基于紫精配体的新型铀酰配位聚合物的合成、结构和光致变色性能

配体的选择直接影响铀酰配合物的自组装模型，对配合物的结构和功能具有决定性作用。在这项工作中，使用水热法实现了多种配体与铀酰离子的组装，合成了三种基于紫精功能基团的铀酰配位聚合物。三种配位聚合物的主体骨架均是一维链状结构。其中，配合物1和2均表现出明显的荧光性质。此外，配合物2具有显著可逆的光致/热致变色性质。紫外-可见光谱和电子顺磁共振(EPR)光谱表明这种可逆的颜色变化是由于紫精配体在光照后产生了紫精自由基所致。这项研究实现了多例基于紫精配体的铀酰配位聚合物的组装合成，为更多贫铀功能性材料的开发提供了思路。     

铀酰大环配体化合物的理论研究进展

锕酰离子与配体的相互作用本质在锕系元素组分离的应用中具有重要意义，因此本课题组近几年一直致力于这方面的研究。本文对铀酰与大环配体形成的配合物的配位结构、稳定性和成键性质进行了综述和规律性总结。首先，研究发现锕酰大环配合物的配位结构取决于大环配体的腔体大小；其次，侧配位时，铀酰倾向于形成1∶2稳定结构，而嵌入式结构时，铀酰倾向于形成1∶1稳定结构；再次，通过对一系列配体的研究，发现环尺寸为18的配体，在与铀酰结合时表现了优异的配位能力，其中[CHP]^4-具有最强的结合能力；最后，这种稳定主要是由于U-N共价性大于U-O及U-S。这些结构规律和成键特征，为实验上筛选合理且高效分离锕系元素的配体提供了重要理论指导。     

9 一种新型酰胺类萃取剂的合成

酰胺类三足化合物具有良好的离子选择性，近年来被广泛研究用于对镧系和锕系离子的萃取。三足配体是一种半刚性结构的化合物，3条侧链可自由翻转形成大小合适的空腔以便与不同的客体分子或离子结合，加之侧链取代基的多样性，使其具有丰富多变的立体配位结构。长期以来，它在配位化学、萃取化学等研究领域有着广泛应用。为进一步研究此类配体的萃取性能，本工作合成了以N-羟甲基水杨酰胺为末端基的三足配体2，2’，2”-三[2-（N-羟甲基甲酰基）苯氧基]三乙胺，并用红外、核磁、紫外、元素分析进行了表征。有关它的萃取性能研究正在进行之中。     

辛醇溶液、水溶液、固态及液-液萃取体系中TRDGA与Pr(Ⅲ)的配位研究

为加深对四烷基-3-氧杂-戊二酰胺(TRDGA)类配体与三价锕/镧离子配位的认识,利用光谱及单晶X射线衍射分析技术,分别在含水辛醇溶液、水溶液、晶体及液-液萃取体系中对比研究了脂溶性N,N′-二甲基-N,N′-二辛基-3-氧杂-戊二酰胺(DMDODGA,L)以及水溶性四甲基-3-氧杂-戊二酰胺(TMDGA,L′)与Pr(Ⅲ)的配位。光谱滴定实验结果表明,两配体在溶液中均可与Pr(Ⅲ)形成金属离子与配体比值为1∶1、1∶2及1∶3的配合物,并获得了配合物稳定常数及标准吸收光谱。配合物中金属离子与配体比值相同时,L和L′与Pr(Ⅲ)形成的每对配合物中Pr(Ⅲ)特征吸收峰的位置及形状均几乎完全相同,说明每对配合物的内配位层结构相同或相近。PrL₃′(ClO₄)₃晶体漫反射光谱与PrL₃³⁺及PrL₃^′3+标准吸收光谱的特征也相同,说明1∶3配合物均为三帽三棱柱配位构型。与加入硝酸根的光谱滴定实验相结合,通过有机相吸收光谱与已知固体/溶液配合...     

中空六棱柱燃料元件热-力学性能研究

中空六棱柱燃料元件在高温气冷堆方面有广泛应用,为研究中空六棱柱燃料元件的堆内性能,评价其失效概率,针对高温气冷堆用中空六棱柱燃料元件进行了热-力学行为分析,采用多物理场耦合的方法计算了中空六棱柱燃料元件的热-力学行为,分析了中空六棱柱燃料元件在较低中子注量条件下的温度场、变形、应力分布以及失效概率。结果表明,中空六棱柱燃料元件的最高运行温度约为1020 K,SiC基体的最大应力约为107.32 MPa、失效概率为3.52×10?4,SiC基体较低的失效概率保证了燃料元件的结构完整性。在较低中子注量下,中空六棱柱燃料元件的运行温度和应力均较低并且可以保证结构完整,具有良好的堆内运行状态。      

铀酰配位介导咔唑三羧酸超分子组装体的结构演变北大核心CSCD

作为一类典型的金属-有机框架材料(MOFs),基于锕系金属节点的MOFs具有其独特的锕系-配体键合方式。然而,这些配位相互作用如何参与并影响有机配体的晶格组装过程仍有待研究。在本工作中,以咔唑三羧酸有机配体与铀酰离子的配位组装为例,通过控制合成条件详细研究了铀酰配位作用对咔唑三羧酸配体晶格组装过程的调控。单晶结构分析表明,随着铀酰金属节点的引入,咔唑三羧酸超分子组装体实现了从氢键-有机网络结构向金属-有机网络结构的逐级演变。在这一调控过程中,不同咔唑三羧酸间的连接方式由羧基氢键对逐渐被铀酰配位作用取代,二维网络结构也从六重穿插非平面网络转变为平面超分子网络和金属-有机配位网络。相关转变过程主要表现在羧基不断参与铀酰中心的配位作用,这一过程也得到了红外光谱的证实。通过本工作的开展,成功揭示了铀酰-配体配位作用调控无机-有机多孔材料合成的分子机制及相关材料结构演变的详细过程。     

99Tcm标记的N-(邻甲硫基苯基)甘氨酰胺和硫醇混配配合物的制备及生物分布

合成了三齿配位林Ｎ－（邻甲硫基苯基）甘氨酰胺（ＭＴＰＧＡ）。其结构经ＩＲ、ＮＭＲ和ＭＳ等表征予以确认。用配位体交换法制备了＾９９Ｔｃ＾ｍ（Ｌ１,Ｌ３）混配配合物（其中Ｌ１为单齿配位体乙硫醇,Ｌ３为三齿配位体ＭＴＰＧＡ）,确定了标记的最佳条件及标记物的稳定性。实验结果表明,＾９９Ｔｃ＾ｍ（Ｌ１,Ｌ３）的标记率在９０％以上,室温下可以稳定约６ｈ。用＾９９Ｔｃ＾ｍ（Ｌ１,Ｌ３）进行了小鼠生物分布研究。结     

N,N-二烷基二甘酰胺酸类配体萃取Pr(Ⅲ)及在水溶液中的配位化学

N,N-二(2-乙基己基)二甘酰胺酸（HL）作为一种三齿单羧酸类萃取剂,在pH=1～4区域至强酸性条件下对三价镧系离子均具有一定的萃取能力,但不同酸度下的萃取机理不同。为更好地确定其配位机理,本文对HL从硝酸盐体系中萃取Pr(Ⅲ)及N,N-二甲基二甘酰胺酸（HL′）在水溶液中与Pr(Ⅲ)的配位化学进行了研究。在测定Pr(Ⅲ)与萃取剂HL在pH=1～4条件下生成萃合物的光谱和组成的基础上,结合水溶性同系物HL′与Pr(Ⅲ)在水溶液中生成的配合物及其光谱和结构,确定了HL与Pr(Ⅲ)在硝酸体系下pH=1～4区域内生成的萃合物有两种：一种是已报道过的具有PrL₃核心的萃合物;另一种是PrL₂NO₃。在水溶液中通过电位滴定法和光谱滴定法研究了HL′与Pr(Ⅲ)生成配合物的稳定常数及在紫外-可见区的吸收光谱。在1 mol/L NaClO₄介质中,去质子化的HL′可与Pr(Ⅲ)形成PrL′²⁺、PrL′⁺₂、PrL′₃ 3种形式配合物,随着配体结合数的增加,Pr(Ⅲ)在400～600 nm的几个特征吸收峰持续红移,吸收强度稍有减弱。在水溶液中通过缓慢挥发获得了PrL′₃单晶化合物,晶体结构测定结果表明,配合物中3个配体均以三齿配体形式与Pr(Ⅲ)配位。通过比较水溶液中PrL′₃配合物、有机相中PrL₃萃合物的吸收光谱以及PrL′₃单晶化合物的固体漫反射光谱,确定在水溶液中PrL′₃配合物及萃取体系中具有PrL₃核心的萃合物中,都有3个三齿配体与Pr(Ⅲ)配位;通过比较水溶液中以1∶2配位的配合物PrL′⁺₂的吸收光谱与组成为PrL₂NO₃的萃合物的吸收光谱,发现590 nm处峰形明显不同,表明萃合物中硝酸根很可能与Pr(Ⅲ)也直接配位。在萃取剂与金属离子浓度比不同时,生成的萃合物种类不同,当萃取剂浓度与金属离子浓度比小于等于2时,推测硝酸根在内层参与配位。     

铼[188Re]羰基化合物标记新双功能螯合剂的研究

合成了三种新的三齿配体L1NH2、L2H和L3NH2,用于设计合成新的以fac-[188Re(CO)3] 为核心的放射性药物.标记条件实验证明,三种配体在低浓度(10-5 mol/L)的条件下,反应时间为60min内,配体标记率可达88%以上,放射化学纯度大于90%.同时合成了冷羰基铼配合物fac-[Re(CO)3L1NH2] 、fac-[Re(CO)3L2H]和fac-[Re(CO)3L3NH2]作为参照标准品.稳定性实验也说明三种标记物均具有很高的体外稳定性,标记后24 h内基本不发生分解;组氨酸和半胱氨酸体外竞争实验证实fac-[188Re(CO)3L1NH2] 和fac-[188Re(CO)3L2H]比fac-[188Re(CO)3L3NH2]稳定,不易被组氨酸和半胱氨酸取代,可能羧基上的-OH与fac-[188Re(CO)3] 的配位能力比吡啶环上的N稍低,也可说明三种配体均是较理想的标记fac-[188Re(CO)3(H2O)3] 的双功能螯合剂.     

深度学习引导的高通量分子筛选用于锶铯的选择性配位北大核心CSCD

试图从配位化学性质差异的角度增进对乏燃料后处理过程中锶铯分离的认识。基于对晶体结构进行数据挖掘和深度学习架构,从8种碱金属和碱土金属元素的配位结构(约3.3×10^(4)个样本)中归纳和分析锶、铯的配位化学性质,尤其是配位键长。通过引入贝叶斯优化工具,建立了高效的transformer模型,可以以很高的准确性预测配体与锶、铯离子分别的结合强度及其差异。作为概念验证,成功对配体分子结构(约9.1×10^(4)个)对锶、铯的潜在配位选择性进行排序,并为未来的配体设计确定了不同官能团对实现配位选择性的贡献度。本研究利用人工智能手段,为乏燃料后处理过程及放射化学语境中元素的配位化学信息及分离技术开发积累基础知识,为后续实验提供指导和参考。     

锝,铼五配位化合物的构型

总结了锝、铼五配位化合物构型的变化规律，并用空腔模型对这些规律进行了解释。铼的五配位化合物皆为高价配合物（氧化态大于四价），在５个配位原子中，当含有１个或５个近距结合原子（带２个或２个以上负电荷的配位原子）时，配合物具有四方锥构型；含有３个近距结合原子时，配合物具有三角双锥构型；含有２个近距结合原子时，配合物具有变形三角双锥构型；含有４个近距结合原子或没有近距结合原子时，五配位结构不稳定。由于锝、铼化学性质相似，这些构型变化规律实际上也是五配位锝化合物的构型变化规律。已测五配位锝化合物的构型种类较少，但都不违反这一构型变化规律。     

基于热-流-固耦合的燃料元件性能分析方法研究

中空棱柱形燃料元件形式和运行工况特殊,没有现成的燃料性能分析软件能够满足计算要求,需要建立新的分析方法。本研究基于COMSOL软件二次开发,采用颗粒增强复合材料的等效物性模型和共轭传热技术实现中空六棱柱形燃料的三维热-流-固耦合计算,通过与美国通用电气公司数据的对比证明了该分析方法的有效性。采用该方法计算了多种燃料元件尺寸和不同轴向功率分布下的热应力和温度,结果表明侧棱处温度最高而内壁面壁厚最薄处热应力最大,壁厚越薄、长度越长,燃料元件的最大热应力和温度越小,展平入口段的轴向功率分布也能够略微降低最大热应力和温度。以上分析方法可以用于新型中空棱柱形燃料元件的优化设计。      

Design study of a channel in the moderator on improving C and O measurement in coal

By introducing a channel in the moderator of a coal analysis setup using neutron-induced gamma technique, more fast neutrons can reach the coal. Then the characteristic gamma-rays of C and O are increased due to neutron inelastic scattering (NIS) reaction, and measurement of the two elements is sufficiently improved. Monte-Carlo simulations have been carried out in this work for the setup with different prism channels. These prism channels have different positions and sizes, but their bottom surfaces are all nearby the neutron source. The results show that, it could obtain the optimum improvement of C and O measurement, by selecting a proper position and size for the prism channel.     

The crystal structure of ThBC

The crystal structure of ThBC has been determined by single crystal X-ray analysis. The lattice parameters of the tetragonal cell were found to be a = 3.762(2), c = 25.246(5) Å. The space group is P4₁22 (D₄³), Z = 8. Intensity measurements were made on a fourcircle diffractometer. The structure was solved by Patterson methods and refined by full matrix least squares calculation. R with isotropic temperature factors is 0.06 for 381 observed reflections. The structure contains tetrahedra and trigonal prisms of Th atoms. The trigonal prisms are centered by boron atoms, carbon atoms have octahedral coordination 5Th + 1B. The crystal structure of ThBC can be generated by a simple shift out of the UBC-type structure. The structural chemistry of ThBC, UBC and YBC is discussed.     

Phase equilibria and crystal structures in the ternary systems: Actinoid metal-transition metal-boron: I. Plutonium-borides with the LuRuB2-type of structure

Ternary borides PuTB₂ have been synthesized from the elements. X-ray powder diffraction analysis proved that all compounds with T = Tc, Re, RuandOs are isotypic and crystallize in the LuRuB₂-type of structure. No isostructural compounds were observed with thorium and uranium. The structural chemistry of the new phases is discussed with respect to the related structure types of MoCoB (anti-PbCl₂ or TiNiSi-type) and FeB.     

Effect of specimen sizes, specimen shapes, and placement directions on compressive strength of concrete

The compressive strength of concrete is used as the most basic and important material property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes may be different from country to country.In this study, the effect of specimen sizes, specimen shapes, and placement directions on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure were carried out by using cylinder, cube, and prism specimens. The test results are curve-fitted using least square method (LSM) to obtain the new parameters for the modified size effect law (MSEL). The analysis results show that the effect of specimen sizes, specimen shapes, and placement directions on ultimate strength is present. In addition, correlations between compressive strengths with size, shape, and placement direction of the specimen are investigated.     

Reduction of Plastic Anisotropy of Zircaloy Cladding by Neutron Irradiation, (II)

Initial plastic deformation behavior of zirconium alloy fuel cladding was described quantitatively by the deformation system of single crystal of α-zirconium, and a model was proposed to simulate the yield behavior of polycrystalline material. Based on the model, effects of crystallographic texture and stress state on the plastic deformation of the cladding were evaluated. Conclusions obtained from this investigation are:

(1) The proposed model shows good agreement with the von Mises' yield criteria for a material with isotropic properties.

(2) Plastic anisotropy of the cladding decreases when neutron irradiation affects prism slip more strongly than the other deformation systems.

(3) Dominant deformation systems for axial tension or internal pressurization of the cladding are predicted to be prism slip or tensile twin, respectively, when the stress state of the cladding reaches the yield condition.     

Influence of polytypism on elementary processes of ion-beam-induced defect production in SiC

Classical molecular dynamics (MD) simulations are performed to investigate elementary ion-beam-induced defect production in 3C– and 4H–SiC. A modified Tersoff potential is used to model the interactions between the atoms. For cases where the C and Si primary knockon atoms (PKAs) start parallel or antiparallel to the [0 0 0 1] direction, the threshold PKA energy for defect formation as well as the final defect configuration and its formation energy are determined. The elementary defects observed in 3C–SiC and 4H–SiC differ significantly whereas the corresponding threshold PKA energies and the formation energies of the configurations are mostly similar. In 4H–SiC new sites for C and Si interstitials are found: one site is situated between two C₃Si₃ hexagonal rings, the other between a C₃ and an Si₃ trigonal ring.     

The crystal structure of Th3B2C3

The crystal structure of Th₃B₂C₃ has been determined by single crystal X-ray analysis. The lattice parameters of the monoclinic cell (first setting) are: $\text{a = 3.703 (2)}\text{A}\text{?}\text{, b = 9.146 (4)}\text{A}\text{?}\text{, c = 3.773 (1)}\text{A}\text{?}\text{and γ = 100.06 (7)°}$; space group: P2/m (C$\text{1}\text{2}{}_{\mathrm{h}}$), Z = 1. Intensity measurements were obtained from a fourcircle diffractometer. The structure was solved by Patterson methods and refined by full matrix least squares calculation. For an asymmetric set of 401 independent reflexions the final R-value is 0.079. The structure contains octahedra, tetrahedra and trigonal prisms of Th-atoms. The trigonal prisms are centered by boron atoms, Th-octahedra by carbon atoms Cl; Carbon atoms C2 actually have octahedral coordination 5 Th + 1 B. The structural chemistry of Th₃B₂C₃ with respect to the crystal structures of ThC and ThBC is discussed.     

123I和99Tcm标记的吲哚类σ2受体放射性示踪剂的设计、稳定化合物的合成及体外生物评价

设计了~(123)I和~(99)Tc~m标记的吲哚类σ_2受体肿瘤放射性示踪剂,合成了其稳定化合物 (Indole-I和Indole-MAMA-Re) 和标记前体(Indole-MAMA).体外受体结合分析结果表明,化合物Indole-I对σ1和σ_2受体的抑制常数K_i值分别为(0.574±0.355) μmol/L和(0.162±0.030) μmol/L(n=3),Indole-MAMA-Re对σ1和σ_2受体的抑制常数K_i值分别为(3.75±2.22) μmol/L和(7.83±4.87) μmol/L(n=3).成功制备了~(99)Tc~m-Indole-MAMA,纯化后经高效液相色谱法(HPLC)分析其放化纯大于90%.今后可在本文化合物的基础上通过结构优化,设计合成对σ_2受体具有高亲和力和选择性的吲哚类SPECT肿瘤显像剂.