Electronic properties of novel 6 K superconductor LiFeP in comparison with LiFeAs from first principles calculations

Very recently, the new 6 K superconductor (SC) LiFeP, the first arsenic-free analog of the family of the so-called “111” FeAs SCs, was discovered. Here, based on first-principle FLAPW-GGA calculations, the band structure, density of states, Fermi surface topology, electron density distribution and effective atomic charges for the new SC LiFeP are investigated for the first time and discussed in comparison with isostructural and isoelectronic LiFeAs. In addition, the theoretical shapes of FeL X-ray emission spectra for LiFeP and LiFeAs are evaluated and compared with available experiments.     

A sensitive amperometric sensor for hydrazine based on Pt nanoparticles-reduced graphene oxide–multi-walled carbon nanotubes composite

The platinum nanoparticles-reduced graphene oxide-multi-walled carbon nanotubes composite (PtNPs-rGO-MWCNTs) has been synthesised by one-step chemical co-reduction strategy in ethylene glycol (EG) system using sodium citrate as reducing agent. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), as well as the electrochemical methods have been used for the characterisation of this composite. Benefiting from the large effective surface and good carrier function of rGO-MWCNTs, PtNPs in this nanocomposite have some excellent characteristics such as small particle size, good dispersion, as well as high electrocatalytic activity. Based on this, a new electrochemical sensor for hydrazine has been fabricated using dropping method. Under the optimum conditions, the linear range for the determination of hydrazine by amperometry at 0.20 V (vs. SCE) in phosphate buffer (pH 7.0) is from 2.0 × 10^?7 mol L^?1 to 2.3 × 10^?3 mol L^?1. The detection limit and sensitivity is 4.5 × 10^?8 mol L^?1 (S/N = 3) and 219.7 μA mM^?1, respectively. This sensor has some attractive analytical features such as low detection limit, wide linear range, high sensitivity, as well as good stability.     

Z型CdIn2S4/ZnSnO3异质结的构筑及其光催化产氢性能

通过高温煅烧ZnSn(OH)₆前驱体制备了双壳中空立方体结构的ZnSnO₃(ZSO),进而采用水热法将CdIn₂S₄(CIS)纳米晶包裹在ZSO表面,成功制备了CdIn₂S₄/ZnSnO₃(CIS/ZSO)异质催化剂。活性产氢实验结果表明,CIS、ZSO物质的量之比为12%时制备的12% CIS/ZSO具有优异的光催化产氢性能,在3 h内产氢量为1 676.48 μmol·g^-1,分别是ZSO和CIS的12倍和8倍。ZSO光催化析氢反应活性的增强归因于CIS/ZSO异质结构的成功构建,异质界面的形成显著提高了光生电子/空穴对的分离效率,降低了其复合率。通过对电荷转移路径的分析,提出了可能的反应机理。     

基于2,4′-二羧基二苯甲酮构筑的具有一维梯状链和一维隧道的三维超分子体系

采用水热法设计合成了两个新型三维超分子化合物H₂L·H₂O (1)和[Ag(bpy)₂]·HL·H₂O (2) (其中bpy=2,2'-联吡啶, H₂L=2,4′-二羧基二苯甲酮),晶体结构分析表明,它们均是通过氢键采用不同的连接方式拓展而成。其中,化合物1 是2,4′-二羧基二苯甲酮和水分子通过O–H···O氢键形成的一维梯状链扩展构筑的三维超分子体系;化合物2 则是2,4′-二羧基二苯甲酮和水分子通过两种氢键形成含有一维隧道的三维超分子体系。有趣的是,[Ag(bpy)₂]⁺ 阳离子通过π–π 堆积和弱的Ag···Ag相互作用连在一起,进而以客体形式填充其中。荧光性质研究表明,由于存在bpy的螯合与堆积效应,化合物2相比配体和化合物1,其荧光发射峰发生红移。     

Two 3D zinc-bpe frameworks constructed from 2-carboxyl/sulfo-terephthalate: Crystal structures and luminescent properties

Two new zinc(II) complexes with the formulas of [Zn(HTma)(Bpe)] (I) and [Zn_1.5(Stp) (Bpe)(H₂O)₂] (II), where H₃Tma = 1,2,4-trimellitic acid, Bpe = 1,2-bis(4-pyridyl)ethane, NaH₂Stp = monosodium 2-sulfoterephthalate, have been prepared under hydrothermal conditions. Structural syntheses show complex I is a five-fold interpenetrated three-dimensional structure based on the diamond-like networks, however, complex II is a Bpe-pillared three-dimensional framework (CIF files CCDC nos. 1404475 (I) and 140447 (II)). Thermоgravimetric analyses show that complex I possesses high thermal stability up to 325°C and the dehydrated product of complex II also begins to decompose from 357°C. The luminescent properties of the two complexes are investigated in solid state.     

石墨烯量子点荧光探针测定肾上腺色腙

通过高温裂解柠檬酸合成了水溶性石墨烯量子点(GQDs),并应用钝化剂PEG2000进行修饰,提高了GQDs的量子产率。应用荧光光谱、紫外-可见光谱、红外光谱对其发光特性进行了研究,测定了荧光寿命。实验发现,在p H=7.40的Tris-HCl缓冲液中,肾上腺色腙(CBZC)对GQDs荧光强度有明显的猝灭作用。基于此提出了以GQDs为探针测定肾上腺色腙的新方法。实验考察了缓冲溶液用量、缓冲溶液种类、量子点浓度、反应时间以及表面活性剂等多种因素对反应体系的影响。当量子点浓度为2.3×10-3mol/L时,肾上腺色腙浓度在4.0×10-7~1.2×10-5mol/L(0.995 6)范围内与荧光猝灭值ΔF呈良好的线性关系,方法检出限为1.5×10-7mol/L,相对标准偏差为0.15%(n=5,c=4.0×10-6mol/L)。该方法对于样品中肾上腺色腙含量测定的回收率为97.46%~101.6%。通过测定温度对猝灭常数的影响以及紫外-可见吸收光谱的变化确定了二者的猝灭过程和相互作用力类型。     

Two Co(Ⅱ) Complexes Constructed from 1-(3,5-Dicarboxybenzyl)-3,5-pyrazole Dicarboxylic Acid:Syntheses,Structures and Magnetic Properties

Two new complexes[Co_2(L)(4,4′-bip)(H_2O)_3]_n (1) and{[Co(L′)_2(phen)]·2H_2O)}_n (2)(H_4L=1-(3,5-dicarboxybenzyl)-3,5-pyrazole dicarboxylic acid,H_3L′=1-(3,5-dicarboxybenzyl)-3-pyrazole carboxylic acid,4,4′-bip=4,4′-bis(1-imidazolyl)biphenyl,phen=1,10-phenanthroline) were synthesized.Complexes 1 and 2have been characterized by IR spectrography,X-ray single-crystal diffraction,elemental analysis and thermogravimetry.1 crystallizes in monoclinic system,space group P2_1/c.Complex 2 crystallizes in monoclinic system,space group I2/a.It is remarkable that in situ hydrothermal decarboxylation was observed during preparing complex 2.In addition,magnetic analysis indicates that antiferromagnetic interaction exists among Co(Ⅱ) ions in complexes 1 and 2.     

Diffusion-influenced deactivation processes in the study of surfactant aggregates

This review follows the evolution of the theories for excited state deactivation by diffusion-influenced quenching in microheterogeneous media, and the application of methods on this basis for the study of surfactant aggregates. From the starting point of the simple model for fluorescence quenching in monodisperse small micelles, the theoretical treatment has taken up polydisperse systems, quenching in long rods and lamellae, various possibilities for exchange of reactants between aggregates, and deactivation in clusters of small micelles. The information that can be obtained by time-resolved excited state deactivation studies is different in different types of systems, and is illustrated with examples from experimental studies. Limitations and possibilities are discussed.     

一种用于检测四环素和对硝基苯酚的高稳定性镉（Ⅱ）金属有机骨架

采用水-溶剂热法合成了1例金属有机骨架（MOF）：{[Cd （L）_0.5（4,4''-bpy）_0.5]·H₂O}_n（1）,其中H₄L=（1,1''∶4'',1″-三联苯）-2,2″,4,4″-四羧酸,4,4''-bpy=4,4''-联吡啶）。通过单晶X射线衍射、元素分析、粉末X射线衍射、热重分析以及红外光谱分析对配合物1的结构进行了表征。单晶结构分析表明1为三维结构,属于单斜晶系,C2/c空间群,Cd （Ⅱ）连接L^4-和4,4''-bpy形成二维平面结构,层与层之间通过L^4-连接,构筑成了三维网状结构。该MOF表现出良好的稳定性并且可以通过荧光猝灭法检测四环素（TET）和对硝基苯酚（4-NP）,四环素和对硝基苯酚的检出限分别为0.15和0.062 μmol·L^-1。此外,还研究了其荧光猝灭机理。1可成功应用于延河水样中TET和4-NP含量的测定。