Properties Of Endohedral Fullerenes Research Articles

Superhalogens inside fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70).

The exploration of endohedral fullerenes has garnered significant attention recently due to their distinctive chemical, electrochemical, and optoelectronic properties. Charge transfer, which usually occurs from encapsulated species to fullerenes, importantly affects the structures and properties of endohedral fullerenes. In this study, we theoretically investigated endohedral superhalogen fullerenes X@C2n (X = BO2, BeF3; 2n = 60, 70), in which the charge is reversely transferred from the fullerene to the superhalogen, by using density functional theory calculations and ab initio molecular dynamics simulations. Both natural population analysis and the quantum theory of atoms in molecules confirm about one electron transfer from the fullerene to the superhalogen, resulting in the formal valence state of X-@C2n+. Energy decomposition analysis on the interaction between the superhalogen and fullerene revealed that electrostatic energy contributes predominantly to the total interaction energy. These endohedral superhalogen fullerenes with cationic fullerenes were predicted to be able to serve as building blocks for one dimensional fullerene-based nanowires when combined with endohedral alkali-metallofullerenes with anionic fullerenes.

Endohedral fullerenes: the importance of electronic, size and shape complementarity between the carbon cages and the corresponding encapsulated clusters

Cage‐cluster complementarity is of crucial importance in determining the sizes and structures, as well as the properties of endohedral fullerenes. The encapsulated atoms or clusters, which are typically in a positively charged state, are irreversibly, mechanically, and electrostatically trapped inside the typically negatively charged cages. These rather exotic compounds exhibit exquisitely complementary properties between their components. Here, we present a short overview to show that size and shape are crucial in determining the specific structures that are formed, and the presence of electrostatic interactions result in structural motifs that are never observed for pristine fullerene cages. Copyright © 2014 John Wiley & Sons, Ltd.

Synthesis of a new class of fullerene derivative Li+@C60O−(OH)7 as a “cation-encapsulated anion nanoparticle”

Metal encapsulation into a cage and chemical modification on the outer surface of fullerenes endow them with some unique characteristic properties. Although the derivatization of endohedral fullerenes holds promise for producing novel new nano-carbon materials, there are few reports about such compounds. Herein, we report the synthesis of lithium encapsulated fullerenol Li(+)@C60O(-)(OH)7 using a fuming sulfuric acid method from [Li(+)@C60](PF6(-)) and characterization of its structure by IR, NMR, FAB mass spectroscopy, and elemental analysis. The hydroxylation of [Li(+)@C60](PF6(-)) is site-selective to preferentially give a single isomer (ca. 70%) with two minor isomers in marked contrast to the reaction of empty C60. We conclude from the analysis of radical species produced in the reaction of a C60 cage with fuming sulfuric acid that this unusual site-selective hydroxylation is caused by the lower HOMO level of Li(+)@C60 than that of empty C60. Furthermore, our results clearly indicate that the internal lithium cation is interacted with the introduced hydroxyl groups, and thus the properties of endohedral fullerenes can be controlled by the external modification of a fullerene cage.

Synthesis of a New Class of Molecule Li+@C60O–(OH)7 as a “Cation-Encapsulated Anion Nanoparticle” by Multihydroxylation of Li-Encapsulated Fullerene

ABSTRACTTreatment of [Li+@C60](PF6–) with 30% fuming sulfuric acid and subsequent hydrolysis gave hydroxylated derivative Li+@C60O–(OH)7. Its structure was deduced by IR, NMR, MALDI-TOF/FAB MS, and elemental analysis. Notably, the reaction of [Li+@C60](PF6–) was site-selective, giving a single major isomer (ca. 70%) with two minor isomers, in marked contrast to the case of empty C60. Furthermore, the results clearly indicate that the internal Li cation was strongly shielded by the surface dipolar hydroxyl groups, and thus it appears that the properties of endohedral fullerenes can be controlled by the external modification of the fullerene cage. Whereas Li+@C60 is relatively insoluble, Li+@C60O–(OH)7 was found to be highly soluble in polar solvents such as DMSO and DMF. The increased solubility is especially desirable for biological/medicinal assays and applications in such research fields.

Buckyball maracas: exploring the inside and outside properties of endohedral fullerenes

Since the experimental observation of the encapsulation of different species inside fullerene (endohedral fullerenes) cages, several research groups have focused their research in the elaboration of new and novel compounds. Exohedral functionalization of the carbon cages has helped in the discovery of new species and has expanded their potential applications in material science and medicine. Our research group has contributed to the discovery, functionalization, and characterization of new and interesting compounds that have been explored in different applications, but mainly in the field of organic photovoltaics. Here, we report the contribution and progress of our research group in the field of buckyball “maracas.” Copyright © 2012 John Wiley & Sons, Ltd.

Optical and structural properties of the endohedral complexes M@C 60 (M = Cs, Li, and Na)

We have studied the M atom type and position effects on the structural and nonlinear optical (NLO) properties of endohedral fullerenes M@C 60 (M = Li, Na, and Cs) using SSH(Su-Schrieffer-Heeger) and SSH-SOS (sum-over-state) approaches. Our results have indicated that the (hyper) polarizability value of M@C 60 must have been enhanced by choosing the proper type and position for M atom. This study proposes a novel way to synthesize and design new NLO materials by using the alkali atoms.

Atoms in carbon cages: the structure and properties of endohedral fullerenes

Encapsulating atoms or molecules inside fullerene cages could give rise to a myriad of novel molecules and materials. The existence of such species is now strongly supported by a growing body of experimental evidence. Fullerene& ndash;metal complexes generally thought to be endohedral are being produced and purified in milligram quantities, and their structure and properties are beginning to be explored