内掺三金属氮化物富勒烯Er3N@C80的几何结构与电子性质理论研究

采用密度泛函理论中的广义梯度近似对Ih-Er3N@C80的几何结构和电子性质进行理论研究. 结构优化发现当Er3N的三个Er原子偏离Ih-C80中五边形和六边形公共边中点时形成的结构最稳定. Er—C和Er—N键是离子键. 能级分析可知: 掺入Er3N后, 碳笼的稳定性提高. 局部态密度图和自旋聚居数分析表明: Er3N的掺入使Ih-C80磁性变大, 而Er3N仍然具有一定的磁性. 垂直电离能和垂直亲和能分析表明: 掺入Er3N后, 碳笼的得失电子能力都有所降低.     

Ca@C88和Ca@C90的合成、分离和表征

利用直流电弧法,合成了含钙的富勒烯金属包合物.通过多步高效液相色谱（HPLC）法,首次分离出含钙的富勒烯金属包合物Ca@C88和Ca@C90 (I,II),用激光解析飞行时间质谱(MAL-DI-TOF MS)和紫外-可见-近红外（UV-Vis-NIR） 光谱进行了表征,并对其分子对称性和电子结构进行了讨论.     

高效合成大分子富勒烯金属包合物

采用直流电弧法, 以掺有金属合金和B₄C粉末的光谱纯石墨棒作为阳极, 在He和NH₃混合气氛中进行电弧放电, 首次高产率合成了一系列Gd₂@C_2n(94≤2n≤142)的大分子双金属富勒烯包合物. 实验证明, 异相物质作为热的载体并同时催化产生了大分子富勒烯金属包合物, 而NH₃则抑制了C₆₀和C₇₀等其它富勒烯的生成.     

富勒烯金属包合物的研究进展*

本文介绍了富勒烯金属包合物的发现、意义、合成和提取分离方法以及各种表征手段, 介绍了对富勒烯金属包合物的电子结构和物理化学性质进行的各种研究。     

N@C60的结构和振动光谱的理论研究

用abinitio分子轨道UnrestrictedHartree-Fock(UHF)方法,对N@C₆₀的几何构型进行了全优化.计算结果表明,N基本上以原子的形式存在于笼中,但N原子与碳笼之间存在一定的相互作用,这与实验结果相符.进一步计算了N@C₆₀的振动光谱,并与C₆₀进行了比较分析.     

水溶性金属富勒烯衍生物的合成和表征

Three water-soluble metallofullerene derivatives have been synthesized.IRand XPSanalysis indicate that they have average compositions of Gd@C₈₂(OH)₂₂, Gd@C₈₂(OH)₆(NHCH₂CH₂SO₃H)₈and Gd@C₈₂(OH)₅(NHCH₂COOH)₉, respectively.They are particularly interesting in medical application.     

Tb3+/Eu3+镧系金属有机框架材料在荧光检测的研究进展

镧系金属有机骨框架（Lanthanide metal organic frameworks,Ln-MOFs）是以镧系离子为中心,与配体有机物组合的多孔材料,具有良好的光学性质,在许多领域有广泛的应用。不同的镧系离子与相应的有机配体结合,可组成不同性能的Ln-MOFs。在众多镧系元素中,Tb3+和Eu3+是良好的发光中心,常被用于组建发光Ln-MOFs。由Tb3+/Eu3+与有机配体形成的Ln-MOFs具有独特的荧光特性、较大stokes位移以及长发光寿命等优点在荧光检测领域具有重要应用。本文综述了基于Tb3+/Eu3+的Ln-MOFs在离子检测、生物标志物检测以及小分子检测领域的研究进展,对Ln-MOFs的发展前景进行了展望。     

Ym@C2n的合成和表征

用Ｙ２Ｏ３，碳粉复合棒为原料，经过二步直流电弧反应，从所得的烟炱中在惰气保护下用ＣＳ２萃取出Ｙ＠Ｃ２ｎ（２ｎ＝６０，７０，８０，８４，９０，９６）和Ｙ２＠Ｃ７６，样品经场解吸质谱（ＦＤＭＳ）和电子顺磁共振（ＥＰＲ）表征，皆发现，Ｙ＠Ｃ８４和Ｙ＠Ｃ９０的含量最高且最稳定。     

15N同位素标记的金属氮化物内嵌富勒烯的合成与表征

利用电弧放电法制备了¹⁵N同位素标记的金属氮化物内嵌富勒烯. 制备过程中使用¹⁵NH₄Cl作为固体氮源, 基于电弧放电方法在氦气气氛中将石墨、金属钪和¹⁵NH₄Cl高温原子化, 合成得到Sc₃¹⁵N@C₈₀和Sc₃¹⁵N@C₇₈. 利用高效液相色谱法进行分离纯化, 并通过质谱、紫外可见吸收光谱和核磁共振碳谱表征了Sc₃¹⁵N@C₈₀, 验证了¹⁵N的成功标记, 还表明合成的Sc₃¹⁵N@C₈₀具有I_h-C₈₀碳笼. 所制备的¹⁵N标记的金属氮化物内嵌富勒烯中含有98%以上的¹⁵N同位素, 将拓展金属富勒烯材料在同位素示踪等领域的应用.     

外电场对N@C60, P@C60, As@C60分子结构和性质的影响

用量子力学方法研究了N@C60, P@C60, As@C60分子的几何和电子特征. 计算结果表明, 形成富勒烯包合物后, 碳笼只有微小的变形, 3种内包原子在笼中处于不同的位置, 碳笼与内包原子之间有明显的电荷转移和自旋轨道相互作用, 生成能分别为6.32, 70.88, -53.05 kJ/mol. 内包原子的3个单占据分子轨道(SOMO)能量变化很大, 并由于和碳笼作用而发生劈裂. 在外电场作用下, 分子的电子密度沿电场方向发生转移.分子的能量随外加电场的增强而降低. 分子轨道能级、能隙及SOMO轨道的能量和能级劈裂也发生了变化.     

Voltammetric Behavior of Water‐Soluble Endohedral Metallofullerene Derivatives

Voltammetric behavior of water‐soluble endohedral metallofullerene derivatives Gd@C₈₂(OH)₅(NHCH₂COOH)₉ (GN) and Gd@C₈₂(OH)₆(NHCH₂CH₂SO₃H)₈ (GS) was characterized in 0.1 M KCl solution by CV and DPV. They showed similar redox behavior, that is, a reversible electroreduction process on HMDE was found; in the mean time, an irreversible oxidation process and an irreversible reduction process on GC electrodes were also observed. The results reveal that these two water‐soluble endohedral metallofullerene derivatives have good electron donating ability and poor electron accepting ability due to hydroxy groups, aminoacetic acid and aminoethyl sulfonic acid connected to the C₈₂ cage in comparison with Gd@C₈₂.     

DFT Studies on Non-IPR C68 and Endohedral Fullerene Sc3N@C68

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

笼内金属富勒烯的合成与分析

自1985年,Smalleyr等人首次在飞行时间质谱仪中检测到C60以来,富勒烯碳原子族的研究便不断深入,最初发现的激光蒸发含稀土化合物的石墨只能得到微量的金属富勒烯,仅限于质谱检测,直到1990年,Kratschmer等人采用石墨电子弧放电首次得到宏观量的富勒烯,才使得富勒烯研究进入了实质性的研究阶段。富勒烯及其化合物的分子结构确定对于研究这类化合物无疑是非常重要的,红外光谱、核磁共振、X射线衍射、质谱以及电化学方法都是非常重要的手段。在富勒烯研究中,质谱是相当重要的,在80年代中期的富勒烯以及富勒烯衍生物如金属富勒烯多面体都在质谱中首次发现的。电弧法成功地得到富勒烯后,质谱因其灵敏度高、用量少、简便、快速等优点,成为富勒烯化合物物理化学性能研究以及结构表征工具,其中激光解吸电离为软电离技术只给出化合物分子质量而不产生碎片离子,已成为研究富勒烯首选的重要工具。     

Isolation and Spectroscopic Characterization of New Endohedral Fullerenes in the Size Gap of C74 to C76

New alkaline earth metal endohedral fullerenes Sr@C₇₄, Sr@C₇₆‐I, II and Ca@C₇₄, prepared by means of the RF‐method, have been isolated using multistep HPLC. The purity was ascertained by anionic LDI TOF mass spectroscopy, considering the isotopic patterns of the compounds. The influence of the incorporated metal on the electronic structure has been studied by VIS‐NIR and Raman spectroscopy. Photoexcited triplet‐state EPR spectroscopy was used to investigate the structure of these otherwise EPR‐silent fullerenes. Displaying the frequency of the cage vs. encapsulated metal vibrational modes as a function of the square root of the reciprocal masses of the metals clearly separates the M³⁺@C_n^3— and the M²⁺@C_n^2— families. This seems to be a generally applicable tool for monitoring the metal to fullerene charge transfer.     

Isolation and Crystallographic Characterization of Two,Nonisolated Pentagon Endohedral Fullerenes: Ho3N@C2(22010)-C78 and Tb3N@C2(22010)-C78

Purified samples of Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ have been isolated by two distinct processes from the rich array of fullerenes and endohedral fullerenes present in carbon soot from graphite rods doped with Ho₂O₃ or Tb₄O₇. Crystallographic analysis of the endohedral fullerenes as cocrystals with Ni(OEP) (in which OEP is the dianion of octaethylporphyrin) shows that both molecules contain the chiral C₂(22010)-C₇₈ cage. This cage does not obey the isolated pentagon rule (IPR) but has two sites where two pentagons share a common C−C bond. These pentalene units bind two of the metal ions, whereas the third metal resides near a hexagon of the cage. Inside the cages, the Ho₃N or Tb₃N unit is planar. Ho₃N@C₂(22010)-C₇₈ and Tb₃N@C₂(22010)-C₇₈ use the same cage previously found for Gd₃N@C₂(22010)-C₇₈ rather than the IPR-obeying cage found in Sc₃N@D_3h-C₇₈.     

KMgF3:Ce3+,Tb3+纳米粒子中Ce3+→Tb3+的发光及能量传递

利用微乳液方法,合成了铈、铽共掺杂的氟镁钾纳米粒子,研究了体系中Ce3+→Tb3+的发光特性以及它们之间的相互作用,结果表明KMgF3:Ce3+Tb3+纳米粒子中存在Ce3+→Tb3+的能量传递过程,即Ce3+可以将吸收的能量直接传递给Tb3+离子,使得Tb3+的绿色发光强度大为增加.