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Fullerenes with novel structures find numerous potential applications, particularly in the fields of biology and pharmaceutics. Among various fullerene derivatives, those exhibiting amphiphilic character and capable of self-assembly into vesicles are particularly interesting, being suitable for delayed drug release. Herein, we report the synthesis and self-assembly of biocompatible hollow nanovesicles with bilayer shells from amphiphilic functionalized fullerenes C 60 R 5 Cl (R=methyl ester of 4-aminobutyric/glutamic acid or phenylalanine). The thus prepared vesicles exhibit sizes of 80-135nm (depending on R) and can be used as delayed-release carriers of anti-cancer drugs such as 5-fluorouracil, cyclophosphamide, and cisplatin, with the time of 5-fluorouracil release from drug-containing vesicles exceeding that of non-encapsulated forms by a factor of three. We further reveal the effect of R on the loading amount and release rate/amount of vesicle-encapsulated drugs, demonstrating a potential pharmaceutical application of the prepared nanovesicles depending on the nature of R., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Have a radical ball! Reaction of C(60)Cl(6) with aryl acetylenes through a copper(I)-mediated annulation route to form fullerocyclobutene derivatives is reported. The fullerocyclobutenes are obtained in 36-53% yields and a possible radical mechanism is proposed for this novel reaction., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The hydrofullerene C(50)H(10) is synthesized by low-pressure benzene-oxygen diffusion combustion. The structure of C(50)H(10) is identified through NMR, mass spectrometry, and IR and Raman spectroscopy as a D(5h) symmetric closed-cage molecule with five pairs of fused pentagons stabilized by ten hydrogen atoms. UV/Vis and fluorescence spectrometric analyses disclose its optical properties as comparable with those of its chloride cousin (C(50)Cl(10)). Cyclic and square-wave voltammograms reveal that the first reduction potential of C(50)H(10) is more negative than that of C(50)Cl(10) as well as C(60), with implications for the utilization of C(50)H(10) as a promising electron acceptor for photovoltaic applications., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

For the first time an easier, operable combustion method is employed for the synthesis of non-IPR fullerene, and an octahydro[60]fullerene with a non-IPR C(60) cage (C(60) isomer (#1809)C(60)) produced by combustion is isolated and characterized by MS, UV-vis, IR, and NMR spectroscopies in combination with DFT calculations. This finding shows that, in addition to chlorine, hydrogen can be an ample cataloreactant for the production of non-IPR fullerene derivatives under such conditions as arc-burning and diffusion combustion.

C(78) is one of the most widely investigated higher fullerenes. Among its huge isomer family, only one non-IPR (IPR = isolated pentagon ring) cage, the C(2)-symmetric (#22010)C(78), was previously stabilized by endohedral derivatization. Here we report a new C(1)-symmetric non-IPR hollow isomer, (#23863)C(78), which was captured as (#23863)C(78)Cl(8) and then subjected to a regioselective substitution reaction with benzyl hydroperoxide to form (#23863)C(78)(OOCH(2)C(6)H(5))Cl(7). The structural connectivity of (#23863)C(78), which contains a pair of fused pentagons, was confirmed by single-crystal X-ray diffraction analysis of the (#23863)C(78)(OOCH(2)C(6)H(5))Cl(7) molecule, which shares the same fullerene core with (#23863)C(78)Cl(8); support for the structure is provided by comparable IR measurements and computation. Theoretical studies suggest that the differences in C-Cl bond length, intermediate stability, and steric effects of the involved molecules account for the chemical regioselectivity of the substitution reaction.

The isolated pentagon rule (IPR) is now widely accepted as a general rule for determining the stability of all-carbon fullerene cages composed of hexagons and pentagons. Fullerenes that violate this rule have been deemed too reactive to be synthesized. The stabilization of non-IPR endohedral fullerenes depends on charge transfer from the encapsulated metal clusters (endoclusters) to fullerene cages, the electronic properties of empty all-carbon cages, the matching size and geometries of fullerene and endocluster, as well as the strong coordination of the metal ions to fused pentagons. The stability of non-IPR exohedral fullerenes can be rationalized primarily by both the 'strain-relief' and 'local-aromaticity' principles. This Review focuses on recent work on stabilization of non-IPR fullerenes, including theoretical and empirical principles, experimental methods, and molecular structures of fused-pentagon fullerenes characterized so far. The special chemical properties of non-IPR fullerenes that distinguish them from IPR-satisfying ones are also emphasized.

Unlike traditional small molecule drugs, fullerene is an all-carbon nanomolecule with a spherical cage structure. Fullerene exhibits high levels of antiviral activity, inhibiting virus replication in vitro and in vivo. In this review, we systematically summarize the latest research regarding the different types of fullerenes investigated in antiviral studies. We discuss the unique structural advantage of fullerenes, present diverse modification strategies based on the addition of various functional groups, assess the effect of structural differences on antiviral activity, and describe the possible antiviral mechanism. Finally, we discuss the prospective development of fullerenes as antiviral drugs. [ABSTRACT FROM AUTHOR]

Photosynthesis in nature uses the Mn4CaO5 cluster as the oxygen-evolving center to catalyze the water oxidation efficiently in photosystem II. Herein, we demonstrate bio-inspired heterometallic LnCo3 (Ln = Nd, Eu and Ce) clusters, which can be viewed as synthetic analogs of the CaMn4O5 cluster. Anchoring LnCo3 on phosphorus-doped graphitic carbon nitrides (PCN) shows efficient overall water splitting without any sacrificial reagents. The NdCo3/PCN-c photocatalyst exhibits excellent water splitting activity and a quantum efficiency of 2.0% at 350 nm. Ultrafast transient absorption spectroscopy revealed the transfer of a photoexcited electron and hole into the PCN and LnCo3 for hydrogen and oxygen evolution reactions, respectively. A density functional theory (DFT) calculation showed the cooperative water activation on lanthanide and O−O bond formation on transition metal for water oxidation. This work not only prepares a synthetic model of a bio-inspired oxygen-evolving center but also provides an effective strategy to realize light-driven overall water splitting. [ABSTRACT FROM AUTHOR]

Isomerism is common in fullerene derivatives, and the isomer‐dependent photovoltaic performance of fullerene derivatives is envisaged recently. This review article outlines recent progresses on isomerism of [6,6]‐phenyl‐C61 (or C71)‐butyric acid methyl esters (PCBMs), one of the most prevalent electronic acceptors in organic or perovskite solar cells. Recent developments about the effects of PCBMs isomers on the photovoltaic performance and device stability of organic or perovskite solar cells are summarized, including the mono‐ and bis‐adduct of PC71BM as well as the bis‐adduct of PC61BM. The open questions and future directions with involvement of isomeric PCBMs are also discussed. [ABSTRACT FROM AUTHOR]

Conical carbon, specifically multi‐walled carbon nanocones (CNCs) and single‐walled carboncones, is a new class of sp2‐hybridized carbon allotrope, in addition to fullerene, carbon nanotubes (CNTs), and graphene. Characterized by a conical and delocalized aromatic configuration, the conical carbon structure is considered the intermediate structure between planar graphene and open‐cage fullerene. CNCs can be stiffer than CNTs and exhibit intriguing physical and chemical properties owing to their unique hollow conical structure, which make these materials promising for application as field emission sources and scanning probes. The research on conical carbon structures is in its nascent stage, mainly because of the limitations in the synthesis and purification of conical carbons. This review summarizes the significant progress in the synthesis of CNCs and carboncones. Particularly, the synthetic methods, which can be divided into traditional physical‐chemical synthesis methods for multi‐walled CNCs and emerging bottom‐up organic synthesis methods for single‐walled carboncones, are comprehensively discussed. In addition, the advantages and disadvantages of the various synthetic methods as well as the possible formation and growth mechanisms of CNCs and carboncones are discussed. Finally, some outlooks on the potential solutions to the synthesis of single‐walled carboncones with uniform apex angles are presented. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Because of its unsaturated bonds, C60 is susceptible to polymerize into dimers. The implications of nitrogen doping on the geometrical and electronic structure of C60 dimers have been ambiguous for years. A quarter‐century after the discovery of azafullerene dimer (C59N)2, we reported its single crystallographic structure in 2019. Herein, the unambiguous crystal structure information of (C59N)2 is elucidated specifically, revealing that the inter‐cage C—C single bond length of (C59N)2 is comparable with that of an ordinary C(sp3)‐C(sp3) single bond, and that the most stable conformer of (C59N)2 is gauche‐conformer with a dihedral angle of 66°. To amend the structural deviations, geometrical structure of (C59N)2 is optimized by a B3LYP‐D3BJ function, which is proved to be more consistent with its single crystal structure than those by the commonly used B3LYP function. Moreover, the calculation method is also suitable for other representative fullerene dimers, such as (C60)2 and its divalent anion. Additionally, the dissociation of (C59N)2 at 473 K under mass spectrometric conditions suggests the inter‐cage C—C bond is relatively weaker than an ordinary C—C single bond, which can be explained by the interaction energies of inter‐cages. [ABSTRACT FROM AUTHOR]

All previously reported C70 isomers have positive curvature and contain 12 pentagons in addition to hexagons. Herein, we report a new C70 species with two negatively curved heptagon moieties and 14 pentagons. This unconventional heptafullerene[70] containing two symmetric heptagons, referred to as dihept‐C70, grows in the carbon arc by a theoretically supported pathway in which the carbon cluster of a previously reported C66 species undergoes successive C2 insertion via a known heptafullerene[68] intermediate with low energy barriers. As identified by X‐ray crystallography, the occurrence of heptagons facilitates a reduction in the angle of the π‐orbital axis vector in the fused pentagons to stabilize dihept‐C70. Chlorination at the intersection of a heptagon and two adjacent pentagons can greatly enlarge the HOMO–LUMO gap, which makes dihept‐C70Cl6 isolable by chromatography. The synthesis of dihept‐C70Cl6 offers precious clues with respect to the fullerene formation mechanism in the carbon‐clustering process. [ABSTRACT FROM AUTHOR]

Despite being widely used as electron acceptor in polymer solar cells, commercially available PC71BM (phenyl-C71-butyric acid methyl ester) usually has a 'random' composition of mixed regioisomers or stereoisomers. Here PC71BM has been isolated into three typical isomers, α-, β1- and β2-PC71BM, to establish the isomer-dependent photovoltaic performance on changing the ternary composition of α-, β1- and β2-PC71BM. Mixing the isomers in a ratio of α/β1/β2=8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC71BM as photoactive layer (PTB7=poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b:4,5- b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophenediyl]]). The three typical PC71BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average-performing PCE of 1.28-7.44 % due to diverse self-aggregation of individual or mixed PC71BM isomers in the otherwise same polymer solar cells. [ABSTRACT FROM AUTHOR]

Buckybowls are fascinating components of supramolecular assemblies owing to their unique bowl-shaped π-surfaces. Herein we present a protocol for the functionalization of a sulfur-doped buckybowl, trithiasumanene, via a brominated intermediate, from which thiolated trithiasumanenes were derived. The curved surface and electron-donating properties of thiolated trithiasumanenes promote their ready assembly with fullerenes to form concave-convex complexes. The supramolecular assembly behavior in solution was investigated by NMR analysis. The structures of supramolecular complexes were unambiguously characterized by crystallography. The crystals of the concave-convex complexes showed high thermal stability and photoconductivity. [ABSTRACT FROM AUTHOR]

The flash vacuum pyrolysis (FVP) technique is useful for preparing curved polycyclic aromatic compounds (PAHs) and caged nanocarbon molecules, such as the well-known corannulene and fullerene C60. However, the operating temperature of the traditional FVP apparatus is limited to ~1250 °C, which is not sufficient to overcome the high energy barriers of some reactions. Herein, we report an ultrahigh-temperature FVP (UT-FVP) apparatus with a controllable operating temperature of up to 2500 °C to synthesize fullerene C60 from a nonaromatic single carbon reactant, i.e., chloroform, at 1350 °C or above. Fullerene C60 cannot be obtained from CHCl3 using the traditional FVP apparatus because of the limitation of the reaction temperature. The significant improvements in the UT-FVP apparatus, compared to the traditional FVP apparatus, were the replacement of the quartz tube with a graphite tube and the direct heating of the graphite tube by impedance heating instead of indirect heating of the quartz tube using an electric furnace. Because of the higher temperature range, UT-FVP can not only synthesize fullerene C60 from single carbon nonaromatic reactants but sublimate some high-molecular-weight compounds to synthesize larger curved PAHs in the future. [ABSTRACT FROM AUTHOR]

Interface engineering that involves in the metal cathodes and the electron transport layers (ETLs) facilitates the simultaneous improvement of device performances and stability in perovskite solar cells (PSCs). Herein, low-temperature solution-processed cerium oxide (CeO x ) films are prepared by a facile sol-gel method and employed as the interface layers between [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM) and an Ag back contact to form PC 61 BM/CeO x double ETLs. The introduction of CeO x enables electron extraction to the Ag electrode and protects the underlying perovskite layer and thus improves the device performance and stability of the p-i-n PSCs. The p-i-n PSCs with double PC 61 BM/CeO x ETLs demonstrate a maximum power conversion efficiency (PCE) of 17.35%, which is superior to those of the devices with either PC 61 BM or CeO x single ETLs. Moreover, PC 61 BM/CeO x devices exhibit excellent stability in light soaking, which is mainly due to the chemically stable CeO x interlayer. The results indicate that CeO x is a promising interface modification layer for stable high-efficiency PSCs. [ABSTRACT FROM AUTHOR]

Arc-discharge of graphite is the most prevalent technique for synthesis of novel fullerenes, but the extreme conditions of the carbon arc prevent any currently available instrument from detecting the reaction species inside. To detour the difficulties for probing the derivatization mechanism in the drastic arc-discharge conditions, C 78 Cl 6 (C 5 Cl 6 ) with prototypical C 2v (2)-C 78 cage has been isolated and characterized in the products of the chlorine-involving carbon arc. The structure of C 2v (2)-C 78 Cl 6 (C 5 Cl 6 ), featuring with fullerene C 2v (2)-C 78 doubly functionalized by chlorine atoms and perchlorinated cyclopentadiene, has been identified by X-ray crystallography. Confirmed by standard Density Functional Theory (DFT) calculations and Car-Parrinello simulations as well as mass spectrometry, the fullerene core has been revealed to form firstly followed then by reaction with chlorine atoms and afterwards with perchlorinated cyclopentadiene, with implication about stepwise reaction temperatures and sequences for the formation of fullerenes and their derivatives in the otherwise inaccessible extreme conditions of the carbon arc. [ABSTRACT FROM AUTHOR]

Formulation engineering, featuring with different ingredients combined, is a useful strategy for making efficient electronic acceptors because it can achieve effects that cannot be obtained from its components when these are used singly. Herein, we show a contour plot with different formulations of isomeric phenyl-C 71 -butyric acid methyl ester (PC 71 BM) as electron acceptors in poly(3-hexylthiophene) (P3HT):PC 71 BM polymer solar cells (PSCs). Upon altering fullerene formulation the PCEs change in the range of 0.87–4.01%. The optimized formulation consisting of ~ 80% α-PC 71 BM, ~ 10% β 1 -PC 71 BM, and ~ 10% β 2 -PC 71 BM exhibits the best PCE of 4.01%, which mainly benefits from the optimum morphology of P3HT-fullerene heterojunction film. The present work demonstrates a successful strategy by controlling morphology of PC 71 BM isomers to improve the PCE of P3HT-based PSCs, and consolidates the photovoltaic performance of polymer solar cells heavily dependent on the formulation of fullerene-based electron acceptors. [ABSTRACT FROM AUTHOR]

Two fullerene C 60 derivatives, 2-(3-ethoxycarbonylpropyloxy)-(5,8)-dihydronaphthyl-(6,7)-[6,6]-C 60 (EDNC) and 2-benzyloxy-(5,8)-dihydronaphthyl-(6,7)-[6,6]-C 60 (BDNC), are introduced into p-i-n type planar heterojunction perovskite solar cells as electron transport materials (ETMs) to investigate electrochemical, charge-transporting, and film-forming properties of fullerene ETMs and the resulting photovoltaic performance in comparison with [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 61 BM). Due to better surface morphology, the EDNC-involving device shows better performance (12.64%) than that of BDNC-based device (7.36%) despite of their similar LUMO energy level, electron mobility, optical properties, and electrochemical properties. Higher power conversion efficiency (PCE) of 15.04% is achieved using PC 61 BM as the ETM, the electronic mobility of PC 61 BM is approximately one order of magnitude higher than that of EDNC, which leads to slightly higher short-circuit current density and fill factor for PC 61 BM-based device. This work demonstrates that factors such as electron mobility and surface morphology should be envisaged in searching for fullerene derivatives as efficient ETM in perovskite solar cells. [ABSTRACT FROM AUTHOR]

Discovery of organic-inorganic hybrid perovskites ignites the dream of next-generation solar cells fabricated by low-cost solution processing. To date, fullerene derivative [6,6]-phenyl-C 61 - butyric acid methyl ester (PC 61 BM), is the most prevalently used electron transport layer for high efficiency p-i-n planar heterojunction perovskite solar cells. Compared with PC 61 BM, pristine fullerenes, such as C 60 and C 70 , have shown superiority of higher electron mobility and much lower costs. Due to the poor solubility and strong tendency to crystallize for pristine fullerenes in solution process, it is still a challenge to deposit compact and continuous film of pristine fullerenes for p-i-n type perovskite solar cells by solution processing. Herein, solution processed pristine fullerenes (C 60 and C 70 ) were used as electron transport layers to replace PC 61 BM in perovskite solar cells with high performance and enhanced stability. Power conversion efficiency of 14.04% was obtained by using mixture of C 60 and C 70 as electron transport layer, which is comparable to that of PC 61 BM based device (13.74%). We demonstrated that the strong tendency of pristine fullerenes to crystallize during solvent removal can be largely mitigated by mixing different kinds of pristine fullerenes. These findings implicate pristine fullerenes as promising electron transport layers for high performance perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Four fullerene derivatives, benzocyclopentane-C60 mono-adduct (BPCMA) and its bis-adduct (BPCBA), acenaphthene-C60 mono-adduct (ACMA) and its bis-adduct (ACBA), were synthesized by cyclopropanation reaction. Geometrical structures and molecular packing of the mono-adduct compounds (BPCMA and ACMA) were identified by X-ray crystallography. As measured by cyclic voltammetry, LUMO energy levels of BPCBA and ACBA are about 0.08 and 0.09eV higher than their corresponding mono-adducts. Even though the power conversion efficiency remains to be improved, the polymer solar cells (PSCs) incorporating P3HT as donor and BPCBA (or ACBA) as acceptor exhibit open-circuit voltage (V oc) of 0.67V (or 0.68V), which is about 0.22V (or 0.23V) higher than the PSCs with the mono-adduct BPCMA (or ACMA) as electron acceptor. In addition, the short-circuit current density (J sc) of the PSCs involving bis-adducts (BPCBA and ACBA) are obviously higher than those based on BPCMA and ACMA. The photovoltaic difference between mono- and bis-adducts can be rationalized by their different behaviors in LUMO energy and molecular packing. [Copyright &y& Elsevier]

Abstract: Two regioselective C60(OCH3)4 derivatives, C60(OCH3)4-PCBM (a methanofullerene derivative of C60(OCH3)4, PCBM=[6,6]-phenyl-C61-butyric acid methyl ester) and C60(OCH3)4-APCBM (an aziridinofullerene derivative of C60(OCH3)4) were synthesized from C60Cl6 and used as acceptor for polymer solar cells. Revealed by cyclic voltammetry, the LUMO energy levels of C60(OCH3)4-APCBM and C60(OCH3)4-PCBM are 0.2 and 0.3eV higher than that of PCBM, respectively. For the polymer photovoltaic cells with fullerene (PCBM, C60(OCH3)4-APCBM or C60(OCH3)4-PCBM) acceptor in combination with poly(3-hexylthiophene) (P3HT) donor, the open-circuit voltage is increased from 0.58V (for PCBM) to 0.63V (for C60(OCH3)4-APCBM) and 0.72V (for C60(OCH3)4-PCBM). The higher open-circuit voltages are reasonably attributed to the higher LUMO levels of the C60(OCH3)4 derivatives because of four electron-donating methoxy groups attached. The photovoltaic performance of C60(OCH3)4-PCBM-based device is higher than that involving C60(OCH3)4-APCBM, largely due to the structural changeability of C60(OCH3)4-APCBM resulting from the rotatable N–C bond bridge therein. This work demonstrates that fullerene derivatives with higher LUMO level can be functionalized from multi-addition of electron-donating groups, and exemplifies that photovoltaic performances of fullerene-based solar cells are sensitive even to trivial bridge between functional group and fullerene core. [Copyright &y& Elsevier]

Abstract: A class of alkoxy substituted dihydronaphthyl-C60 derivatives, such as 2-methoxy-(5,8)-dihydronaphthyl-(6,7)- [6,6]–C60 (MDNC) and its bisadduct (Bis-MDNC) with high-lying LUMO level, were synthesized and evaluated as electron acceptors in polymer solar cells. Influence of substituent groups (methyloxy, benzyloxy, benzoyloxy, hexyloxy, and 3-ethoxycarbonylpropyloxy) on photovoltaic and electrochemical properties regarding these fullerene derivatives were studied. The polymer bulk heterojunction (BHJ) solar cell using Bis-MDNC blend with poly (3-hexylthiophene) (P3HT) as photoactive layer showed a power conversion efficiency (PCE) of 4.58% with an open-circuit voltage (V oc ) of 0.83V, which is superior to the P3HT: PCBM control device (3.25% PCE with V oc of 0.59V). This work exemplifies a facile functionalization and an alterable photovoltaic behavior susceptible to substituent groups in the dihydronaphthyl-C60 derivatives. [Copyright &y& Elsevier]

Abstract: In addition to the traditional Krätschmer–Huffman graphite arc-discharge method, a combustion method has been developed to synthesize fullerenes that defy the isolated pentagon rule (IPR). The C 3 v -symmetric , as well as other non-IPR fullerenes such as the possible non-IPR C60 isomer, have been synthesized as fullerene hydrides in a low-pressure benzene/oxygen diffusion flame. The non-IPR structure of the chromatographically isolated C64 species was unambiguously identified by its HPLC retention time, UV absorption and mass spectrum by comparison with the reference material . The synthesis, isolation and identification of , as described in this work, show that this combustion method is successful, is energy efficient and is a promising candidate for the macroscopic synthesis of non-IPR fullerenes. [Copyright &y& Elsevier]

The graphite arc-discharge in the atmosphere consisting of CCl4 40 Torr and increasing partial pressure of He from 0 to 300 Torr produced, in addition to carbon species such as graphite and fullerenes C60 and C70, numerous chlorinated carbon clusters (CCCs). The yields of some CCCs, including C6Cl6 (perchlorobenzene), C10Cl8 (perchloronaphthalene), C12Cl8 (perchloroacenaphthylene) and C12Cl8 (isomer II), C14Cl8 (isomer I), C16Cl10 (perchlorofluoranthene), C18Cl10 (isomer I and II), and C20Cl10 (isomer I), correspond well with C60 yields, which may imply these CCCs share the same growth mechanism with fullerenes. Such a yield correlation can be used to distinguish the fullerene precursors from the irrelevant by-products, thus contributes to the mechanistic study of fullerene formation. [Copyright &y& Elsevier]

All carbon cages (fullerenes) synthesized so far, such as C60 and its larger homologs, faithfully satisfy the isolated pentagon rule (IPR), which governs the stability of fullerenes comprising hexagons and exactly 12 pentagons. The smaller non-IPR fullerenes, which are predicted to have unusual properties because of their adjacent pentagons and high curvature, are so labile that their properties and reactivity have only been studied in the gas phase. C50-containing soot was synthesized in a modified graphite are-discharge process in which 0.013 arm of CCl4 was added to 0.395 arm of helium.