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1.
The cadmium (II) or lead (II) complex formation with two poly(acrylic acids) of high molecular weight (Mw=2.5×10 5 and 3×10 6) was investigated in dilute aqueous solution (NaNO 3 0.1 mol l −1; 25°C). Potentiometric titrations were carried out to determine the stability constants of the MA and MA 2 complex species formed. Bjerrum’s method, modified by Gregor et al. (J. Phys. Chem. 59 (1955) 34–39), for the study of polymeric acids was used. The results were compared to those previously obtained in the same conditions with copper (II) and nickel (II) . It appeared that the two polymers under study present similar binding properties and that the stability constants of the complex species formed increased in the following order, depending on the metal ion: Ni(II) β102 was found to be close to 7.0) and allowed the formation of the predominant PbA2 species in a quite large pH domain. Finally, the greater stability of PAA complexes compared to those of their monomeric analogs, glutaric and acetic acids, was confirmed. 相似文献
2.
A novel copper(II) thiocyanate complex [Cu(im) 2(NCS) 2] 1 (im=imidazole) has been prepared and characterized by spectroscopic analysis and crystallographic method. This supramolecular compound exhibits a three-dimensional solid state structure constituted by N–HS hydrogen bonds and π–π stacking interactions. The compound in DMF solutions has a very strong third-order non-linear optical (NLO) behavior with absorption coefficient and refractive index 2=1.18×10 −11 mw −1, n2=−9.00×10 −16 m 2w −1, respectively, and third-order NLO susceptibility χ (3) of 7.00×10 −10 esu. 相似文献
3.
Spectrophotometric determinations of palladium(II) and tartaric acid were respectively investigated by using the color reactions between 2(5-nitro-2-pyridylazo)-5-( N-propyl- N-3-sulfopropylamino)phenol(5-NO 2.PAPS) and palladium(II) in strong acidic media, and between 5-NO 2.PAPS, niobium(V) tartaric acid in weak acidic media. The calibration graphs were linear in the range of 0–25 μg/10 ml palladium(II), with an apparent molecular coefficient ( ) of 6.2×10 4 l mol −1 cm −1 at 612 nm, and 0–23 μg/10 ml tartaric acid with =1.08×10 6 l mol −1 cm −1 at 612 nm, respectively. The proposed methods were selective and sensitive in comparison with other chelating pyridylazo dyes–palladium(II) or metavanadic acid–tartaric acid method, and the effect of foreign ions such as copper(II) was negligible for the assay of palladium(II) with 5-NO 2.PAPS. 相似文献
4.
The thermodynamic interactions in aqueous solutions of uncharged polymers were studied. Using a gel-deswelling method, the water activities (chemical potentials) in binary and ternary (two polymers in one solvent) solutions of methylcellulose (MC), polyvinyl alcohol (PVA) and polyvinyl pirrolidone (PVP), respectively were determined at various polymer volume fractions (1.0 × 10 −2 < v2 < 1.0 × 10 −1). On the theoretical basis of the Flory–Huggins approximations, the relevant solvent–segment ( χ12 or χ13) and segment–segment pair interaction parameters ( χ23) have been calculated. The solvent activity curves (ln a1 versus polymer volume fraction) can be well described by a polynomial of third-degree in both the binary and the ternary solutions of the polymers. The solvent–segment interaction parameters exhibit a slight dependence on the polymer concentration. For each binary solution, the χ12−v2 function can be fitted by a straight line wich has a small positive slope. In the mixtures of two polymers, the values of the segment–segment (χ23) interaction parameters were close to zero or sligthly negative (χ23 0 ± 0.03), indicating that under the studied conditions, the polymers in the ternary solutions are compatible. 相似文献
5.
Fulvic acids (FAs) were extracted by alkali extraction from different soil samples in China, then purified using resins and characterized by Fourier transform infrared spectroscopy. The complexing ability of FAs was investigated by measuring the stability constants of rare earth elements (REEs) (La 3+, Ce 3+, Sm 3+, Gd 3+, Y 3+) with FAs by the ion exchange technique. The results indicated that maximum binding ability forY 3+ (4.414.44) was higher than other REEs (La 3+, Ce 3+, Sm 3+, Gd 3+) (0.721.03). There were two types of binding sites in the functional groups of fulvic acids. The complexing reaction followed two steps. The stability constants ( K1 and K2) of REEs with FAs were calculated from experimental data by division of Scatchard plots into two straight-line segments. Y 3+ (log K1=5.72±0.05, log K2=4.83±0.01) also has higher stability constants than the other four REEs (log K1=4.37±0.16, log K2=3.62±0.28). 相似文献
6.
The electrochemical and spectroelectrochemical behavior of the binuclear and trinuclear complexes generated from the association of cis- or trans-[Ru(NH3) 4(pz) 2] 3+/2+ (where pz represents pyrazine) and [RuEDTA(H 2O)] 2−/− complexes has been investigated in aqueous solution. Based on two sets of spectrophotometrically determined equilibrium constants and on the formal redox potentials, the complex network of equilibrium reactions involving mixed valence species has been elucidated. 相似文献
7.
At 25°C, I = 1.0 M (CF 3SO 3−Li ++CF 3SO 3H), [H +] = 0.034–0.274 M and λ = 453 nm, the rate equation for the oxidation of Ti(H 2O), 63+ by bromine was found to be: −d/[Br 2] T/d t= kK/[Br 2][Ti III]/[H +]+ K+ kK/[Br 3−][Ti III]/[H ++ K, where k = 9.2 × 10 −3 M −1 s −1 and K = 4.5 × 10 −3 M. At [H +] = 1.0 M, [Br −] = 0.05–0.4 M, the apparent second-order rate constant decreases as [Br −] increases. The pH-dependence of the oxidation of TiIII-edta by bromine is interpreted in terms of the change in identity of the TiIII-edta species as the pH of the reaction medium changes. The second-order rate constants were fitted using a non-linear least-square computer program with (1/k0edta)2 weighting into an equation of the form: k0edta =k1+k2K1[H+]−1+k3K1K2[H+]−2/1+K1[H+[H+−1+K1K2[H+]−2, with K1 and K2 fixed as earlier determined at 9.55 × 10−3 and 2.29 × 10−9 M, respectively, for the oxidation of bromine. k1=k2=(3.1±0.32)×103M−1s−1 k3=(2.3±0.45)×106N−1s−1. It is proposed that these electron transfer reactions proceed by univalent changes with the production of Br2.− as a transient intermediate. An outer-sphere mechanism is proposed for these reactions. The homonuclear exchange rate for TiIII-edta+TiIV-edta is estimated at 32 M−1 s−1. 相似文献
8.
合成了一种新的具有潜在应用价值的非线性光学(NLO)有机材料1-(芘-1-基)-3-(4-二甲氨基苯基)丙烯酮(PMAK),并通过 NMR、IR、MS和元素分析等技术手段进行了表征。 采用溶液Nd:YAG激光技术测定了PMAK的三阶非线性光学性质并确定了相关参数。 纳秒实验结果:折射率 n2=-3.5×10 -17 m 2/W,吸收系数 β=7.0×10 -10 m/W,极化率 χ(3)=2.54×10 -11 esu,分子超极化率 γ=3.44×10 -30 esu;皮秒实验结果: n2=-2.8×10 -18 m 2/W, β=8.3×10 -11 m/W, χ(3)=2.49×10 -12 esu, γ=3.33×10 -31 esu。 相似文献
9.
The interactions between some acrylic and sulphonic polyanions and some protonated amines (diamines NH 2-(CH 2) x-NH 2, x=2,…,10; linear tri-, tetra-, penta- and hexa-amines) were studied potentiometrically in aqueous solution, at 25°C. For both types of polyanions AL 2H i (L −, monomer of polyanion, A, amine) species are formed, with i=1,…, n ( n=number of amino groups in the amine). The stability of these species is strictly dependent on the polyammonium cation charge, and fairly independent of the type of amine (in diamine species maximum stability is observed for x=4, 5). Acrylic and sulphonic polyanion complexes are considerably stronger than analogous species formed by low molecular weight anions. Mean stability can be expressed as log K=2.87 ζ2/3, for polyacrylic anions and log K=2.42 ζ2/3 for polysulphonic anions ( ζ=absolute value for charge product of reactants). 相似文献
10.
The distribution ratio ( DM) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO 2) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of log DM versus pH plot and log DM versus HMQ concentration plot, the extracted species both in the SF-CO 2 extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ) 2. The distribution constant of HMQ ( KD,HMQ) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ ( DHMQ) on the pH. A linear relationship was observed between log KD,HMQ and the solubility parameter ( δ) of the extraction medium based on the regular solution theory in both the SFE using SF-CO 2 at the pressure of 8.5–40 MPa and the SE systems. The difference in the slope of the log KD,HMQ versus δ plot between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e. CO 2 molecules and the organic solvent molecules. The DM versus δ plot obtained under a given extraction condition using SF-CO 2 (11–40 MPa) and organic solvents showed clear linearity. The DM obtained using SF-CO 2 at relatively low pressure range from 8.5 to 11 MPa was independent of the pressure and the δ of SF-CO 2, which coincides with the experimental fact that the solubility of Pd(MQ) 2 in the SF-CO 2 at 8.5–11 MPa was practically constant. 相似文献
11.
The spectral features of the near-infrared (NIR) dye TG-170 in different solutions and its complexation with several metal ions were investigated. The absorbance maxima of the dye are at λ=819, 805, and 791 nm in dimethyl sulfoxide (DMSO), methanol, and a buffer of pH 5.9, respectively. These values match the output of a commercially available laser diode (780 nm), thus making use of such a source practical for excitation. The emission wavelengths of the dye are at λem =822, 812, and 803 nm in DMSO, methanol, and the buffer, respectively. The molar absorptivity and fluorescence quantum yield increase accordingly. The addition of either an Al(III) ion or Be(II) ion resulted in fluorescence quenching of the dye. The Stern–Volmer quenching constant, KSV, was calculated from the Stern–Volmer plot to be KSV=3.11×10 5 M −1 for the Al(III) ion and KSV=1.17×10 6 M −1 for the Be(II) ion. The molar ratio of the metal to the dye was established to be 1:1 for both metal ions. The stability constant, KS, of the metal–dye complex was calculated to be 4.37×10 4 M −1 for the Al–dye complex and 1.94×10 6 M −1 for the Be–dye complex. 相似文献
12.
One novel chiral copper(II) complex was successfully synthesized from the reaction of chiral 1,3-thiazolidine-2-thione ligand with CuCl 2 in dichloromethane in the presence of Et 3N and DMAP at room temperature. Its unique crystal structure was unambiguously disclosed by X-ray analysis. The crystal is tetragonal, space group I4(1), space group a=15.0875(11), b=15.0875(11), c=19.362(3) Å, =90, β=90, γ=90°, V=4407.4(8) Å 3, Z=8, ρcalc=1.639 mg cm −3. 相似文献
13.
An amide-linked 2,6-bis{[(2-hydroxy-5- tert-butylbenzyl)(pyridyl-2-methyl)-amino]-methyl}-4-methylphenol-ruthenium(II) tris(bipyridine) 2PF 6− complex, 1, was first used to recognize Co(II) in EtOH/H 2O (1:1, v/v) solution, with the ruthenium(II) tris(bipyridine) moiety selected as a fluorophore and the multi-substituted phenol unit chosen as a receptor. The fluorescence quenching of 1 was attributed to the formation of an inclusion complex between multi-substituted phenol unit and Co(II) by 1:1 complex ratio ( K = 2.5 × 10 5), which has been utilized as the basis of the fabrication of the Co(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Co(II)-sensitive chemosensor were investigated. The sensor can be applied to the quantification of Co(II) with a linear range covering from 1.0 × 10 −7 to 5.0 × 10 −5 M and a detection limit of 5 × 10 −8 M. The experiment results show that the response behavior of 1 to Co(II) is pH-independent in medium condition (pH 4.5–9.5) and show excellent selectivity for Co(II) over transition metal cations except Cu(II). The chemosensor has been used for determination of Co(II) in water samples. 相似文献
14.
The syntheses and structural determination of Nd III and Er III complexes with nitrilotriacetic acid (nta) were reported in this paper. Their crystal and molecular structures and compositions were determined by single-crystal X-ray structure analyses and elemental analyses, respectively. The crystal of K 3[Nd III(nta) 2(H 2O)]·6H 2O complex belongs to monoclinic crystal system and C2/ c space group. The crystal data are as follows: a=1.5490(11) nm, b=1.3028(9) nm, c=2.6237(18) nm, β=96.803(10)°, V=5.257(6) nm 3, Z=8, M=763.89, Dc=1.930 g cm −3, μ=2.535 mm −1 and F(000)=3048. The final R1 and wR1 are 0.0390 and 0.0703 for 4501 ( I>2σ( I)) unique reflections, R2 and wR2 are 0.0758 and 0.0783 for all 10474 reflections, respectively. The Nd IIIN 2O 7 part in the [Nd III(nta) 2(H 2O)] 3− complex anion has a pseudo-monocapped square antiprismatic nine-coordinate structure in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd III ion directly. The crystal of the K 3[Er III(nta) 2(H 2O)]·5H 2O complex also belongs to monoclinic crystal system and C2/ c space group. The crystal data are as follows: a=1.5343(5) nm, b=1.2880(4) nm, c=2.6154(8) nm, b=96.033(5)°, V=5.140(3) nm 3, Z=8, M=768.89, Dc=1.987 g cm −3, μ=3.833 mm −1 and F(000)=3032. The final R1 and wR1 are 0.0321 and 0.0671 for 4445 ( I>2σ( I)) unique reflections, R2 and wR2 are 0.0432 and 0.0699 for all 10207 reflections, respectively. The Er IIIN 2O 7 part in the [Er III(nta) 2(H 2O)] 3− complex anion has the same structure as Nd IIIN 2O 7 part in which the eight coordinate atoms (two N and six O) are from the two nta ligands and a water molecule coordinate to the central Nd III ion directly. 相似文献
15.
The bimetallic [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O is characterised by single-crystal X-ray diffraction [S.G. P2 1/ m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1) * separations of 4.77(2), 4.55(2) * and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO 3− between parallel [Pt(1)(NH 3) 4] 2+ planes and the second consists of [W(CN) 8] 3− interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH 3) 4] 2+. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH 3 ligands, water molecules and oxygen atoms of NO 3− counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer. 相似文献
16.
The molecular structures of n-hexane were determined by RHF/4-21G ab initio geometry optimization at 30° grid points in its three-dimensional τ1(C11–C8–C5–C1), τ2(C14–C11–C8–C5), τ3(C17–C14–C11–C8) conformational space. Of the resulting 12×12×12=1728 grid structures, 468 are symmetrically non-equivalent and were optimized constraining the torsions τ1, τ2, and τ3 to the respective grid points, while all other structural parameters were relaxed without any constraints. From the results, complete parameter surfaces were constructed using natural cubic spline functions, which make it possible to calculate parameter gradients, | P|=[(∂ P/∂τ i) 2+(∂ P/∂τ j) 2] 1/2, where P is a C–C bond length or C–C–C angle. The parameter gradients provide an effective measure of the torsional sensitivity of the system and indicate that dynamic activities in one part of the molecule can significantly affect the density of states, and thus the contributions to vibrational entropy, in another part. This opens the possibility of dynamic entropic conformational steering in complex molecules; i.e. the generation of free energy contributions from dynamic effects of one part of a molecule on another. When the conformational trends in the calculated C–C bond lengths and C–C–C angles are compared with average parameters taken from some 900 crystallographic structures containing n-hexyl fragments or longer C–C bond sequences, some correlation between calculated and experimental trends in angles is found, in contrast to the bond lengths for which the two sets of data are in complete disagreement. The results confirm experiences often made in crystallography. That is, effects of temperature, crystal structure and packing, and molecular volume effects are manifested more clearly in bond lengths than bond angles which depend mainly on intramolecular properties. Frequency analyses of the τ1, τ2 and τ3 torsional angles in the crystal structures show conformational steering in the sense that, if τ1 is trans peri-planar (170°≤τ 1≤180°; −180°≤τ 1≤−170°), the values of τ2 and τ3 are clustered closely around the ideal gauche (±60°) and trans (±180°) positions. In contrast, when τ1 is in the region (50°≤τ 1≤70°), there is a definite increase in the populations of τ2 and τ3 at −90 and −150°. 相似文献
17.
The rate constants at which oxidizing and reducing radicals react with the dinuclear iron(III) complex Fe 2O(ttha) 2− were measured in neutral aqueous solution. The rate constants for reduction of the complex by ·CO 2.− CH 3.CHOH and O 2.− were found to be comparable with rate constants previously measured in mononuclear iron(III) polyaminocarboxylate systems. Fe 2O(ttha) 2− reacts slowly with O 2.− ( k8 = (1.2 ± 0.2) × 10 4 dm 3 mol −1 s −1) and, hence, is a relatively poor catalyst for the dismutation of superoxide radical. The hydrated electron reduces the complex at a diffusion-controlled rate in a process which consumes one proton: e aq− + Fe 2O(ttha) 2− → Fe 2III,IIO(ttha) 3− The reduction by carbon-centered radicals produces a (III,II) mixed-valence complex with an absorption spectrum different from that of the Fe 2(II,III) species produced from reduction by the hydrated electron. The oxidizing radicals .OH and ·CO 3− appear to act as reductants of the complex via ligand oxidation rather than by oxidation of the Fe 2IIIO core to Fe 2III,IVO. In the former case ligand attack appears to occur mainly at the methylene carbon of a glycinate group. The decarboxylation product, CO 2, was detected by its aquation reaction in the presence of a pH sensitive dye, bromthymol blue. 相似文献
18.
The collisional behaviour of Ba[6s5d( 3D J)], 1.151 eV above the 6s 2( 1S 0) electronic ground state, in the presence of atomic strontium, has been investigated in the ‘long-time domain' (ca. 100 μs–1 ms) following the pulsed dye-laser excitation of barium vapour at elevated temperature at λ = 553.5 nm (Ba[6s6p( 1P 1)] ← Ba[6s 2( 1S 0)]. Ba( 3D J) is subsequently produced from the short-lived 1P 1 state ( τe = 8.37 ± 0.38 ns) by a number of radiative and collisional processes. It may then be monitored in the ‘long-time domain' by atomic spectroscopic marker methods involving either collisional activation of Ba( 3D J) by Ba( 1S 0) and He buffer gas to yield Ba[6s6p( 3P J)] with subsequent emission from the 3P 1 state ( τe = 1.2 ± 0.1 μs): Ba[6s6p( 3P 1)] → Ba[6s 2( 1S 0)] + hv ( λ = 791.1 nm). Alternatively, emission from Ba( 1P 1) may be monitored at long times following the generation of this short-lived state by energy pooling following self-annihilation of Ba( 3D J) + Ba( 3D J) from Ba[6s6p( 1P 1)] → Ba[6s 2( 1S 0)] + hv ( λ = 553.5 nm). The generation of Ba( 3D J) in the presence of atomic strontium yields emission in the long-time domain from Sr[5s5p( 3P 1)] ( τe = 19.6 μs): Sr[5s5p( 3P 1)] → Sr[5s 2( 1S0)] + hv ( λ = 689.3 nm). Whilst the decay profiles at short times are complex in form, at long times all these atomic profiles show first-order kinetic removal with the decay coefficients for λ = 791.1 nm, 689.3 nm and 553.5 nm emissions in the ratio 1 : 2 : 2, consistent with overall third-order activation of the form: Ba( 3D J) + Ba( 3D J) + Sr( 1S 0) → Sr( 3P J) + 2Ba( 1S 0). The mechanism is modelled in detail, including measurement of integrated emission intensities, yielding kinetic data for fundamental collisional processes. The overall rate constant for the third-order collisional activation of Sr[5s5p( 3P J])from 2Ba[6s5d( 3D J)] + Sr[5s 2( 1S 0)] takes the upper limit of 5.8 × 10 −27 cm 6 atom −2 s −1 ( T = 900 K). The rate constant for the two body collisional quenching of Ba[6s5d( 3D J)] by ground state atomic strontium, Sr[5s 2( 1S 0)], is found to be (2.0 ± 0.1) × 10 −12 cm 3 atom −1 s −1 ( T = 900 K). 相似文献
19.
Two carbon-rich starburst gold(I) acetylide complexes [TEE][Au(PCy 3)] 4 (3, [TEE]H 4=tetraethynylethene) and [TEB][Au(PCy 3)] 3 (6, [TEB]H 3=1,3,5-triethynylbenzene) were prepared and their UV–vis absorption, emission and excitation spectra have been recorded. In fluid CH 2Cl 2 solutions, 3 exhibits prompt 1(ππ*) fluorescence with λ0–0 and λmax at 413 and 428 nm, respectively, while 6 displays 3(ππ*) phosphorescence with λ0–0 and λmax at 446 and 479 nm, respectively. The crystal structure of 3·CH 2Cl 2 has been determined. 相似文献
20.
Two nickel (imidazole) complexes, Ni(im) 6Cl 2·4H 2O (1) and Ni(im) 6(NO 3) 2 (2) (im=imidazole) have been synthesized and characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. 1 crystallizes in the triclinic space group P-1 with a=8.800(6) Å, b=9.081(6) Å, c=10.565(7) Å, =75.058(9)°, β=83.143(8)°, γ=61.722(8)°, V=718.3(8) Å 3, Z=1 and R1 ( wR2)=0.0469 (0.1497). 2 crystallizes in the trigonal space group R-3 with a=12.370(6) Å, b=12.370(6) Å, c=14.782(14) Å, =90.00°, β=90.00°, γ=120.00°, V=1959(2) Å 3, Z=3 and R1 ( wR2)=0.0358 (0.0955). 1 and 2 exhibit different supramolecular network due to their different counter anions and different hydrogen bonding connection. In compound 1, [Ni(im) 6] 2+ cation and counter anions Cl − alternatively array in an ABAB fashion via N–HCl hydrogen bonding. In compound 2, the plane of each NO 32− is almost parallel and each NO 32− connect three different [Ni(im) 6] 2+ cations via N–HO hydrogen bonding. 相似文献
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