C66 fullerene encaging a scandium dimer

Graphendofullerene: a novel molecular two-dimensional ferromagnet

Carbon chemistry has attracted a lot of attention from chemists, physicists and material scientists in the last few decades. The recent discovery of graphullerene provides a promising platform for many applications due to its exceptional electronic properties and the possibility to host molecules or clusters inside the fullerene units. Herein, we introduce graphendofullerene, a novel molecular-based two-dimensional (2D) magnetic material formed by trimetallic nitride clusters encapsulated on graphullerene. Through first-principles calculations, we demonstrate the successful incorporation of the molecules into the 2D network formed by C80 fullerenes, which leads to robust long-range ferromagnetic order with a Curie temperature (T C) of 38 K. Additionally, we achieve a 45% and 18% increase in T C by strain engineering and electrostatic doping, respectively. These findings open the way for a new family of molecular 2D magnets based on graphendofullerene for advanced technologies.

Computational insights into Diels-Alder reactions of paramagnetic endohedral metallofullerenes: M@C82 (M = Sc, Y, La) and La@C72

In fullerene chemistry, Diels-Alder cycloaddition is an essential reaction for exohedral modification of carbon cages. M@C2v(9)-C82 (M = Sc, Y, and La), incorporating one metal atom within the fullerene cage, are key compounds for understanding the impact of both endohedral and exohedral modifications on their electronic structures. In this work, the Diels-Alder (DA) cycloaddition of cyclopentadiene (Cp) to M@C2v(9)-C82 (M = Sc, Y, and La) and La@C2(10612)-C72 was systematically studied using density functional theory. The most reactive bonds were initially chosen for detailed mechanistic exploration, considering both concerted and stepwise mechanisms. Our findings revealed that DA cycloadditions for the three metals (Sc, Y, and La) consistently exhibit the same regioselectivity, favoring the concerted attack on the [5,6] bond. This observation is in agreement with previous experimental and theoretical studies on the regioselectivity of the Diels-Alder reaction between La@C2v(9)-C82 and Cp. In the case of La@C2(10612)-C72, the most favored pathway is the concerted attack on the [6,6] bond both kinetically and thermodynamically. In toluene and ortho-dichlorobenzene, while the energy barriers and the reaction free energies increased to different extents for most pathways, the regioselectivity largely mirrored that observed in the gas phase.

The formation mechanism of Sc-based metallofullerenes: a molecular dynamics simulation study

The practical applications of endohedral metallofullerenes (EMFs) are mainly constrained by their low yields. Understanding the formation mechanisms is therefore crucial for developing methods for high-yield and selective synthesis. To address this, a novel force-field parameter set, "CSc.ff", was created using a single-parameter search optimization method, then molecular dynamics simulations of various systems with a carbon-to-scandium atomic ratio of 12.5 were carried out. The simulations were run under a constant atomic number, volume, and energy (NVE) ensemble. The influence of the working gas, helium, as well as temperature gradients on the formation process was examined. Our simulations reveal that the cage growth patterns of Sc-based EMFs (Sc-EMFs) closely resemble those of hollow fullerenes, evolving from free carbon atoms to chains, rings, and, ultimately, to cage-shaped clusters. Importantly, the Sc-EMFs formed in the simulation frequently exhibit structural defects or under-coordinated carbon atoms. Scandium atoms, whether at the periphery or on the surface of these cages, can be incorporated into the cages, forming Sc-EMFs. Helium was found to not only promote the formation of carbon cages but also facilitate the encapsulation of scandium atoms, playing a crucial role in the formation of cluster fullerenes. Moreover, cooling effectively inhibits the uncontrollable growth of the carbon cage and is essential for forming stable, appropriate-sized cages. This study enhances our understanding of the formation of Sc-EMFs and provides valuable insights for developing more efficient synthetic methods.

Dual modification to stabilize Non-IPR C72 fullerene: A new theoretical strategy

The stabilization of non-IPR fullerenes for their isolation and characterization is an area of recent interest. In the present study, we have explored the stabilization techniques of C₇₂ isomers via endo and exo-modifications and finally approached dual modification. A total of four isomers of C₇₂ have been considered in this study; among them, one is IPR derivative (1), and the rest are non-IPR derivatives with one (2) and two (3 and 4) fused pentagon rings. First, we have studied the endohedral modification by encapsulating one and two La atoms in the C₇₂ cavity. Secondly, we have exohedrally modified the C₇₂ isomers via chlorination by adding four and eight chlorides, respectively. Our final approach is to study the dual modification, where we have implemented both endo exo-modifications together. This dual modification can be achieved in two ways: exo followed by endo and endo followed by exo. For each modification, the relative stability of every modified C₇₂ derivative has been checked by calculating the relative energy with respect to the most stable modified analogue. To find out whether these modifications are energetically feasible or not, we have calculated the binding energy of each modified C₇₂ isomer. The binding energy calculation reveals that the encapsulation and exo-modification techniques are good enough to stabilize the non-IPR C₇₂ derivatives. Moreover, the effectiveness of dual modification has also been established from the enhanced binding energy compared to either endo- or exo-modification. We have also studied the NPA charges on the encapsulated La atoms for each endo- and dual-modified C₇₂ derivative. Furthermore, the AIM study has also been perceived to find out the interaction between the La atom and the fullerene cages for both mono- and di-encapsulated fullerene derivatives and also between La-La centres for di-encapsulated derivatives. Overall, the present theoretical study will provide an idea about the stability of the modified C₇₂ derivatives, which will help the experimentalists to design new strategies for synthesizing modified non-IPR fullerene derivatives that have vast applications in the medicinal and industrial fields.

Ab initio insight into the electrolysis of water on basal and edge (fullerene C20) surfaces of 4 Å single-walled carbon nanotubes

The extreme surface reactivity of 4 Å single-walled carbon nanotubes (SWCNTs) makes for a very promising catalytic material, however, controlling it experimentally has been found to be challenging. Here, we employ ab initio calculations to investigate the extent of surface reactivity and functionalization of 4 Å SWCNTs. We study the kinetics of water dissociation and adsorption on the surface of 4 Å SWCNTs with three different configurations: armchair (3,3), chiral (4,2) and zigzag (5,0). We reveal that out of three different configurations of 4 Å SWCNTs, the surface of tube (5,0) is the most reactive due to its small HOMO-LUMO gap. The dissociation of 1 H2O molecule into an OH/H pair on the surface of tube (5,0) has an adsorption energy of -0.43 eV and an activation energy barrier of 0.66 eV at 298.15 K in pure aqueous solution, which is less than 10% of the activation energy barrier of the same reaction without the catalyst present. The four steps of H+/e- transfer in the oxygen evolution reaction have also been studied on the surface of tube (5,0). The low overpotential of 0.38 V indicates that tube (5,0) has the highest potential efficiency among all studied carbon-based catalysts. We also reveal that the armchair edge of tube (5,0) is reconstructed into fullerene C20. The dangling bonds on the surface of fullerene C20 result in a more reactive surface than the basal surface of tube (5,0), however the catalytic ability was also inhibited in the later oxygen reduction processes.

Catalytic Growth of Ultralong Graphene Nanoribbons on Insulating Substrates

Graphene nanoribbons (GNRs) with widths of a few nanometers are promising candidates for future nanoelectronic applications due to their structurally tunable bandgaps, ultrahigh carrier mobilities, and exceptional stability. However, the direct growth of micrometer-long GNRs on insulating substrates, which is essential for the fabrication of nanoelectronic devices, remains an immense challenge. Here, the epitaxial growth of GNRs on an insulating hexagonal boron nitride (h-BN) substrate through nanoparticle-catalyzed chemical vapor deposition is reported. Ultranarrow GNRs with lengths of up to 10 µm are synthesized. Remarkably, the as-grown GNRs are crystallographically aligned with the h-BN substrate, forming 1D moiré superlattices. Scanning tunneling microscopy reveals an average width of 2 nm and a typical bandgap of ≈1 eV for similar GNRs grown on conducting graphite substrates. Fully atomistic computational simulations support the experimental results and reveal a competition between the formation of GNRs and carbon nanotubes during the nucleation stage, and van der Waals sliding of the GNRs on the h-BN substrate throughout the growth stage. This study provides a scalable, single-step method for growing micrometer-long narrow GNRs on insulating substrates, thus opening a route to explore the performance of high-quality GNR devices and the fundamental physics of 1D moiré superlattices.

An unprecedented C80 cage that violates the isolated pentagon rule

Two Lu2O@C80 isomers have been successfully isolated and unambiguously assigned as Lu2O@C1(31876)-C80 and Lu2O@C2v(5)-C80, respectively, by X-ray crystallography. Interestingly, C1(31876)-C80 is an unprecedented cage with a pair of adjacent pentagons,...

Structural and Spectral Properties of a Nonclassical C66 Isomer with Its Hydrogenated Derivative C66H4 in Theory

X-ray photoelectron and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of a newly discovered nonclassical isomer C 2v -C66(NC), and two classical fullerene isomers C 2-#4466C66 and C s -#4169C66 with their hydrogenated derivatives [C 2v -C66H4(NC), C 2-#4466C66H4, and C s -#4169C66H4] have been calculated at the density functional theory (DFT) level. Significant differences were observed in the electronic structures and simulated X-ray spectra after hydrogenation. Simultaneously, both X-ray photoelectron and NEXAFS spectra reflected conspicuous isomer dependence, indicating that the "fingerprints" in the X-ray spectra can offer an effective method for identifying the above-mentioned fullerene isomers. The simulated ultraviolet-visible (UV-vis) absorption spectroscopy of C 2v -C66H4(NC) has also been generated by means of the time-dependent DFT method, and the calculations are well consistent with the experimental results. Consequently, this work reveals that X-ray and UV-vis spectroscopy techniques can provide valuable information to help researchers explore the fullerene electronic structure and isomer identification on the future experimental and theoretical fullerene domains.

Molecular structures and magnetic properties of endohedral metallofullerenes

Endohedral metallofullerenes have fascinating core-shell structures, with metal atoms or metal clusters encaged in fullerene cages, and they display various chemical, optical and magnetic properties derived from different types of fullerene cages and metal moieties. Fullerene cages can act as carriers to stabilize unusual cluster moieties. Many bizarre species that are hard to produce via synthetic methods survive well under the protection of a fullerene cage, making metallofullerenes ideal platforms for generating new clusters and bonds. Fullerene cages can also be carriers to hold active unpaired electrons. Some metallofullerenes possess electron spin and show intriguing magnetic properties, making them applicable for use in quantum computing, high density information storage and magnetoreception systems. The exploration of new metallofullerenes is still ongoing, while function-oriented studies are also promoted for the future application of metallofullerenes. Herein, we highlight the recent progress in the synthesis, electron spin characteristics and magnetic properties of metallofullerenes. Discussions and an outlook on the future development of metallofullerenes are also stated.

A non-isolated pentagon rule C82 cage stabilized by a stretched Sc3N cluster

A novel cluster fullerene, Sc3N@Cs(39 663)-C82, has been synthesized and characterized. Crystallograpic charaterization unambiguously determines the non-IPR cage structure of Cs(39 663)-C82. Structural analyses further reveal that the Sc3N cluster is notably stretched to facilitate the interaction with the non-IPR fullerene cage.

The Synthesis of Conical Carbon

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.

Revival of Zeolite-Templated Nanocarbon Materials: Recent Advances in Energy Storage and Conversion

Nanocarbon materials represent one of the hottest topics in physics, chemistry, and materials science. Preparation of nanocarbon materials by zeolite templates has been developing for more than 20 years. In recent years, novel structures and properties of zeolite-templated nanocarbons have been evolving and new applications are emerging in the realm of energy storage and conversion. Here, recent progress of zeolite-templated nanocarbons in advanced synthetic techniques, emerging properties, and novel applications is summarized: i) thanks to the diversity of zeolites, the structures of the corresponding nanocarbons are multitudinous; ii) by various synthetic techniques, novel properties of zeolite-templated nanocarbons can be achieved, such as hierarchical porosity, heteroatom doping, and nanoparticle loading capacity; iii) the applications of zeolite-templated nanocarbons are also evolving from traditional gas/vapor adsorption to advanced energy storage techniques including Li-ion batteries, Li-S batteries, fuel cells, metal-O2 batteries, etc. Finally, a perspective is provided to forecast the future development of zeolite-templated nanocarbon materials.

Strain Release of Fused Pentagons in Fullerene Cages by Chemical Functionalization

According to the isolated pentagon rule (IPR), for stable fullerenes, the 12 pentagons should be isolated from one another by hexagons, otherwise the fused pentagons will result in an increase in the local steric strain of the fullerene cage. However, the successful isolation of more than 100 endohedral and exohedral fullerenes containing fused pentagons over the past 20 years has shown that strain release of fused pentagons in fullerene cages is feasible. Herein, we present a general overview on fused-pentagon-containing (i.e. non-IPR) fullerenes through an exhaustive review of all the types of fused-pentagon-containing fullerenes reported to date. We clarify how the strain of fused pentagons can be released in different manners, and provide an in-depth understanding of the role of fused pentagons in the stability, electronic properties, and chemical reactivity of fullerene cages.

A systematic study on the generation of multimetallic lanthanide fullerene ions by laser ablation mass spectrometry

RATIONALE

Laser ablation masss spectromety has been previously proved to be a powerful tool for studying endohedro metallofullerene (EMF) ions. Our previous study showed the possiblity of forming multi-metallofullerene ions containg more than six metal atoms for La, Y and Lu. Thus, it is important to conduct a systematic study on the generation of multi-metallofullerenes and their distribuitons for all lanthanide elements.

METHODS

Experiments were performed on a 7.0 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Laser ablation mass spectra were obtained by laser irradiation on mixtures of graphene and MCl₃ on a stainless steel plate, applying a 355 nm Nd:YAG laser with a typical energy of 2.5 mJ/pulse. Reaction test experiments were performed by introducing O₂ into the FTICR cell with a pulse valve.

RESULTS

Multi-metallofullerene ions Ce2-4C2m+, Pr2-4C2m+, Gd2-4C2m+, Nd3C2m+, Dy2-3C2m+, Tb2-7C2m+, Ho2-6C2m+ were observed in the mass spectra. For the metals Sm and Eu, no multi-metallofullerene ion was observed. No reaction with O₂ was observed in the reaction experiments, verifying that these species had endohedral structures. For the observed series of multi-metallofullerene ions, tri-metallofullerene ions dominated their mass spectra. The results were further compared with previously generated EMF ions for La, Er, Tm, Yb and Lu.

CONCLUSIONS

Endohedral lanthanide metallofullerene ions were generated by laser ablation of graphene and the corresponding metal salts MCl₃ (M = Ce, Pr, Nd, Gd, Tb, Dy and Ho) and studied with a FTICR mass spectrometer. Typically, multi-metallofullerene ions of TbnC2m+2≤n≤780≤2m≤176 and Ho6C2m+2≤n≤674≤2m≤162 were observed. The results show that the formation of multi-EMF ions containing lanthanides that have +3 and + 4 oxidation states is easier than those containing +2 oxidation states in the process of laser ablation.

Crystalline functionalized endohedral C60 metallofullerides

Endohedral metallofullerenes have been extensively studied since the first experimental observation of La@C60 in a laser-vaporized supersonic beam in 1985. However, most of these studies have focused on metallofullerenes larger than C60 such as (metal)@C82, and there are no reported purified C60-based monomeric metallofullerenes, except for [Li@C60]+(SbCl6)- salt. Pure (metal)@C60 compounds have not been obtained because of their extremely high chemical reactivity. One route to their stabilization is through chemical functionalization. Here we report the isolation, structural determination and electromagnetic properties of functionalized crystalline C60-based metallofullerenes Gd@C60(CF3)5 and La@C60(CF3)5. Synchrotron X-ray single-crystal diffraction reveals that La and Gd atoms are indeed encapsulated in the Ih-C60 fullerene. The HOMO-LUMO gaps of Gd@C60 and La@C60 are significantly widened by an order of magnitude with addition of CF3 groups. Magnetic measurements show the presence of a weak antiferromagnetic coupling in Gd@C60(CF3)3 crystals at low temperatures.

Th-Based Endohedral Metallofullerenes: Anomalous Metal Position and Significant Metal-Cage Covalent Interactions with the Involvement of Th 5f Orbitals

Endohedral metallofullerenes (EMFs) containing actinides are rather intriguing due to potential 5f-orbital participation in the metal-metal or metal-cage bonding. In this work, density functional theory calculations first characterized the structure of recently synthesized ThC₇₄ as Th@ D_{3 h}(14246)-C₇₄. We found that the thorium atom adopts an unusual off-axis position inside cage due to small metal ion size and the requirement of large coordination number, which phenomenon was further extended to other Th-based EMFs. Significantly, besides the strong metal-cage electrostatic attractions, topological and orbital analysis revealed that all the investigated Th-based EMFs exhibit obvious covalent interactions between metal and cage with substantial contribution from the Th 5f orbitals. The encapsulation by fullerenes is thus proposed as a practical pathway toward the f-orbital covalency for thorium. Interestingly, the anomalous internal position of Th led to a novel three-dimensional metal trajectory at elevated temperatures in the D_{3 h}-C₇₄ cavity, as elucidated by the static computations and molecular dynamic simulations.

When metal clusters meet carbon cages: endohedral clusterfullerenes

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.

Formation of C2v-C72(11188)Cl4: A Particularly Stable Non-IPR Fullerene

Halogenation has been one of the most used strategies to explore the reactivity of empty carbon cages. In particular, the higher reactivity of non-IPR fullerenes, i.e., those fullerenes that do not satisfy the isolated pentagon rule (IPR), has been used to functionalize and capture these less stable fullerenes. Here, we have explored the stability of the non-IPR isomer C₇₂(11188) with C_2v symmetry, which is topologically linked to the only IPR isomer of C₇₀, as well as its reactivity to chlorination. DFT calculations and Car-Parrinello molecular dynamics simulations suggest that chlorination takes places initially in nonspecific sites, once carbon cages are formed. When the temperature in the arc reactor decreases sufficiently, Cl atoms are trapped on the fullerene surface, migrating from not-so-favored positions to reach the most favored sites in the pentalene. We have also discussed why cage C_2v-C₇₂(11188) is found to take four chlorines, whereas cage C₁-C₇₄(14049) is observed to capture 10 of them, even though these two fullerenes are closely related by a simple C₂ insertion.

Capturing the Unconventional Metallofullerene M@C66 by Trifluoromethylation: A Theoretical Study

The endohedral metallofullerenes M@C₆₆ (M=rare-earth metal) have a unique structure that violates the well-known "isolated pentagon rule" of fullerene science. Although the synthesis of M@C₆₆ has been achieved by using the arc discharge method, the solvent extraction and purification of M@C₆₆ remain challenges because of their radical character and extremely high reactivity. In this paper, the possibility of capturing these missing metallofullerenes by exohedral functionalization of the C₆₆ cage is demonstrated theoretically. Stable trifluoromethylated derivatives of Y@C₆₆ are revealed by density functional theory calculations. Mono- or poly-trifluoromethylation of Y@C₆₆ results in a closed-shell electronic configuration and a large band gap. Thus Y@C₆₆ can be greatly stabilized through trifluoromethylation. The trifluoromethyl group prefers to be attached to the fused pentagon region to relieve local steric strain. The mechanism of isomerization of Y@C₆₆ (CF₃ )₃ is also investigated and it is found that the attached trifluoromethyl group can migrate from a carbon atom to another via a transition state.

Transformation of doped graphite into cluster-encapsulated fullerene cages

An ultimate goal in carbon nanoscience is to decipher formation mechanisms of highly ordered systems. Here, we disclose chemical processes that result in formation of high-symmetry clusterfullerenes, which attract interest for use in applications that span biomedicine to molecular electronics. The conversion of doped graphite into a C₈₀ cage is shown to occur through bottom-up self-assembly reactions. Unlike conventional forms of fullerene, the iconic Buckminsterfullerene cage, I_h-C₆₀, is entirely avoided in the bottom-up formation mechanism to afford synthesis of group 3-based metallic nitride clusterfullerenes. The effects of structural motifs and cluster–cage interactions on formation of compounds in the solvent-extractable C₇₀–C₁₀₀ region are determined by in situ studies of defined clusterfullerenes under typical synthetic conditions. This work establishes the molecular origin and mechanism that underlie formation of unique carbon cage materials, which may be used as a benchmark to guide future nanocarbon explorations.

An understanding of how caged carbon materials self-assemble from doped graphite is a long-standing challenge. Here, the authors show that distinct bottom-up processes lead to the synthesis of high-symmetry clusterfullerenes.

A Cu-atom-chain current channel with a width of approximately 0.246 nm on (5, 0) single-wall carbon nanotube

Continuous miniaturization with improved performance has enabled the development of electronic devices. However, further shrinking of electronic circuits will push feature sizes (linewidths) firmly into the nanoscale. This can cause electronic devices built using current materials (silicon-based) and fabrication processes to not work as expected. Therefore, new materials or preparation technologies are needed for the further miniaturization of electron devices. Here, through theoretical simulation, we show that regular doping of a Cu-atom chain on a single-wall carbon nanotube (SWCNT) can be used to realize an atomic-scale current channel (Cu-atom-chain current channel) with a linewidth of approximately 0.246 nm. Moreover, the atomic-scale Cu-atom-chain current channel shows enhanced conductivity (lower power consumption) compared to a pristine SWCNT. Such a Cu-atom-chain current channel with an atomic-scale linewidth and its method of fabrication (regular doping) may be suitable for the preparation of nanoelectronic devices.

High-throughput powder diffraction measurement system consisting of multiple MYTHEN detectors at beamline BL02B2 of SPring-8

In this study, we developed a user-friendly automatic powder diffraction measurement system for Debye-Scherrer geometry using a capillary sample at beamline BL02B2 of SPring-8. The measurement system consists of six one-dimensional solid-state (MYTHEN) detectors, a compact auto-sampler, wide-range temperature control systems, and a gas handling system. This system enables to do the automatic measurement of temperature dependence of the diffraction patterns for multiple samples. We introduced two measurement modes in the MYTHEN system and developed new attachments for the sample environment such as a gas handling system. The measurement modes and the attachments can offer in situ and/or time-resolved measurements in an extended temperature range between 25 K and 1473 K and various gas atmospheres and pressures. The results of the commissioning and performance measurements using reference materials (NIST CeO₂ 674b and Si 640c), V₂O₃ and Ti₂O₃, and a nanoporous coordination polymer are presented.

Dimetallofullerene M2@C100 or carbide cluster fullerene M2C2@C98 (M = La, Y, and Sc): which ones are more stable?

The geometric and thermodynamic stability of the M₂C₁₀₀ (M = La, Y, and Sc) series was systematically investigated using density functional theory calculations on the level of B3LYP/6-31G(d) ∼ Lanl2dz.

Size-dependence of carbon nanotube confinement in catalysis

An increasing number of studies have demonstrated that confinement within carbon nanotubes (CNTs) provides an effective approach for the modulation of catalysis. It was generally predicted that confinement became stronger with a decreasing diameter of CNTs. However, our present study here overturns the previous expectation: the influence on catalysis is not monotonic. Instead, it exhibits a volcano relationship with CNT diameter. Taking Pt catalyzing O2 conversion and Re catalyzing N2 conversion as probes using density functional theory, we show that only within tubes with an i.d. of ∼1 nm can the activity of metal clusters be enhanced to its maximum. Furthermore, confinement only enhances the catalytic activity of metals with strong intrinsic binding with reactants, whereas it is suppressed for those with weak binding. These findings shed further light on the fundamental effects of confinement on catalysis, and could guide more rational design of confined catalysts.

Another big discovery-metallofullerenes

Several days after the first experimental observation of the 'magic number' soccerball-shaped C60 in a laser-vaporized cluster beam mass spectrum by Kroto and co-workers (Heath et al 1985 J. Am. Chem. Soc. 107, 7779-7780. (doi:10.1021/ja00311a102)) they also found a magic number feature owing to La@C60 in a mass spectrum prepared by laser vaporization of a LaCl3-impregnated graphite rod. With the advent of macroscopic synthesis and the following successful separation and purification of metallofullerenes, both experimental and theoretical studies of metallofullerenes have developed quite rapidly to date so as to elucidate their structural, electronic, magnetic and transport properties. Furthermore, a bottom-up closed network growth mechanism has experimentally been shown to play a crucial role in generating various types of metallofullerenes.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'.

The inner-induced effects of YCN in C76 on the structures and nonlinear optical properties

Very recently, an unprecedented novel monometallic cluster of fullerenes entrapping a yttrium cyanide (YCN) cluster inside a popular C82 cage YCN@Cs(6)-C82 was synthesized and characterized. Inspired by this investigation, four non-IPR YCN@C1(17459)-C76, YCN@C2v(19138)-C76, YCN@C2(17646)-C76, and YCN@C1(17894)-C76 (1, 2, 3, and 4) containing a pair of adjacent pentagons are designed to explore the encapsulated molecular effect on their interaction energies and nonlinear optical properties. The interaction energy (E int) values of 1, 2, 3, and 4 are -481.35 (1), -477.91 (2), -482.04 (3), -482.69 (4) kcal mol(-1), respectively, which shows that the E int value of 4 is the largest. Furthermore, the electron-transfer is mainly from the YCN to C76 cage. When YCN is encapsulated into C76 cage, we can find that the α0 values of the four molecules are very close, ranging from 6.50 × 10(2) to 6.65 × 10(2) au. Significantly, the first hyperpolarizabilities are in relation to the encapsulated molecular: 1.63 × 10(3) (1) > 8.03 × 10(2) (2) > 7.76 × 10(2) (4) > 4.86 × 10(2) au (3), the results show that the βtot value of 1 is the largest. Besides this, the encapsulation of the YCN to C76 cage brings some distinctive changes in its UV-vis spectra along with its other electronic properties that might be used by the experimentalists to develop the potential nonlinear optical nanomaterials based on endohedral metallofullerenes.

Structural interconnections and the role of heptagonal rings in endohedral trimetallic nitride template fullerenes

Recent experiments indicate that fullerene isomers outside the classical definition can also encapsulate metallic atoms or clusters to form endohedral metallofullerenes. Our systematic study using DFT calculations, suggests that many heptagon-including nonclassical trimetallic nitride template fullerenes are similar in stability to their classical counterparts, and that conversion between low-energy nonclassical and classical parent cages via Endo-Kroto insertion/extrusion of C2 units and Stone-Wales isomerization may facilitate the formation of endohedral trimetallic nitride fullerenes. Close structural connections are found between favored isomers of trimetallic nitride template fullerenes from C78 to C82 . It appears that the lower symmetry and local deformations associated with introduction of a heptagonal ring favor encapsulation of intrinsically less symmetrical mixed metal nitride clusters. © 2016 Wiley Periodicals, Inc.

Theoretical study of the structures and first hyperpolarizabilities of C60Cl n and Li@C60Cl n (n = 4, 6, 8, 10)

We recently reported (Song Y-D et al., 2016, J Mol Model 22:50) that doping with Li greatly affects the static first hyperpolarizability of C60Cl2. In this work, with a view to creating nonlinear optical materials with high thermodynamic stability and wide transparent regions, a series of Li@C60Cl n (n = 4, 6, 8, 10) were designed. The structures, electrostatic potentials, electronic structures, absorption spectra, and linear and nonlinear optical properties of C60Cl n and Li@C60Cl n were systematically investigated using density functional theory (DFT) methods. The results of our calculations indicated that the stability of these molecules decreases in the order Li@C60Cl10 > Li@C60Cl8 > Li@C60Cl6 > Li@C60Cl4. It is clear that the number of Cl atoms greatly influences the stability of Li@C60Cl n . Li@C60Cl n showed greater thermodynamic stability than Li@C60Cl2. We also investigated the first hyperpolarizabilities of Li@C60Cl n and found them to be 2973, 3640, 4307, and 2627 au for n = 4, 6, 8, and 10, respectively-higher than that of Li@C60Cl2. Finally, we noted that the transparent region could be modulated by increasing the number of Cl atoms: Li@C60Cl n possess wider transparent regions than that of Li@C60Cl2. We therefore believe that this study has highlighted an effective method for designing nonlinear optical materials with high thermodynamic stability and wide transparent regions.

Tunable electronic and magnetic properties of two-dimensional materials and their one-dimensional derivatives

Low‐dimensional materials exhibit many exceptional properties and functionalities which can be efficiently tuned by externally applied force or fields. Here we review the current status of research on tuning the electronic and magnetic properties of low‐dimensional carbon, boron nitride, metal‐dichalcogenides, phosphorene nanomaterials by applied engineering strain, external electric field and interaction with substrates, etc, with particular focus on the progress of computational methods and studies. We highlight the similarities and differences of the property modulation among one‐ and two‐dimensional nanomaterials. Recent breakthroughs in experimental demonstration of the tunable functionalities in typical nanostructures are also presented. Finally, prospective and challenges for applying the tunable properties into functional devices are discussed. WIREs Comput Mol Sci 2016, 6:324–350. doi: 10.1002/wcms.1251

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Conflict of interest: The authors have declared no conflicts of interest for this article.

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