Ultraviolet spectroscopic study of ferric hydroxide complexation

Ultraviolet absorbance spectra of ferric ions in 0.68m NaClO₄ were studied as a function of pH at 4.0, 14.9, and 25.0°C. The results provided an evaluation of the stability constant for the formation of FeOH²⁺ which is *₁=[FeOH ⁺][H ⁺]/[Fe ³⁺]. The enthalpy change for the reaction Fe³⁺+H₂O FeOH²⁺+H⁺ was calculated as 10.0±0.3 kcal-mole^–1. Increasing temperature was also found to promote the reaction Fe³⁺+2H₂O Fe(OH) ₂ ⁺ +2H⁺. Our results were combined with the results of other to produce an expression describing the first hydrolysis equilibrium at ionic strengths between 0 and 3m and temperatures between 4.0 and 45.0°C at 1 atm total pressure. At 25°C and 0.68m the ionic strength *₁=1.90×10^-3     

聚合氯化铁的制备及其絮凝效果

以赤铁矿和工业盐酸为原料,采用盐酸酸浸和加碱聚合等方法制取聚合氯化铁絮凝剂(PFC),将其用来处理造纸废水,并与市售聚合氯化铁和碱式氯化铝絮凝剂进行比较.结果表明,在碱化度为2∶1、聚合温度为40℃、陈化时间为24h时,自制聚合氯化铁絮凝剂对造纸废水具有较好的处理效果;投加量为1.4mL/L时,造纸废水的浊度降低了99%,化学需氧量(COD)降低了69.55%,优于市售絮凝剂对造纸废水的处理效果;且三种絮凝剂用量相同时,自制的聚合氯化铁絮凝剂形成絮体的速率和沉降速率都较快.     

Dielectric investigation of the effect of ferric chloride on viscose fibres

Measurements of the dielectric constant and the dielectric loss, at frequencies of 0.05-10 kHz over a temperature range of 10–60 °C, were carried out on viscose fibres, viscose with iron adsorbed and with iron removed. The results obtained show that: (i) a relaxation process is observed in the low-frequency region only in the case of the viscose-iron complex, and (ii) the variation of the dielectric constant with temperature showed a transition at about 30 °C with the untreated fibres, and the transition disappeared when the fibres were treated with ferric chloride. These results, together with changes in hydrogen bonding obtained from infrared spectra for these samples are discussed. Oxidation and adsorption of ferric ions can modify the dielectric properties of viscose fibres.     

Synthesis of pyrimidine derivatives via multicomponent reaction catalyzed by ferric chloride

An eco-friendly and practical approach was developed for the synthesis of pyrimidine derivatives via a one-pot, three-component coupling reaction of commercially available aldehydes, alkynes, and indazole3/triazole catalyzed by ferric chloride with good to excellent yields. The advantages of this method include environmentally friendly catalyst, easily available materials, and ease of product isolation.     

聚氯乙烯支载三氯化铁试剂催化醛与乙酸酐反应合成 乙酰缩醛

聚氯乙烯支载三氯化铁(PVC-FeCl3)试剂在室温条件下能方便快速催化各类醛与乙酸酐反应,以良好产率(75%～96%)生成相应乙酰缩醛。     

Crystal field calculation of g values and zero-field splitting for high spin ferric complexes of rhombic character

For high spin ferric ions in rhombic symmetry, we have used a crystal field model to relate term splittings of the ⁴ T ₁, ² T ₂ and ⁴ T ₂ excited states to zerofield split energies and g values of the ⁶ A ₁ term. In this model five crystal field parameters were used, namely, one cubic parameter, two tetragonal parameters and second and fourth order rhombic parameters. In tetragonal symmetry with only three crystal field parameters, a simpler model including only the ⁴ T ₁ and ² T ₂ excited states is adequate to relate term energies to g values and zero-field split energies. However, we have demonstrated the importance of the ⁴ T ₂ state in rhombic crystalline fields. No higher lying terms other than ⁴ T ₂ can influence the ⁴ T ₁ term directly through the tetragonal or rhombic crystal field, Furthermore, we show that the fourth order rhombic crystal field parameter is a key parameter because the rhombic splitting of the dominant low lying ⁴ T ₁ term of high spin ferric complexes depends to first order on the fourth order crystal field potential. We have performed a computer diagonalization of the spin-orbit, electrostatic and crystal field perturbation matrix, and calculated g values and zero-field splittings in seventeen high spin ferric mixed crystalline species of varying rhombicities and for metmyoglobin and cytochrome P-450. The high spin and spin-mixed regions are developed completely to yield the crystal field term energies, zero-field splittings and basis functions together with g values.     

1H NMR spectroscopic study of theert-butyl chloride—aluminum bromide cationic initiating system

The interaction oftert-butyl chloride with aluminum bromide in methylene dibromide at −30°C leads to the formation of two types of adducts, which give signals with δ 2.4 and 3.2 in the¹H NMR spectra in addition to that of free alkyl halide. these signals are attributed to a polarized complex (PC) and ion pair (IP), respectively. An excess of AlBr₃ shifts the equilibria toward IP. The latter contains more AlBr₃ than the polarized complex. Based on the spectral data, we calculated the limiting values of some equilibrium constants. The ability of AlBr₃ to solvate counterions is consistent with the results of isobutylene polymerization under the action of the initiating Bu^tCl−AlBr₃ system at different ratios of the starting concentrations [AlBr₃]₀/[Bu^tCl]₀. An increase in this ratio results in both the acceleration of polymerization and an increase in the relative role of chain transfer reactions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2217–2222, November, 1998.     

Structural studies of the cadmium(II) chloride / sparteine system

The reaction of dichlorocadmium(II) and (-)-sparteine (sp) provides two products, [CdCl₂(sp)]) (1) and (Hsp)₃[Cd₂Cl₇] (2). The latter represents one of the rare known examples exhibiting an isolated Cd₂Cl₇^3? trianion. Both products are formed in the same reaction mixture and single crystals of one of the two products can be obtained selectively by crystallization depending on the co-solvent. The formation and structural characterization of (H₂sp)[CdCl₄] (3) is also reported, crystallizing with either dichloromethane (3a) or water (3b) as guest molecules.     

离子色谱法检测高纯硅微粉中痕量铁和氧化铁杂质

建立了柱后衍生-紫外检测-离子色谱法同时测定高纯硅微粉中痕量铁和氧化铁杂质含量的方法。方法选用具有阴阳离子交换基团的高选择性Thermo Scientific Dionex^TM IonPac^TM CS5A色谱柱,选择与铁形成单一络合形态、中等络合能力的2,6-吡啶二羧酸（PDCA）为淋洗液,在线柱后添加普适性的4-2-吡啶偶氮苯二酚（PAR）金属显色剂,于530 nm波长下准确完成了二价和三价铁离子的分离测定。结果表明,本方法对二价铁离子和三价铁离子的检出限分别为0.013 mg/kg和0.006 mg/kg,线性相关系数r²均大于0.999,实际样品中二价铁和三价铁的加标回收率分别为79%~90%和92%~105%,具有较高的灵敏度、准确度和选择性。该方法可以准确测定高纯硅微粉中痕量二价铁和三价铁的含量,以此结果反馈高纯硅微粉产品中铁杂质含量的不同来源,为其生产工艺的持续优化和改进提供重要的参考数据。     

Cryosynthesis,structure, and spectroscopic properties of aluminum chloride—cobalt(ii) chloride complexes: experiment and calculations

Products of co-condensation of aluminum chloride and cobalt(ii) chloride vapors were studied by low-temperature (80—200 K) IR spectroscopy. In addition to 2 : 1 complexes, previously unknown equimolar associates were found and their IR spectra were investigated. Quantum-mechanical calculations were carried out including electron correlation with the use of the B3LYP and PBE density functionals. The geometric structures were optimized and harmonic vibrational frequencies of the molecules of aluminum chloride, cobalt chloride, and their complexes with different compositions were calculated. Under conditions of limited molecular mobility, the (AlCl₃)₂·CoCl₂ complexes can be stabilized in structures containing the Co atom in a tetrahedral or distorted octahedral environment. Their thermal stability limits were determined. It was found that labile ionic species are generated in the reactions of aluminum chloride complexes with cobalt chloride with different compositions at 120—170 K.     

Comparative study of spectroscopic techniques for the estimation of iron in apple and vegetables

Iron has been determined in apple and vegetables spectrophotometrically, by complexing it with xylenol orange. 1:1 complex formed in a highly acidic medium is measured for its absorbance at its λ_max of 585 nm. The results have been compared by employing atomic absorption technique. Apples and vegetable samples were collected from local markets of Pakistan. Statistical manipulations, t-test and F-test, were performed and it was found that the results from the two techniques have an excellent agreement.     

IR spectroscopic andab initio quantum-chemical study of the products of hydrolysis of silicon tetrafluoride at low water concentrations

According to the results of IR spectroscopic study and quantum-chemical calculations, hydroxo derivatives SiF_4-x(OH)_x are formed in the course of hydrolysis of silicon tetrafluoride in the presence of small amount of water along with hexafluorodisiloxane. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 92–96, January, 1999.     

Viscosity of aqueous calcium chloride solutions at high temperatures and high pressures

Viscosity of six (0.10, 0.33, 0.65, 0.97, 1.40, and 2.00) mol kg⁻¹ binary aqueous CaCl₂ solutions has been measured with a capillary-flow technique. Measurements were made at pressures up to 60 MPa. The range of temperature was from 293 to 575 K. The total uncertainty of viscosity, pressure, temperature, and composition measurements was estimated to be less than 1.6%, 0.05%, 15 mK, and 0.014%, respectively. The effect of temperature, pressure, and concentration on viscosity of binary aqueous CaCl₂ solutions was studied. The measured values of viscosity of CaCl₂(aq) were compared with data, predictions, and correlations reported in the literature. The temperature and pressure coefficients of viscosity of CaCl₂(aq) were studied as a function of concentration and temperature. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for the relative viscosity (η/η₀) to accurate calculate the values of viscosity A- and B-coefficients as a function of temperature. The derived values of the viscosity B-coefficients were compared with the values calculated from the ionic B-coefficient data. The physical meaning parameters V and E in the absolute rate theory of viscosity and hydrodynamic molar volume (effective rigid molar volume of salt) V_k were calculated using present experimental viscosity data. TTG model has been used to compare predicted values of the viscosity of CaCl₂(aq) solutions with experimental values at high pressures.     

Synthesis, spectroscopic and electrochemical studies of a series of transition metal complexes with amino- or bis(bromomethyl)-substituted dppz-ligands: Building blocks for fullerene-based donor-bridge-acceptor dyads

Transition metal complexes with ligands based on dipyrido[3,2-a:2′,3′-c]phenazine (dppz) have been synthesized. As metal fragments the [Ru(bpy)₂]⁺, Re(CO)₃Cl and the [Cu(PPh₃)₂]⁺ moieties have been used. The complexes containing amino- or bis(bromomethyl) substituted dppz ligands can be used for fullerene-based donor-bridge-acceptor dyads. The electronic absorption spectra of these complexes and of the dppz ligands were investigated. The dppz ligands show strong absorptions in the 300 and 390 nm region. An additional absorption band in the visible region (∼440 nm) is observed for the amino-substituted dppz-ligands. Ruthenium complexes exhibited broad absorption bands at 350-500 nm arising from intraligand-based transitions and the MLCT transition. MLCT transitions of the Re(I) and Cu(I) complexes are observed as shoulders of the stronger ligand-based absorption band tailing out to 400-500 nm. The electrochemically active complexes and ligands were studied by cyclic voltammetry and square-wave voltammetry. All ligands show one first reversible one-electron reduction located at the phenazine portion. These reductions are shifted to more positive redox potentials upon complexation. Oxidation potentials for reversible processes could be determined for the Ru²⁺/Ru³⁺ couple. For rhenium(I) and copper(I) complexes one irreversible oxidation process is observed.     

Synthesis and spectroscopic characteristics of σ-vinyl derivatives of platinum(<Emphasis Type="SmallCaps">IV</Emphasis>) chloride complexes

A procedure was developed for the synthesis of previously unknown β-chlorovinyl derivatives of Pt^IV chloride complexes by chloroplatination of terminal alkynes catalyzed by Pt^II chloride complexes. The reaction is highly stereoselective and gives only the products of trans-anti-addition of platinum and chlorine atoms. The regioselectivity of the catalytic reaction formally corresponds to Markovnikov’s rule, e.g., in alkynes containing electron-donating substituents, platinum attacks the terminal carbon atom. The σ-vinyl derivatives of Pt^IV chloride complexes were characterized by IR spectroscopy and ¹H and ¹³C NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2380–2384, October, 2005.     

Ultraviolet photoelectron spectroscopic study on the interface electronic structure of the L-cysteine on Pd surface

L-cysteine is one of the most versatile biomolecules with a unique metal-binding ability. L-cysteine has an outstanding role in the bioelectronics field as a linker between proteins of biomolecules and metal electrodes of the inorganic metals through multiple functional groups. The interface electronic structures between L-cysteine with metals deserve further investigation for applications in bioelectronics. However, the interface electronic structures of L-cysteine and metals have not been well understood. We have previously reported the existence of a new state between the highest occupied molecular orbital (HOMO) of L-cysteine and the Fermi level of the metals for L-cysteine/Au(111), L-cysteine/Ag(111), and L-cysteine/Cu(111) using photoemission spectroscopy and attributed the formation of the new state to an interaction of the d band with HOMO of L-cysteine. In this study, the electronic structure at the interfaces of L-cysteine on a Palladium (Pd) surface is investigated by ultraviolet photoemission spectroscopy (UPS) using synchrotron radiation including work function, secondary electron cutoff (SECO), and HOMO onset; the position of an interface state, charge injection barrier, and ionization energy are estimated. It is observed that thin-film spectra of L-cysteine on Pd surfaces in the valance top region are different from the L-cysteine thick films, and this can be attributed to an interaction between a sulfur-originated state of L-cysteine HOMO with Pd d orbitals. Also, a 0.6-eV SECO shift is estimated due to the charge transferring between L-cysteine and Pd. The results of SECO further confirm the weakening of the Pd–sulfur bond with increasing L-cysteine coverage on Pd.     

Thermal decomposition of humboldtine: A high resolution thermogravimetric and hot stage Raman spectroscopic study

Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates. These oxalates form as a film like deposit on rocks and other host matrices. Humboldtine as the natural iron(II) oxalate mineral is a classic example. Thermogravimetry coupled to evolved gas mass spectrometry shows dehydration takes place in two steps at 130 and 141°C. Loss of the oxalate as carbon dioxide occurs at 312 and 332°C. Dehydration is readily followed by Raman microscopy in combination with a thermal stage and is observed by the loss of intensity of the OH stretching vibration at 3318 cm^-1. The application of infrared emission spectroscopy supports the results of the TG-MS. Three Raman bands are observed at 1470, 1465 and 1432 cm^-1 attributed the CO symmetric stretching mode. The observation of the three bands supports the concept of multiple iron(II) oxalate phases. The significance of this work rests with the ability of Raman spectroscopy to identify iron(II) oxalate which often occurs as a film on a host rock.This revised version was published online in November 2005 with corrections to the Cover Date.