Modulation of active Cr(III) complexes by bath preparation to adjust Cr(III) electrodeposition

The preparation process of the Cr（III） bath was studied based on a perspective of accelerating the formation of active Cr（III） complexes. The results of ultraviolet-visible absorption spectroscopy （UV-Vis） and electrodeposition showed that active Cr（III） complexes in the bath prepared at room temperature in several days were rare for depositing chromium. The increase of heating temperature, time, and pH value during the bath preparation promoted the formation of active Cr（III） complexes. The chromium deposition rate increased with the concentration of active Cr（III） complexes increasing. Increasing the heating temperature from 60 to 96℃, the chromium deposition rate increased from 0.40 to 0.71μm/min. When the concentration of active Cr（III） complexes increased, the grain size of Cr coatings increased, and the carbon content of the coating decreased. It is deduced that Cr（H20）4（OH）L2＋ （L is an organic ligand, and its valence is omitted） is a primary active Cr（III） complex.

Synthesis,Crystal Structure and Interaction with DNA of a Novel Chromium(Ⅲ) Complex Containing Salicylaldehyde Semicarbazone

The novel chromium（Ⅲ） complex with salicylaldehyde semicarbazone was synthesized and characterized by IR spectra and single-crystal X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space group Pbca with a = 8.9849（13）, b = 12.0475（16）, c = 34.522（5）A, V = 3736.9（9）A3, Z = 8, C16H18C1CrN6O5, Mr= 461.81, De= 1.642 g/cm^3, F（000） = 1896,A（MoKα） = 0.799 mm^-1, the final R = 0.0370 and wR = 0.0827 for 2908 observed reflections with I 〉 2σ（I）. The interaction between the chromium（Ⅲ） complex with calf thymus DNA （Ct-DNA） has been investigated by absorption spectroscopy, fluorescence spectroscopy and viscosity measurements. The results indicated that the complex was bonded to Ct-DNA through a non-classical intercalative mode.

Effects of Complexes and pH Buffer Solution in Electrokinetic Oxidation Treatment on Sediments Chromium Removal

Three electrokinetic（EK） experiments were designed to study the remediation efficiency of Cr（Ⅲ） by EK-oxidation method and to investigate the influence of complexes and p H buffer solution in EK-oxidation process. Sediments Cr（Ⅲ） can be oxidized into Cr（Ⅵ） effectively by KMn O4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The p H control and KMn O4 improved the removal of Cr（Ⅵ） and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr（Ⅲ） in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the p H of cathode and anode pond solution on EK-oxidation processes.

Synthesis, Characterization and X-Ray Structure of a Ba(II)/Ag(I)/Cr(III)-Oxalate Salt with Water-Filled Nanochannels

A novel mixed barium(II)/silver(I)/chromium(III) oxalate salt, Ba0.5Ag2[Cr(C2O4)3]·5H2O (1), with open architecture has been synthesized in water and characterized by elemental analysis, vibrational and electronic spectra, and single crystal X-ray structure determination. Compound 1 crystallizes in a monoclinic space group C2/c, with unit cell parameters a = 18.179(3), b = 14.743(2), c = 12.278(2)Å, β = 113.821(3), V = 3010.34(90) Å3, Z = 8. The structure is characterized by a network of anionic [Cr(C2O4)3]3- units connected through the O atoms of the oxalates to Ba2+ and Ag+ sites, forming a three-dimensional coordination polymer with one-dimensional isolated nanochannels parallel to the c axis, and encapsulating hydrogen-bonded guest water molecules. The bulk structure is consolidated by O–H···O bridgings within the nanochannels and by coulombic interactions.

Preparation and Thermal Decomposition of [Cr (salen) (H_2O)_2] Cl

A complex of N.N'-ethylencbis (saliylidenemininato) diaquochromium(III) chloride.[Cr (salen) (H2O)2] Cl was prepared. and its decomposition mechanism was studied by TG and DTA. The IR spectrum of the product of thermal decomposition was examined at the first stage.Kinetic results were obtained from the analysis of TG-DTG curves with three different methods The most probable kinetic functions were suggested by comparison of kinetic parameters,

A Novel Chromium(III) Hybrid Salt, Triethylammonium <i>Trans</i>-Diaquabis(Oxalato-<i>κ</i>²O¹,O²) Chromate(III), (C<SUB>6</SUB>H<SUB>16</SUB>N)[Cr(C<SUB>2</SUB>O<SUB>4</SUB>)<SUB>2</SUB>(H<SUB>2</SUB>O) <SUB>2</SUB>]: Synthesis, Spectroscopic Studies, Thermal Behavior and Crystal Structure

A novel organic-inorganic chromium(III) hybrid salt, triethylammonium trans-diaquabis(oxalato-κ2O1,O2)chromate(III), (C6H16N)[Cr(C2O4)2(H2O)2] (1), has been synthesized in aqueous solution and characterized by elemental and thermal analyses, FTIR and UV-Vis spectroscopies, and by single crystal X-ray structure determination. Compound 1 crystallizes in the orthorhombic system, Pbcn space group with the unit cell parameters a = 11.1776(10), b = 7.6105(10), c = 17.5654(2) Å, α = β = γ = 90°, V = 1494.24(3) Å3, Z = 4 and Z’ = 1/2. The structure of 1 consists of [Cr(C2O4)2(H2O)2]− mononuclear anions and triethylammonium [(C2H5)3NH]+ cations. In the anionic unit, the CrIII ion is six coordinated, in a distorted octahedral geometry, by four equatorial O atoms of two oxalate anions acting as chelating ligands and two O atoms from trans-coordinated water molecules occupying the apical positions with longer metal-oxygen distances. In the solid, O-H … O and N-H … O intra and inter molecular hydrogen bonding interactions connect the components into a 3D network. The triethylammonium cations are disordered among two possible orientations with occupancies rates around 50% for C4, N1, C1a, C1b, C4ii, N1ii, C1aii, C1bii (ii = −x + 1, y, − z + 1/2). The IR spectrum of 1 is consistent with the presence of the various molecular building constituents. The UV-Vis spectrum shows two absorption bands around 564 and 416 nm which are compatible with an anionic chromium (III) complex in an octahedral environment. Thermal studies carried out in air between 25°C and 700°C confirm the anhydrous character of 1 and show that it is stable up to 210°C.

Infrared spectra and normal coordinate analysis of trinuclear μ_3-oxoacetato complexes of chromium and iron

The IR spectra of four u_3-oxo-acetato complexes of Cr(Ⅲ)and Fe(Ⅲ)are reported in this paper.The assignments of v(Cr-L)are made empirically by comparing the IR spectra of serial compounds and experimentally by carrying out a variable-temperature experiment in situ. A simplified model was employed for the normal coordinate analysis of two homo-nuclear skeletons and their force constants have been calculated.In terms of the relationship between the IR spectra and their structure the rationality and reliability of the results are discussed.At the same time the as- signments which are discordant in the references are checked by calculation and the more rational results have been obtained.

Influence of microwave on chromium complex composition in tanning liquor

Since microwave irradiation could promote hydrolysis and olation of chromium tanning liquor,but the influence of microwave on chromium complex component in the liquor was still unknown.Chromium sulphate solution(0%basicity)and 33%basicity chromium tanning liquor were subjected microwave(MW)and water bath(WB)heating,and the samples without any warming were regarded as control.Ion exchange chromatography(IEC)and gel filtration chromatography(GFC)were used to measure the charge composition and molecular size of chromium complexes in each sample.FT-IR was used to characterize the structure of chromium complexes in each composition separated by IEC.Moreover,the chromium tanning liquor after warming was used in hide powder tanning trials to illustrate whether microwave would affect its tanning ability.The results show there are more high positive charge and large molecular size complexes in chromium tanning liquor after warming but the phenomena are more significant in MW samples compared with WB due to non-thermal effect of microwave.In addition,microwave has more powerful effect on 33%basicity chromium tanning liquor hydrolysis and olation to generate larger molecular size complexes.In FT-IR results,the combination pattern between chromium and ligands are changed after warming but there is no difference between WB and MW.The chromium exhaustion and thermal stability of hide powder tanned with chromium tanning liquor after microwave irradiation are both higher.It could conclude that both thermal and non-thermal effects of microwave promote the process together,and the nonthermal effect leads to more high positive charge and large molecular size complexes and has stronger influence on high polarity system.In short,this work would provide theoretical basis for applying microwave in tanning agent modification and chrome tanning process further.

MCM-41 Immobilized Acidic Functional Ionic Liquid and Chro mium（Ⅲ） Complexes Catalyzed Conversion of Hexose into 5-Hydroxymethylfurfural

The development of novel methods to obtain biofuels and chemicals from biomass has been an immediate issue in both academic and industrial communities. In this work, a series of novel catalysts were prepared and character- ized by FT-IR, TGA, XRD, SEM, TEM, ICP-AES, NH3-TPD and BET, which were applied for the conversion of hexose to 5-hydroxymethylfurfural （HMF）. The Cr（Salten）-MCM-41-[（CH2）3SO3HVIm]HSO4 catalyst was the most active catalyst, and a glucose conversion of 99.8% with 50.2% HMF yield was obtained at 140 ℃ for 4 h in dimethyl sulfoxide （DMSO）. The effects of reaction temperature, reaction time, solvents and catalyst dosages were investigated in detail. MCM-41 immobilized acidic functional ionic liquid and chromium（III） Schiff base complex- es as heterogeneous catalysts can be easily recovered by simple filter treatment, exhibiting excellent stability and activity towards hexose conversion. Thus the heterogeneous catalysts were environment-friendly for transforming biomass carbohydrates into fine chemicals.

Rapid Thermolysis Studies of [Pb2（TNR）2（CHZ）2（H2O）2]·4H2O and Cd（CHZ）2（TNR）（H2O）

T-jump/FT-IR spectroscopy was used to study the rapid thermal decomposition activity of [Pb2（TNR）2（CHZ）2（H2O）2]·4H2O and Cd（CHZ）2（TNR）（H2O） under 0.1 MPa Ar atmosphere. The results show that the main gaseous products of [Pb2（TNR）2（CHZ）2（H2O）2]·4H2O are NH3, H2O and HONO, while CO and NO are the major gaseous products of flash pyrolysis of Cd（CHZ）2（TNR）（H2O）. Thus Cd（CHZ）2（TNR）（H2O） is not an eco-friendly and chemically compatible primary explosive. Both compounds liberate volatile metal carbonate, oxide and isocyanate compounds. The combustion temperature and products of the two compounds were calculated by Real code. The results of theoretical calculation show that the combustion temperature of [Pb2（TNR）2（CHZ）2（H2O）2].4H2O is higher than that of Cd（CHZ）2（TNR）（H2O）, there is no HNCO in the combus- tion products and the amount of NO is less than the experiment result from T-jump/FTIR.