共查询到20条相似文献,搜索用时 0 毫秒
1.
《Journal of Coordination Chemistry》2012,65(3):307-309
Abstract The complexation equilibria between Ni(II) and 4-(5′-methyl-3′-isoxazolylazo)resorcinol have been spec-trophotometrically studied in a 20% (v/v) ethanol-water medium at 0.1M NaCIO4 ionic strength and species NiHR (log β111 = 14.83 ± 0.05), NiR (log β101 = 9.32 ± 0.04) and NiR2 (log β102 = 17.84 ± 0.05) are established. 相似文献
2.
Hossein Dehghani Fatemeh Behnoudnia Mohammad Reza Mansournia Sara Bakhshayesh 《Journal of solution chemistry》2009,38(6):771-778
A spectrophotometric method was used for the molecular complexation of ICl3 with para-substituted meso-tetraarylporphyrins (H2t(4-X)pp; X: OCH3, CH(CH3)2, CH3, H and Cl) in methanol/chloroform (2.5% v/v) solution. The equilibrium constants and the thermodynamic parameters were measured
spectrophotometrically at various temperatures for 1:1 molecular complex formation of meso-tetraarylporphyrins as electron
donors with ICl3 as the electron acceptor. The formation constants for the molecular complexes change according to the following trend: [ICl3(H2t(4-OCH3)pp)]>[ICl3(H2t(4-CH(CH3)2)pp)]>[ICl3(H2t(4-CH3)pp)]>[ICl3(H2tpp)]>([ICl3(H2t(4-Cl)pp)]. Further, the thermodynamic parameters, ΔG
o,ΔH
o and ΔS
o, for formation of the complexes were obtained. 相似文献
3.
The present paper describes the complex reaction of α, β,γ, δ-tetra-(2-chlorophenyl} porphyrin with platinum in the presence of the mixture surfactant, sodium dodecylbenzene sulfonate and OP, and a new highly sensitive method for spectrophotometric determination of micro amounts of platinum. Beer's Law was obeyed when the concentration of platinum was in the range of 0?.2μg/25ml. The molar absorptivity was found to be 3.1×106 L mol-1 cm-1 at 417nm. 相似文献
4.
The complexation of Eu(III), Am(III) and Cm(III) with dicarboxylate anions with O, N or S donor groups was measured in I=6.60 mol⋅kg−1 (NaClO4) at temperatures of 0–60 °C by potentiometry and solvent extraction. The complexation thermodynamics of these complexes show
that their stability is due to highly favorable complexation entropies because the complexation enthalpies are endothermic.
Luminescence studies with Eu(III) and Cm(III) were used to measure the hydration numbers of the complexes. NMR spectra of
1H and 13C were used to determine the binding modes of La(III) with the ligands. The formation of 1:1:1 ternary complexes of M(EDTA)− with the dicarboxylate ligands was studied to determine changes in coordination of the metal cation with formation of the
ternary species. The complexation of ternary complexes changes from bidentate to monodentate as the chain length between the
binding sites of the dicarboxylates increases from 1 (malonate) to 4 (adipate). DFT computations were used to confirm the
structural aspects of the interaction of these complexes. 相似文献
5.
The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct
medium influence imposed on the thermochemistry of the equilibrium. The thermochemistry of lactate protonation, when studied
directly in 1.0 mol⋅L−1 sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement
suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process—a solvent extraction method
for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts—may
be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study
the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte.
Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium,
β
101=2.60±0.01, β
102=4.66±0.02 and β
103=5.6±0.1, and for americium, β
101=2.60±0.06, β
102=4.7±0.1 and β
103=6.2±0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently,
the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background
electrolytes such as NaClO4 and NaNO3, does not significantly impact the speciation in solution. 相似文献
6.
The direct catalytic azidation of 2-hydroxy-1,2,2-triarylethanones occurs at room temperature using 2 mol % of InBr3 as Lewis acid and TMSN3 as soluble azide source. 2-Azido-1,2,2-triarylethanones have been isolated in excellent yields. The role of aryl group and stereoelectronic factors indicate that the mechanism may involve the formation of a stable carbenium ion towards azidation. 相似文献
7.
Alyeva A. B. Kolyakina E. V. Stakhi S. A. Sologubov S. S. Markin A. V. Grishin D. F. 《Doklady Chemistry》2021,501(1):225-232
Doklady Chemistry - A one-step convergent method was proposed for the synthesis of branched macromolecules in the presence of conjugated dinitrones (N,N-dimethylglyoxal dinitrone,... 相似文献
8.
9.
Yu. Yu. Zhuk N. G. Strizhakova Yu. A. Maletin 《Theoretical and Experimental Chemistry》2000,36(4):215-219
New trinuclear μ3-oxocentered chromium(III, III, III) complexes were obtained by the self-assembly of ferrocenecarboxylate ligands and the
Cr3O fragment. The complexes were investigated by fast-atom bombardment (FAB) mass spectrometry, cyclic voltammetry, and electronic
and IR spectroscopy.
V. I. Vernadskii Institute of General and Inorganic Chemistry, National Academy of Sciences of Ukraine, 32/34 Prospekt Akademika
Vernadskogo, Kiev 03142, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 4, pp. 233–237,
July–August, 2000. 相似文献
10.
《中国化学快报》1997,(7)
SupportedbyNaturalScienceFoundationforInstitutionsofHigherLearningofAnhui.mcnoGi~driwasfoundtobeastiInulantforplangIowthinl926.wthwaswidefyedinagriuled~andmedtalSCenee.InndmppeadVanCeSonthedeVlOPmenofgib~havbeenInadIl].HoweVerthereisno~onhaaPPljcatitOanalghtalcheInistIyuPtonow.The~formulaof~llinisasfollows-Becauseofthe~ketoneinnim~e,bellinpoSSeSSeSatmp.ShenNdsetal.l'edghammoniUInInO~forthe~etricedonofgib~edinSPtalustothinkthatsom~lyacidsSUchasInol~acidsofboc,PhOSPhOnJS,sili… 相似文献
11.
Cyclic linear-sweep voltammetry was used to study the complexation of Sc(III), Ga(III), In(III) and Ln(III) with eriochrome
red B (ERB). It was established that all metal ions investigated form complex compounds with azodye having a mole ratio, M(III):ERB =
1:2. The hydroxo forms of M(III) ions, which take part in interaction with ERB, were determined by the Nazarenko method. The
stability constants for the formation of these chelates are nearly the same. It was shown that the reduction of the ligand
in the complex does not only depend on the peculiarities of complexation, but the processes occurring in pre-electrode layer
also influence it. 相似文献
12.
Kazbanov V. I. Starkov A. K. Kozhukhovskaya G. A. Kazbanova T. K. Trofimov V. I. Pavlenko N. I. 《Russian Journal of Coordination Chemistry》2001,27(1):65-69
A comparison study of the bis(-oxalato)tetramminediplatinum(II) dimer [Pt2(NH3)4(-C2O4)2] and the oxalatodiammineplatinum(II) chelate [Pt(NH3)2C2O4] is performed. The kinetics and mechanism of substitution of C2O2–
4 for Cl– in aqueous chloride solutions are studied by photoelectronic spectroscopy, gravimetry, and chemical phase analysis within the 1.0–6.7 pH range at 75°C. The rate constants of substitution and the equilibrium constants for a two-step protonation for the dimeric and chelate complexes are calculated. Their solubility in 1 M KCl at 75°C; is determined. The unit cell parameters for [Pt2(NH3)4(-C2O4)2] are determined: a = 3.858 Å, b = 10.704 Å, c = 6.795 Å, = 94.35°. The IR spectra of [Pt(NH3)2C2O4], [Pt2(NH3)4(-C2O4)2], and their deuterated analogs are studied. 相似文献
13.
Guo Qiang SHANGGUAN Jun ZH U Ning WANG Jia Zuan NI Department of Chemistry Jining Medical College Jining Key Laboratory of Rare Earth Chemistry Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun Graduate School of Chinese Academy of Sciences Beijing 《中国化学快报》2005,(12)
Biomimetic hydrolysis of DNA or RNA is of increasing importance in biotechnology and medicine. The ability to cleave nucleic acids efficiently, in a non-degradative manner, and with high levels of selectivity for site or structure will be required by many applications for the manipulation of genes, the design of structural probes and the development of novel therapeutics1. There has been much interest in the development of lanthanide complexes as nucleic acid cleavage agents. It has been fou… 相似文献
14.
K. V. Veksler E. N. Volkova N. S. Vol'berg A. A. Pavlenko V. V. Povet'ev Z. V. Entina S. N. Bogdanova 《Journal of Analytical Chemistry》2003,58(12):1108-1113
Bis(4-(4-nitrophenyl)azo-2-nitrophenyl) disulfide (NADS) has been synthesized for the first time and proposed for the indirect photometric determination of carbon disulfide by dithiocarbamic acid. The reaction, which involves the breaking of the disulfide bond with the formation of colored azothio anions, is carried out in a mixture of dimethylsulfoxide and n-butanol. The high value of the apparent molar absorptivity (2 × 105) is probably due to the autocatalytic character of the reaction. Using NADS, procedures for the determination of carbon disulfide in the atmospheric air of populated areas and in the model gas mixtures designed for the calibration of gas analyzers have been developed and certified. The procedures show high sensitivity and good reproducibility. 相似文献
15.
S. B. Meshkova O. V. Shevchenko V. Yu. Kovalenko P. G. Doga V. P. Gorodnyuk 《Russian Journal of Coordination Chemistry》2018,44(3):220-225
The formation conditions and luminescence of Tb(III) complexes with synthesized copolymers of unsaturated acetylacetone derivatives with styrene and methyl methacrylate were studied. The luminescence intensity of these Tb(III) complexes was found to depend on the β-diketone substituent nature (CH3, CF3, C6H5) and structure (linear, branched) and the β-diketone to monomer ratio in the polymerizing mixture. 相似文献
16.
《Analytical letters》2012,45(13):2241-2254
Abstract The operating conditions for the spectrophotometric determination of bismuth(III) with 1-(4′-bromophenyl)-4,4,6-trimethyl-(1H,4H)-pyrimidine-2-thiol (4′bromo PTPT) as a ligand by a liquid-liquid extraction technique are presented. In acidic conditions bismuth(III) forms a yellow complex with the ligand which can be extracted in chloroform with an absorption maxima at 410 nm. The molar absorptivity is 1.5×104 l mole?1 cm?1 and Sandell's sensitivity is 14.3 ng cm?2. The difference in the absorbance between the chloroform blank and bismuth(III) sample increases linearly in the concentration range 2-14 ppm at 0.3 M hydrochloric acid. The proposed method is extremely sensitive, rapid, reproducible and has been satisfactorily applied to the determination of trace amounts of bismuth(III) in synthetic mixtures, alloys and pharmaceutical formulations and also provides binary separation of bismuth(III) from selenium, tellurium, lead, antimony, copper and gold. The overall process of extraction and determination takes about 15 to 20 min. 相似文献
17.
Tian Le LIN Bao Zhen YAN Gao Fei HU Mei WANG School of Science Beijing University of Chemical Technology Beijing 《中国化学快报》2006,(7)
Quercetin (3, 3’, 4’, 5, 7-pentahydroxyflavone) is one of the most common flavonols present in nature. The complexation of Al(III) by various flavonoids has been suggested to reduce the overload of aluminum in the diet, a metal which has been implicated… 相似文献
18.
The effect ofα-cyclodextrin (α-CD) inclusion complexation on the conformational equilibrium of cyclo- hexane wasstudied with thesemiempirical PM3 molecularorbital calculations. The calculation results indicated that the chair form of cyclohexane is 18.5 kJ·mol-1lower than that of boat one in energy, however, theα-cyclodextrin inclusion complex of boat cycl ohexane is 4.4 kJ·mol-1more stable than the complex of chair form. It demon-strated that the conformational equilibrium of cyclohexane was influenced by theα-CD inclusion complexation. Hence, caution should be given when extrapolating the conformational behaviors of the guest compounds in the supramolecular systems totheir free forms, since the interactionsbetween the host and guest significantly affect the conformation of the guest compounds. 相似文献
19.
A. V. Lekar’ L. A. Yakovishin S. N. Borisenko E. V. Vetrova N. I. Borisenko 《Journal of Analytical Chemistry》2011,66(14):1437-1440
The complexation of antibiotic levomycetin (chloroamphenicol) with triterpene glycoside α-hederin and hederasaponin C was
investigated by electrospray ionization mass spectrometry. The glycosides form complexes with levomycetin in the molar ratio
1: 1. The molecular complex of α-hederin is more stable than the one of hederasaponin C because of the presence of a free
carboxyl group in its aglycone fragment. The carboxyl group of hederasaponin C is involved into the formation of a glycosidic
bond with the trisaccharide unit and is not available for complex formation. 相似文献
20.
Alexander A. Kamnev Alexei G. Shchelochkov Petros A. Tarantilis Moschos G. Polissiou Yurii D. Perfiliev 《Monatshefte für Chemie / Chemical Monthly》2001,51(9):675-681
The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission 57Fe M?ssbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O2) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe3+ → Fe2+ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system. 相似文献