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1.
Encapsulating one to three metal atoms or a metallic cluster inside fullerene cages affords endohedral metallofullerenes (EMFs) classified as mono-, di-, tri-, and cluster-EMFs, respectively. Although the coexistence of various EMF species in soot is common for rare-earth metals, we herein report that europium tends to prefer the formation of mono-EMFs. Mass spectroscopy reveals that mono-EMFs (Eu@C 2n) prevail in the Eu-containing soot. Theoretical calculations demonstrate that the encapsulation energy of the endohedral metal accounts for the selective formation of mono-EMFs and rationalize similar observations for EMFs containing other metals like Ca, Sr, Ba, or Yb. Consistently, all isolated Eu-EMFs are mono-EMFs, including Eu@ D3h(1)-C 74, Eu@ C2v(19138)-C 76, Eu@ C2v(3)-C 78, Eu@ C2v(3)-C 80, and Eu@ D3d(19)-C 84, which are identified by crystallography. Remarkably, Eu@ C2v(19138)-C 76 represents the first Eu-containing EMF with a cage that violates the isolated-pentagon-rule, and Eu@ C2v(3)-C 78 is the first C 78-based EMF stabilized by merely one metal atom. 相似文献
2.
Although all the pure‐carbon fullerene isomers above C 60 reported to date comply with the isolated pentagon rule (IPR), non‐IPR structures, which are expected to have different properties from those of IPR species, are obtainable either by exohedral modification or by endohedral atom doping. This report describes the isolation and characterization of a new endohedral metallofullerene (EMF), La 2@C 76, which has a non‐IPR fullerene cage. The X‐ray crystallographic result for the La 2@C 76/[Ni II(OEP)] (OEP=octaethylporphyrin) cocrystal unambiguously elucidated the Cs(17 490)‐C 76 cage structure, which contains two adjacent pentagon pairs. Surprisingly, multiple metal sites were distinguished from the X‐ray data, which implies dynamic behavior for the two La 3+ cations inside the cage. This dynamic behavior was also corroborated by variable‐temperature 139 La NMR spectroscopy. This phenomenon conflicts with the widely accepted idea that the metal cations in non‐IPR EMFs invariably coordinate strongly with the negatively charged fused‐pentagon carbons, thereby providing new insights into modern coordination chemistry. Furthermore, our electrochemical and computational studies reveal that La 2@ Cs(17 490)‐C 76 has a larger HOMO–LUMO gap than other dilanthanum‐EMFs with IPR cage structures, such as La 2@ D3h(5)‐C 78 and La 2@ Ih(7)‐C 80, which implies that IPR is no longer a strict rule for EMFs. 相似文献
3.
The chemical functionalization of endohedral metallofullerenes (EMFs) has aroused considerable interest due to the possibility of synthesizing new species with potential applications in materials science and medicine. Experimental and theoretical studies on the reactivity of endohedral metallofullerenes are scarce. To improve our understanding of the endohedral metallofullerene reactivity, we have systematically studied with DFT methods the Diels–Alder cycloaddition between s‐ cis‐1,3‐butadiene and practically all X@ Ih‐C 80 EMFs synthesized to date: X=Sc 3N, Lu 3N, Y 3N, La 2, Y 3, Sc 3C 2, Sc 4C 2, Sc 3CH, Sc 3NC, Sc 4O 2 and Sc 4O 3. We have studied both the thermodynamic and kinetic regioselectivity, taking into account the free rotation of the metallic cluster inside the fullerene. This systematic study has been made possible through the use of the frozen cage model (FCM), a computationally cheap approach to accurately predicting the exohedral regioselectivity of cycloaddition reactions in EMFs. Our results show that the EMFs are less reactive than the hollow Ih‐C 80 cage. Except for the Y 3 cluster, the additions occur predominantly at the [5,6] bond. In many cases, however, a mixture of the two possible regioisomers is predicted. In general, [6,6] addition is favored in EMFs that have a larger charge transfer from the metal cluster to the cage or a voluminous metal cluster inside. The present guide represents the first complete and exhaustive investigation of the reactivity of Ih‐C 80‐based EMFs. 相似文献
4.
The chemical functionalization of endohedral (metallo)fullerenes has become a main focus of research in the last few years. It has been found that the reactivity of endohedral (metallo)fullerenes may be quite different from that of the empty fullerenes. Encapsulated species have an enormous influence on the thermodynamics, kinetics, and regiochemistry of the exohedral addition reactions undergone by these species. A detailed understanding of the changes in chemical reactivity due to incarceration of atoms or clusters of atoms is essential to assist the synthesis of new functionalized endohedral fullerenes with specific properties. Herein, we report the study of the Diels–Alder cycloaddition between 1,3‐butadiene and all nonequivalent bonds of the Ti 2C 2@ D3h‐C 78 metallic carbide endohedral metallofullerene (EMF) at the BP86/TZP//BP86/DZP level of theory. The results obtained are compared with those found by some of us at the same level of theory for the D3h‐C 78 free cage and the M 3N@ D3h‐C 78 (M=Sc and Y) metallic nitride EMFs. It is found that the free cage is more reactive than the Ti 2C 2@ D3h‐C 78 EMF and this, in turn, has a higher reactivity than M 3N@ D3h‐C 78. The results indicate that, for Ti 2C 2@ D3h‐C 78, the corannulene‐type [5, 6] bonds c and f , and the type B [6, 6] bond 3 are those thermodynamically and kinetically preferred. In contrast, the D3h‐C 78 free cage has a preference for addition to the [6, 6] 1 and 6 bonds and the [5, 6] b bond, whereas M 3N@ D3h‐C 78 favors additions to the [6, 6] 6 (M=Sc) and [5, 6] d (M=Y) bonds. The reasons for the regioselectivity found in Ti 2C 2@ D3h‐C 78 are discussed. 相似文献
5.
In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc 2S@C 76 which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc 2S@ Td(19151)‐C 76 which satisfies the isolated‐pentagon rule (IPR) possesses the lowest energy, followed by three non‐IPR structures (Sc 2S@ C2v(19138)‐C 76, Sc 2S@ Cs (17490)‐C 76, and Sc 2S@ C1(17459)‐C 76). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc 2S@ Td(19151)‐C 76, Sc 2S@ C2v(19138)‐C 76, and Sc 2S@ C1(17459)‐C 76 have noticeable molar fractions at the fullerene‐formation temperature region (500–3000K), and the Sc 2S@ C1(17459)‐C 76 with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non‐IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV‐vis‐NIR adsorptions, and 13C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc. 相似文献
6.
The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed‐metal Sc–Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH 4 and Ti/CH 4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH 4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH 4 system are Sc 4C 2@C 80 (the most abundant EMF from this synthesis), Sc 3C 2@C 80, isomers of Sc 2C 2@C 82, and the family Sc 2C 2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc 3CH@C 80. The Sc–Ti/CH 4 system produces the mixed‐metal Sc 2TiC@C 2 n (2 n=68, 78, 80) and Sc 2TiC 2@C 2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition‐metal‐containing endohedral fullerenes, Sc 2TiC@ Ih‐C 80, Sc 2TiC@ D5h‐C 80, and Sc 2TiC 2@ Ih‐C 80, were characterized by NMR spectroscopy. The structure of Sc 2TiC@ Ih‐C 80 was also determined by single‐crystal X‐ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc 2TiC‐ and Sc 2TiC 2‐containing clusterfullerenes have Ti‐localized LUMOs. Encapsulation of the redox‐active Ti ion inside the fullerene cage enables analysis of the cluster–cage strain in the endohedral fullerenes through electrochemical measurements. 相似文献
7.
Chemical functionalization of endohedral metallofullerenes (EMFs) is essential for the application of these novel carbon materials. Actinide EMFs, a new EMF family member, have presented unique molecular and electronic structures but their chemical properties remain unexplored. Here, for the first time, we report the chemical functionalization of actinide EMFs, in which the photochemical reaction of Th@ C3v(8)-C 82 and U@ C2v(9)-C 82 with 2-adamantane-2,3′-[3 H]-diazirine (AdN 2, 1) was systematically investigated. The combined HPLC and MALDI-TOF analyses show that carbene addition by photochemical reaction afforded three isomers of Th@ C3v(8)-C 82Ad and four isomers of U@ C2v(9)-C 82Ad (Ad = adamantylidene), presenting notably higher reactivity than their lanthanide analogs. Among these novel EMF derivatives, Th@ C3v(8)-C 82Ad(I, II, III) and U@ C2v(9)-C 82Ad(I, II, III) were successfully isolated and were characterized by UV-vis-NIR spectroscopy. In particular, the molecular structures of first actinide fullerene derivatives, Th@ C3v(8)-C 82Ad(I) and U@ C2v(9)-C 82Ad(I), were unambiguously determined by single crystal X-ray crystallography, both of which show a [6,6]-open cage structure. In addition, isomerization of Th@ C3v(8)-C 82Ad(II), Th@ C3v(8)-C 82Ad(III), U@ C2v(9)-C 82Ad(II) and U@ C2v(9)-C 82Ad(III) was observed at room temperature. Computational studies suggest that the attached carbon atoms on the cages of both Th@ C3v(8)-C 82Ad(I) and U@ C2v(9)-C 82Ad(I) have the largest negative charges, thus facilitating the electrophilic attack. Furthermore, it reveals that, compared to their lanthanide analogs, Th@ C3v(8)-C 82 and U@ C2v(9)-C 82 have much closer metal–cage distance, increased metal-to-cage charge transfer, and strong metal–cage interactions stemming from the significant contribution of extended Th-5f and U-5f orbitals to the occupied molecular orbitals, all of which give rise to their unusual high reactivity. This study provides first insights into the exceptional chemical properties of actinide endohedral fullerenes, which pave ways for the future functionalization and application of these novel EMF compounds.Photochemical reaction of Th@ C3v(8)-C 82 and U@ C2v(9)-C 82 with 2-adamantane-2,3′-[3 H]-diazirine (AdN 2, 1) afforded three isomers of Th@ C3v(8)-C 82Ad and four isomers of U@ C2v(9)-C 82Ad (Ad = adamantylidene), respectively. 相似文献
8.
Purified samples of Ho 3N@ C2(22010)-C 78 and Tb 3N@ C2(22010)-C 78 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 Ho 2O 3 or Tb 4O 7. 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)-C 78 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 Ho 3N or Tb 3N unit is planar. Ho 3N@ C2(22010)-C 78 and Tb 3N@ C2(22010)-C 78 use the same cage previously found for Gd 3N@ C2(22010)-C 78 rather than the IPR-obeying cage found in Sc 3N@ D3h-C 78. 相似文献
9.
We report that Ce@ C2v(9)‐C 82 forms a centrosymmetric dimer when co‐crystallized with Ni(OEP) (OEP = octaethylporphyrin dianion). The crystal structure of {Ce@ C2v(9)‐C 82} 2?2[Ni(OEP)]?4 C 6H 6 shows that a new C?C bond with a bond length of 1.605(5) Å connects the two cages. The high spin density of the singly occupied molecular orbital (SOMO) on the cage and the pyramidalization of the cage are factors that favor dimerization. In contrast, the treatment of Ni(OEP) with M@ C2v(9)‐C 82 (M = La, Sc, and Y) results in crystallization of monomeric endohedral fullerenes. A systematic comparison of the X‐ray structures of M@ C2v(9)‐C 82 (M = Sc, Y, La, Ce, Gd, Yb, and Sm) reveals that the major metal site in each case is located at an off‐center position adjacent to a hexagonal ring along the C2 axis of the C2v(9)‐C 82 cage. DFT calculations at the M06‐2X level revealed that the positions of the metal centers in these metallofullerenes M@ C2v(9)‐C 82 (M = Sc, Y, and Ce), as determined by single‐crystal X‐ray structure studies, correspond to an energy minimum for each compound. 相似文献
10.
Metal–cage and intracluster bonding was studied in detail by quantum theory of atoms in molecules (QTAIM) for the four major classes of endohedral metallofullerenes (EMFs), including monometallofullerenes Ca@C 72, La@C 72, M@C 82 (M=Ca, Sc, Y, La), dimetallofullerenes Sc 2@C 76, Y 2@C 82, Y 2@C 79N, La 2@C 78, La 2@C 80, metal nitride clusterfullerenes Sc 3N@C 2n (2 n=68, 70, 78, 80), Y 3N@C 2n (2 n=78, 80, 82, 84, 86, 88), La 3N@C 2n (2 n=88, 92, 96), metal carbide clusterfullerenes Sc 2C 2@C 68, Sc 2C 2@C 82, Sc 2C 2@C 84, Ti 2C 2@C 78, Y 2C 2@C 82, Sc 3C 2@C 80, as well as Sc 3CH@C 80 and Sc 4O x@C 80 ( x=2, 3), that is, 42 EMF molecules and ions in total. Analysis of the delocalization indices and bond critical point (BCP) indicators such as Gbcp/ ρbcp, Hbcp/ ρbcp, and |Vbcp|/ Gbcp, revealed that all types of bonding in EMFs exhibit a high degree of covalency, and the ionic model is reasonable only for the Ca‐based EMFs. Metal–metal bonds with negative values of the electron‐density Laplacian were found in Y 2@C 82, Y 2@C 79N, Sc 4O 2@C 80, and anionic forms of La 2@C 80. A delocalized nature of the metal–cage bonding results in a topological instability of the electron density in EMFs with an unpredictable number of metal–cage bond paths and large elipticity values. 相似文献
11.
Extraction with 2‐aminoethanol is an inexpensive method for removing empty cage fullerenes from the soluble extract from electric‐arc‐generated fullerene soot that contains endohedral metallofullerenes of the type Sc 3N@C 2n ( n=34, 39, 40). Our method of separation exploits the fact that C 60, C 70, and other larger, empty cage fullerenes are more susceptible to nucleophilic attack than endohedral fullerenes and that these adducts can be readily extracted into 2‐aminoethanol. This methodology has also been employed to examine the reactivity of the mixture of soluble endohedral fullerenes that result from doping graphite rods used in the Krätschmer–Huffman electric‐arc generator with the oxides of Y, Lu, Dy, Tb, and Gd. For example, with Y 2O 3, we were able to detect by mass spectrometry several new families of endohedral fullerenes, namely Y 3C 108 to Y 3C 126, Y 3C 107 to Y 3C 125, Y 4C 128 to Y 4C 146, that resisted reactivity with 2‐aminoethanol more than the empty cage fullerenes and the mono‐ and dimetallo fullerenes. The discovery of the family Y 3C 107 to Y 3C 125 with odd numbers of carbon atoms is remarkable, since fullerene cages must involve even numbers of carbon atoms. The newly discovered families of endohedral fullerenes with the composition M 4C 2n (M=Y, Lu, Dy, Tb, and Gd) are unusually resistant to reaction with 2‐aminoethanol. Additionally, the individual endohedrals, Y 3C 112 and M 3C 102 (M=Lu, Dy, Tb and Gd), were remarkably less reactive toward 2‐aminoethanol. 相似文献
12.
Successful isolation and characterization of a series of Er-based dimetallofullerenes present valuable insights into the realm of metal–metal bonding. These species are crystallographically identified as Er 2@ Cs(6)-C 82, Er 2@ C3v(8)-C 82, Er 2@ C1(12)-C 84, and Er 2@ C2v(9)-C 86, in which the structure of the C1(12)-C 84 cage is unambiguously characterized for the first time by single-crystal X-ray diffraction. Interestingly, natural bond orbital analysis demonstrates that the two Er atoms in Er 2@ Cs(6)-C 82, Er 2@ C3v(8)-C 82, and Er 2@ C2v(9)-C 86 form a two-electron-two-center Er−Er bond. However, for Er 2@ C1(12)-C 84, with the longest Er⋅⋅⋅Er distance, a one-electron-two-center Er−Er bond may exist. Thus, the difference in the Er⋅⋅⋅Er separation indicates distinct metal bonding natures, suggesting a distance-dependent bonding behavior for the internal dimetallic cluster. Additionally, electrochemical studies suggest that Er 2@C 82–86 are good electron donors instead of electron acceptors. Hence, this finding initiates a connection between metal–metal bonding chemistry and fullerene chemistry. 相似文献
13.
Isomerically pure endohedral metallofullerene Dy@C 82( C 2v) was synthesized by the electric arc method, extracted from the soot with o-dichlorobenzene, isolated from the extract by HPLC, and characterized by mass spectrometry and spectrophotometry. The spectrophotometric titration of a solution of endohedral metallofullerene Dy@C 82( C 2v) was conducted with potassium perchlorotriphenylmethide. The concentration of Dy@C82( C 2v) in o-dichlorobenzene was determined, and the molar absorption coefficients for its neutral and anionic forms were calculated (3.0?10 3 (at 927 nm) and 4.0?10 3 mol –1 L cm –1 (at 884 nm), respectively. 相似文献
14.
Eighteen possible isomers of C78(CH2)2 weTe investigated by the INDO method. It was indicated that the most stable isomer was 42,43,62,63-C78(CH2)2, where the -CH2 groups were added to the 6/6 bonds located at the same hexagon passed by the longest axis of C78 (C2v), to form cyclopropane structures. Based on the most stable four geometries of C78(CH2)2 optimized at B3LYP/3-21G level, the first absorptions in the electronic spectra calculated with the INDO/CIS method and the IR frequencies of the C-C bonds on the carbon cage computed using the AM1 method were blue-shifted compared with those of C78 (C2v) because of the bigger LUMO-HOMO energy gap and the less conjugated carbon cage after the addition. The chemical shifts of ^13C NMR for the carbon atoms on the added bonds calculated at B3LYP/3-21G level were moved upfield thanks to the conversion from sp^2-C to sp^3-C. 相似文献
15.
Supramolecular nanocapsule 1 ?(BArF) 8 is able to sequentially and selectively entrap recently discovered U 2@C 80 and unprecedented Sc 2CU@C 80, simply by soaking crystals of 1 ?(BArF) 8 in a toluene solution of arc‐produced soot. These species, selectively and stepwise absorbed by 1 ?(BArF) 8, are easily released, obtaining highly pure fractions of U 2@C 80 and Sc 2CU@C 80 in one step. Sc 2CU@C 80 represents the first example of a mixed metal actinide‐based endohedral metallofullerene (EMF). Remarkably, the host–guest studies revealed that 1 ?(BArF) 8 is able to discriminate EMFs with the same carbon cage but with different encapsulated cluster and computational studies provide support for these observations. 相似文献
16.
We show that electron transfer from the perchlorotriphenylmethide anion (PTM ?) to Y@C 82( C2v) is an instantaneous process, suggesting potential applications for using PTM ? to perform redox titrations of numerous endohedral metallofullerenes. The first representative of a Y@C 82‐based salt containing the complex cation was prepared by treating Y@C 82( C2v) with the [K +([18]crown‐6)]PTM ? salt. The synthesis developed involves the use of the [K +([18]crown‐6)]PTM ? salt as a provider of both a complex cation and an electron‐donating anion that is able to reduce Y@C 82( C2v). For the first time, the molar absorption coefficients for neutral and anionic forms of the pure isomer of Y@C 82( C2v) were determined in organic solvents with significantly different polarities. 相似文献
17.
The reactions of [(μ‐H) 3Re 3(CO) 11(NCMe)] with Sc 2@C 82‐ C3v(8), Sc 2C 2@C 80‐ C2v(5), Sc 2O@C 82‐ Cs(6), C 86‐ C2(17), and C 86‐ Cs(16) have been carried out to produce face‐capping cluster complexes. The Re 3 triangles are found to bind to the sumanene‐type hexagons on the fullerene surface regiospecifically. In contrast, Sc 3N@C 78‐ D3h(5) and Sc 3N@C 80‐ Ih show no reactivity toward [(μ‐H) 3Re 3(CO) 11(NCMe)], probably due to electronic and steric factors. These complexes can be easily purified by using HPLC. Carbonylation of each complex releases the corresponding higher fullerene or endohedral metallofullerene in pure form. Remarkably, the C 86‐ C2(17) and C 86‐ Cs(16) isomers were successively separated through Re 3 cluster complexation/decomplexation. This unique bonding feature may provide an attractive general strategy to purify as yet unresolved fullerene mixtures. 相似文献
18.
Solutions of endohedral Gd@C82(C
2v
) and Ho@C82(C
2v
) metallofullerenes are studied by means of visible and near-IR spectroscopy upon their conversion from neutral to the anionic form via a redox reaction with the electron donor potassium perchlorotriphenylmethide K(18-crown-6)[C(C6Cl5)3]. The concentrations of the studied solutions of endohedral Gd@C82(C
2v
) and Ho@C82(C
2v
) metallofullerenes in o-dichlorobenzene were determined from the spectroscopic data, and their molar extinction coefficients are calculated. 相似文献
19.
Chemical modification of endohedral metallofullerenes (EMFs) is an efficient strategy to realize their ultimate applications in many fields. Herein, we report the highly regioselective and quantitative mono-formation of pyrazole- and pyrrole-ring-fused derivatives of the prototypical di-EMF Y 2@ C3v(8)-C 82, that is, Y 2@ C3v(8)-C 82(C 13N 2H 10) and Y 2@ C3v(8)-C 82(C 9NH 11), from the respective 1,3-dipolar reactions with either diphenylnitrilimine or N-benzylazomethine ylide, without the formation of any bis- or multi-adducts. Crystallographic results unambiguously reveal that only one [6,6]-bond out of the twenty-five different types of nonequivalent C−C bonds of Y 2@ C3v(8)-C 82 is involved in the 1,3-dipolar reactions. Our theoretical results rationalize that the remarkably high regioselectivity and the quantitative formation of mono-adducts are direct results from the anisotropic distribution of π-electron density on the C3v(8)-C 82 cage and the local strain of the cage carbon atoms as well. Interestingly, electrochemical and theoretical studies demonstrate that the reversibility of the redox processes, in particular the reversibility of the reductive processes of Y 2@ C3v(8)-C 82, has been markedly altered upon exohedral functionalization, but the oxidative process was less influenced, indicating that the oxidation is mainly influenced by the internal Y 2 cluster, whereas the reduction is primarily associated with the fullerene cage. The pyrazole and pyrrole-fused derivatives may find potential applications as organic photovoltaic materials and biological reagents. 相似文献
20.
Bingel–Hirsch derivatives of the trimetallic nitride template endohedral metallofullerenes (TNT‐EMFs) Sc 3N@ Ih‐C 80 and Lu 3N@ Ih‐C 80 were prepared by reacting these compounds with 2‐bromodiethyl malonate, 2‐bromo‐1,3‐dipyrrolidin‐1‐ylpropane‐1,3‐dionate bromide, and 9‐bromo fluorene. The mono‐adducts were isolated and their 1H NMR spectra showed that the addition occurred with high regioselectivity at the [6,6] bonds of the Ih‐C 80 fullerene cage. Electrochemical analysis showed that the reductive electrochemistry behavior of these derivatives is irreversible at a scan rate of 100 mV s ?1, which is comparable to the behavior of the pristine fullerene species. The first reduction potential of each derivative is either cathodically or anodically shifted by a different value, depending on the attached addend. Bis‐adducts containing EtOOC‐C‐COOEt and HC‐COOEt addends were isolated by HPLC and in the case of Sc 3N@ Ih‐C 80 the first reduction potential exhibits a larger shift towards negative potentials when compared to the mono‐adduct. This observation is important for designing acceptor materials for the construction of bulk heterojunction (BHJ) organic solar cells, since the polyfunctionalization not only increases the solubility of the fullerene species but also offers a promising approach for bringing the LUMO energy levels closer for the donor and the acceptor materials. 相似文献
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