A conjecture for some partial differential operators on L 2( R n)

OnX =L ²(R ⁿ), letQ = (Q ₁,Q ₂,…,Q _n) andP = (P ₁,P ₂, …,P _n) be the operators given by (Q _jf) (x) =x _jf(x),P _j = - i∂/∂x _j. For anyC ^∞ functionh:R ⁿ →R putH ₀ =h(P) andH =H ₀ + (1 +Q ²)^-δ, where δ > 1/2. By the method of scattering theory we prove thatH _ac, the absolutely continuous part ofH is unitarily equivalent toH ₀ when (a)n = 1 and (b) forn ≥ 2, whenh is in a large class of polynomials. It is conjectured that the results are true for any polynomialh. We use the techniques of Enss’ method and the idea of bound states for momentum.     

Electron-gas interaction potentials for collisions of CaCl(X 2Σ+) and KCl(X 1Σ+) with Ar

Interaction potentials for CaCl(X ²Σ⁺)-Ar and KCl(X ¹Σ⁺)-Ar have been determined. They include a Gordon-Kim electron-gas repulsive part smoothly joined to the long-range van der Waals potential. The van der waals potential for KClAr was taken from Meyer and Toennies. For CaClAr, the necessary molecular parameter were estimated from the Rittner model, which predicts both the dipole and quadrupole moments fairly accurately. The CaClAr interaction potential is quite different from that of KClAr. Due to the outer 4s electron on the Ca⁺ ion. the CaClAr potential exhibits a deep minimum in the odd-order Legendre terms which is expected to have a large effect on the cross sections for collisional rotational excitation. The KClAr potential determined here also shows significant differences in the repulsive and well regions from that predicted by Meyer and Toennies using a site-site model for the repulsive contribution.     

[Cu(dien)Cl]+与DNA及多核苷酸作用的平衡透析研究

用平衡透析法研究了37℃、pH=6.00,离子强度为0.005条件下的[Cu(dien)Cl]~+与DNA、多聚腺苷酸、多聚鸟苷酸以及多聚胞苷酸之间的相互作用。用McGhee和von Hippel法对实验数据进行了分析,求得其结合常数、反映键合过程中(Cu(dien)Cl]~+间相互作用的协同参数以及每个[Cu(dien)Cl]~+所键合的核苷酸残基数。     

Zur kenntnis von [O2]+[Mn2F9]−

[O₂]⁺[Mn₂F₉]^? has been prepared for the first time by reaction of MnO₂ or MnF_x (x = 2,3,4) with a mixture of fluorine and oxygen (P_F2/O₂ ≈ 300–3500 atm., t ≈ 350–550°C) either as a dark red powder or as ruby red needles or plates. From single crystal studies the space group is C2/c - C⁶_2h (No. 15) with a = 17.55₂, b = 8.37₃, c = 9.10₁ Å, β = 102.3°, Z = B (at ?150°C). The crystal structure has been refined to R = 0.053 (1619 unique reflections). From the structure determination [O₂]+[Mn₂F₉] has ‘mänder’ like bands of double chains of [MnF₆] octahedra, which are stacked up in layers parallel to (100) with O₂⁺-cations (d_0?0 = 1.10₀ Å) located between the layers. ν_O2 is at 1838 cm^?1 and the magnetic moment μ_eff = 5.63 B.M. is as expected for a ‘spin only’ case without spin-spin interaction.     

微量热法研究 [Cu(phen)2]2+、[Cu(bpy)2]2+与DNA的作用

用微量热法对菲咯啉合铜([Cu(phen)     

Rate and Equilibrium Data for Substitution Reactions of [Pd(<Emphasis Type="Italic">dien</Emphasis>)Cl]<Superscript>+</Superscript> with <Emphasis Type="Italic">L</Emphasis>-Cysteine and Glutathione in Aqueous Solution

Summary. The kinetics of the complex formation reactions between monofunctional palladium(II) complex, [Pd(dien)Cl]⁺, where dien is diethylene triamine or 1,5-diamino-3-azapentane, with L-cysteine and glutathione were studied in an aqueous 0.10M perchloric acid medium by using variable stopped-flow spectrophotometry. Second-order rate constants, <$>{k_2}^{298}<$>, were (3.89±0.02) 10²M^–1s^–1 for L-cysteine and (1.44±0.01) 10³M^–1s^–1 for glutathione. The negative entropies of activation support a strong contribution from bond formation in the transition state of the process. The hydrolysis of Pd^II complex gave the monohydroxo species, [Pd(dien)(OH)]⁺ and the dimer with a single hydroxo-bridge species, [Pd₂(dien)₂OH]³⁺. L-Cysteine and glutathione ligands form complexes of 1:1 stoichiometry and a dimer with a single ligand bridge. The formation constants of the complexes were determined, and their concentration distribution as a function of pH was evaluated.     

A low-energy passage for C+ + H2 → CH+(1Σ+) + H

Ab initio (SCF and CI) calculations have been performed for the linear approach (C_∝v) of C⁺ to H₂. For the ² Σ⁺ surface the saddle point and barrier height were determined. The interaction of the ²Σ⁺ and ²Π surfaces was investigated, leading to the conclusion that in near-C_∝v symmetry a low-energy path exists by which CH⁺¹ Σ⁺ can be formed, with negligible barrier in excess of endothermicity.     

Electric moments,polarizabilities and hyperpolarizabilities for BH(X1Σ+ and CH+ (X1Σ+)

The electric moments and static polarizabilities of BH(1σ²2σ²3σ², X¹Σ⁺) and CH⁺ (1σ²2σ²3σ², X¹Σ⁺) were calculated at the experimental internuclear separation in the LCAO SCF MO approximation. Most of the molecular properties reported in this paper for BH and CH⁺ appear for the first time and should be close to the Hartree—Fock limit. All tensors up to the fourth rank have been included in this study. The isotropy and anisotropy of the α, β and γ tensors are, in atomic units. $\text{α}$ = 22.71, Δα = ?0.26, $\text{β}$ = 55.1, Δβ = ?183.7, $\text{γ}$ = 12428, Δ₁γ = 37895, Δ₂γ = 25120 for BH and $\text{α}$ = 7.73, Δα = 0.39, $\text{β}$ = ?12.4, Δβ = ?11.7, $\text{γ}$ = 344, Δ₁γ = 1515, Δ₂γ = 750 for CH⁺.     

Synthesis, DNA-binding and photocleavage studies of ruthenium(Ⅱ) complexes [Ru(btz)_3]~(2+) and [Ru(btz)(dppz)_2]~(2+)

Two new ruthenium(Ⅱ) complexes, [Ru(btz)3](ClO4)2 (1) and [Ru(btz)(dppz)2](ClO4)2 (2) (btz = 4,4′-bithi-azole, dppz = dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized and characterized by elemental analysis, 1H NMR, ES-MS and X-ray crystallography. The DNA binding behaviors of two complexes have been studied by spectroscopic and viscosity measurements. The results suggest that complex 1 binds to CT-DNA via an electrostatic mode, while complex 2 via an intercalative mode. Under irradiation at 365 nm,...     

Hydrolysis of the Peptide Bond in N-Acetylated L-Methionylglycine Catalyzed by Various Palladium(II) Complexes: Dependence of the Hydrolytic Reactions on the Nature of the Chelate Ligand in cis-[Pd( L)(H 2O) 2] 21 Complexes

Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺ in which L is ethylenediamine (en), 1,2-propylenediamine (1,2-pn), isobutylenediamine (ibn), 1,2-diaminocyclohexane (1,2-dach), N-methylethylenediamine (Meen), N,N,N,N-tetramethylethylenediamine (Me₄en), S-methyl L-cysteine (MeS-L-HCys), L-methionine (L-HMet), and 2,5-dithiahexane (dth) and dipeptide N-acetylated L-methionylglycine (MeCOMet-Gly) were studied by ¹H NMR spectroscopy. The reactions were carried out in the pH range 2.0–2.5 and at 50°C. In all these reactions, palladium(II) complex bound to a methionine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of methionine. We found that the rate of hydrolysis and mechanism of this reaction are strongly dependent from the nature of the chelate ligand L in palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺.     

Hydrolysis of the Peptide Bond in N-Acetylated L-Methionylglycine Catalyzed by Various Palladium(II) Complexes: Dependence of the Hydrolytic Reactions on the Nature of the Chelate Ligand in cis-[Pd( L)(H 2O) 2] 21 Complexes

Summary. Hydrolytic reactions between various palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺ in which L is ethylenediamine (en), 1,2-propylenediamine (1,2-pn), isobutylenediamine (ibn), 1,2-diaminocyclohexane (1,2-dach), N-methylethylenediamine (Meen), N,N,N,N-tetramethylethylenediamine (Me₄en), S-methyl L-cysteine (MeS-L-HCys), L-methionine (L-HMet), and 2,5-dithiahexane (dth) and dipeptide N-acetylated L-methionylglycine (MeCOMet-Gly) were studied by ¹H NMR spectroscopy. The reactions were carried out in the pH range 2.0–2.5 and at 50°C. In all these reactions, palladium(II) complex bound to a methionine residue effects the regioselective cleavage of the amide bond involving the carboxylic group of methionine. We found that the rate of hydrolysis and mechanism of this reaction are strongly dependent from the nature of the chelate ligand L in palladium(II) complexes of the type cis-[Pd(L)(H₂O)₂]²⁺.     

Nucleophilic Substitution Reactions at Planar Tetra-coordinate Bis-cationic-platinum(II) Complexes. Kinetics of Displacement of Pyridine from {Pt[2,6-bis(methylthiomethyl)pyridine](py)}2+, {Pt[bis(2-pyridylmethyl)amine] (py)}2+ and {Pt[bis(2-(pyridylmethyl)sulphide](py)}2+ Cations

The kinetics of nucleophilic substitution of pyridine in bis-cationic [Pt(L)(py)]²⁺ complexes (L=SNS, NNN, NSN) [SNS=bis(methylthiomethyl)pyridine, NNN=bis(2-pyridylmethyl)amine, NSN=bis(2-pyridylmethyl)sulphide] by a series of nucleophiles (Cl⁻, Br⁻, I⁻, N₃⁻, (C₂H₅)₂S, NH₃, thiourea (tu), NO₂⁻, C₅H¹0NH, SeCN⁻, SCN⁻, CN⁻ when L=SNS; Cl⁻, Br⁻, I⁻, N₃⁻, (C₂H₅)₂S, SCN⁻, NH₃, NO₂⁻ when L=NNN; Br⁻, N₃⁻, NO₂⁻, NH₃, C₅H₁₀NH when L=NSN) have been measured in MeOH at 25 °C, μ =0.1 mol dm⁻³ (LiClO₄ or LiCF₃SO₃). The logarithms of the second-order rate constants calculated at μ=0, log k° ₂, do not follow the dependence upon the n° _Pt scale. In particular, the reactivity of the biphilic reagents tu, SeCN⁻, SCN⁻ and, to a lesser extent, NO⁻ ₂, towards these doubly charged substrates is largely lower than expected on the basis of the n° _Ptscale. There are good linear relationships between logk° ₂ for the bis-cationic substrate [Pt(SNS)(py)]²⁺, chosen as the standard, and log k° ₂ for the same reactions with [Pt(NNN)(py)]²⁺, [Pt(NSN)(py)]²⁺ and other double charged complexes previously studied. A new wide nucleophilicity scale based on [Pt(SNS)(py)]²⁺, that is appropriate to all the bis-cationic substrates, is here proposed     

An INDO-LMO and 13C NMR spectroscopic study of the C-H bonds in tetracyclo[3.2.0.02,7.04,6]heptane (quadricyclane) and tricyclo[3.1.0.02,4]hexane

Using an INDO approximation to Von Niessen's charge density localization method, the percent s character of the C atom hybrid orbitals engaged in C-H bonds is computed for a series of open-chain and cyclic saturated and unsaturated hydrocarbons. A semi-empirical linear relationship is found between these quantities and the experimental nuclear spin-spin coupling constants J_CH (standard deviation 4·98 Hz). The experimental values of J_CH were measured for quadricyclane (1) and tricyclo[3.1.0.0^2,4]hexane (2) and were shown to be in fair agreement with the theoretical predictions. An analogous relationship is also established between the percent s character of the involved C atom hybrid orbital and the C-H bond distance, the standard deviation being 0·0040Å. This relation is used in order to predict the different C-H bond lengths in the vibrational ground state of 1 and 2, for which equal CH distances were assumed in the analysis of electron diffraction experiments. The results indicate that molecular geometries can be refined with the use of semi-empirical correlations of the above mentioned type.     

Lifetimes of N2O+(Ã2Σ+) and COS+(Ã2Π) in selected vibronic levels

Lifetimes of selected vibrational levels of the predissociated òΣ⁺ and Ã²Π electronic states of N₂O⁺ and COS⁺, re- spectively, have been measured. These values have been used in conjunction with previous data on fluorescence quantum yields to obtain predissociation rates for the various vibrational levels.     

Solubility and Ionic Processes in the Cu X 2? MX ?H2O ( X ?=Cl?, Br?; M +=Li+, Na+, K+, NH4+, Cs+) Systems

 Solubility isotherms in the CuBr₂−MBr−H₂O (M ⁺ = Li⁺, Na⁺, Cs⁺) systems at 298.15 K were measured. The results together with other available literature data for copper chloride and bromide systems were treated by hydration analysis, and comparative discussion of ionic processes taking place in the respective saturated solutions was performed.     

Solubility and Ionic Processes in the Cu X 2? MX ?H2O ( X ?=Cl?, Br?; M +=Li+, Na+, K+, NH4+, Cs+) Systems

Summary.  Solubility isotherms in the CuBr₂−MBr−H₂O (M ⁺ = Li⁺, Na⁺, Cs⁺) systems at 298.15 K were measured. The results together with other available literature data for copper chloride and bromide systems were treated by hydration analysis, and comparative discussion of ionic processes taking place in the respective saturated solutions was performed. Corresponding author. E-mail: jitka@prfdec.natur.cuni.cz Received August 6, 2002; accepted (revised) November 29, 2002 Published online April 3, 2003     

Diatomics-in-molecules calculations of potential-energy surfaces for B+(3P) + H2(X 1Σg+)

Collisions of B⁺(³P) with H₂(X ¹Σ_g⁺) have been studied repeatedly using molecular-beam techniques. The theoretical interpretation of the results suffered from missing information about the potential-energy surfaces for this system. This paper reports on diatomics-in-molecules calculations for a wide range of nuclear geometries. The stationary points on the minimum-energy paths are determined. Symmetrically orthogonalized and non-hermitean diatomics-in-molecules versions differ only slightly at the minimum-energy path. The potential-energy surfaces of the 1³A′ and 2³A′ states show dramatical changes with the BHH angle, leading possibly to adiabatic as well as non-adiabatic elementary processes. The 1³A′' and 1³A′ states are nearly degenerate for geometries ranging from the entrance channel to the interaction region. The most favourable configurations of approach on these potential-energy surfaces are those with C₂, symmetry.     

[Fe(phen)3]2+ aquation in aqueous polyacrylamide solution

The aquation of tris(1, 10-phenanthroline) iron(II) has been studied in aqueous polyacrylamide solutions. The rate increases up to 2.8 times at low polymer concentrations, and subsequently decreases. These effects are attributed to changes in the local water activity in the region of the complex.

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(1, 10-) (II) . 2,8 , . .