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排序方式: 共有82条查询结果,搜索用时 945 毫秒
51.
A sensitive potentiometric surfactant sensor based on a highly lipophilic 1,3-didecyl-2-methyl-imidazolium cation and a tetraphenylborate (TPB) antagonist ion was used as the end-point detector in ion-pair potentiometric surfactant titrations using sodium TPB as a titrant. Several analytical and technical grade cationic and ethoxylated nonionic surfactants (EONS) and mixtures of both were potentiometrically titrated.The sensor showed satisfactory analytical performances within a pH range of 3-10 and exhibited satisfactory selectivity for all CS and EONS investigated. Ionic strength did not influence the titration except at 0.1 M NaCl, in which a slight distortion of the second inflexion corresponded with the nonionic surfactant.Two-component combinations of four CS and three EONS were potentiometrically titrated using the sensor previously mentioned as the end-point detector. The quantities of the surfactants varied between 2 and 6 μmol for CS and 2.50 and 7.50 μmol for EONS. The known addition methodology was used for determination of the surfactant with considerably lower concentration in the mixture.Three commercial products containing cationic surfactants as disinfectants and nonionic surfactants were potentiometrically titrated, and the results for both type of surfactants were compared with those obtained with standard conventional methods. 相似文献
52.
Dubravka Matkovi‐alogovi Zora Popovi Gordana Pavlovi
eljka Soldin Gerald Giester 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):409-411
The reaction of 3,4,5,6‐tetrahydropyrimidine‐2‐thione (H4pymtH) with mercury(II) iodide in methanol in a 1:1 molar ratio resulted in the formation of single crystals of the title compound, [Hg(C4H8N2S)I2]. The Hg atom is coordinated by one S atom from H4pymtH at 2.456 (2) Å and by two I atoms at distances of 2.6872 (7) and 2.7044 (6) Å, and has a characteristic deformed trigonal coordination geometry. The molecule has crystallographic m symmetry but the Hg atom is disordered above and below the mirror plane. 相似文献
53.
Dubravka Matkovi‐alogovi Draginja Mrvo‐Sermek Zora Popovi
eljka Soldin 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):m44-m46
The title compound, [Hg(C4H4N2S)(C4H3N2S)]2[HgBr4], consists of [Hg(pymt)(pymtH)]+ complex cations (pymtH is pyrimidine‐2‐thione) lying across twofold rotation axes in space group Fddd, with linearly coordinated mercury at an Hg—S distance of 2.357 (3) Å, and [HgBr4]2− anions lying at sites of 222 symmetry. The Hg atom is additionally coordinated by two N and two Br atoms, forming a 2+4 effective coordination sphere. The protonated ligand is connected via N—H⋯N hydrogen bonds to the neighbouring unprotonated ligand, thus forming infinite chains of cations. 相似文献
54.
Dalibor Mili? Vi?nja Vrdoljak Dubravka Matkovi?-?alogovi? Marina Cindri? 《Journal of chemical crystallography》2009,39(8):553-557
Abstract Red crystals of cis-dioxo(3-methoxysalicylaldehyde 4-methylthiosemicarbazonato-N,O,S)(γ-picoline-N)molybdenum(VI), [MoO2L(γ-pic)], [L2−=CH3OC6H4(O)CH=NN=C(S)NHCH3, 3-methoxysalicylaldehyde 4-methylthiosemicarbazonato] were prepared by the reaction of [MoO2L]
n
with γ-picoline in dry methanol. The title compound crystallized in the monoclinic space group P21/n, a = 6.7984(7) ?, b = 15.9760(12) ?, c = 17.1466(14) ?, β = 93.613(8)°, V = 1858.6(3) ?3, Z = 4. The coordination geometry around the molybdenum center is distorted octahedral with the tridentate thiosemicarbazonato
ligand (L2−) bonded meridionally to the [MoO2]2+ core. The sixth coordination site is occupied by a weakly bound γ-picoline molecule. The adjacent molecules are joined by
the N–H···O hydrogen bonds between their amino and methoxy groups thus forming infinite molecular chains. The three-dimensional
solid-state structure is achieved by the additional C–H···O, C–H···π and van der Waals interactions.
Graphical Abstract In the title compound, [MoO2L(γ-pic)], the tridentate thiosemicarbazonato ligand (L2−) is meridionally bound to the [MoO2]2+ core, while a molecule of γ-picoline completes the distorted octahedral coordination around the metal atom.
相似文献
55.
eljka Soldin Boris-Marko Kukovec Dubravka Matkovi-alogovi Zora Popovi 《Molecules (Basel, Switzerland)》2021,26(16)
Three new mercury(II) coordination compounds, {[HgCl(pic)]}n (1), [HgCl(pic)(picH)] (2), and [HgBr(pic)(picH)] (3) (picH = pyridine-2-carboxylic acid, picolinic acid) were prepared by reactions of the corresponding mercury(II) halides and picolinic acid in an aqueous (1) or alcohol–methanol or ethanol (2 and 3) solutions. Two different types of coordination compounds were obtained depending on the solvent used. The crystal structures were determined by the single-crystal X-ray structural analysis. Compound 1 is a one-dimensional (1-D) coordination polymer with mercury(II) ions bridged by chelating and bridging N,O,O′-picolinate ions. Each mercury(II) ion is four-coordinated with a bidentate picolinate ion, a carboxylate O atom from the symmetry-related picolinate ion and with a chloride ion; the resulting coordination environment can be described as a highly distorted tetrahedron. Compounds 2 and 3 are isostructural mononuclear coordination compounds, each mercury(II) ion being coordinated with the respective halide ion, N,O-bidentate picolinate ion, and N,O-bidentate picolinic acid in a highly distorted square-pyramidal coordination environment. Compounds 1–3 were characterized by IR spectroscopy, PXRD, and thermal methods (TGA/DSC) in the solid state and by 1H and 13C NMR spectroscopy in the DMSO solution. 相似文献
56.
ESI‐MS studies of the non‐covalent interactions between biologically important metal ions and N‐sulfonylcytosine derivatives 下载免费PDF全文
Valentina Ključarić Renata Kobetić Jasmina Rinkovec Snježana Kazazić Dubravka Gembarovski Dijana Saftić Josipa Matić Željka Ban Biserka Žinić 《Journal of mass spectrometry : JMS》2016,51(11):998-1005
The aim of this report is to present the electrospray ionization mass spectrometry results of the non‐covalent interaction of two biologically active ligands, N‐1 ‐ (p‐toluenesulfonyl)cytosine, 1‐TsC, 1 and N‐1 ‐ methanesulfonylcytosine, 1‐MsC, 2 and their Cu(II) complexes Cu(1‐TsC‐N3)2Cl2, 3 and Cu(1‐MsC‐N3)2Cl2 and 4 with biologically important cations: Na+, K+, Ca2+, Mg2+ and Zn2+. The formation of various complex metal ions was observed. The alkali metals Na+ and K+ formed clusters because of electrostatic interactions. Ca2+ and Mg2+ salts produced the tris ligand and mixed ligand complexes. The interaction of Zn2+ with 1–4 produced monometal and dimetal Zn2+ complexes as a result of the affinity of Zn2+ ions toward both O and N atoms. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
57.
Zora Popović Željka Soldin Gordana Pavlović Dubravka Matković-Čalogović Draginja Mrvoš-Sermek Maša Rajić 《Structural chemistry》2002,13(5-6):425-436
Mercury(II) halides, HgX2 (X = Cl–, Br–, I–) react with 1,3-benzothiazole-2-thione (btztH) in methanol solutions giving the HgX2(btztH) and HgX2(btztH)2 types of compounds. Mercury(II) acetate gives the thiolato compound Hg(btzt)2 because of the deprotonation of btztH. Hg(btzt)2 reacts with 2,2-bipyridine (bipy) giving a 1:1 complex. IR, 1H, and 13C NMR spectral studies indicate that btztH acts as a monodenatate ligand through the S thione donor atom in all complexes. The X-ray crystal structure determinations of [HgI2(btztH)]2, HgBr2(btztH)2, Hg(btzt)2, and Hg(btzt)2(bipy) have been carried out revealing tetrahedrally coordinated mercury atom in [HgI2(btztH)]2 and HgBr2(btztH)2, while in Hg(btzt)2(bipy) 2 + 2 coordination is achieved through strong Hg (N(bipy) contacts. A linear coordination in Hg(btzt)2 is not affected by the Hg N contacts, which are longer than in Hg(btzt)2(bipy), but still shorter than the van der Waals sum of mercury and nitrogen covalent radii. [HgI2(btztH)]2 exists as centrosymmetrical dimer with a Hg2I2 bridging core. The dimeric molecules are linked by the intermolecular hydrogen bonds between the terminal iodine atom and the NH group [3.63(1) Å] into infinite chains along the z-axis. There are N–H Br(bridging) intermolecular hydrogen bonds in HgBr2(btztH)2 joining molecules into endless chains along the x-axis. The Br(bridging) atom acts as double proton acceptor and two NH groups as proton donors [NH Br(bridging) 3.278(9) and 3.338(7) Å]. The mercury to sulfur and mercury to halogen bond distances in [HgI2(btztH)]2 and HgBr2(btztH)2 are discussed in relation to the analogous compounds, revealing strong influence of hydrogen bonds on their relative strengths as well as crystal packing requirements of the ligand. The sulfur and halogen atoms are more tightly bound to mercury implicating severe distortion of the coordination polyhedron in the structures in which they do not take part in hydrogen bonds formation. The influence of steric requirements of the ligands in Hg(btzt)2 and Hg(btzt)2(bipy) on the distortion of the mercury coordination polyhedra accompanied with the relative strength of Hg N contacts is considered. 相似文献
58.
Krilov D Gomzi V Herak JN 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(5):1238-1242
Two different copper complexes with cytosine molecules are formed in the process of crystal growth from the aqueous solution with traces of copper. One of them is diamagnetic, turning into paramagnetic upon ionizing irradiation (complex I). The other, the subject of the present study, is paramagnetic (complex II) as prepared. For complex II, EPR spectra demonstrate that the copper ion is coordinated with one nitrogen atom and three oxygen atoms. On the basis of the detailed EPR spectroscopic analysis and quantum-chemical calculations (in the DFT approach) the model of the complex has been proposed. Both experimental data and the theoretical results support the model with the copper atom, located between the two cytosine ribbons, ligated to a nitrogen and an oxygen atom from two opposing cytosine molecules and two oxygen atoms from water molecules. For complex II the Raman spectra demonstrated concerted restructuring of the hydrogen bonding in the cytosine crystal matrix upon insertion of copper ions. 相似文献
59.
We give the Langlands classification for a non-connected reductive quasisplitp-adic groupG, under the assumption thatG/G
0 is abelian (here,G
0 denotes the connected component of the identity ofG). The Langlands classification for non-connected groups is an extension of the Langlands classification from the connected
case. 相似文献
60.
Gordana Pavlovi Zora Popovi
eljka Soldin Dubravka Matkovi‐alogovi 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):61-63
The Hg atom in the title monomeric complex, dichlorobis(3‐imidazolium‐2‐thiolato‐S)mercury(II), [HgCl2(C3H4N2S)2], is four‐coordinate having an irregular tetrahedral geometry composed of two Cl atoms [Hg—Cl 2.622 (2) and 2.663 (2) Å] and two thione S atoms [Hg—S 2.445 (2) and 2.462 (2) Å]. The monodentate thione ligand adopts a zwitterionic form and exists as the 3‐imidazolium‐2‐thiolate ion. The bond angle S1—Hg—S2 of 130.87 (8)° has the greatest deviation from ideal tetrahedral geometry. Intermolecular hydrogen bonds between two of the four N—H groups and one of the Cl atoms [3.232 (8) and 3.238 (7) Å] stabilize the crystal structure, while the other two N—H groups contribute through the formation of N—H?Cl intramolecular hydrogen bonds with the other Cl atom [3.121 (7) and 3.188 (7) Å]. 相似文献