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1.
Zusammenfassung Die Komplexbildung des p-Methylbenzamidoxims (pMB) mit Ni2+ wurde in neutraler und alkalischer Lösung spektrophotometrisch untersucht. In neutraler Lösung wird ein grüner Komplex 11 gebildet, dessen Bildungskonstante 1=1,12 ist. In alkalischer Lösung werden zwei Komplexe (11 und 12) gebildet mit Bildungskonstanten 1=4·105 und 2=0,2.
Nickel complexes with p-methyl benzamide oxime
The complex formation of p-methyl benzamidoxime with Ni2+ was studied spectrophotometrically in neutral and in alkaline solution. A green complex 11 is formed in neutral solution. Its formation constant is 1=1.12. In alkaline solution two complexes (11 and 12) are formed. Their formation constants are 1=4·105 and 2=0,2 resp.


Mit 6 Abbildungen  相似文献   

2.
Summary CoII chloro complexes were studied in MeOH at 25 °C and at constant ionic strength of 1 mol dm–3. Formation of three complexes is postulated for which the overall stability constants are calculated: log 1 = 1.2, log 2 = 1.7 and log 3 = 1.4. The electronic spectra and the formation curves of the identified species are presented for the first time in this medium. The results are compared with those obtained in other alcohols and increasing stability with increasing molecular weight of the solvents is established. Further comparative study showed that the maximum stability of the chloro complexes is found with the CuII ion as the central atom. This confirms the Irving-Williams order of stabilities for the first transition metal complexes in this alcoholic medium and the result is explained in terms of the second ionization potential of the elements.  相似文献   

3.
The disposition of cholesterol inside the -cyclodextrin cavity(-CD) was deduced from oxidation of cholesterol secondary alcoholgroups by Ca(OCl)2 and H2O2 in thepyridine–acetic acid system. The amount of cholest-4-ene-3-one formedwas found to be proportional to the concentration of -cyclodextrin,resulting in 56.1% of ketone. The oxidation rate was enhanced by-cyclodextrin and its methyl, polymer and 1 : 1copper(II)–-cyclodextrin derivatives. Detailed investigationsinvolving UV-visible, 13C- and 1H-NMR(T1, 1D NOE and ROESY) spectroscopic studies were carried out.A binding constant value of 15,385 ± 1500 M-2 wasobtained for the 2 : 1heptakis-2,6-di-O-methyl--cyclodextrin(DM-CD) : cholesterolcomplex in chloroform from UV studies. Proton and solid state13C-CP MAS spectra of the -CD–cholesterol mixtureshowed large magnitude shifts for the protons from the wider end of the-CD cavity as well as those of ring A and ring B of cholesterol. Both1D NOE and ROESY measurements indicated the proximity between ring A andring B protons of cholesterol and the wider end protons of -CD andDM-CD. Besides, analysis of c,i and tau;m from T1measurements showed not only a lowering of rotational motions but a value of 0.016–0.048 for some of the cholesterol protons, typical of aweak complex. Based on these studies, a probable structure for the 2 : 1complex involving two molecules of -CD/DM-CD was proposed withportions of ring A and ring B being present inside the wider end of the-CD/DM-CD cavity and ring D and the side chain attached atposition 17, projecting into the wider end of the secondCD/DM-CD molecule.  相似文献   

4.
In order to explain some discrepancies between the theoretical predictions and the experimental data for the thermodynamic properties of substitutional B 2 phases,Chang's theoretical model is extended by including the influence of second-nearest neighbor interactions. For this purpose a new parameter is introduced which is defined as the ratio of the interchange energies between second-nearest and first-nearest neighbors. Theoretical equations are derived for the compositional dependence of the activity and the partial molar enthalpy. Using literature data, the following phases are re-evaluated in terms of the disorder parameter and the newly introduced parameter : -AuZn, -AuCd, -AgMg, and -NiZn. Very good agreement is found between the theoretical curves and the experimental data for the four systems. The values of obtained range from 0.0 for -NiZn to 0.5 for -AuZn. The inclusion of second-nearest neighbor interactions has little influence on the values of . It is shown that the behavior of the activity curve in -AuZn can be explained in a physically more meaningful way by including interactions between all second-nearest neighbors rather than interactions between gold substitutional defects only, as was done byLibowitz.With 5 Figures  相似文献   

5.
Summary The stability constants n of nitrato complexes of Pr, Nd, Sm, Ho, and Er were determined by UV/Vis spectroscopy. It was found that 1=0.87, 1.24, 1.94, 0.24, 0.11 forM (NO3)2+ (M=Pr, Nd, Sm, Ho, Er) and 2=0.06, 0.04 forM (NO3) 2 + (M=Pr, Nd) at 25 °C. Detailed inspection of the lanthanide spectra shows that increasing nitrate concentration in the solution results in a bathochromic shift of the f-f bands for Nd and Sm which provides evidence for the formation of inner sphere nitrato complexes.
Spektroskopische Untersuchung von Lanthanidennitraten
Zusammenfassung Die Stabilitätskonstanten n der Nitratokomplexe von Pr, Nd, Sm, Ho und Er wurden UV/Vis-spektroskopisch bestimmt. Es ergaben sich Werte von 0.87, 1.24, 1.94, 0.24 und 0.11 für 1 (M(NO3)2+,M=Pr, Nd, Sm, Ho, Er) und 0.06 und 0.04 für 2 (M(NO3) 2 + ,M=Pr, Nd). Eine detaillierte Analyse der Lanthanidenspektren zeigt, daß steigende Nitratkonzentration in Lösung eine bathochrome Verschiebung der f-f-Banden von Nd und Sm bewirkt. Das weist auf die Bildung voninner sphere — Nitratokomplexen hin.
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6.
The synergistic enhancement of the fluorescence intensity of 4,5-benzopiaselenol (I F Se-DAN ) by surfactants (Sf) and -cyclodextrin (-CD) has been studied. The (I F Se-DAN ) in sodium dodecyl sulfate (SDS)//gb-CD was approximately 30 times greater than that in water, and 5–6 times greater than that in either SDS or -CD solutions alone, and a blue-shift of the emission wavelength was observed.1H-NMR experiments and determination of CMC values of Se-DAN/-CD, Se-DAN/SDS, and Se-DAN/SDS/-CD systems reveal that the synergistic fluorescence enhancement was produced by the SDS monomer/-CD inclusion complex. In essence, the synergistic enhancement is due to the altered microenvironment experienced by Se-DAN upon its transfer from water to the hydrophobic cavity upon complexation.  相似文献   

7.
Conformational analysis of inclusion complexes of sodium 3-hydroxy-2-naphthalenecarboxylate with -cyclodextrin and heptakis-(2,3,6-tri-o-methyl)--cyclodextrin in D2O was investigated by 1D and 2D 1HNMR measurements. The results show that part of the naphthyl group of sodium 3-hydroxy-2-naphthalenecarboxylate is situated in the 2,3-OH side of the -cyclodextrin cavity asymmetrically while the whole naphthyl group is included in the heptakis-(2,3,6-tri-o-methyl)--cyclodextrin cavity with the caboxylate and hydroxy group close to the 6-OCH3 group.  相似文献   

8.
1-Alkyl-2-(naphthyl--azo)imidazoles [-NaiR; R = Me (a), Et (b), CH2Ph (c)] react with Pd(MeCN)2Cl2 to yield Pd(-NaiR)Cl2 (2), the i.r. spectra of which support the presence of a cis-PdCl2 configuration. The complexes react with catechols in the presence of Et3N to yield ternary complexes [Pd(-NaiR)(O,O)] [O,O = pyrocatecholato (cat) (3), 4-t-butylcatecholato (tbcat) (4), 3,5-di-t-butylcatecholato (dtbcat) (5), and tetrachlorocatecholato (tccat) (6)], which were characterized by elemental analysis, i.r. and 1H-n.m.r. spectral data. Redox studies by cyclic voltammetry suggest the existence of four successive redox couples wherein two responses, positive to s.c.e. are due to catechol to semiquinone and semiquinone to quinone oxidation, respectively; the couples at negative to s.c.e. are referred to azo reductions. The complexes exhibit ligand-ligand charge-transfer transitions in the near-i.r. region. The band position is largely dependent upon the substitutent on the catechol frame and exhibits negative solvatochromic effects. The transition is qualitatively assigned as the HOMO (cat) LUMO (-NaiR) transition. This fact is also supported by theoretical calculations using the PM3 method.  相似文献   

9.
The compounds, 6-per-O-(t-butyldimethylsilyl)--cyclodextrin(1), 2,3-per-O-benzyl-6-per-O-(t-butyldimethylsilyl)--cyclodextrin(2), 2,3-per-O-benzyl--cyclodextrin (3),2,3,6-per-O-benzyl--cyclodextrin (4),2,3,6-per-O-benzoyl--cyclodextrin (5), are used as keyintermediates in the synthesis of selectively substituted -CD derivatives. Simple and assignable 1H and 13C NMR spectra (chemical shifts and coupling constants) were obtained for compounds1–4 indicating C7 symmetry, 4C1 glucose conformation and major arrangement of H6, H6' atoms at the primary side. The derivative 5, however, gave very broad peaksat room temperature. The peaks could partially be assigned at 270 K, but the broadening was still present at 220 K. This implies that there exist several conformers of similar energyand C1 symmetry that continuously interchange, since there is not a single type of stabilizing interaction thatpredominates. We attributed this phenomenon to the presence of the carbonyl group, which probablydisfavors - stacking and induces random arrangements of the aromatic rings.  相似文献   

10.
The effects of -cyclodextrin (-CyD), heptakis(2,6-di-O-methyl)--cyclodextrin (DMCyD) and heptakis(2,3,6-tri-O-methyl)--cyclodextrin (TMCyD) ontrans-cis photoisomerization of 1-ethyl-4-(4-hydroxystyryl)pyridinium (POH) have been studied in aqueous solutions. The ratio of [cis]/[trans] for POH in the photostationary state at pH 8.54 was remarkably reduced by the presence of CyD or DMCyD. The reduction of the [cis]/[trans] ratio in the photostationary state was explained in terms of the shift of the equilibrium of POH + trans PO trans + H toward PO trans formation. The binding constants of CyD and DMCyD for PO trans were 2.00- and 1.36-fold larger than those for POH + trans , respectively. The binding constants of TMCyD for both species are much smaller than those of CyD and DMCyD. This result indicates that PO trans , which has a betain structure, forms stable complexes with CyD and DMCyD with its hydrophobic parts inside and the charged parts outside the CyD cavities.  相似文献   

11.
Summary The reactions of -diketones and -ketoaldehydes with hydrazine-S-methyl carbodithioate, hydth, have been studied in the absence and presence of metal(II) ions. A series of dimeric monoligand chelates [Ni(-dikhydth-2H)]2 have been isolated. The reaction of these chelates with monodentate Lewis bases yields square planar [Ni(-dikhydth2H)B] chelates. Bisligand chelates of benzoylacetone monohydrazones [M(Bzachydth-H)2] (M=Cu or Zn) have been also synthesized, as have a series of NiII and ZnII chelates of -diketone bishydrazones of the type [M(-dik(hydth)2-2H)].  相似文献   

12.
A new dinuclear ligand L, ethylene[OO-bis-salicylidene--diketone] bearing two symmetrical coordination sites was synthesized by the condensation of salicylaldehyde and acetylacetone, L, with 1,2-dibromoethane under reflux. The ligand L in a 1:1 ratio was treated with CuCl2 and NiCl2 to yield the complexes, tetrachloro bis[OO-bis- salicylidene--diketone copper(II)] and bis[OO-bis-salicylidene--diketone nickel(II)] chloride. The complexes were subsequently characterized by spectroscopic techniques, elemental analysis, i.r., 1H-n.m.r., 13C-n.m.r., u.v.–vis., e.p.r. spectroscopy, and conductance measurements. The conductance measurements in DMF reveal that the CuII complex is covalent while the NiII complex is ionic and the spectral data support the CuII complex to be distorted octahedral whereas the NiII complex has square-planar geometry. The dioxygen binding was studied spectrophotometrically by the oxidation of tetrachloro bis[OO-bis-salicylidene--diketone copper(II)] with pyrocatechol in the presence of oxygen. The kinetic experiments were performed with the copper complex in DMF by monitoring the increase in absorbance over time at pH 8.0 in the presence of pyrocatechol at 25 °C. The kinetic parameters Vmax and KM were determined on the Michaelis–Menten Approach. Redox behavior of the dinuclear copper(II) complex was investigated by cyclic voltammetry in the presence of O2 with the pyrocatechol (substrate) and also without the substrate. The large difference in potentials E0 is indicative of reversible oxygen binding of the complex and distinct catalytic activity.  相似文献   

13.
The complexation behavior of zinc (II) tetraphenylporphyrin-viologen covalently linkedcompounds by a polymethylene chain (ZnPCnV2+; n = 4–9) withtri-O-methyl--cyclodextrin (TM--CD) was investigated by meansof 1H NMR and UV/Vis absorption spectrometry in acetonitrile-water (1:1, v/v).The 1H NMR spectra indicated that ZnPCnV2+ existed as a mixture ofa dimer and a monomer at high concentration (>1 × 10-3 M). The dimerwas degraded to the monomer upon complexation with TM--CD involving theformation of 1:1 and 1:2 (ZnPCnV2+: TM--CD) complexes, whichwas observed by UV/Vis spectrometry. Furthermore, 1H NMR spectra exhibitedthat there are at least two types of structures for these complexes, one is a fastexchanging complex, and another is a slow exchanging one. A slow exchanging complexcould be assigned as a rotaxane type structure in which the methylene chain moiety ofZnPCnV2+ penetrated into the cavity of TM--CD. Discrete formationconstants for these complexes were evaluated. The values were little affected by the spacermethylene chain length (n 7).  相似文献   

14.
The approach tested in this work consists in adapting the Pitzer model, initially designed for aqueous solutions of electrolytes, to the case of solutions with a mixed solvent, without systematically readjusting the coefficients. This modified model was applied successfully to the calculation of the mean activity coefficients of NaBr in the mixed solvent H2O+MeOH, H2O+EtOH and compared with the experimental values obtained from electrode potential measurements.General D dielectric constant - G ex excess Gibbs energy - I ionic strength - k Boltzman's constant - m i molality - N o Avogadro's number - n w number of kilograms of water - R gas constant - T temperature (K) - T c critical temperature - T cm critical temperature of mixed solvent - x i molar fraction - z i ionic charge - electronic charge - osmotic coefficient - ± mean activity coefficient of electrolyte - number of moles of ions given by one mole of electrolyte - M number of moles of cations given by one mole of electrolyte - X number of moles of anions given by one mole of electrolyte - W density of water Debye- Hückel Model A Debye-Hückel parameter - a distance of closest approach of ions in solution - B Debye-Hückel parameter Pitzer Model b numerical parameter of model - numerical parameter of model - 1, 2 numerical parameters of model, used in the case of 2:2 electrolyte - MX (0) numerical parameter of electrolyte MX - MX (1) numerical parameter of electrolyte MX - MX (2) numerical parameter of 2:2 electrolyte MX - C MX numerical parameter of electrolyte MX - binary interaction parameter - ternary interaction parameter  相似文献   

15.
From the stems of Crimean ivyHedera taurica Carr. (fam. Araliaceae) we have isolated previously known glycosides of oleanolic acid — the 3-O-[O--L-rhamnopyranosyl-(12)--L-arabinopyranoside], the 3-O--D-glucopyranuronoside, and the 3-O-[O--D-galactopyranosyl-(12)--D-glucopyranuronoside]; known glycosides of hederagenin — the 3-O--L-arabinopyranoside, the 3--D-glucopyranoside, the 3-O-[O--D-glucopyranosyl-(12)-O--L-arabinopyranoside], and the 3-O--D-glucopyranuronoside; and also the new triterpene glycoside St-D2, hederagenin 3-O-[O--L-rhamnopyranosyl-(12)--D-glucopyranoside].Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 411–416, May–June, 1997.  相似文献   

16.
Regression analysis was used to derive equations for estimaing thermodynamic stability constants for complexes of Cr2+ (log° 1[Cr2+L] = 0.53log° n [H n L]) and Cr3+ (log° 1[Cr3+L] = 0.88log° n [H n L]) from the known protonation constants of H n L ligands and for determining stability constants of Cr2+ and Cr3+ complexes from the available stability constants of Cu2+ complexes (log° 1[Cr2+L] = 0.76log° 1[Cu2+L] and log° 1[Cr2+L] = 0.60log° 1[Cr3+L], respectively). Parameters of the Panteleon–Ecka equation for calculating stability constants of Cr2+ complexes ( = 0.57) and Cr3+ complexes ( = 0.69) with two and three bidentate ligands were also determined. The ratio of logarithmic stability constants for complexes with the same metals but with different metal ionic charges was found to be approximately equal to the ratio of charges on the central ions. The stability constant of Cr(II) sulfate complex was calculated.  相似文献   

17.
Lipophilic bis--diketones have been prepared by covalently linking two-diketone subunits. Potentiometric studies on liquid membrane electrode cell assemblies showed no improvement of the ion selectivities induced by the bridged systems in comparison to unbridged-diketones. The dissociation constants of the enol functions in the bis--diketones indicate that under the conditions of the EMF measurement probably only one-diketone unit is deprotonated in the liquid membrane phase. The complexation of these-diketones with Mg2+ and Ca2+ was studied by13C NMR-monitored titrations in a homogeneous organic phase.On leave from the Chemistry Department, University of Warsaw, Warsaw, Poland  相似文献   

18.
Evidence of the interaction among the [PbAc]+ and[PbEDTA]-2 with the -cyclodextrin (-CD)is shown, using a 24 factorial design. The factors used werethe [Pb(II)], [-CD], [Ac-] and [EDTA] concentrationsat pH = 6.2. The statistical results indicate that the changes inchemical response for these species are associated to theinteraction among these factors. Spectrophotometric andelectrochemical studies were undertaken to assess the interactions.The equilibrium constants for inclusion complexes were determinedFor -CD-[PbAc]+ and -CD-[PbEDTA]-2.  相似文献   

19.
N-Chloroacetyl--glycopyranosylimines were synthesized from various monosaccharide (hexoses, pentoses, deoxysugars, uronic acids, and sugar phosphates) and a disaccharide (lactose) byN-acylation of the corresponding -glycosylamines with chloroacetic anhydride in DMF In some cases, treatment of rnonosacc harides with NH3 in the presence of (NH4)2CO3 in MeOH or aqueous MeOH was more efficient than the methods previously described, as it gave -glycosylarnines in higher yields.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1848–1851, July, 1996.  相似文献   

20.
Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/2, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of99Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/3, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.  相似文献   

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