Untersuchung der Iouenassoziation im System Natriummetavanadat-Natriumchlorid-Wasser mit der Ultrazentrifuge

Zusammenfassung Am Beispiel des Systems Na₄(VO₃)₄-NaCl-H₂O wird untersucht, in welcher Weise Ultrazentrifugenmessungen im Sedimentationsgleichgewicht durchgeführt werden müssen, um die molare Masse und die Ladungszahl von Polymerelektrolyten in ternären Systemen unter der Bedingung von nicht vernachlässigbaren Wechselwirkungen zwischen Polymerund Fremdelektrolyt zu bestimmen. Es erweist sich, daß die experimentellen scheinbaren molaren Massen nicht nur auf die Polymerkonzentration Null extrapoliert werden müssen, sondern auch auf die Fremdelektrolytkonzentration Null. Es gelingt, die Ableitung (alnyPX_z/amBx)mPX_z an der StellemPX_z = 0 mol kg_-1 mit einer scheinbaren mittleren Ladungszahlz _app des Polymeranions zu korrelieren. Zwischen dieser und der stöchiometrischen Ladungszahlz des Polymeranions besteht die Beziehungz _app = Z =az, so daß die Dissoziationskonstante des Polymerelektrolyten für die summarische Dissoziation berechnet werden kann. Die aus dieser Korrelation folgenden Abhängigkeiten der scheinbaren mittleren Ladungszahlen und der Ableitung (alnypx _z /amBX)Mpx _z = 0 von der Konzentration des Fremdelektrolyten werden experimentell bestätigt.

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Summary The system Na₄(VO₃)₄-NaCl-H₂0 is taken as an example for ultracentrifugal measurements at sedimentation equilibrium to determine the molar mass and the valency of a polymer electrolyte in a ternary system when interactions exist between the polymer and the supporting electrolyte. The experimental apparent molar mass is obtained by extrapolation to zero value of concentration of both the polymeric and supporting electrolyte. It is possible to correlate the quantity (alnyPX _z /amBX)^mPX_z at the point ^m PX _z = 0 mole kg^-1 with the apparent valency _zapp of the polymeric anion.z _app is related to the stoichiometric valency by the equationz _app = _z =a.Z. Thus the dissociation constant can be calculated for complete dissociation of the polymer electrolyte. The dependence of _zapp and (aln _y PX _z /a ^m _BX ) ^m PX _z = 0 on concentration of the supporting electrolyte called for in the correlation is verified experimentally.

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Mit 4 Abbildungen und 4 Tabellen     

Ultrafast Photodynamics of the Indoline Dye D149 Adsorbed to Porous ZnO in Dye‐Sensitized Solar Cells

We investigate the ultrafast dynamics of the photoinduced electron transfer between surface‐adsorbed indoline D149 dye and porous ZnO as used in the working electrodes of dye‐sensitized solar cells. Transient absorption spectroscopy was conducted on the dye in solution, on solid state samples and for the latter in contact to a I^?/I₃^? redox electrolyte typical for dye‐sensitized solar cells to elucidate the effect of each component in the observed dynamics. D149 in a solution of 1:1 acetonitrile and tert‐butyl alcohol shows excited‐state lifetimes of 300±50 ps. This signature is severely quenched when D149 is adsorbed to ZnO, with the fastest component of the decay trace measured at 150±20 fs due to the charge‐transfer mechanism. Absorption bands of the oxidized dye molecule were investigated to determine regeneration times which are in excess of 1 ns. The addition of the redox electrolyte to the system results in faster regeneration times, of the order of 1 ns.     

The kinetics of electroreduction of europium(III) cations at bismuth single-crystal electrode

Electroreduction of Eu(ClO₄)₃ and Eu₂(SO₄)₃ has been studied at electrochemically polished \textBi( 01[`1] ) {\text{Bi}}\left( {01\bar{1}} \right) single-crystal electrode in an acidic HClO₄ or H₂SO₄ (pH ~3) aqueous solution with LiClO₄ or Na₂SO₄ additions as a surface inactive electrolyte. The Eu³⁺ cations electroreduction rate depends on the electrode potential applied and the concentration of the supporting electrolyte as well as the concentration of the Eu³⁺ ions. At the more negative electrode potentials than the zero charge potential (zcp), the diffusion current plateaus were observed. The values of the rate constant for the heterogeneous reaction calculated at zcp are independent of the base electrolyte concentration studied. Analysis of the kinetic data corrected for the electrical double-layer effect shows that the coincidence of the corrected Tafel plots can be achieved, assuming that the effective charge of a reactant (+1.6) is significantly lower than it would be expected (z _A = +3).     

C.I. Reactive Orange 16-dodecylpyridinium chloride interactions in electrolytic solutions

The effect of electrolytes on the interaction between an anionic dye and a cationic surfactant was investigated spectrophotometrically in submicellar concentration range at certain temperature. The spectral change of the azo dye C.I. Reactive Orange 16 (RO16) exhibits a high sensitivity to the polarity of dye's environment. Dodecylpyridinium chloride (DPC) affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results formation of complex and therefore a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte cations cause an increase of the absorbance of DPC-RO16 ion-pair complex in the following order: Ca(2+)>Na(+)>NH(4)(+)>K(+)>Mg(2+), also for electrolyte anions Br(-)>Cl(-)>SO(4)(2-). Furthermore, this order can be changeable with increasing electrolyte concentration. The increase on absorbance value with increasing electrolyte concentration is explained as charge screening. The increase or decrease on absorption spectra of RO16-DPC solution depends on concentration range of the electrolyte added. As an increase on absorbance value with increasing electrolyte concentration is explained as charge screening, a decrease in this value for higher concentration of electrolyte is attributed as the charge of micelle shape.     

Beiträge zur Chemie der Pyrrolpigmente,LVIII Phytochrommodellstudien: Konformationsanalytische Untersuchungen an 2,3-Dihydrobilatrien-abc-Derivaten

Two 3,4-dihydropyrromethenones and two 2,3-dihydrobilatrienes-abc O-methylated at rings A and D resp. have been prepared. Their configurations were established as (Z), (E), (Z, Z, Z) and (Z, Z, Z), respectively, using¹H-NMR-techniques (NOE); they are also shown to exist predominantly in the lactam form. Within the pyrromethene fragment of the bilatrienes the pyrrolic and pyrroleninic ring type depends on the position of O-methylation. A helical all-synperiplanar conformation in solution could be established for all cases by applying the lanthanide induced shift (LIS) technique.

     

Excellent Performance of Few‐Layer Borocarbonitrides as Anode Materials in Lithium‐Ion Batteries

Borocarbonitrides (B_xC_yN_z) with a graphene‐like structure exhibit a remarkable high lithium cyclability and current rate capability. The electrochemical performance of the B_xC_yN_z materials, synthesized by using a simple solid‐state synthesis route based on urea, was strongly dependent on the composition and surface area. Among the three compositions studied, the carbon‐rich compound B_0.15C_0.73N_0.12 with the highest surface area showed an exceptional stability (over 100 cycles) and rate capability over widely varying current density values (0.05–1 A g^?1). B_0.15C_0.73N_0.12 has a very high specific capacity of 710 mA h g^?1 at 0.05 A g^?1. With the inclusion of a suitable additive in the electrolyte, the specific capacity improved drastically, recording an impressive value of nearly 900 mA h g^?1 at 0.05 A g^?1. It is believed that the solid–electrolyte interphase (SEI) layer at the interface of B_xC_yN_z and electrolyte also plays a crucial role in the performance of the B_xC_yN_z .     

Study of Lysozyme Glycation Reaction by Mass Spectrometry and NMR Spectroscopy

The Advanced Glycation End Products (AGEs) are the causative substances of lifestyle‐habit illness. To elucidate the glycation mechanism of the protein, the reaction of lysozyme with D ‐glucose was analyzed by the fluorescence, TOF‐MS, and ¹³C‐NMR spectroscopy under the physiological condition. The fluorescence intensity of lysozyme in the glycation solution increased proportionally with a reaction time of ten weeks. The MALDI‐TOF‐MS spectra of the reaction solution after two weeks showed a peak at m/z 15066, which indicated the presence of a larger molecule than the native lysozyme (m/z 14331), and new peaks at m/z 30105 (dimer) and 45000 (trimer) were also observed. The spectral analysis supported the assumption of a continuous glycation reaction of D ‐glucose with lysozyme and a 30% transformation of lysozyme to the dimeric form during ten weeks. The ¹³C‐NMR spectra of lysozyme showed six [¹³C]‐labeled signals by the glycation reaction with [¹³C]‐glucose after two weeks of reaction. The combined analysis of TOF‐MS and ¹³C‐NMR spectra uncovered that first products of the glycation reaction of lysozyme with D ‐glucose can be observed already three hours after starting the reaction and that nine D ‐glucose units are attached during ten weeks at 37°.     

Lanthanide‐Based Layer‐Type Two‐Dimensional Coordination Polymers Featuring Slow Magnetic Relaxation,Magnetocaloric Effect and Proton Conductivity

Three lanthanide‐based two‐dimensional (2D) coordination polymers (CPs), [Ln(L)(H₂O)₂]_n, {H₃L=(HO)₂P(O)CH₂CO₂H; Ln=Dy³⁺ (CP 1 ), Er³⁺ (CP 2 )} and [{Gd₂(L)₂(H₂O)₃}^.H₂O]_n, (CP 3 ) were hydrothermally synthesized using phosphonoacetic acid as a linker. Structural features revealed that the dinuclear Ln³⁺ nodes were present in the 2D sheet of CP 1 and CP 2 while in the case of CP 3 , nodes were further connected to each other forming a chain‐type arrangement throughout the network. The magnetic studies show field‐induced slow magnetic relaxation property in CP 1 and CP 2 with U_eff values of 72 K (relaxation time, τ₀=3.05×10^?7 s) and 38.42 K (relaxation time, τ₀=4.60×10^?8 s) respectively. Ab‐initio calculations suggest that the g tensor of Kramers doublet of the lanthanide ion (Dy³⁺ and Er³⁺) is strongly axial in nature which reflects in the slow magnetic relaxation behavior of both CPs. CP 3 exhibits a significant magnetocaloric effect with ?ΔS_m=49.29 J kg^?1 K^?1, one of the highest value among the reported 2D CPs. Moreover, impedance analysis of all the CPs show high proton conductivity with values of 1.13×10^?6 S cm^?1, 2.73×10^?3 S cm^?1 and 2, 6.27×10^?6 S cm^?1 for CPs 1 – 3 , respectively, at high temperature (>75 °C) and maximum 95 % relative humidity (RH).     

Efficient removal of MB dye using litchi leaves powder adsorbent: Isotherm and kinetic studies

Removal of Methylene Blue (MB) dye using Litchi Leaves Powder (LLP) material was carried out in batch mode. Effect of the mass of the adsorbent (0.1–2.5 g/L), pH of the solution (2−12), starting concentration of MB dye (50–150 mg/L), ionic strength using NaCl (0.1–0.5 M) as an electrolyte, contact time (0–60 min) on the adsorption of MB dye was studied. To calculate pH at which LLP material surface becomes neutral point of zero charge (pH_pzc) is also determined and found to be 6.48. Removal process best fit in the pseudo-second-order kinetic model as indicated by its higher R² value (0.999). Isotherm models (Freundlich and Langmuir) were fitted to the data obtained from the experiment to understand the adsorption behaviour. Result shows that experimental data were fitted to the both isotherm models (Freundlich and Langmuir) as indicated by higher R² value for both Freundlich (0.991) and Langmuir (0.994) model, and it was determined that LLP has a maximum adsorption capacity of 119.76 mg/g.     

Reconstruction of Solid Electrolyte Interphase with SrI2 Reactivates Dead Li for Durable Anode-Free Li-Metal Batteries

Without excess Li, anode-free Li-metal batteries (AFLMBs) have been proposed as the most likely solution to realizing highly-safe and cost-effective Li-metal batteries. Nevertheless, short cyclic life puzzles conventional AFLMBs due to anodic dead Li accumulation with a local current concentration induced by irreversible electrolyte depletion, insufficient active Li reservoir and slow Li⁺ transfer at the solid electrolyte interphase (SEI). Herein, SrI₂ is introduced into carbon paper (CP) current collector to effectively suppress dead Li through synergistic mechanisms including reversible I⁻/I₃⁻ redox reaction to reactivate dead Li, dielectric SEI surface with SrF₂ and LiF to prevent electrolyte decomposition and highly ionic conductive (3.488 mS cm⁻¹) inner layer of SEI with abundant LiI to enable efficient Li⁺ transfer inside. With the SrI₂-modified current collector, the NCM532/CP cell delivers unprecedented cyclic performances with a capacity of 129.2 mAh g⁻¹ after 200 cycles.     

Electroreduction of peroxodisulfate anion at Bi(111) single-crystal plane electrode

Electroreduction of peroxodisulfate anion on electrochemically polished face Bi(111) in aqueous NaF solution with different additions of Na₂S₂O₈ is studied by rotating-disc voltammetry. The S₂O ₈ ^2- electroreduction rate depends on the electrode potential and base-electrolyte concentration, i.e. on the diffuse layer thickness. The kinetic current densities atE = const are obtained by the Koutecky-Levich method and used for the determination of the apparent rate constants of electroreduction of S₂O ₈ ^2- . The charge number of the reacting S₂O ₈ ^2- species is obtained; it depends on the surface-inactive electrolyte concentration and the electrode potential. The ψ₀ potential values at the outer Helmholtz plane, obtained for various NaF + H₂O systems according to Gouy-Chapman-Stern-Grahame (GCSG) model, are used for constructing corrected Tafel plots (CTP), which are linear atE- ψ₀ < -0.9 V (SCE). The charge transfer coefficient oc for electrochemically polished Bi(111) somewhat decreases with the concentration of the base electrolyte (0.22 ≤α ≤0.27), but the value of α is practically independent of the S₂O ₈ ^2- concentration in solution if c_NaF = const. However, CTP noticeably depend onc _NaF. Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth. Submitted in English.     

D-A-D-based Unsymmetrical Thiosquaraine Dye for the Dye-Sensitized Solar Cells†

In dye-sensitized solar cell, modulating the electronic properties of the sensitizer by varying the donor, π-spacer, acceptor and anchoring groups help optimizing the structure of the dye for better device performance. Here, a donor–acceptor–donor-based unsymmetrical thiosquaraine sensitizer ( SQ5S ) has been designed and synthesized. Photophysical, electrochemical, theoretical and photovoltaic characterizations of SQ5S dye have been compared with its oxygen analog, SQ5 . The incorporation of the sulfur atom in the acceptor unit of SQ5S dye showed an intense peak at 688 nm, which was 38 nm of red-shifted and showed the panchromatic light harvesting response with the onset of 850 nm compared with SQ5 dye. The LUMO and HOMO energy levels are well aligned with the conduction band of TiO₂ and the redox potential of electrolyte for the charge injection and the dye-regeneration processes, respectively. Photovoltaic efficiency of 1.51% (V_OC 610 mV, J_SC 3.07 mA cm⁻², ff 81%) has been achieved for SQ5S dye, whereas SQ5 showed the device performance of 5.43% (V_OC 723 mV, J_SC 9.3 mA cm⁻², ff 80%). The decreased device performance for the dye SQ5S has been attributed to the favorable intersystem crossing process associated with the photoexcited SQ5S that reduces the driving force for the charge injection process.     

Multifunctional Molecular Material Combining Photocurrent Generation and Second-Order Optical Nonlinearity in LB Monolayer Films

ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｌｅｃｕｌａｒｎｏｎｌｉｎｅａｒｏｐｔｉｃｓ (ＮＬＯ)ｈａｓａｔｔｒａｃｔｅｄｉｎ ｃｒｅａｓｉｎｇｉｎｔｅｒｅｓｔｏｖｅｒｔｈｅｐａｓｔｔｅｎｙｅａｒｓ ,ｂｅｃａｕｓｅｏｆｔｈｅｉｒｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｖａｒｉｏｕｓｆｉｅｌｄｓｉｎｃｌｕｄｉｎｇｔｅｌｅｃｏｍ ｍｕｎｉｃａｔｉｏｎｓ ,ｏｐｔｉｃａｌｄａｔａｓｔｏｒａｇｅａｎｄｐｒｏｃｅｓｓｉｎｇａｎｄｏｐｔｉ ｃａｌｐｏｗｅｒｌｉｍｉｔａｔｉｏｎ .1,2 Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｐ…     

Collision‐induced dissociation mass spectra of glucosinolate anions

Collision‐induced dissociation (CID) mass spectra of differently substituted glucosinolates were investigated under negative‐ion mode. Data obtained from several glucosinolates and their isotopologues (³⁴S and ²H) revealed that many peaks observed are independent of the nature of the substituent group. For example, all investigated glucosinolate anions fragment to produce a product ion observed at m/z 195 for the thioglucose anion, which further dissociates via an ion/neutral complex to give two peaks at m/z 75 and 119. The other product ions observed at m/z 80, 96 and 97 are characteristic for the sulfate moiety. The peaks at m/z 259 and 275 have been attributed previously to glucose 1‐sulfate anion and 1‐thioglucose 2‐sulfate anion, respectively. However, based on our tandem mass spectrometric experiments, we propose that the peak at m/z 275 represents the glucose 1‐thiosulfate anion. In addition to the common peaks, the spectrum of phenyl glucosinolate (β‐D ‐Glucopyranose, 1‐thio‐, 1‐[N‐(sulfooxy)benzenecarboximidate] shows a substituent‐group‐specific peak at m/z 152 for C₆H₅‐C(?NOH)S^?, the CID spectrum of which was indistinguishable from that of the anion of synthetic benzothiohydroxamic acid. Similarly, the m/z 201 peak in the spectrum of phenyl glucosinolate was attributed to C₆H₅‐C(?S)OSO₂^?. Copyright © 2009 John Wiley & Sons, Ltd.     

Constructing Organic D–A–π‐A‐Featured Sensitizers with a Quinoxaline Unit for High‐Efficiency Solar Cells: The Effect of an Auxiliary Acceptor on the Absorption and the Energy Level Alignment

Four organic D–A –π‐A‐featured sensitizers (TQ1, TQ2, IQ1, and IQ2) have been studied for high‐efficiency dye‐sensitized solar cells (DSSCs). We employed an indoline or a triphenylamine unit as the donor, cyanoacetic acid as the acceptor/anchor, and a thiophene moiety as the conjugation bridge. Additionally, an electron‐withdrawing quinoxaline unit was incorporated between the donor and the π‐conjugation unit. These sensitizers show an additional absorption band covering the broad visible range in solution. The contribution from the incorporated quinoxaline was investigated theoretically by using DFT and time‐dependent DFT. The incorporated low‐band‐gap quinoxaline unit as an auxiliary acceptor has several merits, such as decreasing the band gap, optimizing the energy levels, and realizing a facile structural modification on several positions in the quinoxaline unit. As demonstrated, the observed additional absorption band is favorable to the photon‐to‐electron conversion because it corresponds to the efficient electron transitions to the LUMO orbital. Electrochemical impedance spectroscopy (EIS) Bode plots reveal that the replacement of a methoxy group with an octyloxy group can increase the injection electron lifetime by a factor of 2.4. IQ2 and TQ2 can perform well without any co‐adsorbent, successfully suppress the charge recombination from TiO₂ conduction band to I₃^? in the electrolyte, and enhance the electron lifetime, resulting in a decreased dark current and enhanced open circuit voltage (V_oc) values. By using a liquid electrolyte, DSSCs based on dye IQ2 exhibited a broad incident photon‐to‐current conversion efficiency (IPCE) action spectrum and high efficiency (η=8.50 %) with a short circuit current density (J_sc) of 15.65 mA cm^?2, a V_oc value of 776 mV, a fill factor (FF) of 0.70 under AM 1.5 illumination (100 mW cm^?2). Moreover, the overall efficiency remained at 97 % of the initial value after 1000 h of visible‐light soaking.     

Adiabatic compressibility of polyelectrolytes in aqueous solutions. II. Poly(4-vinyl-N-n-butylpyridinium bromide)

The adiabatic compressibility for two samples (F-1 with DP-3748 and F-2 with DP-2114) of poly(4-vinyl-N-n-butylpyridinium bromide) in aqueous solution has been determined from ultrasonic velocity and density data. The sample (F-1) with the higher degree of polymerization shows comparatively higher velocity and density in solution. However, the evidence for the difference in compressibility is not very decisive. The apparent molal volume ΦV₂ and apparent molal compressibility ΦK₂ for F-1 are found to be slightly higher than for F-2. In aqueous solution, the decrement of adiabatic compressibility per unit concentration, (β₁ ? β)/c, is found to be almost constant throughout the entire concentration range, whereas in the presence of excess added electrolyte (1.0M KBr solution), the compressibility decrement shows a decrease with dilution. The latter values are lower than those found in water, since the molecules, in the presence of excess electrolyte, are coiled up more and are less compressible. The ΦV₂ and ΦK₂ values in water are constant throughout the entire concentration range, as the free counterions formed on dissociation in the dilute region are not solvated and hence contribute little to the compressibility. On the other hand, in the presence of excess KBr (1.0M), the ΦV₂ and ΦK₂ values show a sharp decrease with increase of polyelectrolyte concentration and finally attain a constant value. This is explained by the fact that because of the formation of a charge-transfer complex between the bromide ion and the polycation, more than the equivalent number of bromide ions is bound, leaving free an equal amount of K⁺ ions which are solvated and cause the lowering of apparent volumes and compressibilities. Condensation of charges begins at a certain polyelectrolyte concentration, and no further increase of K⁺ ions is observed. A special situation arises in 0.1M KBr solution. The ΦV₂ and ΦK₂ values at first increase sharply with increase of polyelectrolyte concentration, but then level off to attain a constant value, at comparatively high concentration. In 2.0% poly(4-vinyl-N-n-butylpyridinium bromide) solution, the concentration of polymer repeat unit (0.08M) is almost equal to the concentration of the added electrolyte (0.1M KBr) used to suppress dissociation. As the polyelectrolyte concentration in 0.1M KBr solution is progressively decreased, more bromide ions are made available for forming the charge-transfer complex with the polycation, leaving the K⁺ ions free to contribute to the compressibility.     

New Amphiphilic Polypyridyl Ruthenium（Ⅱ） Sensitizer and Its Application in Dye-Sensitized Solar Cells

Amphiphilic polypyridyl mthenium（Ⅱ） complex cis-di（isothiocyanato）（4,4＇-di-tert-butyl-2,2＇-bipyridyl）（4,4＇- dicarboxy-2,2＇-bipyridyl）ruthenium（Ⅱ）（K005） has been synthesized and characterized by cyclic voltammetry, ^1H NMR, UV-Vis, and FT-IR spectroscopies. The sensitizer sensitizes TiO2 over a notably broad spectral range due to its intense metal-to-ligand charge-transfer （MLCT） bands at 537 and 418 nm. The photophysical and photochemical studies of K005 were contrasted with those of cis-Ru（dcbpy）2（NCS）2, known as the N3 dye, and the amphiphilic ruthenium（Ⅱ） dye Z907. A reversible couple at E1/2=0.725 V vs. saturated calomel electrode （SCE） with a separation of 0.08 V between the anodic and cathodic peaks, was observed due to the Ru^Ⅱ/Ⅲ couple by cyclic voltammetry. Furthermore, this amphiphilic ruthenium complex was successfully used as sensitizers for dye-sensitized solar cells with the efficiency of 3.72% at the 100 mW·cm^-2 irradiance of air mass 1.5 simulated sunlight without optimization of TiO2 films and the electrolyte.     

Structural studies on aryl‐substituted enaminoketones and their thio analogues. Part I. Analysis of high‐resolution 1H, 13C NMR and 13C CP MAS spectra combined with GIAO‐DFT calculations

A series of aryl‐substituted enaminoketones and their thio analogues in CDCl₃ solution and in the solid state were studied by the use of high‐resolution ¹H and ¹³C as well as ¹³C cross polarization magic angle spinning (CP MAS) NMR spectra in combination with gauge including atomic orbitals‐density functional theory (GIAO‐DFT) calculations performed at the B3PW91/6–311 + + G(d,p) level of theory using the B3PW91/6‐311 + + G(d,p)‐optimized geometries. The analysis of the ¹³C NMR spectra in solution was done by using the Incredible Natural Abundance DoublE QUAntum Transfer Experiment (INADEQUATE) technique, whereas trends observed in the ¹³C shielding constants, calculated for the compounds studied, were a great help in assigning most of the signals in the ¹³C CP MAS NMR spectra. It was established on the basis of the experimental and theoretical NMR data that both groups of compounds exist in the form of Z‐s‐Z‐s‐E isomers in CDCl₃ solution as well as in the solid state, with the NH hydrogen atom involved in intramolecular hydrogen bonding. This conclusion is in agreement with the fact that some of the compounds studied reveal liquid‐crystalline properties. Three‐bond H, H and C, H coupling constants measured in solution played a crucial role in the structure elucidation. Copyright © 2009 John Wiley & Sons, Ltd.     

Spectral,kinetic, and redox properties of basic fuchsin in homogeneous aqueous and sodium dodecyl sulfate micellar media

Effect of anionic surfactant on the optical absorption spectra and redox reaction of basic fuchsin, a cationic dye, has been studied. Increase in the absorbance of the dye band at 546 nm with sodium dodecyl sulfate (SDS) is assigned to the incorporation of the dye in the surfactant micelles with critical micellar concentration (CMC) of 7.3 × 10^?3 mol dm^?3. At low surfactant concentration (<5 × 10^?3 mol dm^?3) decrease in the absorbance of the dye band at 546 nm is attributed to the formation of a dye–surfactant complex (1:1). The environment, in terms of dielectric constant, experienced by basic fuchsin inside the surfactant micelles has been estimated. The association constant (K_A) for the formation of dye–SDS complex and the binding constant (K_B) for the micellization of dye are determined. Stopped‐flow studies, in the premicellar region, indicated simultaneous depletion of dye absorption and formation of new band at 490 nm with a distinct isosbestic point at 520 nm and the rate constant for this region increased with increasing SDS concentration. The reaction of hydrated electron with the dye and the decay of the semireduced dye are observed to be slowed down in the presence of SDS. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 629–636, 2003     

镁合金表面原位生长有机膦酸盐薄膜及耐蚀行为

利用超声辅助的浸渍涂布方法,在AZ91D镁合金表面原位生长了氨基二乙酸亚甲基膦酸镁铝薄膜,其中包含具有纳米尺度的变形六边形板状颗粒。塔菲尔极化曲线、电化学阻抗谱测量表明,修饰后的AZ91D镁合金的耐腐蚀行为依赖于浸渍所用的膦酸浓度、pH值、温度及时间等。在3.5%NaCl溶液中,未修饰的AZ91D其腐蚀活化能是18.1 kJ.mol-1,而在1.5 mmol.L-1膦酸溶液中pH值分别是1.7、11.5时浸渍涂布有机膦酸盐薄膜后,AZ91D的腐蚀活化能分别是27.9、37.8 kJ.mol-1。