X射线荧光光谱法测定聚合物材料中铅和镉

提出了X射线荧光光谱法测定聚合物材料中铅和镉的方法。将粒径小于4mm的样品颗粒置于样品杯中,保持样品厚度大于16mm,加盖后按仪器工作条件进行测定。铅和镉的线性范围依次在1 033μg.g-1和980μg.g-1以内,检出限依次为0.31μg.g-1和0.69μg.g-1。方法用于分析标准物质(ERM-EC680k和ERM-EC681k),测定值与认定值相符。     

Novel Two‐Dimensional Porous Materials for Electrochemical Energy Storage: A Minireview

Two dimensional (2D) porous materials have great potential in electrochemical energy conversion and storage. Over the past five years, our research group has focused on Simple, Mass, Homogeneous and Repeatable Synthesis of various 2D porous materials and their applications for electrochemical energy storage especially for supercapacitors (SCs). During the experimental process, through precisely controlling the experimental parameters, such as reaction species, molar ratio of different ions, concentration, pH value of reaction solution, heating temperature, and reaction time, we have successfully achieved the control of crystal structure, composition, crystallinity, morphology, and size of these 2D porous materials including transition metal oxides (TMOs), transition metal hydroxides (TMHOs), transition metal oxalates (TMOXs), transition metal coordination complexes (TMCCs) and carbon materials, as well as their derivatives and composites. We have also named some of them with CQU‐Chen (CQU is the initialism of Chongqing University, Chen is the last name of Lingyun Chen), such as CQU‐Chen‐Co?O‐1, CQU‐Chen‐Ni?O?H‐1, CQU‐Chen‐Zn?Co?O‐1, CQU‐Chen‐Zn?Co?O‐2, CQU‐Chen‐OA?Co‐2‐1, CQU‐Chen‐Co?OA‐1, CQU‐Chen‐Ni?OA‐1, CQU‐Chen‐Gly?Co‐3‐1, CQU‐Chen‐Gly?Ni‐2‐1, CQU‐Chen‐Gly?Co?Ni‐1, etc. The introduction of 2D porous materials as electrode materials for SCs improves the energy storage performances. These materials provide a large number of active sites for ion adsorption, supply plentiful channels for fast ion transport and boost electrical conductivity and facilitate electron transportation and ion penetration. The unique 2D porous structures review is mainly devoted to the introduction of our contribution in the 2D porous nanostructured materials for SC. Finally, the further directions about the preparation of 2D porous materials and electrochemical energy conversion and storage applications are also included.     

新型薁磺酸镉配位聚合物的合成及其晶体结构

以薁磺酸钠为配体,通过溶液法合成了一种新型一维链状聚合物（1）,其结构和性能经IR, X-射线单晶衍射和热重分析表征。1属单斜晶系,空间群P2₁/c,晶胞参数a=2.349 6(7) nm, b=0.562 48(18) nm, c=1.148 7(4)nm。 1的中心Cd（Ⅱ）与4个薁磺酸阴离子的4个氧原子及两个水分子的两个氧原子配位,形成六配位八面体构型。配合物1通过磺酸基桥连作用将相邻的两个Cd（Ⅱ）形成一维链状结构。     

Stacking of Exfoliated Two‐Dimensional Materials: A Review

In recent years, two‐dimensional (2D) atomic crystals represented by graphene have opened up new fields of 2D physics. Layered materials with atomic layer thickness are self‐assembled into van der Waals heterostructures by weak van der Waals forces without considering lattice matching. Van der Waals heterostructures can not only enhance the performance of its constituent materials but also show new characteristics. High‐quality heterostructures require mechanically cleaved intrinsic 2D materials and flexible 2D material stacking techniques. Here, we summarize in detail the reliable exfoliation methods for large‐area single‐layer 2D materials and the dry and wet stacking techniques with high success rates. The twisted bilayer graphene is used as an example to briefly introduce the single‐crystal tearing method, which is currently the most practical method for preparing isotropic twisted heterostructures with high‐precision rotation angles. We hope to provide a valuable reference for researchers of 2D materials.     

Percolation in Two‐Dimensional Copolymer Systems

The aim of the study is the investigation of the percolation phenomena in some model copolymer systems. Diblock, triblock, random copolymers, and a blend of homopolymers are studied. For this purpose, we developed an idealized model of polymeric systems. The positions of polymer segments are restricted to vertices of a simple cubic lattice. The chains are at good solvent conditions – the excluded volume is the only interaction between the segments of the chain. The properties of the model chains are determined by means of Monte Carlo simulations with a sampling algorithm based on chain's local changes of conformation. The differences and similarities in the percolation behavior are shown and discussed. The percolation threshold is found to be very weakly dependent on the chain length, however, it appears that the main factor that influenced the percolation threshold is the screening effect of other parts of chains.

     

Synthesis,Crystal Structure,and Characterization of Two Novel One‐ and Two‐Dimensionally Polymeric Copper(II) Phosphonoacetates

Blue single crystals of Cu[μ₂‐OOC(CH₂)PO₃H] · 2H₂O ( 1 ) and Cu_1.5[μ₃‐OOC(CH₂)PO₃] · 5H₂O ( 2 ) were prepared in aqueous solution. In compound 1 [space group C2/c (no. 15) with a = 1623.3(2), b = 624.0(1), c = 1495.5(2) pm, β = 122.45(1)°], Cu is coordinated by three oxygen atoms stemming from the hydrogenphosphonoacetate dianion and three water molecules to form a distorted octahedron. The Cu–O bonds range from 190.4(3) to 278.5(3) pm. The connection between the Cu²⁺ cations and the hydrogenphosphonoacetate dianions leads to a two‐dimensional structure with layers parallel to (101). The layers are linked by hydrogen bonds. In compound 2 [space group P1 (no. 2) with a = 608.2(1), b = 800.1(1), c = 1083.6(1) pm, α = 94.98(1)°, β = 105.71(1)°, γ = 109.84(1)°], two crystallographically independent Cu²⁺ cations are coordinated in a square pyramidal and an octahedral fashion, respectively. The Cu–O bonds range from 192.9(2) to 237.2(2) pm. The coordination of the phosphonoacetate trianion to Cu(1) results in infinite polyanionic chains parallel to [100] with a composition of {Cu(H₂O)[OOC(CH₂)PO₃]}_n^n–. Hydrated Cu(2) cations are accommodated between the chains as counterions. 1 and 2 show structural features of cation exchangers. Magnetic measurements reveal a paramagnetic Curie‐Weiss behavior. Compound 2 shows antiferromagnetic coupling between Cu²⁺ ions due to a super‐superexchange coupling. The UV/Vis spectra of 1 suggest three d–d transition bands at 763 nm (²B₁ → ²E), 878 nm (²B₁ → ²B₂), and 1061 nm (²B₁ → ²A₁). Thermoanalytical investigations in air show that compound 1 is stable up to 165 °C, whereas decomposition of 2 begins at 63 °C.     

Synthesis,Structure and Characterization of a Novel One‐dimensional Tube‐like Cadmium Coordination Polymer

By the self‐assembly of 2‐aminobenzimidazole ( L ), Nadca (Nadca = dicyanamide sodium) and CdCl₂, a novel one‐dimensional (1D) Cd^II coordination polymer [Cd(μ_1,5‐dca)(μ_1,3,5‐dca) L ]_n ( 1 ) ( L = 2‐aminobenzimidazole) has been synthesized and structurally characterized by single crystal X‐ray diffraction, element analysis and FT‐IR spectra. In 1 μ_1,5‐bidentate and μ_1,3,5‐tridentate dca ligands bridge Cd^II ions to form a 1D tube‐like structure, which presents a new 1D tubular structural motif of (3.4(2))(3(2).4(2).5(3)) topology in M‐dca systems (M = metallic). Solid‐state blue fluorescence spectrum of 1 also has been determined and compared with that of free ligand.     

Percolation in Two‐Dimensional Copolymer‐Solvent Systems

In this work, the structure of a strictly 2D dense polymer film for some model copolymer systems: diblock, triblock, and random copolymers is studied. An idealized model of these macromolecular systems is developed where positions of polymer beads are restricted to vertices of a simple cubic lattice and chains are under good solvent conditions (the excluded volume is the only interaction between beads of the chain and solvent molecules). The properties of the system are determined by means of Monte Carlo simulations with a sampling algorithm based on chain's local cooperative changes of conformation. Scaling of the chain size is studied and the influence of the polymer concentration on the chain's size and shape is discussed. The differences and similarities in the behavior of the percolation thresholds of one component in chains with different bead sequences are also shown and discussed. The percolation threshold is found to be weakly dependent on the chain length and more sensitive to the total polymer concentration.

     

Two‐Dimensional Phosphorus Oxides as Energy and Information Materials

Phosphorene is a rising star in electronics. Recently, 2D phosphorus oxides with higher stability have been synthesized. In this study, we theoretically explored the structures and properties of 2D phosphorus oxides. We found that the structural features of P_xO_y vary with the oxygen content. When the oxygen content is low, the most stable P_xO_y material can be obtained by the adsorption of O atoms on phosphorene. Otherwise, stable structures are no longer based on phosphorene and will contain P–O–P motifs. We found that P₄O₄ has a direct band gap (about 2.24 eV), good optical absorption, and high stability in water, so it may be suitable for photochemical water splitting. P₂O₃ adopts two possible stable ferroelectric structures (P₂O₃‐I and P₂O₃‐II) with electric polarization perpendicular and parallel to the lateral plane, respectively, as the lowest‐energy configurations, depending on the layer thickness. We propose that P₂O₃ could be used in novel nanoscale multiple‐state memory devices.     

Synthesis and Structural Characterization and Thermal Properties of a Novel Aza‐aromatic Base Adduct of Cadmium Thenoyltrifluoroacetonate: A precursor for Pure Phase Nano‐sized Cadmium(II) Oxide

A novel aza‐aromatic base adduct of cadmium(II) thenoyltrifluoroacetonate, [Cd(phen)(ttfa)₂] ( 1 ), (phen = 1, 10‐phenanthroline; ttfa = thenoyltrifluoroacetonate) was synthesized and characterized by elemental analysis, IR, ¹H NMR, and ¹³C NMR spectroscopy, thermal analysis as well as X‐ray crystallography. The single‐crystal structure of this complex shows that the coordination number of the Cd²⁺ ions are six with two nitrogen donor atoms from aza‐aromatic base ligands and four oxygen donors from two thenoyltrifluoroacetonate ligands. The supramolecular features in these complexes are directed by weak directional intermolecular interactions. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are in agreement with the crystal structure. The CdO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average size of the nanoparticles was estimated by the Scherrer equation with the diameter about 45 nm. The morphology and size of the prepared CdO samples were further observed using SEM.     

Synthesis,Crystal Structures,and Urease Inhibitory Activities of Three Novel Thiocyanato‐bridged Polynuclear Schiff Base Cadmium(II) Complexes

Three novel thiocyanato‐bridged polynuclear cadmium(II) complexes, [Cd(HL1)(NCS)₂(μ_1,3‐NCS)]_n ( 1 ), [CdL2(μ_1,3‐NCS)₂]_n ( 2 ), and [CdL3(μ_1,3‐NCS)₂]_n ( 3 ) (L1 = N‐methyl‐N′‐(1‐pyridin‐2‐ylmethylidene)ethane‐1,2‐diamine, L2 = 2‐(cyclopropyliminomethyl)‐6‐methoxyphenol, L3 = 2‐(cyclopentyliminomethyl)‐6‐methoxyphenol), have been synthesized and structurally characterized by elemental analysis, IR spectra and single‐crystal X‐ray diffraction. Each cadmium(II) atom in the complexes is in an octahedral coordination. The urease inhibitory activities of the complexes were evaluated. All of them showed potent inhibitions against jack bean urease.     

Two‐Dimensional Conducting Polymers: Synthesis and Charge Transport

Current technological advances and prolific endeavors have entrenched two‐dimensional conducting polymers as the rapidly emerging interface across a diversity of functional materials for flexible electronics, sensors, ion‐exchange membranes, biotechnology, catalysis, energy storage, and conversion. Rational design and fabrication of polymeric nanostructures enriched with well‐ordered geometry are appealing and endorse significant impact on their in‐built electrical, optical, and mechanical properties. In particular, recent interest in controlled hierarchical assembly of monomers/oligomers proved the free‐standing sheet‐like structures with exotic features of high conductivity and flexibility. Yet, the ongoing research to make nanometer‐thick polymers suffers from limitations to access large‐area, mechanical stability, and high‐range internal ordering. In this perspective, we focus on the radical approaches that highlight confinement‐entitled features of two‐dimensional polymeric materials correlating to their interface or template‐assisted synthesis, structure–property relationship, charge transport properties, and future scopes for relevant practical enactments. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1169–1176     

SCN-桥联的一维链配位聚合物[Cd(dafo)(SCN)2]n的合成及晶体结构

A new one-dimensional compound [Cd(dafo)(SCN)₂]_n(dafo=4,5-diazafluoren-9-one) has been synthesized and characterized by single crystal X-ray diffraction. It crystallizes in the orthorhombic system; space group Pbca with a=1.708 6(5), b=1.303 6(4), c=2.592 6(8) nm, V=5.775(3) nm³, and Z=16. The crystal structure revealed that the structure of [Cd(dafo)(SCN)₂]_n features μ-1,3-thiocyante bridges and 1D chains. It consists of octahedrally coordinated Cd atoms. Both Cd(1) and Cd(2) are surrounded by two nitrogen atoms from dafo, two S atoms and two N atoms from two di-μ-1,3 thiocyanato bridges. CCDC: 251185.     

Crystal‐Field Tuning of Photoluminescence in Two‐Dimensional Materials with Embedded Lanthanide Ions

Lanthanide (Ln) group elements have been attracting considerable attention owing to the distinct optical properties. The crystal‐field surroundings of Ln ions in the host materials can determine their energy level splitting, which is of vital importance to tailor their optical properties. 2D MoS₂ single crystals were utilized as the host material to embed Eu³⁺ and energy‐level splitting was achieved for tuning its photoluminescence (PL). The high anisotropy of the 2D host materials makes them distort the degenerate orbitals of the Ln ions more efficiently than the symmetrical bulk host materials. A significant red‐shift of the PL peak for Eu³⁺ was observed. The strategy for tailoring the energy level splitting of Ln ions by the highly designable 2D material crystal field provides a new method to extend their optical properties.     

Synthesis and Characterization of a Novel Two‐Dimensional Network Polymer Containing 18‐ and 26‐Membered Organotin Macrocycles

The reaction of 4‐mercaptophenylacetic acid with dimethyltin dichloride in the presence of sodium ethoxide in ethanol affords a novel two‐dimensional organotin network structure compound 1, which is an unusual network containing dinuclear 18‐membered and tetranuclear 26‐membered organotin macrocycles. The compound has been characterized by elemental analysis, IR, and ¹H, ¹³C, and ¹¹⁹Sn NMR spectroscopy. Furthermore, we have also characterized the compound by X‐ray crystallography.