Vapor phase acylation of phenol over Hβ, CeHβ and SO42-/ZrO2a

Phenol acylation on Hβ, CeHβ and SO₄ ^2-/ZrO₂ using acetic acid and acetic anhydride as acylating agents is compared in the temperature range 250-400°C. Acetic acid formed phenyl acetate (PA) and o-hydroxy acetophenone (o-HAP) and acetic anhydride formed p-hydroxyacetophenone (p-HAP ) along with PA and o-HAP. The formation of o-HAP and p-HAP, the products of C-acylation of phenol using acetic acid is proposed by studying phenyl acetate conversion on Hb, CeHβ and SO₄ ^2-/ZrO₂. Our studies show that for phenol acylation the most suitable acid site is available on CeHβ. This revised version was published online in June 2006 with corrections to the Cover Date.     

Theoretical study of the 2Σu+ and 2Σg+ states of Li2− and Na2−

Ab initio calculations are performed to obtain potential energy curves for the X¹Σ_g⁺ state of Li₂ and Na₂ and the X²Σ_g⁺ and A²Σ_g⁺ states of their anions. The A²Σ_g⁺ M₂^? curves are found to intersect the X¹Σ_g⁺M₂ curves at low energies and are expected to play a major role in the e^? + M₂ → M^? + M process.     

Theoretical study of the structure and stability of the Na2Cl+, NaCl 2? , Na3Cl 2+ , and Na2Cl 3? ions

The geometrical parameters, normal vibration frequencies, and thermochemical characteristics of the Na₂Cl⁺, NaCl ₂ ⁻ , Na₃Cl ₂ ⁺ , and Na₂Cl ₃ ⁻ ions in saturated vapors over sodium chloride were calculated by the ab initio methods including electron correlation. According to calculations, the Na₂Cl⁺ and NaCl ₂ ⁻ triatomic ions have a linear equilibrium D _∞h configuration. The pentaatomic ions can exist in the form of the D _∞h linear isomer, C _2v planar cyclic isomer, or D _3h bipyramidal isomer. At ∼1000 K the Na₃Cl ₂ ⁺ and Na₂Cl ₃ ⁻ ions exist predominantly in the form of the linear isomers. The energies and enthalpies of the ion-molecule reactions involving the above ions were calculated. The formation enthalpy of the ions Δ_f H ⁰(0 K) was determined: 230 ± 2 kJ/mol (Na₂Cl⁺), −96 ± 4 kJ/mol (Na₂Cl ₃ ⁻ ), −616 ± 2 kJ/mol (NaCl ₂ ⁻ ), and −935 ± 4 kJ/mol (Na₂Cl ₃ ⁻ ). Original Russian Text Copyright ? 2007 by T. P. Pogrebnaya, A. M. Pogrebnoi, and L. S. Kudin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 6, pp. 1053–1061, November–December, 2007.     

Electronic structure and reactivity of PO 43? , P2O 74? phosphate and SO 42? , S2O 72? sulfate anions

Group-theoretical analysis and molecular orbital methods were used to obtain (in analytical form) the electronic structure and reactivity of the PO ₄ ³⁻ , SO ₄ ²⁻ and P₂O ₇ ⁴⁻ , S₂O ₇ ²⁻ anions. The reactivity of the anions is dictated by the availability of lone electron pairs on the top quasidegenerate MOs in the form of linear combinations of group orbitals from atomic orbitals (AOs) of peripheral oxygen atoms for PO ₄ ³⁻ , SO ₄ ²⁻ and the central (bridging) atom for P₂O ₇ ⁴⁻ , S₂O ₇ ²⁻ . These electron pairs are responsible for the donor-acceptor interactions during complexation, clustering, and other (addition, substitution, etc.) reactions. Original Russian Text Copyright ? 2005 V. A. Zasukha, A. P. Shpak, V. V. Trachevskii, and E. V. Urubkova __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 3, pp. 405–415, May–June, 2005.     

聚阴离子掺杂LiMnO_(2-y)X_y(X=BF_4~-,SiO_3~(2-),MoO_4~(2-),PO_4~(3-),BO_3~(3-))材料的合成及其电化学性能

采用水热法合成了聚阴离子掺杂LiMnO2-yXy(X=BF4-,SiO32-,MoO42-,PO43-,BO33-,y=0.01、0.03、0.05)锂离子电池正极材料。通过X射线粉末衍射(XRD)、X光电子能谱(XPS)、扫描电镜(SEM)和恒电流充放实验,研究了不同掺杂离子和掺杂量对产物结构和电化学性能的影响。结果表明,少量聚阴离子的掺杂未改变正交LiMnO2的晶体类型,但增大了材料晶胞体积,改善了材料的电化学循环性能。电化学交流阻抗(EIS)测试结果表明,聚阴离子掺杂增大了材料电荷转移阻抗,但明显提高了材料中Li+的扩散能力。     

Predissociation of the C2Σu+ state of N2+

Two mechanisms for the predissociation of the C²Σ_u⁺ state of N₂⁺ are discussed - the accidental mechanism and a direct, homogeneous process C → B²Σ_u⁺. The matrix elements for the latter channel are dominated by a contribution from the nuclear kinetic energy operator, containing a Franck-Condon integral of form 〈?|?/?R|υ′〉.     

Trace determination of TeO42?, TeO32?, AsO2? and VO3? by differential pulse polarography and resolution of binary and ternary mixtures of selected oxyanions

Summary A differential pulse polarographic method has been applied to the determination of trace concentrations of TeO ₄ ^2– , TeO ₃ ^2– , AsO ₂ ^– and VO ₃ ^– . The dependence of the differential pulse peak on various parameters was studied and optimum conditions for the analytical determination of these oxyanions were found. Limits of detection and quantitation have been calculated for the differential pulse polarographic determination of the investigated oxyanions. The selectivity of this technique for the determination of binary (TeO ₄ ^2– -TeO ₃ ^2– , TeO ₄ ^2– -AsO ₂ ^– and TeO ₄ ^2– -VO ₃ ^– ) mixtures and a ternary (TeO ₄ ^2– -TeO ₃ ^2– -AsO ₂ ^– ) mixture has also been reported.

---

Spurenbestimmung von TeO ₄ ^2– , TeO ₃ ^2– , AsO ₂ ^– und VO ₃ ^– durch Differential-Puls-Polarographie und Trennung binÄrer sowie ternÄrer Gemische von ausgewÄhlten Oxyanionen

     

S42+ and S42− : an ab initio study

The structures of S₄²⁺ and S₄^2? have been investigated by ab initio calculations using the GAUSSIAN 70 system of programs and the 44-31G basis set. Electronic singlet states of the square form and three possible conformations of the chain structure were examined for both ions, and the singlet rectangle form of S₄^2? was also investigated. The anti chain form of S₄²⁺ was found to be 78.3 kJ mol^? more stable than the square form, in contrast to previous experimental data. S₄^2?is predicted to adopt the chain structure with the anti conformation.     

Wavelength-resolved fluorescence lifetimes of gas-phase ions: CO2+ and CS2+

A method is described for measuring wavelength-resolved fluorescence lifetimes of ions formed by HeIα photoionization, using electric-field drift of the ions in competition with fluorescence. Fluorescence lifetimes of 216 and 232 ns for the 357 nm and 378 nm peaks of N₂O⁺, and 3.5 μs for the à → X? band of CS₂⁺, were measured. The wavelength-resolved à → X? band of CO₂⁺ showed no significant dependence of fluorescence lifetime on V′, but there is some indication of variation in the CS₂⁺ lifetimes in the à → X? band.     

Recombination energy of N22+

The recombination energy of N₂²⁺ has been computed using N₂²⁺, N₂²⁺ and N₂ potential curves from the literature. Vibrational overlaps and energies liberated in the various N₂²⁺³∑^?_g,¹∑_g⁺, ³Π_u, ¹Π_u → N₂⁺(X²∑⁺_g, A ²∑⁺_g, A ²Π_u, B²∑_u⁺,C²∑_u⁺) vibronic transitions have been computed and used as input for determination of the N₂⁺ recombination energy.     

Low-lying states of cs22+

Using an MC SCF CI method, wavefunctions for the ground state ¹∑⁺_g and the excited states of the symmetries ¹∑⁺_g, ¹Π_g, and ¹Δ_g of the Cs²⁺₂ ionic system are generated. The potential curves for eleven ¹∑⁺_g twelve ¹Π_g, and six ¹Δ_g states are calculated. Results suggest a small charge-transfer cross section for the reaction CS⁺ + Cs⁺ → Cs CS²⁺.     

Some ab initio calculations related to the predissociation of the C2Σu+ state of N2+

Ab initio calculations in the “first-order wavefunction” CI approximation have been performed for several states of N₂⁺ with ²Σ_u⁺, ²Σ_u^?, ⁴Π_u symmetry. A calculation of the electronic factor of the vibronic interaction between the B²Σ_u⁺ and C²Σ_u⁺ states seems to support the suggestion of Tellinghuisen and Albritton that the C state is predissociated by the continuum of the B state through nuclear momentum coupling.     

MOF-1和Tb@MOF-1荧光探针的设计、 合成及对痕量Cr2O72-、 S2O82-离子的识别

采用5-((4-吡啶基)甲氧基)-异烟酸(H₂PLIA)、1,3,5-三(1-咪唑基)-苯(TIB)合成了金属有机骨架[Cd(PLIA)(TIB)]_n (MOF-1),MOF-1是具有理想一维孔道的二维结构化合物,其一维孔道由柔性三角形PLIA^2-配体和刚性三角形TIB配体间隔形成。利用MOF-1 易掺杂的优势,采用后修饰合成策略制备了Tb@MOF-1。对MOF-1 和Tb@MOF-1 进行了基本表征及荧光探针性能研究。2种探针材料具有相同的结构。MOF-1和Tb@MOF-1分别对水溶液中的Cr₂O₇^2-和S₂O₈^2-离子具有较强荧光识别能力,均有响应时间快,稳定性、选择性、灵敏度高的特点。研究了MOF-1和Tb@MOF-1对Cr₂O₇^2-和S₂O₈^2-的荧光识别机理,其不同可能与Tb³⁺离子掺杂有关。     

Further studies of the N2+ + N2 → N4+ association reaction

Data are presented which strongly suggest that stabilisation of the excited intermediate (N₄⁺)* complex in the reaction (1) N₂⁺ + 2N₂ (rate coefficient k₁) occurs via N₂ switching whereas for (2) N₂⁺ + N₂ + He (rate coefficient k₂) it occurs via superelastic He collisions. This explains the differing temperature variations of k₁ and k₂ previously obtained for these reactions. Drift tube data are also presented which show how k₁ varies with N₂⁺/N₂ centre-of-mass energy as compared with thermal energy.     

MOF-1和Tb@MOF-1荧光探针的设计、合成及对痕量Cr2O72-、S2O82-离子的识别

采用5-（（4-吡啶基）甲氧基）-异烟酸（H₂PLIA）、1,3,5-三（1-咪唑基）-苯（TIB）合成了金属有机骨架[Cd （PLIA）（TIB）]_n （MOF-1）。MOF-1是具有理想一维孔道的二维结构化合物,其一维孔道由柔性三角形PLIA^2-配体和刚性三角形TIB配体间隔形成。利用MOF-1易掺杂的优势,采用后修饰合成策略制备了Tb@MOF-1。对MOF-1和Tb@MOF-1进行了基本表征及荧光探针性能研究。2种探针材料具有相同的结构。MOF-1和Tb@MOF-1分别对水溶液中的Cr₂O₇^2-和S₂O₈^2-离子具有较强荧光识别能力,均有响应时间快,稳定性、选择性、灵敏度高的特点。研究了MOF-1和Tb@MOF-1对Cr₂O₇^2-和S₂O₈^2-的荧光识别机理,其不同可能与Tb³⁺离子掺杂有关。     

Bestimmung von NO2? und NO3? in Lebensmitteln mit Hilfe chromatographischer Methoden

Zusammenfassung WÄhrend NO ₂ ^– problemlos nach dem Griess-Verfahren bestimmt werden kann, treten bei der spektralphotometrischen Erfassung von NO ₃ ^– hÄufig Störungen auf.Zum Nachweis geringer NO ₃ ^– -Mengen eignet sich die Nitrierung von p-Kresol zu 4-Methyl-2-nitrophenol, das durch Wasserdampfdestillation aus dem Reaktionsgemisch abgetrennt und nach überführung in Toluol durch HPLC bzw. GC bestimmt wird.Zur schnellen Erfassung von NO ₂ ^– neben NO ₃ ^– kann neben der Ionen-Chromatographie an AnionenaustauschersÄulen vorteilhaft die Ionen-Paar-Chromatographie an RPSÄulen eingesetzt werden. Durch parallele Anwendung verschiedener Methoden gelingt es, NO ₂ ^– - und NO ₃ ^– -Gehalte auch von komplex zusammengesetzten Lebensmitteln über einen weiten Konzentrationsbereich mit gro\er Genauigkeit störungsfrei zu ermitteln.

---

Determination of NO ₂ ^– and NO ₃ ^– in foods by chromatography

Summary The determination of NO ₂ ^– is achieved by the Griess procedure without problems, whereas during the analysis of NO ₃ ^– by spectrophotometric methods disturbances often occur.Small amounts of NO ₃ ^– are detectable after nitration of p-cresol, subsequent separation of 4-methyl-2-nitrophenol by steam distillation and its determination by HPLC or GLC after extraction with toluene. To enable a rapid determination of NO ₂ ^– as well NO ₃ ^– , apart from the ionchromatographic method with anion-exchange columns the comparatively equal ion-pair chromatographic system using RP columns may also be used. By the parallel use of different methods it is possible to determine the NO ₂ ^– and NO ₃ ^– contents, even in complex matrices, over a wide concentration range with a large degree of accuracy and a minimum of disturbances.

---

---

Nach einem Vortrag anlÄ\lich des Deutschen Lebensmittelchemikertages, München 1983     

Coincidence studies of fluorescence and dissociation processes in electronic excited states of I2+, Br2+, IBr+ and ICl+

The PIFCO technique in which mass-selected photoion—fluorescence photon coincidences are counted, was used to investigate whether I₂⁺, IBr⁺ and ICl⁺ fluoresce. Measurements were made of lifetimes and fluorescence quantum yields of electronic excited states of these ions. Emission was discovered for I₂⁺ and IBr⁺, but ICl⁺ apparently does not fluoresce. Information on the radiative properties of Br₂⁺ was obtained as a by-product of the work on IBr⁺. Fragment ion kinetic energy releases were determined and provide information on dissociative ionization processes in the halogen and interhalogen ions studied.     

Determination of Cl?, NO3? and SO42? in Pore waters of sediments

Summary It is shown that ion chromatography can be successfully employed for the determination of Cl^–, NO ₃ ^– , and SO ₄ ^2– in pore waters of sediment cores. Using three examples of different sediment cores from the Elbe river estuary the application and the relevance of the results are demonstrated.

---

Bestimmung von Cl^–, NO ₃ ^– und SO ₄ ^2– in Sediment-Porenwässern

Zusammenfassung Es wird gezeigt, daß die Analyse von Cl^–, NO ₃ ^– und SO ₄ ^2– in Porenwässern von Sedimentkernen mit Vorteil durch ein ionenchromatographisches Verfahren durchgeführt werden kann. An drei Beispielen von Sedimentkernen aus unterschiedlichen Bereichen des Elbeaestuars wird die Einsatzmöglichkeit und die Aussagekraft der Methode demonstriert.

---

---

Lecture given at the Symposium on Inorganic Anion Analysis, Regensburg, 19.–21.9. 1984     

Electronic structure of Re2Cl82−

The multiple scattering Xα method has been used to calculate the ordering of both occupied and unoccupied one-electron energy states of Re₃Cl₈^2?. Single crystal polarized electronic spectra of [(n-C₄H₉)₄N]₂[Re₂Cl₈] have been measured at 5 K. Principal band maxima are observed at 14 180 (z), 30870 (xy), and 39 215 (z) cm^?1. The calculation, observed polarizations, and a comparison of band positions in Re₂Cl₈^2? and Re₂Br₈^2? suggest the following transition assignments for the former complex: 14 180 cm^?1, b_2gδ → b_1uδ*; 30 870 cm^?1, e_g → b_1uδ*; 39 215 cm^?1, e_uπ → e_gπ*.     

The electronic structure of N4O62+ and the bonding interaction of NO+ and NO3−

The results are reported of an MO-SCF-CNDO/2 study of the experimental and optimal geometries of the N₄O₆²⁺ion cluster. The calculations are shown to support the stable existence of the N₄O₆²⁺ complex and the suggestion of its discoverers [1] on the role of NO⁺ in the N₂O₄ solutions. The proposed interpretation of the bonding interaction explains why the shortest N β O distances are found with the NO⁺ ions which have their nitrogen atoms displaced out of the NO₃^? plane.