧化氢酶同银（I）离子的反应是一个自动催化过程。     

Kinetics for the reaction of phenyl radical with phenylacetylene and styrene

The kinetics for the reactions of C₆H₅ with phenylacetylene and styrene have been measured by CRDS in the temperature range 297-409 K under an Ar pressure of 3.6 Torr. The total rate constants can be given by the following Arrhenius expressions (in units of cm³ mol⁻¹ s⁻¹): k₁(C₆H₅ + C₆H₅C₂H) = 10^13.0±0.1exp [−(2430 ± 150)/RT] and k₂(C₆H₅ + C₆H₅C₂H₃) = 10^13.3±0.1 exp [−(2570 ± 180)/T]. Additional DFT and MP2 calculations have been carried out to assist our interpretation of the measured kinetic data. The addition of C₆H₅ to the terminal CH_x (x = 1 or 2) sites is predicted to be the dominant channel for both reactions. The calculated bimolecular rate constants are in reasonable agreement with experimental values for the temperature range studied.