Preparation and photocatalytic activity of Sb2S3/Bi2S3 doped TiO2 from complex precursor via gel-hydrothermal treatment

Sb₂S₃/Bi₂S₃ doped TiO₂ were prepared with the coordination compounds [M(S₂CNEt)₃] (M=Sb, Bi; S₂CNEt=pyrrolidinedithiocarbamate) as precursors via gel-hydrothermal techniques. The doped TiO₂ were characterized by XRD, SEM, XPS and UV-vis diffuse reflectance means. The photocatalyst based on doped TiO₂ for photodecolorization of 4-nitrophenol (4-NP) was examined. The optimal Bi₂S₃/Sb₂S₃ content, pH and different doped techniques have been investigated. Photocatalytic tests reveal that M₂S₃ doped TiO₂ via the gel-hydrothermal route performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP).     

Pb(II) and Mn(II) Coordination Compounds Involving 5,5′‐(1,4‐Phenylene)bis(1H‐tetrazole):Synthesis,Characterization, and Effect on Thermal Decomposition of Ammonium Perchlorate

Two coordination compounds [Pb₄(BDT)₃(OH)₂(H₂O)₄]·H₂O ( 1 ) and [Mn(H₂O)₆]·(HBDT)₂·2H₂O ( 2 ) [H₂BDT?5,5′‐(1,4‐phenylene)bis(1H‐tetrazole)] had been hydrothermally synthesized. 1 and 2 had been characterized by single‐crystal X‐ray diffraction, IR, elemental and thermal analyses. Structural analysis reveals that 1 exhibits 2D layer structure extended through BDT with two different coordination modes rings in transverse and vertical. 2 consists of [Mn(H₂O)₆]²⁺, free HBDT and water. In addition, 1 and 2 were explored as luminescent materials and additives to promote the thermal decomposition of ammonium perchlorate by differential scanning calorimetry.     

三维无溶剂含能Ag-MOF的制备、热分解动力学及爆炸性能

Solvent molecules can significantly reduce the heat of detonation and stability of energetic metal-organic framework (EMOF) materials, and the development of solvent-free EMOFs has become an effective strategy to prepare high-energy density materials. In this study, a solvent-free EMOF, [Ag₂(DTPZ)]_n (1) (N% = 32.58%), was synthesized by reacting a high-energy ligand, 2, 3-di(1H-tetrazol-5-yl)pyrazine (H₂DTPZ), with silver ions under hydrothermal conditions, and it was structurally characterized by elemental analysis, infrared spectroscopy, X-ray diffraction, and thermal analysis. In 1, the DTPZ²⁻ ligands that adopted a highly torsional configuration bridged the Ag⁺ ions in an octadentate coordination mode to form a three-dimensional framework (ρ = 2.812 g∙cm⁻³). The large steric effect and strong coordination ability of DTPZ²⁻ effectively prevented the solvent molecules from binding with the metal centers or occupying the voids of 1. Moreover, the strong π-π stacking interactions [centroid-centroid distance = 0.34461(1) nm] between the tetrazole rings in different DTPZ²⁻ ligands provided a high thermal stability to the framework (T_e = 619.1 K, T_p = 658.7 K). Thermal analysis showed that a one-step rapid weight loss with intense heat release primarily occurred during the decomposition of 1, suggesting potential energetic characteristics. Non-isothermal thermokinetic analyses (based on the Kissinger and Ozawa-Doyle methods) were performed using differential scanning calorimetry to obtain the thermoanalysis kinetic parameters of the thermodecomposition of 1 (E_a = 272.1 kJ·mol⁻¹, E_o = 268.9 kJ·mol⁻¹; lgA =19.67 s⁻¹). The related thermodynamic parameters [enthalpy of activation (ΔH^≠ = 266.9 kJ·mol⁻¹), entropy of activation (ΔS^≠ = 125.4 J·mol⁻¹·K⁻¹), free energy of activation (ΔG^≠ = 188.3 kJ·mol⁻¹)], critical temperature of thermal explosion (T_b = 607.1 K), and self-accelerating decomposition temperature (T_SADT = 595.8 K) of the decomposition reaction were also calculated based on the decomposition peak temperature and extrapolated onset temperature when the heating rate approached zero. The results revealed that 1 featured good thermal safety, and its decomposition was a non-spontaneous entropy-driven process. The standard molar enthalpy for the formation of 1 was calculated to be (2165.99 ± 0.81) kJ·mol⁻¹ based on its constant volume combustion energy determined using a precise rotating oxygen bomb calorimeter. Detonation and safety performance tests revealed that 1 was insensitive to impact and friction, and its heat of detonation (10.15 kJ·g⁻¹) was higher than that of common ammonium nitrate explosives, such as octogen (HMX), hexogene (RDX), and 2, 4, 6-trinitrotoluene (TNT), indicating that 1 is a promising high-energy and insensitive material.     

Syntheses,characterization and thermal properties of the lanthanide complexes with 2-mercaptonicotinic acid and 1,10-phenanthroline

Fourteen new complexes with the general formula of Ln(Hmna)₃(phen) (H₂mna = 2-mercaptonicotinic acid and phen = 1,10-phenanthroline) were synthesized and characterized by elemental analyses, IR spectra and thermogravimetric analyses. In addition, molar specific heat capacities were determined by a microcalorimeter at 298.15 K. The IR spectra of the complexes showed that the Ln³⁺ coordinated with the oxygen atoms of H₂mna and the nitrogen atoms of phen. The complexes decomposed directly to oxides Ln₂O₃, CeO₂, Pr₆O₁₁, and Tb₄O₇ in one step. The values of molar specific heat capacities for fourteen solid complexes were plotted against the atomic numbers of lanthanide, which presented as “tripartite effect”. It suggested a certain amount of covalent character existed in the bond of Ln³⁺ and ligands, according with nephelauxetic effect of 4f electrons of rare earth ions. The article is published in the original.     

原位水热合成的二(2,4-二(对硝基苯)-1,3,5-环戊二烯铜配合物的实验和理论研究

以4-硝基对苯腈,氨水和铜盐反应于在原位水热条件下合成了二（2,4-二（对硝基苯）-1,3,5-环戊二烯铜配合物,通过单晶X射线衍射,元素分析,红外,核磁光谱和热重分析等手段对其进行了表征。结构分析表明,铜与四个源自原位合成的配体上的氮原子配位形成平面四边形构型。基于密度泛函的理论计算对配合物的热力学稳定性进行了阐释。     

Chitooligosaccharide Copolymers: Synthesis and Aqueous Self-assembly

Novel water-soluble amphiphilic graft copolymers (COS-g-PCL-b-MPEG) were synthesized by the coupling reaction between chitooligosaccharide (COS) and MPEG-b-PCL-COOH, which was synthesized via ring-opening polymerization of ε-caprolactone (CL) using MPEG as an initiator and subsequent carboxylation by succinic anhydride. The chemical composition of the graft copolymers was confirmed by ¹H-NMR spectra and FT-IR spectrometry. The thermal properties and crystallinity of the copolymers were observed by DSC and XRD measurements, which showed the existence of separate backbone and graft chain phases in the copolymer. The micellar behavior via self-assembly of the graft copolymers in aqueous solution was studied using pyrene fluorescence dye technique. AFM measurements showed that the micelles had a spherical morphology at the critical micelle concentration (CMC) and ranged in size from 20–45 nm. The amphiphilic ternary biodegradable graft copolymer endows the hydrophilic outer shell of micelles with structural and functional diversification, which might be desirable for drug delivery applications.     

疲劳寿命估算的能量法及其实验研究

根据疲劳损伤滞后能等效原理,导出了缺口件与光滑件的当量应力关系,通过Ｎｅｕｂｅｒ公式和饱和应力应变关系,可确定当量应力取值;采用定量方程随机化方程,建立了γ－ｐ－ε－Ｎ曲线（置信度－可靠度－应变－寿命曲线）公式及其实验测试方式;根据疲劳累积损伤理论和γ－ｐ－ε－Ｎ曲线公式,得到了随机载荷谱作用下构件疲劳寿命估算公式;最后,实验验证了复杂实测载荷谱作用下,ＬＹ１２ＣＺ铝合金含孔试样的疲劳寿命估算结果     

Thermokinetics on the reaction of formation of Dy[(C<Subscript>5</Subscript>H<Subscript>8</Subscript>NS<Subscript>2</Subscript>)<Subscript>3</Subscript>(C<Subscript>12</Subscript>H<Subscript>8</Subscript>N<Subscript>2</Subscript>)]

The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen?H₂O) in absolute ethanol at 298.15 K has been determined as (-16.12 ± 0.05) kJ?mol^-1 by a microcalormeter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29) kJ?mol^t-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.     

3,7-二硝基亚氨基-2,4-二氮杂双环[3,3,0]辛烷的放热分解反应动力学

在程序升温条件下 ,用DSC研究了标题化合物的放热分解反应动力学 .用线性最小二乘法、迭代法以及二分法与最小二乘法相结合的方法 ,以积分方程、微分方程和放热速率方程拟合DSC数据 .在逻辑选择建立了微分和积分机理函数的最可几一般表达式后 ,用放热速率方程得到相应的表观活化能 (Ea)、指前因子 (A)和反应级数 (n)的值 .结果表明 :该反应的微分形式的经验动力学模式函数、Ea 和A值分别为 (1-α) 0 .44、2 30 .4kJ/mol和 10 18.16s-1.借助加热速率和所得动力学参数值 ,提出了标题化合物放热分解反应的动力学方程 .该化合物的热爆炸临界温度为 30 2 .6℃ .上述动力学参数对分析、评价标题化合物的稳定性和热变化规律十分有用 .     

Benzenedicarboxylate-modulated zinc(II)-3,5-bis(3-pyridyl)-1H-1,2,4-triazole frameworks: syntheses, structures and luminescent properties

Abstract  

Based on the polydentate ligand 3,5-bis(3-pyridyl)-1H-1,2,4-triazole (3,3′-Hbpt), three coordination compounds [Zn(3,3′-Hbpt)(ip)]·2H₂O (1), [Zn(3,3′-Hbpt)(5-NO₂-ip)]·H₂O (2), and [Zn(3,3′-Hbpt)₂(H₂pm)(H₂O)₂]·2H₂O (3) have been hydrothermally constructed with H₂ip, 5-NO₂-H₂ip and H₄pm as auxiliary ligands (H₂ip = isophthalic acid, 5-NO₂-H₂ip = 5-NO₂-isophthalic acid, H₄pm = pyromellitic acid). Structural analysis reveals that Zn(II) ions serve as four-coordinated, five-coordinated, and six-coordinated connectors in 1–3, respectively, while 3,3′-Hbpt adopts μ-N_py and N_py coordination modes in two typical conformations in these target coordination compounds. Dependently the applied ligand, compounds 1–3 exhibit either 1D channel, cage or chain structures, respectively. In addition, the luminescence properties of 1–3 have been investigated in the solid state at room temperature.