C_(60)加合物的X-射线晶体结构已确定

美国加州大学伯克利分校的化学家新近测定了C_(60)O_sO_4·(4-Me_3C—C_5H_4N_2),加合物的x-射线晶体结构。这是第一个有关C_(60)化合物的晶体结构,从而首次直接证实了C_(60)(buckminsterfullerence)分子形似足球。晶体结构的测定表明O_sO_4中的两个氧原子加成到了C_(60)分子中两个毗邻碳原子上,碳-碳键没有断裂,这两个碳原子的位置类似于萘环骨架中的     

六齿硅节点、阴离子有机框架化合物的合成

最近Arne Thomas小组利用可逆的Si—O化学反应,成功实现了一锅法合成基于八面体二负离子SiO_6构筑的硅酸盐有机框架聚合物,打破了硅基晶体框架材料仅在高压相中存在六齿配位结构的情况,证实低压条件下也可以实现六齿配位聚合物的合成,并且所得聚合物BET比表面积高达1276m~2·g~(-1)。通过高分辨率粉末X射线衍射、密度泛函理论和成对分布函数,所得阴离子框架聚合物——M_2[Si(C_(16)H_(10)O_4)1.5]存在2D和3D两种晶体结构,其中反离子M为Li~+、Na~+、K~+,C_(16)H_(10)O_4为9,10-二甲基蒽-2,3,6,7-四唑。     

C60衍生物的MALDI-TOFMS分析

C_(60)衍生物在超导、非线性光学、催化、材料和生物活性等方面有巨大的潜在应用价值。C_(60)衍生物大多为固体,蒸汽压较低,采用需要加热才能够使样品气化电离的质谱或"硬"电离质谱方法进行测定,易造成C_(60)衍生物分解并释放出配体。近年来国内外应用基体辅助激光解吸软电离质谱法成功分析了许多不同类型的C_(60)衍生物如卤化C_(60)酰胺化C_(60)芳基化C_(60)、C_(60)部花菁、煤基C_(60)烟灰萃取产物、金属C_(60)衍生物以及C_(60)乙二胺膜等。本文报道采用MALDI-TOFMS法分析C_(60)酯衍生物和C_(60)吡咯烷衍生物的结果。     

不同质量Cn笼电子结构和UV谱的理论研究

用INDO/2和INDO/CI方法研究了C_(24)、C_(50)、C_(60)和C_70的电子结构和UV谱。稳定性的顺序为C_(60)～C_(70)>C_(50)>>C_(24)。以C_(60)为中心向两边的C_n原子簇,其UV谱发生红移。     

苯基稀土氯化物的合成及其表征

1970年,Hart等首先合成了Sc(C_6H_5)_3、Y(C_6H_5)_3、LiLa(C_6H_5)_4和LiPr(C_6H_5)_4。1972年,Cotton等测定了[Lu(2,6-(CH_3)_2C_6H_3)_4]·[Li·4THF]的晶体结构。1986年,陈文启等人合成了Nd(C_6H_5)_3,Gd(C_6H_5)_3和LiNd(C_6H_5)_4。本文首次合成了苯基稀土氯化物C_6H_5LnCl_2·nTHF(Ln=Pr,Sm,Gd,n=3,4);C_6H_5LnCl_2·LiCl·nTHF(Ln=Pr、Nd、Sm、Gd,n=2、3、5);(C_6H_5)_2GdCl·LiCl·2THF;[(C_6H_5)_2NdCl]_2·LiCl·4THF。测定了C_6H_5GdCl_2·4THF的晶体结构。     

富勒烯作为模板剂的碗烯基分子笼构筑的自组装

设计合成了四吡啶基取代的碗烯衍生物COPY2.通过核磁研究表明,在模板分子C_(60)或C_(70)存在下,配体COPY2与金属钯分别在室温和55℃下通过自组装形成1∶1分子笼络合物C_(60/70)?COPY2-Pd.当络合物C_(60)?COPY2-Pd与C_(70)等物质的量混合或者络合物C_(70)?COPY2-Pd与C_(60)等物质的量混合于90℃加热48h后,络合物C_(60)?COPY2-Pd与C_(70)?COPY2-Pd的比例均为4∶1.将配体COPY2与Pd(CH_3CN)_2Cl_2加入等物质的量C_(60)和C_(70)混合物中加热平衡后,络合物C_(60)?COPY2-Pd与C_(70)?COPY2-Pd的比例同样为4∶1.当C_(60)和C_(70)的比例为2∶1时,体系中只生成络合物C_(60)?COPY2-Pd;而当C_(60)和C_(70)的比例为1∶2时,平衡后络合物C_(60)?COPY2-Pd与C_(70)?COPY2-Pd的比例为3.3∶1.这些结果表明,配体COPY2在金属钯存在时对C_(60)络合能力强于C_(70)的络合能力.加入DMAP能够实现络合物解离,释放笼内富勒烯并回收COPY2.因此,配体COPY2可应用于室温下对C_(60)的富集.     

π-烯丙基稀土配合物的合成、结构及其催化烯烃聚合反应机理的研究 Ⅰ.LiLn(π-C_3H_5)·nD的合成和结构表征

1970年Coutts成功地合成了第一个π-烯丙基稀土配合物(C_5H_5)_2ScC_3H_5。但由于其稳定性差仅有几篇报道。1987年黄祖恩等报道了Li_2Ce(C_3H_5)_5·3D(D为二氧六环)的晶体结构。1991年吴文玲等报道了第二个π-烯丙基稀土配合物(C_3H_5)_2CeCl_5Mg~2(tmed)_2的晶体结构。     

碳氮共渗层中不稳定氮化物的提取—固溶氮的测定

为了深入研究氮在钢中的作用机理,氮的分析、相分析、特别是固溶氮的测定日趋重要。但定量测定钢中固溶氮的方法迄今未见报导。本文通过对由18CrMnNiMo钢的碳氮共渗层中所提取的及人工合成的Fe_4N、Mn_4N、AlN、TiN、CrN、M_3(C_1N)、M_7C_3、M_(23)C_6等相的电化学及化学性质的研究,提出了一种定量提取钢中不稳定氮化物的电解制度,并建立了分别定量测定固溶氮及化合氮的方法。确立了“固溶氮”、“化合氮”及“总氮”的真正涵义及其同测定方法之间的关系。选定了测定钢中氮的合理的方法。     

环戊烷基（或烯丙基）环戊二烯基稀土二氯化物的合成

本文报导环戊烷基(或烯丙基)环戊二烯基稀土二氯化物的合成。用元素分析,热分析、红外光谱、质谱和核磁共振谱表征了这两类化合物组成为C_5H_9C_5H_4LnCl_2·nTHF和C_3H_5C_5H_4LnCl_2·nTHF(Ln=Nd,Sm,Gd;n=0,1,2,3)测定了反应中间体C_5H_9C_5H_4Na·THF的晶体结构。     

含卤原子碳六十C60X的电子结构及导电性

用量子化学EHMO方法对碳六十C_(60)及含卤原子碳六十C_(60)X(F,Cl,Br,I)的电子结构进行了计算. 据此, 对C_(60)、C_(60)X及C_(60)X_y(y=1-10)的导电性进行了讨论.     

Formation of one-dimensional C60 rows on TiO2(110)-1 x 2-cross-link structure and their local polymerization

Adsorption and growth of a C(60) monolayer on a TiO(2)(110)-1 x 2-cross-link structure were investigated by scanning tunneling microscopy (STM). Single C(60) molecules were preferentially anchored at the cross-link site due to interaction with undercoordinated Ti cations, and C(60) rows grew along the troughs between the 1 x 2-added rows. The C(60) monolayer structure is characterized by closely packed (r(C(60)-C(60)) = 1.0 nm) C(60) rows that are paired with every second added row (separation of paired rows is 1.1 nm). By applying a high negative bias voltage (-3.5 V) to an STM tip on the C(60) monolayer, C(60) oligomers were formed accompanied with the contraction of C(60)-C(60) distance along the C(60) row and bright contrast in the STM image.     

Density functional theory calculations for endohedral complexes of non-pi C60H60 cage with small guest molecules

Hybrid density-functional theory (B3LYP) calculations were carried out to determine the structures and energies of endohedral complexes of non-pi C(60)H(60) with H(2), CO, and LiH. It was demonstrated that the endohedral complexes of C(60)H(60) with the above three guest molecules are more stable than the corresponding complexes with C(60). Furthermore, the interaction between C(60)H(60) and the inside H(2) or CO is negligible, but the formation of the LiH-C(60)H(60) complex is exothermic with a stabilization energy of -6.0 kcal/mol. While the bond lengths of H(2) and CO changed a little when placed inside the cages, that of the LiH molecule increased and decreased inside C(60)H(60) and C(60), respectively.     

Self-assembly of well-defined mono and dual end-capped C(60) containing polyacrylic acids in aqueous solution

Well-defined stimuli-responsive mono and dual fullerene (C(60)) end-capped poly(acrylic acid)s (PAA-C(60) and C(60)-PAA-C(60)) were synthesized by reacting C(60) with well-defined mono and dual azide end-functionalized poly(tert-butyl acrylate)s, followed by hydrolysis. The aggregation behaviors of these C(60) end-capped polymers in aqueous solution were examined using potentiometric and conductometric titrations and static and dynamic light scattering as well as transmission electron microscopy (TEM). Both PAA-C(60) and C(60)-PAA-C(60) show pH-responsive and water-soluble properties at high pH. Both polymers self-assemble to form large compound micelles (LCMs) in aqueous solutions. The LCMs of PAA-C(60) exist as "compact aggregates", whereas the LCMs of C(60)-PAA-C(60) possess a "core-shell" structure with a larger size and aggregation number. The micelles for both polymers swell upon neutralization, where the R(h) of PAA-C(60) micelles increases from approximately 44 to approximately 102 nm and the R(h) of C(60)-PAA-C(60) aggregates varies from approximately 89 to approximately 128 nm with increasing degree of neutralization. The lower swelling of the dual end-capped C(60)-PAA-C(60) system is related to its higher C(60) content, which enhances the interpolymer chain hydrophobic association that restrains the swelling of micellar aggregates.     

Structure and stability of tube and cage Ge60H60

A tube Ge(60)H(60) isomer in D(5d) symmetry with fused five-membered rings located at the ends of the tube is more stable than the fullerene-like I(h) cage isomer at the B3LYP/cc-pVDZ level of theory. Introducing endo Ge-H bonds increases the stability of both cage and tube isomers. The most stable tube isomer can admit six endo Ge-H bonds. The cage isomer can admit 10-12 endo Ge-H bonds (H(10)@Ge(60)H(50) and H(12)@Ge(60)H(48)), and they also represent the most stable Ge(60)H(60) isomers. The stability order and structural patterns of Ge(60)H(60) are the same as those found for the corresponding Si(60)H(60) isomers. Moreover, it is found that the 6-31G(d,p) basis set fails to predict the relative energies of the Ge(60)H(60) isomers and the Ge(6)H(6) isomers.     

Valence electronic charge density of distorted C60- monomers in polymerized KC60 and RbC60

We investigate the valence electronic charge density of the C(60) (-) monomers in (C(60) (-))(n) polymer chains in K- and RbC(60) by means of a nonorthogonal tight-binding formalism using experimental data on the positions of the carbon atoms. Various configurations of the C(60) cages are considered. Starting from the ideal icosahedral C(60) structure and moving to the realistic, experimentally determined spatial configuration of the C(60) cages in K- and RbC(60), we observe a systematic increase of the electric quadrupole moments on the C(60) (-) monomers. We also confirm the validity of factorizing the charge density of a C(60) (-) monomer into an angular and a radial part.     

C(60)-exTTF-C(60) Dumbbells: cooperative effects stemming from two C(60)s on the radical ion pair stabilization

[structure: see text] The presence of a second C(60) cage in C(60)-exTTF-C(60) triads [exTTF = 9,10-bis(1,3-dithiol-2-ylidene)-9,10-anthraquinone] has beneficial effects on the stabilization of the radical ion pair formed upon irradiation in comparison with the related C(60)-exTTF dyad. Although C(60)-exTTF-C(60) ensembles show no electronic interaction between the electroactive units in the ground state, their irradiation leads to C(60)(*)(-)-exTTF(*)(+)-C(60) species with lifetimes on the order of 600 ns in benzonitrile; these lifetimes are twice those determined for the analogous C(60)-exTTF dyad.     

Alteration of nC60 in the presence of environmentally relevant carboxylates

C(60) forms colloidally stable nanoscale particles (nC(60)) when mixed with water for extended periods. Past studies have shown that macromolecules such as natural organic matter (NOM) and proteins accelerate nC(60) formation and stabilize the resulting nanoparticles. To better elucidate the mechanisms underlying this behavior, nC(60) was produced via extended mixing in the presence of sodium citrate and other carboxylates. Carboxyl groups are a predominant functional group in many environmentally relevant macromolecules, thus studies examining carboxyl-C(60) interactions are merited. nC(60) produced in the presence of citrate (cit/nC(60)) and other carboxylates differs from nC(60) produced in water alone (aq/nC(60)), exhibiting enhanced negative surface charge, smaller particle size, and different spectroscopic characteristics. Importantly, the simultaneous detection of irregular nC(60) nanoparticles and small, regularly shaped nC(60) suggests that mixing-mediated "top-down" and carboxyl group-mediated "bottom-up" processes occur concurrently when nC(60) is produced in the presence of carboxylates and, by extension, in the presence of carboxylate-containing macromolecules. The "bottom-up" process is expected to involve molecular C(60) or small clusters of C(60) molecules as an important intermediate.     

Photoinduced processes in a tricomponent molecule consisting of diphenylaminofluorene-dicyanoethylene-methano[60]fullerene

Photoinduced intramolecular processes in a tricomponent molecule C60(>(CN)2-DPAF), consisting of an electron-accepting methano[60]fullerene moiety (C60>) covalently bound to an electron-donating diphenylaminofluorene (DPAF) unit via a bridging dicyanoethylenyl group [(CN)2], were investigated in comparison with (CN)2-DPAF. On the basis of the molecular orbital calculations, the lowest charge-separated state of C60(>(CN)2-DPAF) is suggested to be C60*-(>(CN)2-DPAF*+) with the negative charge localized on the fullerene cage, while the upper state is C60(>(CN)2*--DPAF*+). The excited-state events of C60(>(CN)2-DPAF) were monitored by both time-resolved emission and nanosecond transient absorption techniques. In both nonpolar and polar solvents, the excited charge-transfer state decayed mainly through initial energy-transfer process to the C60 moiety yielding the corresponding 1C60, from which charge separation took place leading to the formation of C60*-(>(CN)2-DPAF*+) in a fast rate and high efficiency. In addition, multistep charge separation from C60(>(CN)2*--DPAF*+) to C60*-(>(CN)2-DPAF*+) may be possible with the excitation of charge-transfer band. The lifetimes of C60*-(>(CN)2-DPAF*+) are longer than the previously reported methano[60]fullerene-diphenylaminofluorene C60(>(C=O)-DPAF) with the C60 and DPAF moieties linked by a methanoketo group. These findings suggest an important role of dicyanoethylenyl group as an electron mediating bridge in C60(>(CN)2-DPAF).     

Effects of flour or flaxseed oil upon testis mass in rats subjected to early weaning

Study evaluates testis mass in rats subjected to early weaning and subsequently nourished with diet containing flour or flaxseed oil. Pups were weaned for separation from mothers at 14 days (early weaning, EW) and 21 days (control, C). After 21 days, the control group (C60) was nourished with control diet. EW was divided as: control (EWC60), flaxseed flour (EWFF60) and flaxseed oil (EWFO60) group diets for the next 60 days. At 21st and 60th day, body mass, serum cholesterol and triglycerides and testis mass were evaluated. At 21 day, EW group showed lower (p < 0.05) body mass, serum cholesterol and testis mass. At 60 days, EWC60 and EWFO60 groups showed lower (p < 0.05) body mass (vs. C60 and EWFF60). EWFF60 group showed lower (p < 0.05) serum cholesterol (vs. EWC60 and EWFO60) and higher (p < 0.05) testis mass (vs. C60, EWC60 and EWFO60). Flaxseed flour (vs. oil) was associated with higher testis mass following early weaning.     

Photoinduced charge-separation and charge-recombination processes of fullerene[60] dyads covalently connected with phenothiazine and its trimer

Photoinduced charge-separation and charge-recombination processes of fullerene[60] dyads covalently connected with phenothiazine and its trimer (PTZ n -C 60, n = 1 and 3) with a short amide linkage were investigated. A time-resolved fluorescence study provided evidence of charge separation via the excited singlet state of a C 60 moiety ( (1)C 60*), which displayed high efficiencies in various solvents; Phi (S) CS (quantum yield of charge separation via (1)C 60*) = 0.59 (toluene) to 0.87 (DMF) for PTZ 1-C 60 and 0.78 (toluene) to 0.91 (DMF) for PTZ 3-C 60. The transient absorption measurement with a 6 ns time resolution in the visible and near-IR regions showed evidence of the generation of radical ion pairs in relatively polar solvents for both dyads. In nonpolar toluene, only PTZ 1- (3)C 60* was observed for PTZ 1-C 60, whereas PTZ 3- (3)C 60* as well as the radical ion pair state in equilibrium were observed for PTZ 3-C 60. The radical ion pairs had relatively long lifetimes: 60 (DMF) to 910 ns ( o-dichlorobenzene) for (PTZ) 1 (*+)-C 60 (*-) and 230 (PhCN) to 380 ns ( o-dichlorobenzene) for (PTZ) 3 (*+)-C 60 (*-). The small reorganization energy (lambda) and the electronic coupling element (| V|) were estimated by the temperature dependence of the charge-recombination rates, i.e., lambda = 0.53 eV and | V| = 1.6 cm (-1) for (PTZ) 3 (*+)-C 60 (*-).