In this work, the nonradiative relaxation of excited states in C20, C60, C70, C76, C84, C86, and C90 fullerenes is studied using a nonadiabatic molecular dynamics approach. In qualitative agreement with prior experimental findings, we find that the relaxation rates decrease with an increase in the size of the fullerenes despite the increased densities of excited electronic states and nonadiabatic couplings. We rationalize this trend by coherent population distribution over the dense manifold of electronic excited states facilitated by strong nonadiabatic couplings and small energy gaps between such states. The spreading out of the quantum population over multiple states is quantified by the Shannon entropy, which shows the initial growth consistent with the initial ultrafast coherent transfer. We observe that overall energy relaxation times correlate with the rate of the Shannon entropy decay in the longer time limit. This work suggests the emergence of effective electronic friction in dense manifolds of electronic states as a consequence of the correlation of its enhanced coherent dynamics with the dynamics of electronic Shannon entropy as a practical metric for state diffusion in nonadiabatic dynamics.

Abstract Elastomeric materials play crucial roles in complex electromechanical systems. However, their inadequate tribological performance under demanding operating conditions often leads to premature failure. This study introduces a multiscale synergistic design concept that introduces fullerene (FLN) and graphene (G) as hybrid fillers within an elastomer matrix, aimed at developing a high-performance elastomeric composite. The FLN/G composite elastomer test blocks were prepared by compounding and thermal vulcanization. Their microstructures, chemical compositions, and tribological properties were systematically characterized over a temperature range of 35 °C to 55 °C. The characterization results revealed that FLN exhibits a nanospherical structure, while G possesses a wrinkled two-dimensional sheet structure. Both materials feature surfaces rich in oxygen-containing functional groups, which significantly enhance their interfacial compatibility with the matrix. Tribological tests demonstrated that, compared to unmodified elastomers and single-filler systems, the FLN/G composite exhibited the lowest friction coefficient and wear volume at both temperatures, indicative of a pronounced synergistic effect. Microscopic morphology analysis of the worn surfaces revealed that the performance enhancement originates from a synergistic “rolling-shielding” lubrication mechanism, facilitated by the “micro-bearing” rolling effect of FLN alongside the sheet shielding and load-bearing effects of G. This study provides a novel design strategy and theoretical foundation for the development of a new generation of high-performance, long-life elastomeric sealing materials.

Highly-symmetric molecules often exhibit degenerate tight-binding states at the Fermi edge. This typically results in a magnetic ground state if small interactions are introduced in accordance with Hund’s rule. In some cases, Hund’s rule may be broken, which signals pair binding and goes hand-in-hand with an attractive pair-binding energy. We investigate pair binding and Hund’s rule breaking for the Hubbard model on high-symmetry fullerenes C _{20} 20 , C _{20} 20 , C _{40} 40 , and C _{60} 60 by using large-scale density-matrix renormalization group calculations. We exploit the SU(2) spin symmetry, the U(1) charge symmetry, and optionally the \mathbb{Z}_N ℤ N spatial rotation symmetry of the problem. For C _{20} 20 , our results agree well with available exact-diagonalization data, but our approach is numerically much cheaper. We find a Mott transition at U_c\sim2.2t U c ∼ 2.2 t , which is much smaller than the previously reported value of U_c\sim4.1t U c ∼ 4.1 t that was extrapolated from a few datapoints. We compute the pair-binding energy for arbitrary values of U U and observe that it remains overall repulsive. For larger fullerenes, we are not able to evaluate the pair binding energy with sufficient precision, but we can still investigate Hund’s rule breaking. For C _{28} 28 , we find that Hund’s rule is fulfilled with a magnetic spin-2 ground state that transitions to a spin-1 state at U_{c,1}\sim 5.4t U c , 1 ∼ 5.4 t before the eventual Mott transition to a spin singlet takes place at U_{c,2}\sim 11.6t U c , 2 ∼ 11.6 t . For C _{40} 40 , Hund’s rule is broken in the singlet ground state at half filling, but is restored if the system is doped with one electron. Hund’s rule is also broken for C _{60} 60 , and the doping with two or three electrons results in a minimum-spin state. Our results are consistent with an electronic mechanism of superconductivity for C _{60} 60 lattices. We speculate that the high geometric frustration of small fullerenes is detrimental to pair binding.

Fullerene molecules, a class of allotropic carbon nanomaterials, were investigated for their potential to inhibit SARS-CoV-2 by targeting its spike glycoprotein through molecular docking simulations. Both blind and targeted docking methods were employed to evaluate interactions between various fullerene sizes (C20, C28, C60, C78, C84) and the spike glycoprotein. In the blind docking method, with the exception of C84, all fullerene interactions are distributed over the entire surface of the spike glycoprotein. In the targeted docking method, C78 and C84 interactions are closer to the actual binding sites of angiotensin-converting enzyme 2 (ACE2) on the spike glycoprotein. The most negative binding affinity value was found for fullerene C84, with a value of -15.9 kcal/mol, primarily via hydrophobic interactions. Binding affinity correlated positively with fullerene size; larger fullerenes demonstrated a greater capacity to obstruct the ACE2 binding site. Smaller fullerenes (C20, C28) were ineffective, binding at unrelated regions. C60 showed moderate potential, with 85% of its binding occurring at the ACE2 site. In contrast, C78 and C84 exhibited 100% of their docking directly at the ACE2 binding site, indicating stronger inhibition potential. These findings underscore the significance of fullerene size in enhancing spike protein interaction and suggest that larger fullerenes, especially C84, may serve as promising candidates for SARS-CoV-2 entry inhibition.

A systematic analysis for the determination of the optimum fullerene cage for encapsulation of xenon dimers was carried out using density functional theory and activation strain analysis. Our calculations indicate that tubular-like fullerenes are better candidates for the encapsulation of xenon atoms. However, the tubular-like structure should have at least a diameter that is proportional to the van der Waals radius of encapsulated atoms. Our calculations indicate that the smallest fullerene that can stabilize the encapsulation of the xenon dimers in an energetically favorable dimeric state is Xe2@C120 ([10,0] C120-D5h(10766)). When going to higher order fullerenes, the dispersion interaction will dominate over all other interactions. However, the additional space provided by the tubular-like fullerene leads to elongation of the distance between the encapsulated xenon atoms, thus hampering the formation of a xenon-xenon chemical bond.

1-Organo-4-(4'-tetrafluoropyridyl)[60]fullerenes have been developed as an efficient organic fullerene ligand for site-selective η2-coordination with platinum and palladium. Experimental results and theoretical calculations indicate that the tetrafluoropyridine groups in the 1,4-asymmetrically modified structure of C60 play a crucial role in regulating site selectivity. Furthermore, a one-pot, highly site-selective trifunctionalization of C60 with indole, pentafluoropyridine, and M(PPh3)4 (M = Pt, Pd) has been successfully achieved.

This study examines the structural complexity of fullerene graphs using Hosoya entropy as a measure. The entropy values were calculated for various fullerene structures, including F3,1s,F4,2s and fullerenes ranging from C20 to C100.The relationship between the size of the fullerenes and the entropy is intuitively clear: the larger the fullerenes, the higher the value of entropy because of increased structural complexity and diversity of equivalence classes. Smaller fullerenes, like C20, have lower entropy, a consequence of their simpler and more symmetrical molecular structure. These findings provide theoretical insights into structural intricacies of fullerenes and their possible applications in material science and nanotechnology.

In this paper, the stability, geometric and electronic properties of boron doped small fullerenes C20, C24, C28 were investigated using density functional theory (DFT) methods. Average bonds lengths were calculated and the stability of optimized structures was estimated. An analysis of one-electron spectra and the density of states (DOS) allowed us to define the mechanisms for the change in the band gap and to determine the dependence of this parameter on the concentration of boron atoms. The established dependence of the band gap on the concentration of impurity atoms suggests the possibility of controlling the refractive index of the considered nanomaterials by doping with different concentrations of boron atoms, which indicates the applicability of such an approach to the construction of heterostructures in general and photonic crystals in particular. The obtained results can be useful for the fabrication of the novel optoelectronic devices which are used in infocommunication systems for the manipulating and transformation of optical signals.

This study investigates the encapsulation of the F- anion within fullerene and silsesquioxane (POSS) cage frameworks, using both Intermolecular Quantum Analysis (IQA) and Quantum Theory of Atoms in Molecules (QTAIM) at the DFT level of theory to analyze the effects of the F- presence on cage stability, as well as the nature of its interactions with the given framework. A detailed understanding of the energetic and electronic consequences of F- encapsulation is necessary to inform future design strategies for molecular encapsulation and ion stabilization in these and similar cage systems. The results suggest that the interaction between F- and the cage highly depends on steric and electronic factors; encapsulation generally destabilizes the cage, although certain systems show stabilization due to favorable interatomic interactions, as indicated by IQA analysis. The ion itself is stabilized in most systems, with POSS showing a significantly stronger stabilization than fullerenes. QTAIM analysis at bond critical points (BCPs) and cage critical points (CCPs) highlights the nature of the interactions, with electrostatic forces and charge redistribution being the primary stabilizing factors. The overall balance and stability of the F--cage complexes seem to be governed by the delicate interplay between steric compression and electrostatic interactions.

The investigation of non-IPR (isolated pentagon rule) fullerenes is limited to theoretical studies since there is simply no or very little sample available that allows investigating these compounds. The discovery of fullerenes in crude oil provided a suitable sample system. The information that might be gathered about these non-IPR fullerenes can be useful for developing synthetic routes and study their properties for potential future applications. Investigations using high-resolution mass spectrometry (HRMS) were conducted to understand the stability of these fullerenes. The experimental results are supported by density-functional-theory (DFT) calculations. The outcome of HRMS and DFT provided results on relative quantity, stability and basic mechanistic fragmentation information. The results showed that non-IPR fullerenes were present in higher abundances than the most stable C 60 - buckminsterfullerene . The investigation of C 30 to C 44 indicates C 32 and C 36 to be the most stable congeners, which is in accordance with the existing theory. The mechanism of fragmentation is, in general, marked by the loss of C 2 and a subsequent Stone-Wales-transformation into an energetically more stable isomer. The fragmentation behavior differs with size as the smaller fullerenes disintegrate easier instead of losing C 2 -units. This study shows that crude oil makes up a very useful sample system for the investigation of non-IPR fullerenes.

Encapsulations of carbon dioxide into D2(22)-C84 and D2d(23)-C84 fullerenes are evaluated. The encapsulation energy is computed with the DFT M06-2X/6-31+G* approach corrected for the basis set superposition error evaluated by the counterpoise method. The resulting encapsulation energy for CO2@D2(22)-C84 and CO2@D2d(23)-C84 amounts to substantial values of −14.5 and −13.9 kcal/mol, respectively. The energy gain is slightly larger than for CO@C60, already synthesized with a high-temperature and high-pressure treatment—so that a similar preparation of CO2@C84 could be possible. The calculated rotational constants and IR vibrational spectra are presented for possible use in detection. The stability of (CO2)2@C84 is also briefly discussed.

The size matching between the internal cluster and the outer cage is widely used to explain the former's configuration in endohedral clusterfullerenes (ECFs). For example, the trimetallic nitride (M3N) clusters within smaller fullerenes are expected to become more relaxed in larger ones due to the weak cage confinement. However, recent single-crystal X-ray diffraction (SCXRD) experiments reveal that, although being planar in C80, the Sc3N cluster exhibits an abnormal pyramidal shape in Cs(51365)-C84 and D3(19)-C86. This phenomenon can be explained by the "spider effect," which occurs when a small cluster meets a large cage. Herein, to further solve this puzzle and deeply understand the internal cluster configurations of ECFs, density functional theory calculations were conducted for nine SCXRD-characterized Sc3N@C2n (2n = 68, 70, 78-86) nitride clusterfullerenes. After successfully reproducing their structural characteristics, we found that all their cluster configurations can be rationalized by the electrostatic potentials (ESPs) inside the corresponding C2n6- anionic empty cages. These cage anions exhibit rather different ESP distributions, and the intramolecular host-guest electrostatic interactions drive the three Sc3+ cations toward the more negative region and the central N3- anion toward the less negative one, thus resulting in a planar or slightly pyramidal shape of the whole (Sc3N)6+ unit. Moreover, besides these nitride ECFs, ESPs can explain the internal cluster configurations of other types of ECFs as well. Different from the conventional viewpoint, which focuses only on the cluster and cage sizes, our work uncovers the overlooked role of ESPs in affecting the cluster configurations besides the most important metal-cage interactions. Based on this finding, we further demonstrated that one could easily regulate the internal cluster shape by changing the ESPs.

We consider a water molecule under tight confinement in the small-sized fullerenes (C , C , C ) within the density functional theory (DFT) calculations with suitable exchange-correlation functionals. Such nanoscopic molecular cages provide an ideal setup to study their characteristic properties not present in the condensed phase. The water molecule entirely loses its feature of typical water when it is confined in small fullerenes of size equal to C or smaller, in which the asymmetric O-H stretching vibration occurs at a lower wavenumber than the symmetric stretching. We study the response of the confined water molecule to the applied electric fields in terms of change in geometrical parameters, NMR spin-spin coupling constants, dipole moment, HOMO-LUMO (HL) gap, and vibrational frequency shift. The electric field shielding property of small-sized fullerene cages is explored and found to be strongly correlated with the HL gap. Since the electric field modulates the gap to decrease generally, shielding efficiency varies with field strength, thereby making large fields better shielded than small fields for the small penetration factor at large fields. The results that hold significance for technological applications are discussed.

Fullerene whiskers (FLW)s are thin rod-like structures composed of C60 and C70 fullerene (FL). The shape of FLWs suggests potential toxic effects including carcinogenicity to the lung and pleura, similar to effects elicited by asbestos and multi-walled carbon nanotubes (MWCNT)s. However, no long-term carcinogenic studies of FL or FLW have been conducted. In the present study we investigated the pulmonary and pleural carcinogenicity of FL and FLW. Twelve-week-old male F344 rats were administered 0.25 or 0.5 mg FL, FLW, MWCNT-7, and MWCNT-N by intra-tracheal intra-pulmonary spraying (TIPS). Acute lung lesions and carcinogenicity were analyzed at 1 and 104 weeks after 8 doses/15 days TIPS administration. At week 1, FLW, MWCNT-7, and MWCNT-N significantly increased alveolar macrophage infiltration. Expression of Ccl2 and Ccl3, reactive oxygen species production, and cell proliferation were significantly increased by administration of MWCNT-7 and MWCNT-N but not FL or FLW. At week 104, the incidence of bronchiolo-alveolar adenoma plus adenocarcinoma was significantly increased in the MWCNT-7 and MWCNT-N groups, and the incidence of mesothelioma was significantly increased in the MWCNT-7 group. No significant induction of pulmonary or pleural tumorigenesis was observed in the FL or FLW groups. The number of 8-OHdG-positive cells in the alveolar epithelium was significantly increased in the MWCNT-7 and MWCNT-N groups but not in the FL or FLW groups. FL and FLW did not exert pulmonary or pleural carcinogenicity in our study. In addition, oxidative DNA damage was implicated in MWCNT-induced lung carcinogenesis, suggesting that it may be a useful initial marker of carcinogenicity.

Which fits better?. Centered and non-Centered coordination modes of small endohedral Fullerenes, insights from Ti@C28 and Zr@C28

Abstract For the first time, dedicated stretching bond force constant (kr), and bulk modulus () of small boron nitride fullerenes (BNFLs) or BxNx cages (x = 12, 16, 20, 24, and 36) are determined using density functional theory (DFT). The results indicate that for the set of selected BNFLs, their kr and values are found to be within the ranges 5.139–5.738 mdyn Å−1 and 0.645–1.217 TPa respectively. The behavior of the mechanical properties of BNFLs shows that kr values increase for larger BNFLs, whereas the predicted values increase with decreased BNFL diameters. It is notable to find that some values for these properties are found with magnitudes greater than those reported for some carbon nanostructures. The kr and values predicted by DFT can be used as an input for structural models to describe the elastic behavior of BNFLs, contributing to the understanding of the mechanical properties of BNFLs and potentiating their applications in various areas of nanotechnology.

Preparation of fullerene-containing nanocomposite materials based on high-density polyethylene via environmental crazing and their performance

The Superatom Molecular Orbitals (SAMO) in fullerene derivatives are of great interests which gives a wide basement for many electronic applications. In this work, the Density Functional Theory reveals the SAMO states of endohedrally doped C80 derivatives with Li, Sc, Mn, Ti, Ca, Fe, and Co atoms in molecular and periodic structures. The choice and position of metal atoms in endohedrally doped C80 derivatives largely affects the orientation of SAMO energies and wavefunction distributions. Among various derivatives, the Co-substituted C80 constitutes the lowest SAMO energy. The charge transfer study infers the influence of metal atoms inside the cage on SAMO energies. At higher energies, pz-, 2s-, and pxy- SAMO bands have been overlapped with higher dispersion bands which depict the increased intermolecular interaction in delocalized bands causing a larger dispersion. These results give new insights for future studies on lowering SAMO energy nearly to the fermi level in higher fullerenes.

Host-guest dynamics in porous trimesic acid supramolecular network on graphene. Outstanding stability of the coronene guest

A detailed understanding of how molecules interact with two-dimensional materials, particularly concerning energy level alignment and charge transfer processes, is essential to incorporate functional molecular films into next-generation 2D material-organic hybrid devices. One of the major challenges in integrating molecular films in field-effect transistors is facilitating ambipolar charge transport, which is often hindered by the large electronic gap of the organic layers. This work compares the adsorption site-dependent energy level alignment of C60, C70, and C84 fullerenes induced by the spatial variation of the electrostatic surface potential of the h-BN/Rh(111) Moiré superstructure. As the size of the fullerenes increases, the HOMO-LUMO gap shrinks. In the case of C84, we find an intrinsic charge transfer from the substrate to the fullerenes adsorbed in the Moiré pore centers, rendering them negatively charged. The electric field effect-induced charging of neutral fullerenes and discharging of intrinsically negatively charged fullerenes are investigated using scanning tunneling spectroscopy, non-contact atomic force microscopy, and Kelvin probe force spectroscopy. Our findings show that on metal-supported h-BN, the LUMO level of C84 is sufficiently close to the Fermi energy that it can be neutral or 1e− negatively charged depending on slight variations of the electrostatic potential. The findings propose a path to make ambipolar charge transfer accessible and efficient by circumventing the need to overcome the fullerenes’ electronic gap.