2′,5′-寡核苷酸C_(2′P_5′)C_(2′P_5′)A的合成

近年来发现用干扰素处理过的细胞胞浆提取物和双链RNA、ATP一起培养,可以生成一个低分子量的蛋白合成抑制剂,即5′-三磷酸-三聚2′,5′-腺苷酸(Ⅰ)。由于(Ⅰ)具有天然核酸中不存在的2′,5′-磷酸酯链以及它的抗病毒活性,因此引起不少化学家的兴趣,已有不少文章报导了(Ⅰ)及其类似物的合成,同时也发现不含三磷酸的三聚2′,5′-腺苷酸(Ⅱ)也同样具有活性。为了进一步研究(Ⅰ)的结构与活性关系,本文报导了用胞嘧啶碱基代替腺嘌呤碱基的(Ⅱ)的类似物C_(2′P5′)C_(2′P5′)A(Ⅲ)的合成。     

Syntheses and crystal structures of (18-crown-6)bis(perchlorato-O,O′)strontium and (18-crown-6)bis(perchlorato-O,O′)barium

Two complexes, namely, (18-crown-6)bis(perchlorato-O,O′)strontium (I) and (18-crown-6)bis(perchlorato-O,O′)barium (II), are synthesized. Their crystal structures are determined by X-ray diffraction analysis. The structures of I (space group P2₁/c, a = 15.266 Å, b = 11.080 Å, c = 13.235 Å, β = 109.20°, Z = 4) and II (space group P2₁/n, a = 8.330 Å, b = 11.202 Å, c = 11.752 Å, β = 98.38°, Z = 2) are solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.077 (I) and 0.041 (II) against 3714 (I) and 2478 (II) independent reflections (CAD-4 diffractometer, λMoK _α radiation). Complex molecules [Sr(18C6)(ClO₄)₂] in the structure of I and [Ba(18C6)(ClO₄)₂] in II (in the inversion center)—are of the host-guest type. The Sr²⁺ or Ba²⁺ cation is localized in the center of a cavity of the 18-crown-6 ligand and coordinated by its all six O atoms. In compounds I and II, the coordination polyhedron of the Sr²⁺ and Ba²⁺ cations (coordination number 10) can be described as a distorted hexagonal bipyramid with two bifurcated vertices at two O atoms of two ClO ₄ ^? ligands, which are disordered in I and II and each of them has two orientations.     

Crystal structure of a new binuclear complex bis(2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo(3.3.0)octane-3,7-dione-o,o′)-tetraaqua-hexakis(nitrato-o,o′)-dieuropium(III)

A centrosymmetric binuclear complex of europium(III) nitrate with bicyclic bisurea (2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo(3.3.0)octane-3,7-dione, or mebicar, Mk) [Eu(C₈H₁₄N₄O₂)(H₂O)₂(NO₃)₃]₂ (I) is synthesized and its atomic structure (CIF file CCDC No. 1451437) is determined. The crystals of I are triclinic: space group \(P\overline 1 \), a = 9.8343(4) Å, b = 10.2544(4) Å, c = 10.9411(4) Å, α = 74.366(3)°, β = 67.734(4)°, γ = 67.673(4)°, V = 934.32(7) ų, ρ(calc.) = 2.03398 g/cm³, Z = 1. The europium atom is coordinated by two oxygen atoms of two Mk molecules connected by a symmetry operation, three bidentate nitrate anions, and two water molecules. The coordination polyhedron of the europium atom is a 10-vertex polyhedron, the Eu…Eu distance is 9.7433(6) Å.     

3-(N)-4-(Pyrazolo-4′,5′)-chinolin

Zusammenfassung Da bei Wiederholung der vonK. Eiter undMaria Nagy angegebenen Darstellung der Verbindung I diese in 59% iger Ausbeute erhalten werden konnte, wurde die Behauptung vonD. W. Ockenden undK. Schofield, wonach die Verbindung I nach unseren Angaben nicht herzustellen war, widerlegt.Weiters konnte bewiesen werden, daß eine vonSchofield undTheobald als 3-(Pyridyl-x)-lepidin bezeichnete Verbindung in Wirklichkeit die Verbindung I ist.     

Crystal structure of diaquatetrakis (μ-2,6-dichlorobenzoato-o,o′)dicopper(II)

Summary A new copper(II) complex of the formula [Cu(C₇H₃O₂Cl₂)₂·H₂O]₂ crystallizes in the triclinic system (space group P ). The cell parameters area=7.267(3),b=10.687(3),c= 10.934(3) Å, =99.88(3), =96.25(3), =94.78(3)°,V=827.1(5)ų,Z=1,D _c=1.853(1), andD _m=1.85 Mg/m³. The two copper atoms in the molecule are held together by the four carboxylate groups of the organic ligands, and each copper atom is further bonded to a water molecule, resulting in a square pyramidal geometry. The Cu-O(carboxylate) distances are in the range of 1.955(2)-1.975(2)Å, and Cu-O(water) and Cu-Cu distances are 2.166(2) and 2.605(1)Å, respectively.

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Kristallstruktur von Diaquatetrakis(-2,6-dichlorobenzoato-o,o)dikupfer(II)

Zusammenfassung Ein neuer Kupfer(II)-Komplex mit der Formel [Cu(C₇H₃O₂Cl₂)₂·H₂O]₂ kristallisiert im triklinen System (Raumgruppe P ) mit den Zellparameterna=7.267(3),b=10.678(3),c=10.934(3)Å, =99.88(3), =96.25(3), =94.78(3)°,V=827.1(5)ų,Z=1,D _c=1.853(1) undD _m=1.85 Mg/m³. Die beiden Kupferatome im Molekül werden von den vier Carboxylatgruppen der organischen Liganden zusammengehalten. Jedes Kupferatom ist zusätzlich an ein Wassermolekül gebunden, woraus eine quadratisch pyramidale Geometrie resultiert. Die Cu-O(Carboxylat)-Abstände liegen in einem Bereich von 1.955(2)–1.975(2)Å; die Cu-O(Wasser)- und Cu-Cu-Abstände betragen jeweils 2.166(2) und 2.605(1)Å.

     

CH3(2A′)自由基与臭氧反应机理的量子化学研究

用量子化学UMP2方法，在6-311++G**基组水平上研究了CH3(2A′)自由基与臭氧反应机理，全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型，在UQCISD(T)/6-311++G**水平上计算了它们的能量；并对它们进行了振动分析，以确定中间体和过渡态的真实性；同时应用经典过渡态理论计算了反应的速率常数，并与实验值进行了比较, CH3自由基与臭氧反应速率常数的理论计算结果为: 4.73×10－14 cm3•molecule－1•s－1，与实验报导的结果(k=2.52×10－14 cm3•molecule－1•s－1)很接近，同时发现CH3(2A′)自由基与O3的反应是强放热反应.     

(n,n′) production of99mTc by252Cf fission neutrons

Activation technique was employed to determine the²⁵²Cf spectrum averaged cross section of the⁹⁹Tc(n,n)^99mTc reaction. Two different -spectrometric methods were applied. One of the measurements was relative to that of the cross-section value of¹¹⁵In (n,n)^115mIn reaction, while the other one was absolute. The measured values are 179±49 mb and 195±43 mb for the relative and absolute measurement, respectively.     

Laser photolysis of interaction of poly-guanylic acid (5′) with anthraquinone-2-sulfonate

The electron transfer reaction between triplet anthraquinone-2-sulfonate and poly- guanylic acid (5′) in CH3CN-H2O (97:3) has been investigated by 248 nm (KrF) laser flash photolysis. The transient absorption spectra and kinetics obtained from the interaction of triplet anthraquinone-2-sulfonate and poly[G] demonstrate that the primary ionic radical pair, radical cation of poly[G] and radical anion of anthraquinone-2-sulfonate have been detected simultaneously. The free energy changes in the process of the electron transfer were also calculated.     

Functionalized zinc(II) dithiocarbamate complexes: Synthesis,spectral and molecular structures of bis(N-cyclopropyl-N-4-methoxybenzyldithiocarbamato-S,S′)zinc(II) and (2,2′-bipyridine)bis(N-cyclopropyl-N-4-methoxybenzyldithiocarbamato-S,S′)zinc(II)

Two new zinc and dithiocarbamate integrated metal complexes such as bis(N-cyclopropyl-N-4-methoxybenzyldithiocarbamato-S,S′)zinc(II) (1) and (2,2′-bipyridine)bis(N-cyclopropyl-N-4-methoxybenzyldithiocarbamato-S,S′)zinc(II) (2) have been synthesized and their spectral investigations viz., FT-IR, ¹H and ¹³C NMR as well as single crystal X-ray diffraction studies have been accomplished. Single crystal X-ray analysis of the complex 1 reveals the presence of distorted trigonal bipyramidal and tetrahedral coordination geometry around the zinc. The dithiocarbamate motif acts as bidentate chelating and bidentate bridging ligands between the zinc ions furnishing centrosymmetric dimeric molecules. In the complex 2, the zinc is in a distorted octahedral environment with a ZnS₄N₂ chromophore. The supramolecular frameworks in the complexes 1 and 2 have been sustained by CH?S, CH?O and CH?π (ZnCS₂, and chelate) interactions. Computational studies on complexes 1 and 2 have been executed utilizing DFT-B3LYP/ LANL2DZ method. In both the cases, the HOMO-LUMO calculations imply the occurrence of effective charge transfer within the molecule. Further, the MEP analysis of 1 and 2 implies the negative potential sites are sulfur of NCS₂ and oxygen of OCH₃ and the positive potential sites are nitrogen of NCS₂ in both the complexes along with 2,2′-bipyridine for complex 2. The former sites are susceptible for electrophilic reactions while the latter for nucleophilic reactions.     

Electrochemical and electrocatalytic properties of tetra(pyridyl-4′,3′)porphin series derivatives

A comparative study of electrochemical and electrocatalytical properties of 5,10,15,20-tetra(pyridyl-4′)porphin (para-isomer, H₂TPy[4]P) and 5,10,15,20-tetra(pyridyl-3′)porphin) (meta-isomer, H₂TPy[3]P) and also of their metallocomplexes with Co(II), Cu(II), Zn(II) is carried out by cyclic voltammetry in 0.1 M KOH. The dependence of the form of cyclic I vs. E curves, the redox potentials, and the electrocatalytic activity of compounds in the reaction of molecular oxygen ionization on the heteroatom position in pyridyl fragments and the nature of complexing ion is elucidated.     

Novel method for the synthesis of dinucleoside-(N3′ → P5′)-phosphoramidothioates

A new approach for the synthesis of dinucleoside-(N3′ → P5′)-phosphoramidothioates based on the Atherton–Todd reaction has been developed using nucleoside H-thiophosphonates and 3′-amino-2′,3′-dideoxynucleosides with an unprotected 5′-hydroxyl group. A mixture of P-diastereomers of dinucleosides was separated by column chromatography into fast migrating and slow migrating isomers. Based on single crystal X-ray diffraction analysis, the absolute configuration at the phosphorus atom in the slow eluting diastereomer of the dinucleoside-(N3′ → P5′)-phosphoramidothioate G_NPSG_NHTr was assigned as Rp.     

Investigation of {1,2-bis(diphenylphosphino)ethane-P,P′}-(dithiocarbonato-S,S′)-nickel(II)

Summary The reaction of bis(iso-propylxanthato)nickel(II) with 1,2-bis(diphenylphosphino)ethane (dppe) in a 11 molar ratio affords [Ni(S₂CO)(dppe)], which, on the basis of its magneto-chemical and spectral properties, has been characterized as a square-planar Ni complex. The complex was one-electron irreversibly oxidized at a potential of 0.673 V versus s.c.e. The crystal and molecular structure of a twinned crystal of the complex has been elucidated, and consists of two crystallographically independent molecules in which each Ni atom is coordinated by two S atoms from the dithiocarbonate ligand and two P atoms from the dppe ligand in an approximately square-planar arrangement.     

Cobalt(II) and nickel(II) complexes of N(4′) substituted 3- and 4-acetylpyridine thiosemicarbazones

Co^II and Ni^II complexes of N(4)-methyl and N(4)-ethyl thiosemicarbazones derived from 3- and 4-acetylpyridine have been prepared and characterized by microanalyses, magnetic susceptibility and molar conductivity measurements and by their electronic, i.r. and n.m.r. (in the case of Ni^II complexes) spectra.     

Dinucleoside (5′ → 3′)-O,S-Phosphorodithioates - New Class of Dinucleotide Analogues

Abstract

Nucleoside 3′-0- and 5′-O-phosphorodithioates have been recently described by Caruthers et al.¹ as a new type of nucleotide analogues. These compounds have also been obtained in our Laboratory by one-pot dithiaphospholane approach.² We now report on the transformation of some of these derivatives into new class of dinucleotide analogues. We have found that nucleoside 3′-O-phosphorodithioates (1) react in DMF solution with 5′-bromo-5′-deoxythymidine to give in high yield corresponding dinucleoside (5′→3′)-O,S-phosphorodithioates (2) - first examples of a new class of dinucleotide analogues possessing the internucleotide phosphorothioate linkage with one of the sulfur atoms in a 3′-bridging position.     

A_a-B_b(B′)_b型缩聚反应在热固化反应过程中的溶、凝胶分配

Flory、Gordon和唐敖庆从相同的基本假定出发,用不同的几率方法提出了凝胶化理论,统称为经典的凝胶化理论,对A_a-B_b(B′)_b体系,汤心颐等曾研究过其凝胶化范围,但只得到了临界反应程度,我们用经典的统计方法,以甘油和丁二酸酐为模型化合物,研究了溶胶分数与反应程度的关系,并导出了酸/醇摩尔比r_b与r_b′的关系式。     

Bis(N-benzyl-N-furfuryldithiocarbamato-S,S′)mercury(II) as a precursor for the preparation of mercury sulfide nanoparticles

Bis(N-benzyl-N-furfuryldithiocarbamato-S,S′)mercury(II), [Hg(bzfdtc)₂] (1) and bis(N,N-difurfuryldithiocarbamato-S,S′)mercury(II), [Hg(dfdtc)₂] (2) were synthesized and characterized by IR, NMR and single-crystal X-ray crystallography. Single-crystal X-ray structures of 1 and 2 indicate that both complexes are dimeric, with each mercury in a distorted [HgS₅] square pyramidal geometry. The thioureide (N¹³CS₂) carbon signals were observed at 206.8 and 206.7 ppm for 1 and 2, respectively, with very weak intensity, characteristic of the quaternary carbon signal. Complex 1 has been used as a precursor for the preparation of HgS nanoparticles. The as-prepared HgS nanoparticles have been characterized by powder XRD, FESEM, EDAX, UV–visible and IR spectroscopies. FESEM images of HgS nanoparticles show that the particles are spherical in shape. The blue shift in the absorption maxima in the UV–visible spectra of HgS1 and HgS2 is a consequence of the quantum confinement effect.     

Humidity-sensing and DNA-binding ability of bis(4-benzylpiperazine-1-carbodithioato-k2 S,S′)nickel(II)

Bis(4-benzylpiperazine-1-carbodithioato-k² S,S?)nickel(II), 1, was prepared by metathesis of sodium salt of 4-benzylpiperazine-1-carbodithioate with nickel(II) chloride in 2?:?1 ratio. Complex 1 was characterized by analytical techniques including elemental analysis, FT-IR, UV–visible spectroscopy, and X-ray single-crystal analysis. The latter technique confirmed square-planar geometry around Ni with the formation of NiS₄ core with two shorter and two longer Ni–S bonds. The packing diagram revealed a supramolecular chain structure mediated by unconventional H?H dihydrogen bonds that resulted in a chair and a ladder-like structure when viewed along the a-axis and c-axis, respectively. The thin-film coating resulted in a microporous film with a band gap of 1.69 eV. Complex 1-based sensor was fabricated to check the humidity-sensing properties of the material. Resistance of the device decreased by two orders of magnitude and capacitance was enhanced with the increase of relative humidity. The DNA binding study proved 1 to be a good DNA binder with binding constant value of 1.4 × 10⁴ M^?1.     

(RC_2R′)Co_2(CO)_6及其与Lewis碱反应的电化学研究

合成了两种新的簇合物(C_6H_5C≡CC_6H_4-Br-p)Co_2(CO)_(6-x)(PPh_3)_x(n=1,2),并用循环伏安法研究了一系列(RC≡CR’)Co_2(CO)_(6-x)L_x (n=0,1,2;L=PPh_3)和(RC≡CR’)Co_2(CO)_6与PPh_3在丙酮中的电化学行为.对于(RC≡CR’)Co_2(CO)_(6-x)L_x,其主要电极过程为(RC≡CR’)Co_2(CO)_(6-x)L_x+e(RC≡CR’)Co_2(CO)_(6-x)L_x~-此过程的还原电势E_p~(red)的大小与RC≡CR’及L有关.当C_2Co_2骨架上的电荷密度增大时,簇合物难被还原,却易被氧化.说明簇合物的前线分子轨道的能级既与钴有关,也与配体有关.簇合物得到一个电子形成的自由基是电子迁移催化反应的催化剂.     

STRUCTURE AND CATALYTIC PROPERTIES OF PALLADIUM(II) (ACETYLACETONATO- κ2O,O′)BIS(TRIS(DIETHYLAMINO)PHOSPHINE) TETRAFLUOROBORATE

Journal of Structural Chemistry - The structure of complex [Pd(acac){P(NEt2)3}2]BF4 (I) is determined by XRD. In the crystal structure of I, the coordination sphere of palladium is characterized by...