富勒烯金属有机配合物的研究进展

介绍了近几年来富勒烯金属包合物、富勒烯球体与金属键联形成的配合物、富勒烯有机衍生物与金属原子形成的配合物以及富勒烯-有机金属配合物形成的共晶的研究进展.     

Ca@C72的结构、电子光谱及非线性光学性质的理论研究

用密度泛函(DFT)方法(BLYP／3—21G^*)研究了Ca@C72的三种异构体．用ZINDO方法对Ca@C72的电子光谱进行了计算,Ca@C72在1200—1400nm范围内的光谱吸收是由HOMO→LUMO的跃迁引起的．其最强吸收在230nm左右,与实验值吻合较好．同时计算了三种构型的二阶、三阶非线性光学系数,并与C72和Ca@C74进行了比较,预测Ca@C72是较好的非线性光学材料．     

金属富勒烯包合物

金属富勒烯包合物是目前国际上富勒烯化学研究的热点课题之一。近几年来，金属富勒烯包合物在制备，分离，结构及性质上的研究都取得了一定的进展。文章对近年来金属包合物的研究进行综合评述与分析。     

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。     

含镧金属富勒烯不同溶剂的高温高压提取

将金属原子或离子置于以Ｃ６０、Ｃ８２为代表的富勒烯笼内形成金属富勒烯包合物是目前富勒烯研究的热点课题［１～３］．合成的金属富勒烯常伴随生成较难分离的空心富勒烯,传统的索氏提取法效率又较低,使得金属富勒烯的深入研究受到限制［１,２］．本文采用改进的高温...     

内嵌金属碳氮化物团簇富勒烯的稳定性与生成机理

对新结构富勒烯金属包合物的探索是富勒烯领域中的研究重点。本文从内嵌团簇与富勒烯碳笼尺寸匹配的角度出发,对基于金属碳氮化物团簇的新结构富勒烯金属包合物进行了研究。通过量子化学计算研究了M_3NC团簇(M=Y,La,Gd)内嵌在D_2(186)-C_(96)和D_2(35)-C_(88)分子中所形成包合物的稳定性和电子结构,发现富勒烯碳笼接受内嵌团簇转移的六个电子形成了稳定结构。结合文献已报道过的Sc_3NC@I_h(7)-C_(80)分子,阐明了M_3NC团簇与富勒烯碳笼之间的尺寸匹配效应,并发现D_2(186)-C_(96)、D_2(35)-C_(88)和I_h(7)-C_(80)三种富勒烯碳笼均具有五元环均匀分布的结构特点。我们对富勒烯之间的转变路径进行了研究,提出了不含Stone-Wales异构化过程的富勒烯直接生成机理,即可以通过增加碳原子的过程使五元环重排,在保持稳定性结构单元的同时转变为更大碳笼。     

金属氮化物包合物Tb3N@C80的分离和表征

在利用电弧放电法合成铽的富勒烯笼内金属包合物时,首次观察到Tb₃N@C₈₀的存在,并用两步HPLC法将其分离和提纯.进一步的实验结果表明,氮气的加入是导致Tb₃N@C₈₀生成的原因.并用MALDI-TOF-MS和UV-Vis-NIR光谱对其进行了表征.     

富勒烯的化学研究进展

本文评述了富勒烯化学研究的新进展, 从[ 60 ]、[ 70 ]富勒烯的化学修饰、富勒烯金属包合物、掺杂富勒烯、碳纳米管以及富勒烯的化学合成等几个方面着重介绍了国际上富勒烯研究的热点, 对进一步研究的方向进行了讨论。     

我国C60和碳纳米管的研究进展

自从Ｃ６０富勒烯、碳主管被发现和大量制备以来的十几年,由于其独特的分子结构和化学、物理性质,使它们成为目前研究的热点。在这十几年里,我国在这些方面的研究取得了些重要的研究成果。本文从我国在富勒烯的制备和分离,理论,富勒烯的化学修饰,富勒烯在电、磁、光材料中的应用,富勒烯金属包合物的研究以及碳纳米管的研究等方面进行了回顾。     

Ca@C74的结构、电子光谱及二阶非线性光学性质的理论研究

用密度泛函(DFT)方法(BLYP/3-21G)研究了Ca@C74的稳定几何构型,并用ZINDO系列方法对Ca@C74的电子光谱及二阶非线性光学系数进行了理论计算研究,结果表明,Ca@C74的稳定性较C74增强,碳笼向外扩展.离域范围扩大,且其光谱吸收峰较C74向短波方向移动,其二阶非线性光学系数较C74大大增加.     

具有D_(6h)对称性的C_(36)碱土金属衍生物电子结构的密度泛函研究

运用密度泛函方法,在Ｂ３ＬＹＰ／６－３１Ｇ水平上对Ｂｅ＠ Ｃ３６、Ｍｇ＠ Ｃ３６、Ｃａ＠ Ｃ３６分子进行构型全优化,分析了不同碱土内嵌原子对其几何结构、电子结构、稳定性等性质的影响,进而讨论碱土金属原子的嵌入对Ｃ３６笼的稳定性的影响,并得到其稳定性规律。     

Theoretical investigation of C56 fullerene isomers and related compounds

All the 924 classical isomers of fullerene C(56) have been investigated by PM3, and some most stable isomers are refined with HCTH/3-21G and B3LYP6-31G(d) methods. D(2):003 with the least number of adjacent pentagons is predicted to be the most stable isomer at B3LYP/6-31G(d) level, while C(s):022 and C(2):049 possess nearly degenerate energies with relative energies of 0.03 and 3.90 kcal/mol, respectively. However, as to dianionic C(56)(2-) fullerene, C(2v):011 is predicted to be the most stable isomer. Investigations also show that the encapsulation of Ca atom in C(56) fullerene is exothermic and the metallofullerenes Ca@C(56) can be described as Ca(2+)@C(56)(2-). The computed relative stabilities show that the D(2):003 behaves more thermodynamically stable than other isomers in a wide temperature interval, and C(2v):011 should also be an important component. The electronic isomerization of C(56) (C(2v):011) and C(50) (D(5h):002) indicates that this phenomenon might be rather general in fullerenes and causes different properties, thus bringing about new possible applications of fullerenes. The static second-order hyperpolarizabilities of the three most stable isomers are slightly larger than that of C(60).     

High Temperature Seedless Synthesis of Au NRs Using BDAC/CTAB Co-surfactant

Au nanorods have been successfully synthesized at 90°C by using hexadecyltrimethylammonium bromide (CTAB) and benzyldimethylammoniumchloride hydrate (BDAC) co-surfactant. At 90 °C, the reaction time was less than 10 s, and the longitudinal surface plasmon absorption band could vary between 680 and 770 nm by adjusting the molar ratio of BDAC to CTAB from 2 to 0.5. At 90 °C, nanorods with a longitudinal surface plasmon absorption peak of 770 nm can be obtained when the molar ratio of BDAC to CTAB was 3:2.     

Large endohedral fullerenes containing two metal ions, Sm2@D2(35)-C88, Sm2@C1(21)-C90, and Sm2@D3(85)-C92, and their relationship to endohedral fullerenes containing two gadolinium ions

The carbon soot obtained by electric arc vaporization of carbon rods doped with Sm(2)O(3) contains a series of monometallic endohedral fullerenes, Sm@C(2n), along with smaller quantities of the dimetallic endohedrals Sm(2)@C(2n) with n = 44, 45, 46, and the previously described Sm(2)@D(3d)(822)-C(104). The compounds Sm(2)@C(2n) with n = 44, 45, 46 were purified by high pressure liquid chromatography on several different columns. For endohedral fullerenes that contain two metal atoms, there are two structural possibilities: a normal dimetallofullerene, M(2)@C(2n), or a metal carbide, M(2)(μ-C(2))@C(2n-2). For structural analysis, the individual Sm(2)@C(2n) endohedral fullerenes were cocrystallized with Ni(octaethylporphyrin), and the products were examined by single-crystal X-ray diffraction. These data identified the three new endohedrals as normal dimetallofullerenes and not as carbides: Sm(2)@D(2)(35)-C(88), Sm(2)@C(1)(21)-C(90), and Sm(2)@D(3)(85)-C(92). All four of the known Sm(2)@C(2n) endohedral fullerenes have cages that obey the isolated pentagon rule (IPR). As the cage size expands in this series, so do the distances between the variously disordered samarium atoms. Since the UV/vis/NIR spectra of Sm(2)@D(2)(35)-C(88) and Sm(2)@C(1)(21)-C(90) are very similar to those of Gd(2)C(90) and Gd(2)C(92), we conclude that Gd(2)C(90) and Gd(2)C(92) are the carbides Gd(2)(μ-C(2))@D(2)(35)-C(88) and Gd(2)(μ-C(2))@C(1)(21)-C(90), respectively.     

Optical excitation and absorption spectra of C50Cl10

C50Cl10 [S. Y. Xie et al., Science 304, 699 (2004)] has been synthesized in large quantities enabling the capture of the labile fullerene C50. In this Communication, we report ab initio calculations on the optical excitation and absorption spectra of C50Cl10. We successfully explain and assign the measured UV-visible absorption spectrum of C50Cl10. The first singlet excitation for C50Cl10 is optically forbidden, and its optical absorption gap is redshifted by 0.6 eV (110 nm) relative to that of C60. We demonstrate that passivating C50 with 10 hydrogen atoms and replacing one Cl in C50Cl10 by one methoxy group lead to 100 nm blueshift and 90 nm redshift of the optical gap predicted for C50Cl10, respectively, suggesting C50 derivatives are suitable for tunable optical applications.     

New pyrrolo[3,2-b]pyrrole derivatives with multiple-acceptor substitution: Efficient fluorescent emission and near-infrared two-photon absorption

Two new D-π-A organic chromophores, 1,2,4,5-tetra(4-cyanophenyl)pyrrolo[3,2-b]pyrrole (4CNPP) and 1,2,3,4,5,6-hexa(4-cyanophenyl)pyrrolo[3,2-b]pyrrole (6CNPP), were developed by modifying the electron-rich pyrrolo[3,2-b]pyrrole (PP) unit with four and six 4-cyanophenyls respectively. The compounds exhibited bright blue emissions in low- to high-polarity solvents, with high Ф_fs of 88–90% in toluene, as well as impressive two-photon absorption cross-sections at the near-infrared (NIR) 700?nm.     

Dendron-tethered and templated CdS quantum dots on single-walled carbon nanotubes

CdS nanoparticles on the surface of single-walled carbon nanotubes (SWNTs) were templated and stabilized through the initial attachment of 1 --> 3 C-branched amide-based dendrons and were both photophysically and morphologically characterized. The CdS clusters were shown to be ca. 1.4 nm in diameter as calculated from their optical absorption spectra and exhibited reduced fluorescence emission intensity at 434 nm compared to that of CdS quantum dots stabilized by untethered dendrons due to partial emission quenching by the SWNT. Unchanged UV absorption behavior of these materials indicated that they are stable > 90 days at 25 degrees C.     

Chelating Metal Ions in a Metal-Organic Framework for Constructing a Biomimetic Catalyst Through Post-modification

Crystal engineering, as a burgeoning technology, has been widely used to construct metalloporphyrins biomimetic catalysts. Herein, a bimetallic metal-organic framework (MOF) was constructed by 4-(4-carboxyphenyl)-1,2,4-triazole ligand, Co²⁺ and Zr⁴⁺ metal ions by solvothermal reaction(named PFC-88). A N,N-chelation site was found between the two adjacent ligands in PFC-88, consequently a porphyrin-like structure was obtained through chelating Fe³⁺ in this site by post-modification, named PFC-88-Fe. The result of a single crystal X-ray technology verified that Fe ions were successfully metalated in the N,N-chelation site of PFC-88, which is assisted by the X-ray absorption near-edge structure(XANES) spectra. An o-phenylenediamine oxidation reaction was applied to assessing the catalytic activity of PFC-88-Fe, in which the absorbance increases of phenazine-2,3-diamine at λ=418 nm were recorded by absorption spectroscopy in kinetic mode, exhibiting the application potential as a biomimetic catalyst.     

Non-Fickian water vapor sorption dynamics by Nafion membranes

Dynamics of water absorption from a saturated vapor and water desorption into dry air for Nafion 1100 EW ionomers have been measured for film thicknesses between 51 and 606 microm and at temperatures ranging from 30 to 90 degrees C. Water absorption and desorption exhibit two distinct non-Fickian characteristics: (1) desorption is 10 times faster than absorption and (2) the normalized mass change does not collapse to a single master curve when plotted against time normalized by membrane thickness squared, t/l2, for either absorption or desorption. Water desorption data were fit well by a model in which diffusion is rapid and interfacial mass transport resistance is the rate-limiting process for water loss. Water absorption is described by a two-stage process. At early times, interfacial mass transport controls water absorption, and at longer times, water absorption is controlled by the dynamics of polymer swelling and relaxation.