Theoretical investigation into coordination and selectivity of uranyl-unilateral benzotriazole salophens (X = O/S) for R/S-triadimefons

The design of new uranyl-ligands (uranyl-Ls) is of great significance for the separation and utilization of uranium. In this paper, the triazole group was introduced into uranyl-salophen (uranyl-S) to form new asymmetric uranyl-unilateral benzotriazole salophen (uranyl-UBS); we further replaced two oxygen atoms of uranyl-UBS with two sulfur atoms to generate uranyl-unilateral benzotriazole thio-salophen (uranyl-UBTS) as a new receptor. Then, we comprehensively explored coordination models of uranyl-UBS and uranyl-UBTS with R/S-triadimefons (R/S-TDFs) enantiomers as the guests using density functional theory calculations at the B3LYP//RECP/6-311G** level; we then investigated enantioselectivity recognition of the new receptors to the guests R/S-TDFs. The results indicated that the uranium atoms of the receptors uranyl-S, uranyl-UBS and uranyl-UBTS could coordinate with the carbonyl oxygens in guests R/S-TDFs to form complexes of guest-receptors R/S-TDFs-uranyl-Ls that exhibited two stable V-shaped structures with quite different properties. It was found that the coordination ability to the guests R/S-TDFs is uranyl-UBTS > uranyl-UBS > uranyl-S, while the enantioselectivity for the guests is uranyl-UBTS > uranyl-S > uranyl-UBS and, when the receptor is the same, R-TDF has stronger coordination ability than S-TDF. These results provide information and theoretical supports for the experiments of asymmetric uranyl-UBS with R/S-TDFs, and produce a reference for further exploring the coordination characteristics of asymmetric uranyl-salophen with the triazole derivatives.     

多光子电离下醇类团簇中的反应

应用Nd:YAG(Spectra-Physics LAB-170)脉冲激光器输出的355nm紫外激光实现了对甲醇、乙醇及正丙醇的多光子电离,对每一种样品通过质谱技术都观测到了两个质子化团簇离子系列:(R..3OH)nH 和(R1,2,3OH)n(H2O)H (R1,2,3代表CH2、CH2CH2及CH2CH3CH2),结合在HF/STO-3G和B3LYP/6-31G 水平上的从头计算对其反应通道做了分析,发现其产生经过了团簇内部的质子转移反应及离子-分子反应,且质子主要来自于羟基上的氢离子.并结合从头算分析了(R1,2,3OH)nH 的结构,给出了幻数团簇(R1,2,3OH)3H 的构型.同时对(R1,2,3)n(H2O)H 系列只在n值较大时出现做了相应的解释.     

气溶胶单粒子粒径的实时测量方法研究

介绍了近期研制的一台实时测量大气气溶胶单粒子粒径和化学成分的仪器在如何测量气溶胶单粒子粒径方面的测量原理及特点，并结合激光解吸附电离飞行时间质谱技术，利用该仪器对木屑燃烧产生的烟气气溶胶粒子的实时测量结果. 关键词： 气溶胶粒子 空气动力学粒径测量方法 激光解吸附电离 飞行时间质谱     

Imprints of molecular orbitals using photoelectron angular distribution by strong laser pulses of circular polarization

We theoretically investigate the strong-field ionization of H+2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron's angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron's angular distribution are split into two parts if the photoelectron energy is sufficiently high.     

532nm丙酮和丁酮多光子电离解离研究

利用激光质谱法,通过分析丙酮和丁酮的多光子电离飞行时间质谱,对其532nm多光子电离机制进行了研究. 结果发现丙酮相干吸收若干光子跃迁到高能超激发态,再继续吸收光子产生各种碎片离子,而丁酮先解离后电离. 两质谱中都有质荷比为4、6、8的离子,原则上是高价离子,但在相似条件下未见相关报道,因此对离子出险原因及确认尚待进一步研究. 实验中丁酮发生异构现象,其异构体电离解离出较强的C2H3O+(m/e=43).丙酮没有相关离子产生.     

266nm激光下三乙胺分子多光子电离质谱研究

利用YAG激光器输出的四倍频激光对三乙胺分子的共振增强双光子电离过程进行了研究,获得了三乙胺分子的飞行时间质谱,母体离子及碎片离子信号达29种之多.对碎片离子（C₂H₅）₂N⁺CH₄（86⁺）异常漂移做了分析,发现了异常漂移是由于离子信号强度过强时,86⁺之前的25种离子对其25次瞬间减速效应强于之后的3种离子对其3次瞬间加速效应造成的.     

Metal-Carboxyl Helical Chain Secondary Units Supported Ion-Exchangeable Anionic Uranyl–Organic Framework

As a less explored avenue, actinide-based metal-organic frameworks (MOFs) are worth studying for the particularity of actinide nodes in coordination behaviour and assembly modes. In this work, an azobenzenetetracarboxylate-based anionic MOF supported by uranyl–carboxyl helical chain units was synthesized, incorporating linear uranyl as the metal centre. This kind of helical chain-type building unit is reported for the first time in uranyl-based MOFs. Structural analysis reveals that the formation of helical chain secondary units can be attributed to restricted equatorial coordination of rigid flat azobenzene ligand to uranyl centres. Meanwhile, this newly-synthesized anionic material has been used to remove Eu³⁺ ions, as a non-radioactive surrogate of Am³⁺ ion, through an ion-exchange process with [(CH₃)₂NH₂]⁺ ions in its open channels, as evidenced by a combination of ¹H NMR spectroscopy, EDS and PXRD.     

532nm激光作用下甲基异丙基酮的电离解离研究

在532 nm激光波长下,利用时间飞行质谱(TOF-MS)对甲基异丙基酮的多光子电离解离机制进行了研究.实验结果显示,母体分子首先发生α断裂并且吸收(2+2)个光子到达离子态.主要的质谱峰C_2H_3~+,CH_3COC_3H_7~+,CH_3~+等在质谱图中清晰可见.结合Guassian03,运用HF/3-21G、CIS/3-21G对基态和激发态的构型进行了优化和频率计算,发现激发态的碳氧键变为介于碳氧单键和双键之间特殊键,并用QST2方法找到了其中的过渡态,对三个状态的几何结构参数进行了分析得出了其解离过程是α键断裂和基团构象转化协同进行的结论.     

Synthesis and magnetism of μ-isophthalato dinuclear lanthanide(Ⅲ) complexes

Seven new μ-isophthalato dinuclear lanthanide(Ⅲ) complexes, namely [Ln2(IPHTA)(Me2-phen)4-(ClO4)2](ClO4)2 (Ln = La, Nd, Sm, Eu, Gd, Ho, Er), where Me2-phen denotes 2,9-dimethyl-1, 10-phenanthroline (Me2-phen) , IPHTA represents isophthalate dianion, have been synthesized and characterized by elemental analyses, molar conductance measurements, IR, ESR and electronic spectra. The variable-temperature magnetic susceptibilities of [Gd2( IPHTA) (Mez-phen)4 (ClO4)2] (ClO4)2 complex were measured in the temperature range of 4-300 K and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H = - 2JS1 · S2, giving the exchange parameter J =- 0.19 cm-1 . This result is commensurate with a weak antiferromagnetic spin-exchange interaction between Gd(Ⅲ)-Gd(Ⅲ) ions within the complex.     

乙醚团簇的激光电离质谱及从头计算

应用激光多光子电离质谱与超声脉冲分子束技术研究了乙醚团簇，实验中观测到乙醚的碎片离子以及强度较小的(E)H⁺，(E)^＋₂和(E)₂H⁺(E代表CH₃CH₂OCH₂CH₃)，没有发现更大尺寸的团簇离子.结合从头计算理论，在B3LYP/6-311++G(d,p 关键词： 乙醚团簇 偶极-偶极相互作用 从头计算