Endohedral metallofullerenes (EMFs), a new class of hybrid molecules formed by encapsulation of metallic species inside fullerene cages, exhibit unique properties that differ distinctly from those of empty fullerenes because of the presence of metals and their hybridization effects via electron transfer. This critical review provides a balanced but not an exhaustive summary regarding almost all aspects of EMFs, including the history, the classification, current progress in the synthesis, extraction, isolation, and characterization of EMFs, as well as their physiochemical properties and applications in fields such as electronics, photovoltaics, biomedicine, and materials science. Emphasis is assigned to experimentally obtained results, especially the X-ray crystallographic characterizations of EMFs and their derivatives, rather than theoretical calculations, although the latter has indeed enhanced our knowledge of metal–cage interactions. Finally, perspectives related to future developments and challenges in the research of EMFs are proposed. (381 references)

Current status and future developments of endohedral metallofullerenes

In this tutorial review taking X-ray crystallographically characterized compounds as a starting point a walk is taken through the electronic and structural properties of endohedral metallofullerenes After classification of the fullerenes according to the encapsulated guest, particular attention is given to identifying factors that determine the selection of a particular carbon cage network by the internal metal cluster Some of the physical rules that determine which particular fullerene cage is formed will be discussed Concepts such as charge transfer between the cage and the guest metal ions, the topology of the cage, the separations between the 12 pentagons on the fullerene surface, and the effect of entropic factors are used to rationalize the selection of a particular cage The roles of electrochemistry and vibrational spectroscopy in combination with theoretical calculations are considered in understanding the structures of the endohedral fullerenes

Endohedral metallofullerenes: a unique host–guest association

Fullerenes have the characteristic of a hollow interior, and this unique feature triggers intuitive inspiration to entrap atoms, ions or clusters inside the carbon cage in the form of endohedral fullerenes. In particular, upon entrapping an otherwise unstable metal cluster into a carbon cage, the so-called endohedral clusterfullerenes fulfil the mutual stabilization of the inner metal cluster and the outer fullerene cage with a specific isomeric structure which is often unstable as an empty fullerene. A variety of metal clusters have been reported to form endohedral clusterfullerenes, including metal nitrides, carbides, oxides, sulfides, cyanides and so on, making endohedral clusterfullerenes the most variable and intriguing branch of endohedral fullerenes. In this review article, we present an exhaustive review on all types of endohedral clusterfullerenes reported to date, including their discoveries, syntheses, separations, molecular structures and properties as well as their potential applications in versatile fields such as biomedicine, energy conversion, and so on. At the end, we present an outlook on the prospect of endohedral clusterfullerenes.

When metal clusters meet carbon cages: endohedral clusterfullerenes

THE synthesis of fullerenes encapsulating various metal atoms within the carbon cage (endohedral metallofullerenes) has stimulated wide interest1,2 because of their unusual structural and electronic properties. Most of the metallofullerenes prepared so far have been based on C82, and have incorporated lanthanum1,3á¤-5, yttrium6,7, scandium8á¤-10 and most of the lanthanide elements11,12′. Although there has been some debate about the endohedral nature of these compounds2,13,14, observations using scanning tunnelling microscopy15,16, extended X-ray absorption fine structure17,18, transmission electron microscopy19 and electron spin resonance3,6á¤-8,10 have strongly suggested that the metal atoms are indeed inside the fullerene cages; theoretical calculations20,21 also indicate that this is the case. But until now, no structural model has been derived experimentally to confirm the endohedral nature of the metallofullerenes. Here we report the results of a synchrotron X-ray powder diffraction study of Y@C82 that confirms that the yttrium atom is located within the carbon cage. The yttrium atom is displaced from the centre of the C82 molecule and is strongly bound to the carbon cage.

Confirmation by X-ray Diffraction of the Endohedral Nature of the Metallofullerene Y@C_82.

The electrochemical behavior of cerium(III/IV) complexes: Thermodynamics, kinetics and applications in synthesis

The row of endohedral fullerenes is extended by a new type of sulfur-containing clusterfullerenes: the metal sulfide (M2S) has been stabilized within a fullerene cage for the first time. The new sulfur-containing clusterfullerenes M2S@C82-C3v(8) have been isolated for a variety of metals (M = Sc, Y, Dy, and Lu). The UV−vis−NIR, electrochemical, and FTIR spectroscopic characterization and extended DFT calculations point to a close similarity of the M2S@C82 cage isomeric and electronic structure to that of the carbide clusterfullerenes M2C2@C2n. The bonding in M2S@C82 is studied in detail by molecular orbital analysis as well as with the use of quantum theory of atom-in-molecules (QTAIM) and electron localization function (ELF) approaches. The metal sulfide cluster formally transfers four electrons to the carbon cage, and metal−sulfur and metal−carbon cage bonds with a high degree of covalency are formed. Molecular dynamics simulations show that Sc2S cluster exhibits an almost free rotation around the C3 ax...

Metal Sulfide in a C82 Fullerene Cage: A New Form of Endohedral Clusterfullerenes

Redox reactions of endohedral fullerenes, and especially their oxidation, usually result in a change of the redox state of the carbon cage. Here we demonstrate that an oxidation of the endohedral species is possible bypassing the fullerene cage in an unprecedented reversible cascade electron transfer under anodic conditions. The first Ce-based non-scandium mixed-metal nitride clusterfullerene (NCF) Lu2CeN@C80(Ih) was synthesized and isolated. The electronic and vibrational properties of Lu2CeN@C80 are characterized by UV-vis-NIR and FTIR spectroscopies and the cage structure of Lu2CeN@C80 is determined by 13C NMR spectroscopy to be C80(Ih). At room temperature the NMR peak positions are shifted from the normal values of the diamagnetic M3N@C80 NCFs because of the unpaired f-electron localized on the Ce atom in the Ce3+ state. The variable-temperature NMR study enabled the estimation of the diamagnetic terms in the 13C chemical shifts, which were found to be close to those of diamagnetic M3N@C80 NCFs. The electrochemical properties of Lu2CeN@C80 were investigated by cyclic and square wave voltammetry, revealing two electrochemically irreversible but chemically reversible reduction steps and one reversible oxidation step. As the oxidation potential is significantly less positive than that in all other M3N@C80 NCFs, we conclude that an oxidation of the endohedral Ce occurs with the formation of Lu2CeIVN@C80+, the first endohedral metallofullerene species with the tetra-valent cerium atom. This hypothesis is also supported by DFT calculations.

An endohedral redox system in a fullerene cage: the Ce based mixed-metal cluster fullerene Lu2CeN@C80

Using guanidinium salts 1 and 2 as the new nitrogen sources, metal nitride clusterfullerenes (NCFs) based on a variety of metals (Dy, Sc, Y, Gd, Lu, and mixed metals Sc/Dy, Sc/Gd, Sc/Lu, and Lu/Ce) have been synthesized based on a new "selective organic solid" (SOS) route. The synthesis of Dy-NCFs by using Dy/1 was studied in detail, and the optimum molar ratio of 1/Dy/C has been determined to be 2.5:1:10. For several representative metals such as Sc, Y, Gd, Dy, and Sc/Dy, we quantitatively compared the yield of M(3)N@C(80) synthesized by the SOS route with the reported "reactive gas atmosphere" route, thereby indicating that the yield of M(3)N@C(80) by using 1 could be comparable to that obtained by the reactive gas atmosphere route. Three other nitrogen sources (3-5) were also studied for comparison, which were mixed with Dy metal but did not result in the formation of Dy-NCF. A possible reaction scheme for the solid-state reaction of 1, metal, and graphite is proposed. The SOS route appears to be a general route for the synthesis of NCFs that promises both high selectivity of NCFs and high reproducibility of the fullerene yield. Another advantages of the SOS route compared to the reported "trimetallic nitride template" (TNT) process and the reactive gas atmosphere route is that no additional heating pretreatment is needed, thus simplifying the procedure and being much more facile.

A Facile Route to Metal Nitride Clusterfullerenes by Using Guanidinium Salts: A Selective Organic Solid as the Nitrogen Source

Electrochemical Tuning of Spin States of the Endohedral Metallofullerene Y@C82 as Probed by ESR Spectroelectrochemistry

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Lin Zhang

Author Tools

Chat about Author

Papers

Metal Sulfide in a C82 Fullerene Cage: A New Form of Endohedral Clusterfullerenes

An endohedral redox system in a fullerene cage: the Ce based mixed-metal cluster fullerene Lu2CeN@C80

A Facile Route to Metal Nitride Clusterfullerenes by Using Guanidinium Salts: A Selective Organic Solid as the Nitrogen Source

Electrochemical Tuning of Spin States of the Endohedral Metallofullerene Y@C82 as Probed by ESR Spectroelectrochemistry