高配位3d过渡金属单离子磁体磁各向异性研究

单离子磁体(SIMs)因其磁性双稳态和慢弛豫机制而在高密度信息存储、量子计算和分子自旋电子学等方面具有潜在的应用价值。其中3d过渡金属单离子磁体(3d‑SIMs)磁构关系较为简单且易于分析,因此得到了众多研究者的关注。目前文献上报道的大多数3d‑SIMs通常具有较低的配位数,而对于高配位(七配位和八配位)的3d‑SIMs缺少深入而系统的研究。我们结合近年来的研究成果,从磁各向异性的基本性质、实验表征和理论计算3个方面出发,对高配位3d过渡金属单离子磁体的配位环境、磁各向异性和慢磁弛豫行为进行了综述,分析了配位构型和配位原子等配位环境对高配位3d过渡金属单离子磁体磁各向异性的影响,为高配位3d过渡金属单分子磁体的设计与调控提供思路。

纳米尺度高配位活性钛TS-1的制备及性能评价

以低成本模板剂四丙基溴化铵和硅溶胶为原料,利用蒸汽辅助干胶晶化法,通过添加晶种的方式合成出纳米级TS-1分子筛。再经二次水热晶化,采用乙胺和四丙基溴化铵的混合溶液对其进行处理,制备出了含有六配位钛的高活性TS-1分子筛。采用X射线衍射、紫外漫反射可见光谱、紫外拉曼光谱、傅里叶变换红外光谱、固体核磁共振、N2物理吸附-脱附测试对其物理化学性质进行了表征,并考察了其对丙烯环氧化反应的催化性能。结果表明,纳米级TS-1分子筛后处理生成了活性更为优异的六配位钛物种,且其孔道结构得到了改善,比表面积明显增大;其催化丙烯环氧化反应的活性明显提高,双氧水转化率由二次晶化处理前的47.59%增至二次晶化72 h的85.79%。

一种高配位钨酸盐体系Sr_3WO_6:Eu红色荧光粉的制备与发光性能研究

采用简单的柠檬酸络合法合成了一系列具有高配位钨酸盐体系Sr3WO6：Eu红色荧光粉,该体系红色荧光粉在近紫外光区域具有较强的吸收能力,发射峰主要位于～616nm处,来源于Eu3＋的5 D0-7F2跃迁,具有高的色纯度,适合应用在近紫外LED上。研究了用Li^＋、Na^＋、K^＋分别作为电荷补偿剂对其发光性能的影响,发现采用K＋做电荷补偿剂时,发射强度可以明显提高,色纯度为98.6%,色坐标为（0.655,0.339）。

磷与生命化学

许多事实证明磷在生命中起着重要作用、例如基因的材料DNA和RNA是磷酸二酯，RNA不仅是信息的载体，同时也具有催化作用。许多辅酶是磷酸酯和焦磷酸酯，生物的主要能量储存仓库ATP也是磷酸酯，许多新陈代谢的中间体是磷酸酯的缀合物，细胞膜的主要组成部分是磷脂双分子层，所以说磷酯及其酸酐在生物界中起着十分重要的作用。

Fabricating high-loading Fe-N4 single-atom catalysts for oxygen reduction reaction by carbon-assisted pyrolysis of metal complexes

Iron-based single-atom catalysts with nitrogen-doped carbon as support(Fe-SA/NPC)are considered effective alternatives to replace Pt-group metals for scalable application in fuel cells.However,synthesizing high-loading Fe-SA catalysts by a simple procedure remains challenging.Herein,we report a high-loading(7.5 wt%)Fe-SA/NPC catalyst prepared by carbon-assisted pyrolysis of metal complexes.Both the nitrogen-doped porous carbon(NPC)support with high specific surface area and ο-phenylenediamine(o-PD)play key roles role in the preparation of high-loading Fe-SA/NPC catalysts.The results of X-ray photoelectron spectroscopy,high-angle annular dark-field scanning transmission electron microscopy,and X-ray absorption fine structure spectroscopy experiments show that the Fe atoms are anchored on the carbon carriers in a single-atom site configuration and coordinated with four of the doped nitrogen atoms of the carbon substrates(Fe-N_(4)).The activities of the Fe-SA/NPC catalysts in the oxygen reduction reaction increased with increasing iron loading.The optimized 250Fe-SA/NPC-800 catalyst exhibited an onset potential 0.97 V of and a half-wave potential of 0.85 V.Our study provides a simple approach for the large-scale synthesis of high-loading single-atom catalysts.

Self-assembled energetic coordination polymers based on multidentate pentazole cyclo-N_5^-

Coordination to form polymer is emerging as a new technology for modifying or enhancing the properties of the existed energetic substances in energetic materials area. In this work, guanidine cation CN3 H6+ (Gu) and 3-amino-1,2,4-triazole C2H4N4(ATz) were crystallized into NaN5 and two novel energetic coordination polymers(CPs),(NaN5)5[(CH6-N3)N5](N5)3–(1) and(NaN5)2(C2H4N4)(2) were prepared respectively via a self-assembly process. The crystal structure reveals the co-existence of the chelating pentazole anion and organic component in the solid state. In polymer 1, Na+and N5– were coordinated to form a cage structure in which guanidine cation [C(NH2)3]+ was trapped;for polymer 2, a mixedligand system was observed;N5 – and ATz coordinate separately with Na+and form two independent but interweaved nets. In this way, coordination polymer has been successfully utilized to modify specific properties of energetic materials through crystallization. Benefiting from the coordination and weak interactions, the decomposition temperatures of both polymers increase from 111°C(1D structure [Na(H2 O)(N5)]?2 H2 O) to 118.4 and 126.5°C respectively. Moreover, no crystallized H2 O was generated in products to afford the anhydrous compounds of pentazole salts with high heats of formation( >800 kJ mol–1). Compared to traditional energetic materials, the advantage in heats of formation is still obvious for the cyclo-N5– based CPs, which highlights cyclo-N5– as a promising energetic precursor for high energy density materials(HEDMs).

Analysis on spectral gain characteristics of PPMgLN based quasi-phase-matching optical parametric amplification

A deep understanding of the spectral gain characteristics of optical parametric oscillators (OPOs) and optical parametric amplifiers (OPAs) is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching (QPM) parametric conversion process using the periodically poled 6% (mol/mol) MgO doped LiNbO3 (PPMgLN) as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that: (1) The full width at half maximum (FWHM) of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; (2) The gain coefficient decreases gradually with the increase of parametric wavelength; (3) The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; (4) There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser.

Optimization of the thermoelectric properties of poly(nickel-ethylenetetrathiolate) synthesized via potentiostatic deposition

The coordination polymer poly（nickel-ethylenetetrathiolate） （poly（Ni-ett））, formed by nickel（Ⅱ） and 1,1,2,2-ethenetetrathiolate （ett）, is the most promising N-type organic thermoelectric material ever reported; it is synthesized via potentiostatic deposition, and the effect of different applied potentials on the optimal performance of the polymers is investigated. The optimal thermoelectric property ofpoly（Ni-ett） synthesized at 0.6 V is remarkably greater than that of the polymers synthesized at 1 and 1.6 V, exhibiting a maximum power factor of up to 131.6μW/mK2 at 360 K. Furthermore, the structure-property correlation ofpoly（Ni-ett） is also extensively investigated. X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses revealed that the larger size of crystalline domains and the higher oxidation state of poly（Ni-ett） synthesized at 0.6 V possibly results in the higher bulk mobility and carrier concentration in the polymer chains, respectively, accounting for the enhanced power factor.

Au NP@silica@europium coordination polymer nanocomposites for enhanced fluorescence and more sensitive monitoring reactive oxygen species

Au nanoparticle（Au NP）@SiO2@TDA-Eu nanocomposites were prepared by a two-step process： Au NP@SiO2 nanocomposites were prepared by a modified onepot process. Then the europium coordination polymer was deposited on the surface of the Au NP@SiO2 by mixing 2,2＇-thiodiacetic acid [S（CH2 COO）2^（2-）, TDA] and Eu（NO3）3·6 H2 O in ethanol via a hydrothermal method. The maximum fluorescent enhancement factor of the nanocomposites was 6.81 at 30 nm thickness of silica between the core of the Au NP and the shell of TDA-Eu. The prepared nanocomposites exhibit more sensitive monitoring of reactive oxygen species.

Activating multisite high-entropy alloy nanocrystals via enriching M–pyridinic N–C bonds for superior electrocatalytic hydrogen evolution

The activation of multisite high-entropy alloy(HEA)electrocatalysts is helpful for improving the atomic utilization of each metal in water electrolysis catalysis.Herein,well-dispersed HEA nanocrystals on Nrich graphene with abundant M–pyridinic N–C bonds were synthesized through an ultrasonic-assisted confinement synthesis method.Operando Raman analysis and density functional theory calculations revealed that the electrocatalysts presented the optimal electronic rearrangement with fast ratedetermined H_(2)O dissociation kinetics and favorable H^(*)adsorption behavior that greatly enhanced hydrogen generation in alkaline electrolyte.A small overpotential of only 138.6 mV was required to obtain the current density of 100 mA cm^(-2) and the Tafel slope of as low as 33.0 mV dec^(-1),which was considerably smaller than the overpotentials of the counterpart with poor M–pyridinic N–C bonds(290.4 mV)and commercial Pt/C electrocatalysts(168.6 mV).The atomic structure,coordination environment,and electronic structure were clarified.This work provides a new avenue toward activating HEA as advanced electrocatalysts and promotes the research on HEA for energy-related electrolysis.