两个2,6-二氨基-3,5-二硝基吡嗪-1-氧化物含能配合物的合成、晶体结构及催化性能

合成了2,6-二氨基-3,5-二硝基吡嗪-1-氧化物(LLM-105)₂种含能配合物[Cu₄O₂(C₄N₆O₅H₂)₂(CH₃COO)₂(DMF)₂]·DMF(1)((C₄N₆O₅H₂)^2- 为配体LLM-105失去2个H⁺)和[Co(C₄N₆O₅H₃)₃]·7H₂O(2)((C₄N₆O₅H₃)^- 为LLM-105失去1个H⁺),用X射线单晶衍射法测定了其分子结构。配合物1属正交晶系,空间群为Pbca,配合物2属三斜晶系,空间群为R3。用DSC,TG-DTG技术对配体和2个配合物的热分解进行了研究。用Kissinger法和Ozawa-Doyle法对配合物热分解过程中放热峰的表观活化能进行了计算。同时研究了2种配合物对AP热分解催化效果的影响,结果表明,2种配合物使AP的高温分解峰温分别提前117.42和71.85℃,分解放热量增加1916.97和1433.76J·g^-1,对AP热分解具有非常显著的催化效果。     

N-杂环卡宾-吡啶基钌光敏染料的电子结构和光谱性质的理论研究

以N749染料为母体,保留三联吡啶配体(tcterpy)作为辅助配体,利用两齿的N-杂环卡宾-吡啶配体(NHC-py)替代2个硫氰酸(NCS)配体设计了一系列同时含有三齿配体和两齿配体的染料分子1~4.利用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法对染料分子1~4及母体分子N749的几何结构、电子结构和光谱性质进行了系统的理论研究.研究结果表明,该系列分子具有良好的光吸收性能,最低能吸收波长可达到800 nm,吸收跃迁为MLCT/LLCT混合跃迁.     

纳米孔缺陷导致单层黑磷电荷局域极大抑制非辐射电子-空穴复合的时域模拟

通常认为缺陷加速黑磷的非辐射电子-空穴复合,阻碍器件性能的持续提高。实验打破了这一认识。采用含时密度泛函理论结合非绝热分子动力学,我们发现P-P伸缩振动驱动非辐射电子-空穴复合,使纳米孔修饰的单层黑磷的激发态寿命比完美体系延长了约5.5倍。这主要归因于三个因素。一,纳米孔结构不但没有在禁带中引入深能级缺陷,而且由于价带顶下移使带隙增加了0.22 eV。二,除了带隙增加,纳米孔减小了电子和空穴波函数重叠,并抑制了原子核热运动,从而使非绝热耦合降低至完美体系的约1/2。三,退相干时间比完美体系延长了1.5倍。前两个因素战胜了第三个因素,使纳米孔结构激发态寿命延长至2.74 ns,而其在完美体系中约为480 ps。我们的研究表明可以制造合理数量和形貌的缺陷,如纳米孔,降低黑磷非辐射电子-空穴复合,提高光电器件效率。这一研究对于理解和调控黑磷和其它二维材料的激发态性质有重要意义。     

1，1'-二羟基-5，5'-联四唑的镧系金属配合物的合成、表征及热行为

以1,1′-二羟基-5,5′-联四唑(H_2BTO)为配体,镧系金属离子作为金属中心,采用溶剂热法制备了5种金属配合物:[La_2(BTO)_3(H_2O)_8]·2H_2O (1)、[Ce_2(BTO)_3(H_2O)_8]·2H_2O (2)、[Pr_2(BTO)_3(H_2O)_8]·2H_2O (3)、[Sm_2(BTO)_3(H_2O)_8]·2H_2O (4)和[Nd_2(BTO)_3(DMF)_4]·6H_2O (5)。通过单晶X射线衍射和元素分析对5种配合物的结构进行了表征。结果表明,5种配合物均属于单斜晶系,P2_1/n空间群。利用差示扫描量热法研究了配合物1～4的热稳定性,采用Kissinger法和Ozawa法分别计算了其热分解动力学参数。     

石墨烯条带的电子结构与性质:电场及长度效应

在密度泛函理论(DFT)和含时密度泛函理论(TDDFT)的基础上对宽度上含有8个zigzag链的石墨烯条带(8-ZGNR)的基态和激发态的性质进行了理论研究,着重考察了条带长度及电场的影响.B3LYP杂化泛函的计算结果显示:在基态上,8-ZGNR的最低能量态并不具有磁性,随着长度的增加,才会显示出反铁磁的性质.静电场的加入使8-ZGNR显示出反铁磁性和半金属性.在激发态上,诱导电子会随着外激光脉冲的变化而发生移动和变化,但是相比而言,α自旋电子更容易被激发而产生较明显的诱导电子密度,而β自旋电子则更容易脱离外激光场的控制而产生非绝热现象.     

共晶含能材料研究进展

共晶是不同种类的分子(两种或两种以上)通过氢键等分子间相互作用,形成具有特定结构和性能的多组分分子晶体,不同含能材料形成共晶可以有效改善炸药的感度、安全性等性能。针对目前高能炸药的改性需求,共晶在含能材料领域中的应用具有巨大的潜力。综述了共晶的形成原理及生长特性,总结了常见共晶的制备方法和表征方法,评述了含能材料共晶的研究现状和发展前景。     

臭氧直接氧化法回收碘

选用淀粉为指示剂,保持溶液pH为4-5,控制O3的通入量,将废液中的I-定量氧化至I2,废液由蓝绿色突变为棕色,剩余I-的浓度小于4×10^-5mol·L^-1,I2的回收率可达97．4％。     

木耳中含氯苯酚类化合物的气相色谱法测定研究

建立了同时测定木耳中10种含氯苯酚类化合物的气相色谱/微电子捕获检测(GC/μECD)分析方法。样品经过硫酸水解、水蒸气蒸馏、乙酸酐乙酰化,正己烷萃取,经浓缩和定容后,用GC/μECD测定,外标法定量。实验结果表明:含氯苯酚类化合物在0.010~0.50 mg·L-1范围内呈良好的线性关系,相关系数均大于0.995,检出限为0.5~2.0μg·kg-1,样品加标回收率为83.4%~103.5%,相对标准偏差(RSD)为1.5%~10.2%。     

可见光铋系光催化剂的研究进展

当前工业发展导致了严重的能源和环境危机,光催化为这一难题提供了有效的解决方案.然而在实际应用中,传统氧化物光催化剂宽的带隙限制了它的可见光吸收,于是窄带隙光催化剂成为了研究的热点.其中铋系光催化剂以其高的可见光光催化活性引起了人们的广泛关注.因此本文介绍了铋系光催化剂的种类、制备、形貌、复合、性能等方面的研究现状,并展望了含铋可见光催化剂发展前景.     

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.