First-principles study of electronic properties of interfacial atoms in metal-metal contact electrification

The mechanism of contact electrification between metals was studied using the first-principles method, taking the Ag-Fe contact as an example. Charge population, charge density difference, the orbitals and densities of states （DOS） were calculated to study the electronic properties of the contacting interfacial atoms. Based on the calculation, the amount of contact charge was obtained. The investigation revealed that the electrons near Fermi levels with higher energies transfer between the outermost orbitals （s orbitals for Ag and d orbitals for Fe）. Meanwhile, polarized covalent bonds form between the d electrons in the deep energy states. These two effects together lead to an increase of charge magnitude at the interface. Also, the electrons responsible for electrification can be determined by their energies and orbitals.

Synthesis,Crystal Structure and Luminescent Property of a Novel Pt(Ⅱ) Complex with Weak Metal-metal Interaction

The title complex cis-bis（tetrahydrothiophene）-bis（nitrate） platinum（H）, （tht）2Pt（NO3）2, was the reducing product from potassium hexachloroplatinate（IV） K2PtC16 where the platinum is tetra-valenced. Crystal data for CsH16N206PtS2： monoclinic, space group P21/c, a = 9.8833（5）, b = 8.6744（4）, c = 18.6407（9）A,β = 114.401（3）°, V = 1455.35（12）A3 Z = 4, Mr = 495.44, Dc = 2.261 g/cm3, F（000） = 944,μ = 9.950 mm-1, 2（MoKa） = 0.71073 A, T= 293（2） K, 2θmax = 54.96°, GOOF = 1.033, R = 0.0350 and wR = 0.0785 for 2572 observed reflections with I 〉 2σ（I）. X-ray diffraction studies reveal that the title complex has interesting weak metal-metal interactions and two molecules linked by metal-metal interaction exist as a group. Luminescent spectrum illuminates red emission of the complex at room temperature.

Dicobalt Complex with Metal-metal Interaction of a Naphthyridine and Pyrazine Amine Ligand

Molecular structure of a naphthyridine and pyrazine amine ligand, N2,N7-di（pyrazin-2-yl）-1,8-naphthyri-dine-2,7-diamine（H2dpznda 1） was studied, and a three-dimensional supramolecular network with a double helix chain structure through intermolecular hydrogen bonds and π-π interactions between the naphthyridine and pyrazine rings was depicted. Through ligand 1, [Co2（μ2-dpznda）2（μ2-CH3OH）2]（2） was obtained and two ligands coordinate to two Co2＋）as tetradentate bridging ligands. Single crystal and magnetism study on 2 revealed that the complex exhibited weak yet significant metal-metal interaction.

Poly(Ionic Liquid) as an Anion Exchange Membrane for a 3.3 V Copper–Lithium Battery

Metal–metal battery bears great potential for next-generation large-scale energy storage system because of its simple manufacture process and low production cost.However,the cross-over of metal cations from the cathode to the anode causes a loss in capacity and influences battery stability.Herein,a coating of poly(ionic liquid)(PIL)with poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide)(PDADMA^(+)TFSI^(−))on a commercial polypropylene(PP)separator serves as an anion exchange membrane for a 3.3 V copper–lithium battery.The PIL has a positively charged polymer backbone that can block the migration of copper ions,thus improving Coulombic efficiency,long-term cycling stability and inhibiting self-discharge of the battery.It can also facilitate the conduction of anions through the membrane and reduce polarization,especially for fast charging/discharging.Bruce-Vincent method gives the transport number in the electrolyte to be 0.25 and 0.04 for PP separator without and with PIL coating,respectively.This suggests that the PIL layer reduces the contribution of the internal current due to cation transport.The use of PIL as a coating layer for commercial PP separator is a cost-effective way to improve overall electrochemical performance of copper–lithium batteries.Compared to PP and polyacrylic acid(PAA)/PP separators,the PIL/PP membrane raises the Coulombic efficiency to 99%and decreases the average discharge voltage drop to about 0.09 V when the current density is increased from 0.1 to 1 mA cm^(−2).

HYDROGENATION ACTIVITY OF ADSORBINGRESIN SUPPORTED PALLADIUM—METALLIC OXIDE CATALYSTS

Hydrogenations for olefinic double bonds catalyted by the Pd-Fe2O3/D3520 resin and Pd-Bi2O3/D3520 resin were reported. These catatysts were characterized by IR spectra and XPS methods. The XPS investigation indicated that the-electron transfer from Fe atom in Fe2O3 to Pd, enhanced the hy-drogenation activity of the catalysts,and Bi2O3 drew electrons from Pd, leading to the lowering of the hydrogenation rate. When Pd/Bi atom ratio = 1, the hydrogenation was inhibited entirely. The IR spectra of resin 1)3520 showed no significant changes when Pd and the metallic oxides were supported on the polymer particles. That indicates that there are no obvious inter-actions between Pd (or metallic oxides) and supporter. Finally , a possible hydrogenation mechanism ,was also supposed.

Synthesis and Crystal Structure of a Two-dimensional Silver Framework Constructed by H_2idc (H_2idc = Iminodiacetic Acid)

A new compound formulated [Ag2(idc)](NO3)?H2O (H2idc = iminodiacetic acid) was synthesized under mild conditions and characterized by IR spectrum and single-crystal X-ray diffraction. The crystal crystallizes in the monoclinic system, space group of P21/n with a = 5.5029(2), b = 11.1316(5), c = 15.5319 (1) ?, β = 96.038(3)o, V = 946.15(6) ?3, Z = 4, R = 0.0619 and wR = 0.1606. Its structure is a 2D polymer, whose repeat units consist of dinuclear silver cluster coordinated by two bridging iminodiacetic acids. In the complex, the Ag(I) ions adopt three coordinate fashions, and the Ag-Ag metal-metal contacts of 2.8418 ? are observed.

Quantum Chemistry Studies on the Fe-Cu Interactions and ^(31)P NMR in Fe(CO)_3(Ph_2Ppy)_2(CuX_n) (X_n=Cl_2^(2-),Cl^-,Br^-)

In order to study the Fe-Cu interactions and their effects on 31p NMR, the structures of mononuclear complex Fe（CO）3fPhzPpy）a 1 and binuclear complexes Fe（CO）3（PhEPpy）z（CuXn） （2： Xn = Cl2^2-, 3： Xn = Cl-, 4： Xn = Br-） are calculated by density functional theory （DFT） PBE0 method. For complexes 1, 3 and 4, the 31p NMR chemical shifts calculated by PBE0-GIAO method are in good agreement with experimental results. The 31p chemical shift is 82.10 ppm in the designed complex 2. The Fe-Cu interactions （including Fe→Cu and Fe←Cu charge transfer） mainly exhibit the indirect interactions. Moreover, the Fe-Cu（I） interactions （mostly acting as σFe-p→4Scu and aFe-C→4Scu charge transfer） in complexes 3 and 4 are stronger than Fe-Cu（Ⅱ） interactions （mostly acting as σFe-p→4Scu and σFe-p←4Sc,） in complex 2. In complex 2, the stronger Fe←Cu interac- tions, acting as σFe-p←44SCu charge transfer, increase the electron density on P nucleus, which causes the upfield 31p chemical shift compared with mononuclear complex 1. For 3 and 4, although a little deshielding for P nucleus is derived from the delocalization of σFe-p→4Scu due to the Fe→Cu interactions, the stronger σFe-c→np charge-transfer finally increases the electron density on P nucleus. As a result, an upfield 31p chemical shift is observed compared with 1. The stability follows the order of 2〉3=4, indicating that Fe（CO）3（PhzPpy）2（CuCl2） is stable and could be synthesized experimentally. The N-Cu（Ⅱ） interaction plays an important role in the stability of 2. Because the delocalization of σFe-p→4SCu and σFe-c→πc-o weakens the a bonds of Fe-C and ~r bonds of CO, it is favorable for increasing the catalytic activity of binuclear complexes. Complexes 3 and 4 are expected to show higher catalytic activity compared to 2.

Mo8^ⅤW2^ⅥO26（C5H5N）8·2H2O： A Novel Mixed-valence Heterometal Polyoxometalate

A new mixed-valence heterometal cluster Mo8VW2VIO26（C5H5N）8·2H2O has been synthesized under solvothermal conditions and characterized by X-ray single-crystal diffraction, IR, UV-vis and XPS spectroscopy. The title compound crystallizes in the triclinic system, space group P1 with a = 11.708（3）, b = 12.018（4）, c = 13.316（4） A, α = 112.184（4）, β = 97.844（4）, γ = 110.043（3）°, V = 1551.9（8） A3 and Z = 1 at 293（2） K. The final full-matrix least-squares refinement converged to R = 0.0414 for 4460 observed unique reflections with I 〉 2σ（I） and w R = 0.1290 for all data（5352） and S = 1.015. In addition, its thermal stability and fluorescent property have also been investigated.

ScY@C_(3v)(8)-C_(82):Metal-Metalσ^(2)Bond in Mixed Rare-Earth Di-metallofullerenes

Comprehensive Summary The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds.Herein,we report the synthesis and characterization of a novel heteronuclear di-metallofullerene,ScY@C_(3v)(8)-C_(82),which contains a mixed rare-earth metal-metal bond.ScY@C_(3v)(8)-C_(82)was successfully synthesized by arc-discharging method and characterized by mass spectrometry,UV-vis-NIR spectroscopy and single-crystal X-ray diffraction crystallography,which unambiguously determined its molecular structure.Theoretical calculations were also performed to study the optimized positions of Sc-Y metallic dimer and the electronic configuration.The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C_(3v)(8)-C_(82)cage,i.e.,(ScY)4+@(C_(3v)(8)-C_(82))4-.In particular,a covalent Sc-Yσ2 bond,which has never been reported before,is proven to be formed inside C_(3v)(8)-C_(82)fullerene cage.This work presents a novel di-metallofullerene containing mixed rare-earth metal-metal bond and expands the understanding of metal-metal bonding of rare earth elements.

Structure and Composition of Metal-Metal Amorphous Alloys

Many experimental results have shown that the property of amorphous alloys has certain relation with composition, because the change in composition can result in change in structure of amorphous alloys.So in order to understand the influence

Strong preciousmetal–metal oxide interaction for oxygen reduction reaction:A strategy for efficient catalyst design

Oxygen reduction reaction(ORR)is an electrochemical reaction in which dissolved oxygen in an electrolyte is reduced toOH−/H2Owhen receiving electrons.This reaction plays a crucial role in shaping the efficiency of both metal-air batteries and fuel cells,and precious metals are the dominant catalysts carrying out the ORR in their cathodes.However,how to manipulate the electronic structure of precious metals as active sites to further promote ORR performance and maximize the utilization rate is still under development.Metal oxide serves as suitable and promising support that can strongly interact with precious metals for both activity and durability enhancement.Herein,we present recent research updates on strong precious metal-metal oxide interaction(SPMMOI)utilized in ORR.We start by introducing the background of ORR,the issues to be solved,and its practical applications followed by a thorough discussion of the reaction mechanism and comprehensive evaluation protocols of performance.We then provide a complete understanding of theworking principle of SPMMOI and highlight the related advances.Finally,we summarize the merits of the precious metal-metal oxide systemand propose the research direction aswell as some urgent problems to be addressed in the future.

A nonlinear equivalent circuit method for analysis of passive intermodulation of mesh reflectors

Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.

Unprecedented 1D Mixed-metal Polynuclear Cyclometalated Platinum Complexes： Synthesis, Structural Characterization and Spectroscopic Properties

The complexes [Pt2L2（μ-dppm）]（ClO4）2 （1） and {[Pt2L2（μ-dppm）Li（CH3CN）2]（ClO4）3}n （2）, where HL is 6-[4-（diethoxyphosphorylmethyl）phenyl]-2,2′-bipyridinyl and dppm is bis（diphenylphosphino）methane, have been synthesized and characterized. In complex 1 the platinum（Ⅱ） center adopts a distorted square planar coordination geometry. The polymer 2 exhibits a ＂stairstep＂ configuration with one-dimensional Pt（Ⅱ）N^N^CPO- Li（Ⅰ）-OPC^N^ NPt（Ⅱ） mixed-metal units which are linked through dppm. Both complexes have metal-metal interaction with Pt- Pt distances of 3.325（2） and 3.1432（9） A, respectively, and display strong metal-metal-to-ligand charge-transfer （MMLCT） triplet state emission. The density-functional-theory calculation was used to interpret the absorption spectra of the complexes.

Advances on supramolecular assembly of cyclometalated platinum(Ⅱ) complexes

Organoplatinum（Ⅱ） compounds have received enormous attention over the past decades due to their square-planar geometry as well as intriguing photo-physical properties.Self-assembly has emerged as an excellent approach to create well-ordered supramolecular architectures with tunable properties,which underpin the role of solvent-directed approach for the design of functional materials.In this minireview,the recent advances on supramolecular self-assembly of cyclometalated platinum（Ⅱ） complexes have been discussed.During the self-assembly process,non-covalent Pt-Pt and π-π interactions play crucial roles in controlling the structures and functions of the resulting assemblies.

Photofunction-Directed Coordination Molecular Engineering

Molecular engineering has emerged as a highly interdisciplinary field of study on function-directed molecular design,material synthesis,and property optimization,accompanied by a deep understanding of the structure-property relationship.In this review,our recent progress on the design and preparations of photofunctional metal complexes and related materials is summarized from the perspective of coordination molecular engineering.In particular,a series of cyclometalated diruthenium complexes with near-infrared(NIR)electrochromic property have been synthesized by engineering the bridging ligand structures.A group of ruthenium-amine conjugated complexes with multistage NIR electrochromism are obtained on the basis of a multicenter strategy.By engineering the ligand structures,a series of new ruthenium and platinum complexes are synthesized to show switchable luminescence in response to various stimuli.In addition,photoluminescent ruthenium,iridium,and platinum complexes are assembled to afford micro/nanocrystals with well-defined morphology and luminescent properties.

Macrocyclic versus acyclic preorganization in organoplatinum(Ⅱ)-based host-guest complexes

Two host-guest systems have been constructed,by employing structurally similar terpyridine platinum(II)macrocycle and molecular tweezer as the synthetic receptors.The macrocycle/guest complex displays low-energy emission signal,reinforced non-covalent binding affinity,and enhanced photosensitization capability than those of the molecular tweezer/guest one.The discrepancy between macrocyclic and acyclic preorganization modes originates from the different numbers of Pt(II)Pt(II)metal-metal bonds in host-guest complexation structures.

A One-dimensional Linear Polymeric Au(Ⅰ) Compound With Strong Au-Au Interaction: Preparation and Structure of [AuS_2CNEt_2]_(4n)

Dialkyldithiocarbamate （R2NCS-2） acting as either bridging or terminal ligand plays an important role in modern coordination chemistry. The molecules of the univalent coinage metals （Cu, Ag, and Au） with dialkyldithiocarbamate ligands form a class of compounds in which the sterical restriction influences strongly the crystal structures, and several types of polymerizates were found. However, only a few structures in linear form

Solvent-Assisted Supramolecular Assembly of Cyclotetrasiloxane– Functionalized Alkynylplatinum(II) Terpyridine Complexes

Our present study demonstrated and explored the solvent effects on the association mechanism of the supramolecular nanomaterials in a series of cyclo-tetrasiloxane-appended alkynylplatinum(II)terpyri-dine complexes.Through the delicate balance of molecular interactions,some of these complexes were found to exhibit molecular association prop-erties,with possible morphological transformation in response to solvent polarities.