Oxidation of catechol catalyzed by β-cyclodextrin-Cu(Ⅱ) complexes and its reaction kinetics

以β-环糊精(β-CD)作为骨架,经磺酰化反应、卤代反应和与L-组氨酸的亲核取代反应,得到了两种β-环糊精-组氨酸衍生物配体,再将配体与Cu(Ⅱ)配位,合成了具有多酚氧化酶催化活性的β-环糊精-Cu(Ⅱ)配合物。采用元素分析、傅里叶变换红外光谱、核磁共振波谱和原子吸收光谱等方法对配体和配合物的结构进行了表征。以O₂为氧化剂,用分光光度法测定了它们催化邻苯二酚氧化反应的性能,并考察了反应温度、pH值等因素对催化反应速率的影响。结果表明：β-环糊精-Cu(Ⅱ)配合物具有良好的催化性能;C-2位修饰得到的环糊精类金属衍生物因为活性基团与反应中心之间相对位置适宜,表现出较大的加速效果;反应动力学表明组胺基配位Cu(Ⅱ) 、β- CD疏水空腔和碱催化作用是反应加速的3个因素。     

Synthesis of tributyl citrate catalyzed by Ce(SO4)2·4H2O/ NH2SO3H

研究了柠檬酸与正丁醇在Ce(SO₄)₂·4H₂O/ NH₂SO₃H复配催化剂催化作用下制备柠檬酸三丁酯的工艺条件。实验结果表明Ce(SO₄)₂·4H₂O/ NH₂SO₃H催化合成柠檬酸三丁酯的最佳反应条件为：醇酸摩尔比为4.0∶1,催化剂用量为1.5%（以柠檬酸质量计）,m[Ce(SO₄)₂·4H₂O]∶m(NH₂SO₃H)=2∶1,反应温度为150 ℃,反应时间为7 h,酯化率＞98.5%,精制后产品纯度>99.5%。     

Polymerization of β-pinene with ethylaluminum dichloride (C2H5AlCl2)

The main goal of this work is to study the cationic polymerization of terpenes, particularly of β-pinene, with alkylaluminum catalysts. Some experiments at different polymerization temperatures (10, 20, and 50°C) were carried out with ethylaluminum dichloride catalyst, C₂H₅AlCl₂. From the results, it is possible to draw some general conclusions about the evolution of chain growth during polymerization. This work also includes the influence of reaction temperature on some properties of the final resin, particularly the molecular weight distribution, the softening point, and the Gardner color index. The role of reducing agents, such as iodine, during the distillation of the final resin is also evaluated with respect to color and softening point. As a result of this investigation, the Mark–Howink constants for terpene resins in toluene and dicloromethane as solvents have also been experimentally determined, thus allowing a more precise use of size exclusion chromatography in the characterization of such natural based products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2558–2565, 2001     

Synthesis and crystallographic characterisation of Mg(H2dhtp)(H2O)5·H2O

A mononuclear complex of composition Mg(H₂dhtp)(H₂O)₅·H₂O has been prepared and characterised crystallographically.     

Facile synthesis and molecular structure of the tris(amine) complex [PdCl(H2NBz)3]Cl·H2O

Reaction of Na₂[PdCl₄] with three equivalents of benzylamine at room temperature led to the isolation of [PdCl(H₂NBz)₃]Cl·H₂O in near quantitative yield, a rare example of a tris(monoamine)functionalised palladium(II) centre. A crystal structure showed that the three phenyl groups lie on the same side of the PdN₃Cl plane and the metal-bound chloride is hydrogen bonded to the co-crystallised water.     

Halogenation of β-keto-sulfones using KX/H2O2 in aqueous medium: Synthesis of α-halo β-keto-sulfones and α-halomethyl sulfones

Synthesis of α-halo β-keto-sulfones and α-halomethyl sulfones is described by the reaction of β-keto-sulfones with potassium halides in the presence of hydrogen peroxide in aqueous acidic medium afforded the corresponding α-halo β-keto-sulfones at room temperature in excellent yields. Further the α-halo β-keto-sulfones on treatment of aqueous alkali underwent base-induced cleavage to yield α-halomethyl sulfones.     

Hydrothermal synthesis, crystal structure and properties of complex [Co (odpa) (phen) 2 ( H2O )] · H2O

以4,4’-氧化二苯四羧酸二酐和1,10-邻菲啰啉为配体在水热条件下合成了标题配合物,并用元素分析、红外光谱、X-射线单晶衍射以及热重分析对配合物进行了表征.晶体结构分析表明配合物为三斜晶系,P-1空间群a=11.190(2)(A),b=12.587(2) (A),c=13.097(3)(A),α=102.688(3)°,β=105.751(2)°,γ =92.615(2)°,V =1721.1(6)A3,Z=2.配合物为单核结构,相邻的单核分子通过氢键的识别作用形成一维超分子双链.π…π堆积作用和C-H…π之间弱相互作用将邻近超分子双链的进一步扩展为三维超分子结构.     

Hydrothermal synthesis and tuning of size and morphology of α-Co(OH)2 and α-Co2(OH)3Cl nanostructures as precursors for nanosized Co3O4

This study aims to investigate the hydrothermally synthesized cobalt(II) hydroxide-based materials, which will be thermally converted to generate Co₃O₄ nanostructures; an important class of materials characterized by good electrochemical, catalytic and optical properties. First, cobalt(II) hydroxide nanostructures were prepared via hydrothermal hydrolysis of two different precursors (cobalt(II) chloride salt and dichlorobis(thiourea)cobalt(II) complex) exposure to an ammonia atmosphere, and then the obtained α-Co(OH)₂ and α-Co₂(OH)₃Cl nanostructures were calcined to produce Co₃O₄ nanostructures that were characterized by FT-IR, XRD, UV–vis DRS and SEM techniques. The effects of the nature of the precursor, its concentration, and of the temperature and reaction time on size and morphology of the product were also investigated.     

One-pot syntheses,structures and properties of two novel 1-D copper complexes: [CuII2(Hbpdc)2Cl2]2·2H2O and CuI(H2bpdc)Cl (H2bpdc = 2,2′-bipyridyl-5,5′-dicarboxylic acid)

Two novel 1-D copper complexes {[Cu^II₂(Hbpdc)₂]Cl₂}₂·2H₂O (1) and Cu^I(H₂bpdc)Cl (2) (H₂bpdc = 2,2′- bipyridyl-5,5′-dicarboxylic acid) have been one-pot hydrothermally synthesized by reaction of H₂bpdc, CuCl₂·2H₂O, PrCl₃ and glacial acetic acid and structurally characterized by IR spectroscopy, X-ray photoelectron spectroscopy and single-crystal X-ray diffraction. Single-crystal structural analyses show that 1 is a novel 1-D stair-like chain constructed from centric tetra-copper clusters {[Cu^II₂(Hbpdc)₂]Cl₂}₂ by means of Cu–O weak coordination interactions whereas 2 displays a 1-D comb-like chain built by [Cu^I(H₂bpdc)Cl] units through Cl^? bridges. More interestingly, 1 and 2 were one-pot hydrothermally synthesized, which is very rare in synthetic chemistry. The photofluorescence properties of 1 and 2 have been investigated.     

High-pressure behavior and phase stability of Na2B4O6(OH)2·3H2O (kernite)

The high-pressure behavior of kernite [ideally Na₂B₄O₆(OH)₂·3H₂O, a ~ 7.02 Å, b ~ 9.16 Å, c ~ 15.68 Å, β = 108.9°, Sp Gr P2₁/c, at ambient conditions], an important B-bearing raw material (with B₂O₃ ≈ 51 wt%) and a potential B-rich aggregate in radiation shielding materials, has been studied by single-crystal synchrotron X-ray diffraction up to 14.6 GPa. Kernite undergoes an iso-symmetric phase transition at 1.6-2.0 GPa (to kernite-II). Between 6.6-7.5 GPa, kernite undergoes a second phase transition, possibly iso-symmetric in character (to kernite-III). The crystal structure of kernite-II was solved and refined. The isothermal bulk modulus (K_V0 = β^-1_P0,T0, where β_P0,T0 is the volume compressibility coefficient) of the ambient-pressure polymorph of kernite was found to be K_V0 = 29(1) GPa and a marked anisotropic compressional pattern, with K(a)₀: K(b)₀: K(c)₀~1:3:1.5., was observed. In kernite-II, the K_V0 increases to 43.3(9) GPa and the anisotropic compressional pattern increases pronouncedly. The mechanisms, at the atomic scale, which govern the structure deformation, have been described.     

Comparative Study of Reactive Dyes Oxidation by H2O2/UV,H2O2/UV/Fe2+ and H2O2/UV/Fe° Processes

The decolorization and mineralization of two reactive dyes C.I. Reactive Blue 4 (RB 4) and C.I. Reactive Blue 268 (RB 268) were studied using various advanced oxidation processes (AOPs) such as H₂O₂/UV, H₂O₂/UV/Fe²⁺, and the H₂O₂/UV/Fe°. All processes were performed within a laboratory-scale photo-reactor setup. The experimental results were assessed in terms of absorbance (A) and total organic carbon (TOC) reduction. The main degradation products were identified by high resolution gas chromatography/high resolution mass spectrometry analyses. The results of our study demonstrated that the additions of moderate concentrations of H₂O₂ and Fe catalyst during the AOPs evidently increased the decolorization efficiencies within the first few minutes of the processing time (5–10 min) for both tested dyes, and prolonged irradiation does not necessarily significantly improve decolorization. On contrary, TOC removal rate increased with the processing time and with the addition of the catalyst from 40–50% up to 70–80% at defined experimental conditions. All the tested AOPs were very successful methods for RB 268 decolorization, having very complex structure and much higher molecular weight compared to the dye RB 4. This is important from both economic and ecological points of view.     

Synthesis,structure, and characterization of polymeric lanthanide 2-aminoterephthalate frameworks [Ln2(atp)3(H2O)2]·dmf·4H2O

X-ray crystallography reveals four isostructural lanthanide polymeric solids, [Ln₂(atp)₃(H₂O)₂]·dmf·4H₂O (atp = 2-aminoterephthalate; dmf = N,N′-dimethylformamide; Ln = La (1), Ce (2), Pr (3) and Nd (4), respectively) that are obtained from the solvothermal synthesis which are crystallized in an interesting 3D polymeric framework with a (4,4,6)-linked {4²·8⁴}{4⁴·6²}₂{4⁸·6⁶·8}₂ fsy net topology. Upon excitation at 350 nm, they all show the solid state ligand-centered luminescences but both 2 and 3 also exhibit the weak lanthanide-based characteristic emissions in the visible region at room temperature. The cyclic voltammetric investigation indicates that 2 exhibits appreciable electrochemical activity for formaldehyde.     

Enantioselective epoxidation catalyzed by silicagel supported (Salen)-Mn (Ⅲ) complex in ionic liquid

进行了以Jacobsen催化剂、硅胶型 (Salen)-Mn（Ⅲ）配合物为催化剂（1,2）,以离子液体1-丁基-3-甲基咪唑四氟硼酸盐（BMIMBF₄）和1-丁基-3-甲基咪唑六氟磷酸盐（BMIMPF₆）为反应介质,次氯酸钠为氧化剂,乙酸铵为轴向配体催化非官能团烯烃（苯乙烯、α-甲基苯乙烯、茚）的不对称环氧化反应。通过实验对比发现,反应介质离子液体与二氯甲烷相比可以有效提高催化反应的速率和ee值,并且离子液体BMIMPF₆辅助催化能力高于（BMIMBF₄）;硅胶载体型配合物在离子液中催化烯烃具有比均相Jacobsen催化剂更好的立体催化效果。如a-甲基苯乙烯,在离子液BMIMPF₆反应中获到97%～100%的ee值,且反应循环5次后催化剂活性没有明显的下降。     

Hydrothermal synthesis,crystal structure and physical properties of {[Gd(H2O)4(μ2-C6NO2H5)2Gd(H2O)4](μ3-C6NO2H4)2(ZnCl3)2} · 2H2O · 2Cl

A bimetallic 4f–3d tetranuclear complex {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} · 2H₂O · 2Cl (1) has been synthesized via hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Complex 1 is characterized by a tetranuclear Gd₂Zn₂ structure with the gadolinium and zinc atoms interconnected by isonicotinic acid ligands. The tetranuclear species of {[Gd(H₂O)₄(μ₂-C₆NO₂H₅)₂Gd(H₂O)₄](μ₃-C₆NO₂H₄)₂(ZnCl₃)₂} link to isolated chlorine ions and water molecules via π?π interactions and hydrogen bonds to yield a 3-D supramolecular framework. Photoluminescent investigation reveals that the title complex displays an emission in ultraviolet region. The solid-state diffuse reflectance spectra of 1 reveal the presence of a sharp optical gap of 3.66 eV.     

Six- and five-coordinated complexes of Co(II) with 2-(2′-pyridyl)quinoxaline. Crystal structures of the complexes [CoLCl2(DMF)] and [CoL2(H2O)2](ClO4)2·H2O·2CH3OH

Reaction of Co(II) perchlorate hexahydrate and anhydrous Co(II) chloride with the ligand 2-(2′-pyridyl)quinoxaline (L) leads to the formation of the novel five- and six-coordinated complexes CoLCl₂(DMF) (1) and [CoL₂(H₂O)₂](ClO₄)₂·H₂O·2CH₃OH (2), correspondingly. The crystal structures of the above complexes show a trigonal bipyramidal geometry around the metal atom for complex 1 and a distorted octahedral geometry for complex 2.     

Preparation and Characterization of α-(Fe, Al)2O3 Solid Solutions by Sol–Gel Method

The aim of this paper is to synthesize α-(Fe, Al)₂O₃ solid solutions from precursors prepared by the sol–gel method. The powders were characterized by X-ray diffraction, particle size analysis and TGA-DSC. The results indicated that the precursor prepared by sol–gel method will translate into α-(Fe, Al)₂O₃ solid solutions after calcined at 1300 °C for 3 h, with the average grain size of 14 μm. And Fe₂O₃ reduced the temperature of the γ-Al₂O to α-Al₂O₃ phase transition from 1,300 to 850 °C.     

Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

Synthesis and nanostructure of [Mo(C6H4O2)3]·2(C4H8N2O) and the synthesis from 1,2-PDA to (C4H8N2O)

Continuing our work on the synthesis of MoO₂L₂ and MoO₃L_AL_B that show excellent anti-cancer activities in vitro, the MoL₃ have been synthesized by the solvothermal reaction of Na₂MoO₄ with catechols and 1,2-DPA in the mixed solvent of MeCN/MeOH. X-ray diffraction revealed that Mo in chiral octahedral geometry coordinate with three catechol ligands formed three five-membered rings, and the [Mo(C₆H₄O₂)₃] are linked by hydrogen bonds Mo(OC₆H₄)O…H–N(C₄H₈O)N–H…O(C₆H₄O)Mo through the by-product (C₄H₈N₂O) that are formed by one 1,2-DPA with one CO₂ on the catalysis of Mo-complex. Also, we have disassembled bulk crystal into nano-aggregates, and under TEM mono-lamella morphology of nanostructures was observed, which agrees well with the previous conclusion that the morphologies of the nano-aggregates are associated with the quantum motifs in their crystal lattices. [Mo(C₆H₄O₂)₃] have also been characterized by UV–vis spectra, cyclic voltammogram and thermogravimetric analysis.