Silicon-phthalocyanine bonding with SiO2 matrix and its strong optical limiting effects

Silicon-phthalocyanine (SiPc) is chemically bonded to 3-aminopropltriethoxysilane (NH2(CH2)3Si(OC2H5)3, KH550) by the nucleophilic substituted reaction between the active chlorine of silicon dichlorine phthalocyanine (SiPcCl2) and amino-group of KH550. The reacted product is hybridized with 3-glycidoxypropltrimethoxysilane (CH2OCHCH2O(CH2)3Si(OCH3)3, KH560) with sol-gel processing to form sol-gel inorganic material with good physical-chemical and optical properties. Due to tethering SiPc to the network, the aggregation of SiPc is effectively prevented in sol-gel derived matrix, and the doping concentration of SiPc in the form of monomer in the matrix is greatly enhanced. The cross-linkage of SiPcCl2 and KH550 is estimated and confirmed with FT-IR spectra. The optical limiting effects (OLE) of the gel with different content of SiPc are investigated with a frequency double Q-switched Nd3+:YAG laser of 8 nsec. pulse.     

Li1+xAlxTi2-x(PO4)3(x=0~0.4)溶胶-凝胶法合成及其性质

以乙酸锂、硝酸铝、钛酸丁酯、磷酸二氢铵为原料,利用溶胶-凝胶法合成锂离子Li_1+xAl_xTi_2-x(PO₄)₃(x=0~0.4)固体电解质体系,检测结果表明：Li_1+xAl_xTi_2-x(PO₄)₃体系具有较好的结晶性,合成的粉末与烧结片之间的结晶性与结构差异不大;当Al³⁺掺杂量逐步增加时,离子电导率逐渐增大,并在x=0.3时达到最大值,但掺杂量进一步增加时,离子电导率迅速下降;活化能的变化趋势与离子电导率相反.     

Modification and investigation of silica particles as a foam stabilizer

As a solid foam stabilizer, spherical silica particles with diameters ranging from 150 to 190 nm were prepared via an improved Stöber method and were subsequently modified using three different silane coupling agents to attain the optimum surface hydrophobicity of the particles. Fourier transform infrared (FTIR) spectra and the measured contact angles were used to characterize the surface properties of the prepared particles. The foam stability was investigated by the foam drainage half-life and the expansion viscoelastic modulus of the liquid film. The results demonstrate that all of the modified silica nanoparticles effectively improve the foam stability. The surface hydrophobicity of the modified particles is found to be a key factor influencing the foam stability. The optimum contact angle of the particles lies in the approximate range from 50° to 55°. The modifier molecular structure used can also influence the stabilizing foam property of the solid particles. The foam system stabilized by (CH₃)₂SiCl₂-modified silica particles exhibits the highest stability; its drainage half-life at maximum increases by 27% compared to that of the blank foam system and is substantially greater than those of the foam systems stabilized by KH570- and KH550-modified particles.     

Synthesis of new bis-diphenyl-22-and diphenyl-11-membered ring N-pivot lariat crown ethers

Bis-diphenyl 22 and 11-Membered Ring N-pivot lariat Crown Ethers^[1,2] were prepared by one step reaction of 2,2′-dihydroxy-diphenyl with N-tosyl-diethanolamine ditoskylate in DMF at refluxing temperature under N₂, Using anhydrous potassium carbonate as condensing agent, respectirely. The tosyl group of (1,2) were removed by treatment with 40% HBr in AcoH in the presence gf a large amount of phenol to give correspondence crown ether compounds (3,4). New N-pirot lariat crown thers (5,6) were prepared by one step reaction of (3) with RBr (R=?CH₂CH=CH₂, ?CH₂(CH₂)₁₄CH₃) in CH₃CN at, refluxing temperature under N₂, Using anhydrous K₂CO₃ as condensing, agent. New N-pivot lariat croon ether(7) were prepared by one step reaction (4) withn-bromohexadecane in CH₃CN at refluxing temperature under N₂, Using anhydrous potassium carbonate as condensing agent. New compounds (1,3,5,6,7) were characterized by IR,¹H NMR, Ms and elemental analysis.     

Syntheses, characterization, crystal structure and magnetic properties of copper(Ⅱ)α, β-unsaturated carboxylate complexes with trimethyl phosphate

Two ternary complexes Cu2A4[OP(OCH₃)₃]₂ (A represents CH₂== CH—COO- and CH₂== C(CH₃)—COO-) have been synthesized, and elemental analyses, IR, ESR, electronic reflectance spectra and magnetic studies were carried out. The single crystal X-ray diffraction shows that Cu₂[CH₂== C(CH₃)—COO]₄[OP(OCH₃)₃]₂ is triclinic, with space group P1, a = 1.05128(13), b = 1.7559(5), c = 1.94479(3) nm, α = 91.263(14)°, β = 102.559(6)°, γ = 106.339(13)°, Z = 4 and R = 0.0668. Two copper(Ⅱ) atoms are bridged by four a -methacrylate groups, and each copper(Ⅱ) atom is coordinated with a trimethyl phosphate molecule in the axial position, forming a distorted square pyramidal configuration. The symmetric center is between the two copper(Ⅱ) atoms, and the Cu-Cu bond distance is 0.26098(6) nm. The Cu-Cu distance and magnetic studies suggest that there exist antiferromagnetic interactions between the two copper(Ⅱ) atoms.     

Surface chemical structure of titania-silica nanocomposite powder

Titania-silica （TS） nanocomposite powder with three different composite structures, containing 10-30 mol% SiO2 in each structure, have been prepared by sol-gel processes. The surface characteristics of these titania-silica samples have been investigated by X-ray photo-emission spectroscopy （XPS） and high resolution transmission electron microscopy （HRTEM）. The study for all TS oxides annealed at 773 and 1173 K showed： an abnormal surface enrichment in Si increased with increasing annealing temperature; the Ti^3＋, Ti^2＋, Si^3＋ and Si^2＋ oxides coexisted with Ti^4＋ and Si^4＋ oxides, and the contents of these Ti/Si suboxides increased with increasing SiO2 content and annealing temperature; there was a layer rich in O on the topmost surface and the excess O could be attributed to the chem-adsorption of H2O; different composite structures could lead to different contents of Ti/Si suboxides. These results indicated that the surface of TS oxide powder derived by sol-gel process was a double layer with enriched O first and then SiOx/TiOy（x, y〈2）. Ti/Si suboxides could result from the thermal diffusion of Ti^4＋ and Si^4＋, which might be induced by the strong interaction between Ti^4＋ and Si^4＋.     

Rate constants for the reaction of ozone with <Emphasis Type="Italic">n</Emphasis>-butyl, <Emphasis Type="Italic">s</Emphasis>-butyl and <Emphasis Type="Italic">t</Emphasis>-butyl methyl sulfides

The rate constants for the ozone reactions with n-butyl methyl sulfide （n-BMS, CHaCH2CH2CH2SCH3）, sec-butyl methyl sulfide （s-BMS, CH3CH2（CH3）CHSCHa） and tert-butyl methyl sulfide （t-BMS, （CH3）3CSCH3） were measured using our smog chamber under supposedly pseudo-first-order conditions at 30002 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are （1.23 ± 0.06）×10-19, （5.08 ± 0.19）×10-20 and （2.26 ± 0.14）×10-20 cm3 molecule-1· s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.     

纳米SiO2的制备及性能研究

 用溶胶—凝胶法制备了纳米SiO₂,考察了溶胶的浓度和pH值对凝胶时间的影响,并用FT-IR,XRD和TEM研究了其在热处理过程中的物相及显微结构.结果表明:溶胶浓度和溶胶pH值对凝胶时间影响较大.在温度为600℃时,经过烧结晶化,可制得纳米二氧化硅,其平均粒径20nm,外观形状呈球形,且热稳定性良好.     

Synthesis and characterization of carbon-bridged bis(phenolate) lanthanum alkoxides and their catalytic behavior for the polymerization of L-lactide

Four lanthanum alkoxides stabilized by a carbon-bridged bis(phenolate) ligand were synthesized and their catalytic behavior for the ring-opening polymerization of L-lactide was explored. Reactions of [(MBMP)LaCp(THF) 2 ] (MBMP 2 = 2,2′-methylene-bis(6-tert-butyl-4-methyl phenoxo)) with HOCH 2 Ph, HOCH 2 CF 3 , HOCH(CH 3 ) 2 , and HOCH 2 CH 2 N(CH 3 ) 2 , respectively, in a 1:1 molar ratio in THF gave the dimeric lanthanum alkoxo complexes [(MBMP)Ln(μ-OR)(THF) 2 ] 2 (OR = OCH 2 Ph(1), OCH 2 CF 3 (2), OCH(CH 3 ) 2 (3), OCH 2 CH 2 N(CH 3 ) 2 (4)]. These complexes were well characterized, and the definitive molecular structure of complex 1 was determined. It was found that complexes 1 to 4 are efficient initiators for the ring-opening polymerization of L-lactide. The structure of the alkoxo groups has a significant effect on the catalytic behavior, and complex 2 can initiate L-lactide polymerization in a controlled manner.     

Al2O3-SiC纳米复合陶瓷的制备及其表征

以分析纯Al(NO₃)₃·9H₂O, (CH₂)₆N₄和粒径为30 nm的SiC粉末为原料, 采用溶胶-凝胶(sol-gel)方法制备干凝胶, 经煅烧合成Al₂O₃-SiC纳米陶瓷粉, 利用真空热压装置对粉末进行烧结. 通过X射线衍射(XRD)、 扫描电镜(SEM)和维氏硬度实验分析了不同SiC含量和不同烧结温度的Al₂O₃-SiC陶瓷样品的结构、 形貌、 晶粒尺寸和硬度, 并研究了其机理.     

Investigation of adsorption of surfactant at the air-water interface with quantum chemistry method

Density functional theory （DFT） of quantum chemistry was used to optimize the configuration of the anionic surfactant complexes CH3（CH2）7OSO3^- （H2O）n （n=0-6） and calculate their molecular frequencies at the B3LYP/6-311＋G^＊ level. The interaction of CH3（CH2）7OSO3^- with 1 to 6 water molecules was investigated at the air-water interface with DFT. The results revealed that the hydration shell was formed in the form of H-bond between the hydrophilic group of CH3（CH2）7OSO3^- and 6 waters. The strength of H-bonds belongs to medium. Binding free energy revealed that the hydration shell was stable. The increase of the number of water molecules will cause increases of the total charge of hydrophilic group and S10-O9-C8 bond angle, but decreases of the alkyl chain length and the bond lengths of S10-O11, S10-O12 as well as S10-O13, respectively.     

Theoretical characterization of single-electron iodine-bond weak interactions in CH3…I-Y（Y=BH2,H,CH3,C2H3,C2H,CN,NC）systems

Iodine-involved single-electron halogen bonds (SEXBs) weak interactions in the systems of CH3···I-Y(Y = BH2, H, CH3, CH==CH2, C≡CH, CN, NC) were investigated for the first time using B3LYP/6-311++G(d,p) and MP2/aug-cc-pVTZ computational levels (the relativistic effective core potential basis set of Lanl2dz was used on iodine atom). The interaction energies between two moieties with basis set super-position error corrections for the seven complexes are -0.57, -1.36, -3.80, -2.17, -4.49,-6.33 and -8.64 kJ mol-1 (MP2/aug-cc-pVTZ ), respectively, which shows that SEXBs interactions are all weak. Natural bond orbital theory analysis revealed that charges flow from CH3 to the I-Y moiety. The total amount of natural bond orbital charge transfer (ΔNC) from the CH3 radical to I-Y increases in the order CH3…IBH2 < CH3…IH ≈ CH3…ICH3 ≈ CH3···IC2H3 < CH3…ICCH< CH3…ICN< CH3…INC. Atoms-in-molecules theory was used to investigate the topological properties of the bond critical points in the seven SEXB structures.     

Synthesis and crystal structure of hydroquinone-β-cyclodextrin complex

The title inclusion complex with the formula [(C₄₂H₇₀O₃₅)₂·(C₆O₂H₆)₃·(H₂O)_21.2(CH₃OH)₂] has been crystallized and characterized by single crystal X-ray analysis. The complex crystallizes in the triclinic system, space group P1, with a = 1.5500 (1), b = 1.5536(1), c = 1.8246(1) nm, α = 113.17(2), β = 99.12(2), γ = 103.37(3)o, V = 3.7739 (4) nm³, Z = 1; D_c = 1.343 g/cm³, μ = 0.124 mm^-1, F(000) = 1594, R = 0.0795 and S = 0.9639. Two independent molecules of β -cyclodextrin (β -CD) form a “head-to-head” dimer. The fairly important factor of the position and stability of the guest in the host cavity is the solvation of the polar group of the guest.     

Acidic catalysis of microporous polyoxometalate H3PW12O40/Sio2 in acetal reaction between benzaldehyde and ethylene glycol

Microporous Keggin-type polyoxometalate material was synthesised by supporting H3PW12O40 into a silica matrix via a sol-gel technique. The silica-supported 12-tungstophosphoric acid ( H₃PW₁₂O₄₀/Sio₂ ) obtained is insoluble and readily separable porous materials with uniform micropores (0. 57 nm) and a high specific surface area (350. 5 m2/g) in oxygen-containing polar solvents. H3PW12 O4o/Si02 was characterized by infrared spectrophotometer (IR). ultraviolet-visible spectrophotometer (UV-vis). inductively coupled plasma (ICP)> thermogravimetric analysis (TGA) and Brunner-Emmett-Teller method (BET) measurements. H3PWi204o/Si02 obtained catalyzed the acetal reaction between benzaldehyde and ethylene glycol to produce 2-phenyl-l > 3-dioxolane more efficiently than the typical solid acids such as SO4 /ZrO2' Nafion-H and H-ZSM-5. Conversion was 93. 8% for benzaldehyde during the reaction period of 2 h. H₃PW₁₂O₄₀/Sio₂ kept its initial activity during three times of reuse. The initial acetal reaction follows a second-order kinetics model at 298 K.     

The enhanced corrosion resistance of UMAO coatings on Mg by silane treatment

The surface silanization was carried out on ultrasonic micro-arc oxidation(UMAO) coatings on pure magnesium using KH550 as silane coupling agent(SCA). The surface morphology, chemical bonds and corrosion resistance of the silane films were investigated by scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FTIR) and electrochemical workstation, respectively. The results showed that hybrid coatings were successfully prepared on pure magnesium by UMAO-Na OH(1 mol/L, 2 mol/L, 3 mol/L)-SCA processing. The organic films with Si–O–Mg bonds are helpful for the reduction of the pores in UMAO coatings. The pores decreased with increasing Na OH concentration. Compared with single UMAO treatment, the corrosion potentials(Ecorr) of magnesium plates with UMAO-Na OH(1 mol/L,2 mol/L, 3 mol/L)-SCA treatment increased by 29 m V, 53 m V and 75 m V, respectively, meanwhile the corrosion current density(Icorr) reduced one to two orders of magnitude. It indicated that the corrosion resistance of the coatings was improved by silane treatment.     

Fabrication and characterization of nanocrystalline Al/Al12（Fe,V）3Si alloys by consolidation of mechanically alloyed powders

The aim of this study was to produce bulk nanocrystalline Al/Al12（Fe,V）3Si alloys by mechanical alloying （MA） and subsequent hot pressing （HP） of elemental powders. A nanostructured Al-based solid solution was formed by MA of elemental powders for 60 h. After HP of the as-milled powders at 550℃ for 20 min, the Al12（Fe,V）3Si phase was precipitated in a nanocrystalline Al matrix. Scanning electron microscopy （SEM） images of the bulk samples represented a homogeneous and uniform microstructure that was superior to those previously obtained by rapid solidification-powder metallurgy （RS-PM）. Nanostructured Al-8.5Fe-1.3V-1.7Si and Al-11.6Fe-1.3V-2.3Si alloys ex-hibited high HV hardness values of～205 and～254, respectively, which are significantly higher than those reported for the RS-PM counter-parts.     

Preparation and performance of dye-sensitized solar cells based on ZnO-modified TiO<Subscript>2</Subscript> electrodes

The ZnO-modified TiO₂ electrode was prepared by adding Zn(CH₃COO)₂·2H₂O to the TiO₂ colloid during the sol-gel production process, and was used in dye-sensitized solar cells (DSCs). The open circuit voltage (V _OC) and fill factor (ff) of the cells were improved significantly. The performances of the ZnO-modified TiO₂ electrode such as dark current, transient photocurrent, impedance, absorption spectra, and flat band potential (V _fb) were investigated. It is found that the interface charge recombination impedance increases and V _fb shifts about 200 mV toward the cathodic potential. The effect mechanism of ZnO modification on the performance of DSCs may be that ZnO occupies the surface states of the TiO₂ film.     

Direct determination of trace silicon in lanthanum oxide by using a selective volatility and slurry sampling-FETV-ICP-AES

A new method for determination of trace sillicon in high purity lanthanum oxide by using electrothermal vaporization (ETV)-ICP-AES with polytetrafluoroethylene (PTFE) slurry as a fluorinating reagent has been proposed. Under the optimized experimental conditions, the fluorination reactions of analyte (Si) and matrix(La) with PTFE in the graphite furnace took place at high temperature, and the fractional volatilily between Si and La was observed. Based on this principle the matrix interference could be eliminated. The detection limit of Si was 4.0μg·L⁻¹, and the RSD was 3.4%(C=0.2mg·L⁻¹,n=10). The procedure proposed has been applied successfully to determine trace Si in La₂O₃ without any chemical pre-treatment. Supported by the National Natural Science Foundation of China Qin Yongchao: born in Dec. 1953, ph. D., Assciate Professor     

Tricolor white emitting phosphor co-doped with Eu, Dy in SiO2 matrix

A Eu, Dy co-doped SiO2 matrix, white emitting phosphor was prepared by the sol-gel technique. Strong red, green and blue emissions located at 618 nm, 573 nm and 400-550 nm were observed under UV laser excitation at room temperature. Such techniques as FT-IR and TGA-DSC were used to measure the microstructure of the luminescent material. The influence of the preparation techniques on the luminescence property of the Eu, Dy co-doped SiO2 matrix, such as anneal temperature, anneal time, dried atmosphere and the components of the matrix, was systematically studied, and the luminescence mechanism was interpreted. The red emission is the strongest when annealed at 750℃. However, blue emission appears when annealed at 700℃ and is the intensest at 900℃. For the samples dried in vacuum, Eu^3＋ is more easily deoxidized to Eu^2＋ at lower temperatures, because the samples dried in the air compared with that dried in vacuum need higher temperature to form network structures. Only the SA and SAB matrix annealed at 850℃ had blue emission in the four matrices （SA, SAB, SB, S） xerogel and the emission in the SAB matrix was stronger than that in the SA matrix. This may be due to the eutectic phase formed by the oxide boron, alkaline oxide and alumina in the SAB matrix, which constructs network structures and stabilizes the emission center and enhances the blue emission.     

Synthesis of LiCo<Subscript>0.3</Subscript>Ni<Subscript>0.7</Subscript>O<Subscript>2</Subscript> as cathode materials for lithium ion batteries by citric acid-assisted sol-gel method

The synthesis process of LiCo0.3Ni0.7O2 was investigated by FT-IR, mass spectroscopy, elemental analysis, SEM, BET, TG/DTA and XRD in this paper. The results revealed that lithium and transition metal ions were trapped homogeneously on an atomic scale throughout the precursor. Li2CO3, NiO and CoO are the intermediate products obtained after decomposition of the precursor and Li2CO3 undergoes direct reactions with NiO and CoO to form LiCo0.3Ni0.7O2. Moreover, the kinetics of formation of LiCo0.3Ni0.7O2 by dtrate sol-gel method is faster than the case of the conventional solid-state reaction between lithium carbonate and corresponding reactants. The single phase of LiCo0.3Ni0.7O2 was synthesized at temperature as low as 550℃. The discharge capacity of LiCo0.3Ni0.7O2 increases from 127 to 185 mAh/g as the caldnation temperature increasing from 550 to 750℃. After 100 cycles, the discharge capacity of the sample calcined at 750℃ is 155 mAh/g. The electrochemical study shows that the LiCo0.3Ni0.7O2 has high discharge capacity and good cycling behavior for lithium ion batteries.