Search

CH 4 @C 60 was the first example within which an organic molecule has been embedded in C 60 . CH 4 can rotate freely in the molecular cage, and the carbon skeleton structure of the C 60 has no obvious deformation. The electronic structure of CH 4 @C 60 and interaction between C 60 and CH 4 were studied under quantum mechanical calculation method. The different reaction sites on C-C bonds in C 60 and the weak Van der Waals interaction between CH 4 and C 60 were shown clearly. These results and the orbital interaction between CH 4 and C 60 were helpful for understanding and further application of this unique biggest organic molecule CH 4 contained in C 60 structure so far., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Molecular junctions are a versatile test bed for investigating nanoscale thermoelectricity and contribute to the design of new cost-effective environmentally friendly organic thermoelectric materials. It was suggested that transport resonances associated with discrete molecular levels could play a key role in thermoelectric performance, but no direct experimental evidence has been reported. Here we study single-molecule junctions of the endohedral fullerene Sc3N@C80 connected to gold electrodes using a scanning tunnelling microscope. We find that the magnitude and sign of the thermopower depend strongly on the orientation of the molecule and on applied pressure. Our calculations show that Sc3N inside the fullerene cage creates a sharp resonance near the Fermi level, whose energetic location, and hence the thermopower, can be tuned by applying pressure. These results reveal that Sc3N@C80 is a bi-thermoelectric material, exhibiting both positive and negative thermopower, and provide an unambiguous demonstration of the importance of transport resonances in molecular junctions.

Paramagnetic endohedral fullerenes and phthalocyanine (Pc) complexes are promising building blocks for molecular quantum information processing, for which tunable dipolar coupling is required. We have linked these two spin qubit candidates together and characterized the resulting electron paramagnetic resonance properties, including the spin dipolar coupling between the fullerene spin and the copper spin. Having interpreted the distance-dependent coupling strength quantitatively and further discussed the antiferromagnetic aggregation effect of the CuPc moieties, we demonstrate two ways of tuning the dipolar coupling in such dyad systems: changing the spacer group and adjusting the solution concentration.

The orientation of different N-substituted [N@C60]fulleropyrrolidine derivatives hosted in a nematic liquid crystal matrix has been studied by electron spin resonance spectroscopy. In this study, variations on the zero field splitting parameter of the guest species are employed as a means of determining their degree of orientation. Fulleropyrrolidines with more rigid N-substituents are preferentially oriented in the liquid crystal matrix, whereas those with less rigid substituents are almost randomly distributed. Additionally, the orientation of a C60 fullerene cage bearing a nitroxide radical has also been investigated in comparison.

Dyads of endohedral nitrogen fullerene and porphyrin have been synthesized. In the two-radical-center dyad, the copper(II) tetraphenylporphyrin suppressed the electron spin resonance (ESR) signal of N@C(60) through intramolecular dipolar coupling with a strength of 27.0 MHz. Demetalation of the metalloporphyrin moiety of the dyad, which effectively turned the two-radical-center dyad into a single-radical-center dyad, recovered 82% of the ESR signal of N@C(60). Such mechanism of switching a spin state on and off could find use in molecular spintronics applications., (© 2012 American Chemical Society)

A clear understanding of the interactions between the building blocks of self-assembled molecular materials is essential for rational design of functional nanostructures. Intermolecular interactions have been investigated for three different classes of fullerenes in single-walled carbon nanotubes (SWNTs); van der Waals molecule – molecule and molecule – SWNT interactions control the geometry of the molecular arrays inside nanotubes; electrostatic intermolecular forces influence the alignment of polar endohedral fullerenes M@C82; and hydrogen bonding between functionalised fullerenes has a significant effect on the selectivity of insertion of functionalised fullerenes into SWNTs. [ABSTRACT FROM AUTHOR]

Metallofullerenes are interesting molecules with unique structures and physicochemical properties. After they are formed in the arc-discharge process, they are first buried in the carbon soot, which requires solvent extraction to fish them out, normally followed by HPLC separation. In this minireview, we summarize the main procedures developed to obtain pure metallofullerenes, including well-established extraction with conventional fullerene solvents followed by HPLC (procedure (I) as well as several methods developed for isolation and purification of unstable fullerenes insoluble in conventional fullerene solvents, including chemical modification followed by dissolution (II.1), chemical functionalization during extraction followed by HPLC (II.2), and chemical functionalization of ionic EMFs after redox-extraction followed by HPLC (procedure II.3). The main focus here is on procedure II.3, for which the current status and future perspective are discussed. [ABSTRACT FROM AUTHOR]

The interaction of fullerenes and their derivatives with environmental molecules such as oxygen or water was crucial for the rational design of low-dimensional materials and devices. In this paper, the near-edge X-ray absorption fine structure (NEXAFS), X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy (XPS) shake-up satellites were employed to distinguish the oxides and hydrates of the fullerene C60 and azafullerene C59N families. The study includes various isomers, such as the open [5,6] and closed [6,6] isomers of C60O, C60H(OH), C60-O-C60, C60H-O-C60H, C59N(OH) and C59N-O-C59N, based on density functional theory. These soft X-ray spectra offered comprehensive insights into the molecular orbitals of these azafullerene molecular groups. The oxygen K-edge NEXAFS, carbon and oxygen K-edge XPS shake-up satellite spectra provided valuable tools for distinguishing oxides or hydrates of fullerene C60 and azafullerene C59N. Our findings could significantly benefit the development of fullerene functional molecular materials and expand the application scope of soft X-ray spectroscopy as a molecular fingerprinting tool for the fullerene family. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The experimental investigation of rare‐earth metal‐metal bonds remains a challenge in the study of chemical bonds. Herein, we report the synthesis and characterization of a novel heteronuclear di‐metallofullerene, ScY@C3v(8)‐C82, which contains a mixed rare‐earth metal‐metal bond. ScY@C3v(8)‐C82 was successfully synthesized by arc‐discharging method and characterized by mass spectrometry, UV‐vis‐NIR spectroscopy and single‐crystal X‐ray diffraction crystallography, which unambiguously determined its molecular structure. Theoretical calculations were also performed to study the optimized positions of Sc‐Y metallic dimer and the electronic configuration. The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C3v(8)‐C82 cage, i.e., (ScY)4+@(C3v(8)‐C82)4–. In particular, a covalent Sc‐Y σ2 bond, which has never been reported before, is proven to be formed inside C3v(8)‐C82 fullerene cage. This work presents a novel di‐metallofullerene containing mixed rare‐earth metal‐metal bond and expands the understanding of metal‐metal bonding of rare earth elements. [ABSTRACT FROM AUTHOR]

We report the formation of an interconnected, three-dimensional, mesoporous polymeric fullerene oxide framework via thermal [3 + 2] cyclo-additions of monomeric C60 and fullerene oxides (C60On), formed upon thermal decomposition of C60Br24, causing the eliminations of bromine atoms in an oxygen atmosphere at an elevated temperature of 200 °C. The newly formed mesoporous fullerene oxide framework is found to be a low bandgap semiconductor capable of acting as a photocatalyst similar to graphitic C3N4. The sunlight-assisted photocatalytic degradation of the methylene blue dye is demonstrated. To have a better understanding of the mechanism of the [3 + 2] cyclo-additions of monomeric C60 and fullerene oxides, a theoretical investigation has been carried out and the energetics of the reaction C60O + C60 → C120O is calculated. [ABSTRACT FROM AUTHOR]

Polarizability exaltation is typical for (C60)n nanostructures. It relates to the ratio between the mean polarizabilities of (C60)n and C60: the first one is higher than the n-fold mean polarizability of the original fullerene. This phenomenon is used in the design of novel fullerene compounds and the understanding of its properties but still has no chemical rationalization. In the present work, we studied the distributed polarizability of (C60)2 and isomeric (C60)3 nanoaggregates with the density functional theory method. We found that polarizability exaltation increases with the size of the nanostructure and originates from the response of the sp2-hybridized carbon atoms to the external electric field. The highest contributions to the dipole polarizability of (C60)2 and (C60)3 come from the most remote atoms of the marginal fullerene cores. The sp3-hybridized carbon atoms of cyclobutane bridges negligibly contribute to the molecular property. A similar major contribution to the molecular polarizability from the marginal atoms is observed for related carbon nanostructures isomeric to (C60)2 (tubular fullerene and nanopeanut). Additionally, we discuss the analogy between the polarizability exaltation of covalently bonded (C60)n and the increase in the polarizability found in experiments on fullerene nanoclusters/films as compared with the isolated molecules. [ABSTRACT FROM AUTHOR]

Encapsulation of atoms or small molecules inside fullerenes provides a unique opportunity for study of the confined species in the isolated cavity, and the synthesis of closed C60 or C70 fullerenes with enclosed atoms or molecules has recently developed using the method of 'molecular surgery'; in which an open-cage intermediate fullerene is the host for encapsulation of a guest species, before repair of the cage opening. In this work we review the main methods for cage-opening and closure, and the achievements of molecular surgery to date. 'Molecular surgery' is a useful method through which to create endohedral fullerenes that aren't accessible by conventional physical methods of trapping small atoms and molecules. Here, the authors review the organic chemistry behind molecular surgery, describing the methods to access open-cage intermediates alongside the cage-closing chemistry. [ABSTRACT FROM AUTHOR]

The study of isolated atoms or molecules inside a fullerene cavity provides a unique environment. It is likely to control the outer carbon cage and study the isolated species when molecules or atoms are trapped inside a fullerene. We report the Diels–Alder addition reaction of 9,10-dimethyl anthracene (DMA) to H2@C60 while 1H NMR spectroscopy is utilized to characterize the Diels–Alder reaction of the DMA with the fullerene. Through 1H NMR spectroscopy, a series of isomeric adducts are identified. The obtained peaks are sharp, precise, and straightforward. Moreover, in this paper, H2@C60 and its isomers are described for the first time. [ABSTRACT FROM AUTHOR]

Our previous studies (Shields et al 2020 J. Phys. B: At. Mol. Opt. Phys. 53 125101; Shields et al 2020 Euro. Phys. J. D 74 191) have predicted that the atom-fullerene hybrid photoionization properties for X = Cl, Br and I endohedrally confined in C60 are different before and after an electron transfers from C60 to the halogen. It was further found as a rule that the ionization dynamics is insensitive to the C60 level the electron originates from to produce X âˆ'@ C 60 + . In the current study, we report an exception to this rule in F@C60. It is found that when the electron vacancy is situated in the C60 level that participates in the hybridization in Fâˆ'@ C 60 + , the mixing becomes dramatically large leading to strong modifications in the photoionization of the hybrid levels. This novel effect is fundamentally based on a level-crossing phenomenon driven by the electron transfer in F@C60. But when the vacancy is at any other pure level of C60, the level-invariance is retained showing weak hybridization. Even though this case of F@C60 is an exception in the halogen@C60 series, the phenomenon can be more general and can occur with compounds of other atoms caged in a variety of fullerenes. Possible experimental studies are suggested to benchmark the present results. [ABSTRACT FROM AUTHOR]

The serendipitous discovery of dumb‐bell‐shaped C120 under high‐speed vibration milling conditions is described. The mechanochemical protocol has been employed to synthesize the He‐, H2‐ or H2O‐encapsualted C120, the cross‐dimer C130, trimer C180, bridged C60 dimers as well as products from many other reactions of fullerenes, carbon nanotubes and graphenes. Mechanochemistry extended to various reactions of non‐fullerene molecules is briefly discussed. What is the most favorite and original chemistry developed in your research group? Mechanochemistry and fullerene chemistry. How do you get into this specific field? Could you please share some experiences with our readers? The poor solubility of fullerenes in common organic solvents prompts scientists to seek alternative protocol for fullerene chemistry. An idea of performing chemical reactions of fullerenes in the absence of any organic solvent was conceived when I was a guest research fellow in Kyoto University. That was how I first got into the mechanochemical reactions of fullerenes, and made the serendipitous discovery of fullerene dimer C120. How do you supervise your students? I encourage my graduate students to do scientific research of their own ideas within the scope of my group's research interests. I usually emphasize scientific rigor and intolerance of research misconduct to the graduate students when they first join my group. I provide them my guidance on how to do each piece of scientific work including detailed discussion of encountered problems, even spectral analysis and ChemDraw drawing, manuscript writing, etc. What is the most important personality for scientific research? Curiosity, creativity, and persistence. What are your hobbies? Sports, mainly jogging and running nowadays. How do you keep balance between research and family? My balance has heavily leaned toward work thanks to the understanding and support from my family. [ABSTRACT FROM AUTHOR]

Photoionization calculations of the endofullerene molecule Cl@C60 with an open-shell chlorine atom are performed in the linear response density functional theory based on a spherical jellium model of C60. Cross sections for atom–fullerene hybrid photoemission studied show the effects of the hybridization symmetry, the giant plasmon and the molecular cavity. Comparisons with the results of Ar@C60 provide insights into the role of a shell-closing electron and its influence on the dynamics. The results for Cl@C60 are further compared with those of a more stable configuration that results after a C60 electron transfers to Cl forming Cl−@. This comparison reveals noticeable differences in the ionization properties of the antibonding hybrid state while the bonding hybrid remains nearly unaltered showing a magnification covering the entire giant plasmon energy range. These predictions should raise interest in probing the molecular configuration using photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perfluorophenyl functionalities have been introduced as side chain substituents onto regioregular poly(3-hexyl thiophene) (rr-P3HT), under various percentages. These functional groups were then converted to azides which were used to create polymeric hybrid materials with fullerene species, either C60 or C70. The P3HT-fullerene hybrids thus formed were thereafter evaluated as potential compatibilizers of BHJ active layers comprising P3HT and fullerene based acceptors. Therefore, a systematic investigation of the optical and morphological properties of the purified polymer-fullerene hybrid materials was performed, via different complementary techniques. Additionally, P3HT:PC70BM blends containing various percentages of the herein synthesized hybrid material comprising rr-P3HT and C70 were investigated via Transmission Electron Microscopy (TEM) in an effort to understand the effect of the hybrids as additives on the morphology and nanophase separation of this typically used active layer blend for OPVs. [ABSTRACT FROM AUTHOR]

The reactions of [(μ-H)3Re3(CO)11(NCMe)] with Sc2@C82- C3 v(8), Sc2C2@C80- C2 v(5), Sc2O@C82- Cs(6), C86- C2(17), and C86- Cs(16) have been carried out to produce face-capping cluster complexes. The Re3 triangles are found to bind to the sumanene-type hexagons on the fullerene surface regiospecifically. In contrast, Sc3N@C78- D3 h(5) and Sc3N@C80- Ih show no reactivity toward [(μ-H)3Re3(CO)11(NCMe)], probably due to electronic and steric factors. These complexes can be easily purified by using HPLC. Carbonylation of each complex releases the corresponding higher fullerene or endohedral metallofullerene in pure form. Remarkably, the C86- C2(17) and C86- Cs(16) isomers were successively separated through Re3 cluster complexation/decomplexation. This unique bonding feature may provide an attractive general strategy to purify as yet unresolved fullerene mixtures. [ABSTRACT FROM AUTHOR]

The process of bending empty carbon nanotubes (10,10) and the tube filled by fullerenes C60 was investigated. The polymerization of fullerenes and the chemical interaction between the fullerenes and the tube wall is observed in the tube filled with fullerenes in the bending of 270 degrees. It was found that the minimum angle of the bending, which is required for the polymerization, is equal to 16 degrees. The inside of the nanotube is transformed into a wave-like. We used two methods: the empirical and the quantum–mechanical methods. The simulation until the polymerization of fullerenes is carried out by the empirical method and the polymerization process are modeled by the tight binding method. [ABSTRACT FROM AUTHOR]

In situ low-voltage aberration corrected transmission electron microscopy (TEM) observations of the dynamic entrapment of a C60 molecule in the saddle of a bent double-walled carbon nanotube is presented. The fullerene interaction is non-covalent, suggesting that enhanced π-π interactions (van der Waals forces) are responsible. Classical molecular dynamics calculations confirm that the increased interaction area associated with a buckle is sufficient to trap a fullerene. Moreover, they show hopping behavior in agreement with our experimental observations. Our findings further our understanding of carbon nanostructure interactions, which are important in the rapidly developing field of low-voltage aberration corrected TEM and nano-carbon device fabrication. [Figure not available: see fulltext.] [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules. Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices. TNEFs were discovered in 1999 by Stevenson et al. ; for the first time derivatives of the TNEF acceptor, Lu3N@C80, are synthesized and integrated into OPV devices. The reduced energy offset of the molecular orbitals of Lu3N@C80 to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (Voc) to 260 mV above reference devices made with [6,6]-phenyl-C61-butyric methyl ester (C60-PCBM) acceptor. PCEs >4% have been observed using P3HT as the donor material. This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset. [ABSTRACT FROM AUTHOR]

The structures and electronic properties of nanoscale “peapods,” i.e., C50 fullerenes inside single-walled carbon nanotubes (SWCNTs), were computationally investigated by density functional theory (DFT). Both zigzag and armchair SWCNTs with diameters larger than 1.17 nm can encapsulate C50 fullerenes exothermically. Among the SWCNTs considered, (9,9) and (16,0) SWCNTs are the best sheaths for both D3 and D5h isomers of C50, corresponding to 0.32–0.34 nm tube-C50 distances. The orientation of C50 inside nanotubes also affects the insertion energies, which depend on the actual tube-fullerene distances. The insertion of D3 and D5h isomers of C50 is somewhat selective; the less stable D5h isomer can be encapsulated more favorably inside SWCNTs at same tube-C50 spacing. Because of the weak tube-C50 interaction, the geometric and electronic structures of the peapods do not change greatly for the most stable configurations, but the selectivity in the interwall spacing and isomer encapsulation can be useful in separating various carbon fullerenes and their isomers. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [ABSTRACT FROM AUTHOR]

Abstract: Trimetallic nitride template fullerenes have been deposited onto a variety of substrates in order to elucidate the substrate–fullerene interactions. We have investigated self-assembled island formation and molecular detail of Er3N@C80 and Sc3N@C80 on Ag/Si(111), Au(111)/mica, Si(111), and Si(001) using variable temperature scanning tunnelling microscopy (STM). At room temperature, the fullerenes self-assemble into monolayer-high hexagonal close-packed islands on Ag-passivated Si(111) whereas annealing at elevated temperatures (250–300°C) is necessary for the self-assembly of close-packed islands on Au(111). Intra-molecular resolution of the fullerenes has been achieved at liquid nitrogen temperature on Ag/Si(111) and already at room temperature on Si(001), when the rotation of the fullerenes is frozen. Whereas the bonding between the fullerenes and Si surfaces is mainly covalent, it appears to be mainly van-der-Waals on the other surfaces. [Copyright &y& Elsevier]

The antioxidant potential (capacity and activity) of aqueous fullerene dispersions (AFD) of non-functionalized C60, C70, and Gd@C82 endofullerene (in micromolar concentration range) was estimated based on chemiluminescence measurements of the model of luminol and generation of organic radicals by 2,2′-azobis(2-amidinopropane) dihydrochloride (ABAP). The antioxidant capacity was estimated by the TRAP method, from the concentration of half-suppression, and from the suppression area in the initial period. All three approaches agree and show that the antioxidant capacity of AFDs increased in the order Gd@C82 < C70 < C60. Mathematical modeling of the long-term kinetics data was used for antioxidant activity estimation. The effect of C60 and C70 is found to be quenching of the excited product of luminol with ABAP-generated radical and not an actual antioxidant effect; quenching constants differ insignificantly. Apart from quenching with a similar constant, the AFD of Gd@C82 exhibits actual antioxidant action. The antioxidant activity in Gd@C82 is 300-fold higher than quenching constants. [ABSTRACT FROM AUTHOR]

In the present work, we report the successful synthesis and characterization of six (two new) fullerene mono- and di-pyrene derivatives based on C60 and C70 fullerenes. The synthesized compounds were characterized by spectral methods (ESI-MS, 1H-NMR, 13C-NMR, UV-Vis, FT-IR, photoluminescence and photocurrent spectroscopy). The energy of HOMO and LUMO levels and the band gaps were determined from cyclic voltammetry and compared with the theoretical values calculated according to the DFT/B3LYP/6-31G(d) and DFT/PBE/6-311G(d,p) approach for fully optimized molecular structures at the DFT/B3LYP/6-31G(d) level. Efficiency of solar cells made of PTB7: C60 and C70 fullerene pyrene derivatives were analyzed based on the determined energy levels of the HOMO and LUMO orbitals of the derivatives as well as the extensive spectral results of fullerene derivatives and their mixtures with PTB7. As a result, we found that the electronic and spectral properties, on which the efficiency of a photovoltaic cell is believed to depend, slightly changes with the number and type of pyrene substituents on the fullerene core. The efficiency of constructed solar cells largely depends on the homogeneity of the photovoltaic layer, which, in turn, is a derivative of the solubility of fullerene derivatives in the solvent used to apply these layers by spincoating. [ABSTRACT FROM AUTHOR]

The present paper describes rotations of C60 fullerene molecules in the solid phase of a fullerite. The conducted studies show that these relatively large molecules rotate according to the same laws as macroscopic bodies, i.e., according to the laws of classical mechanics. The performed calculations confirm that fullerene rotations do not cause friction. We suggest a method for a strong increase in the internal energy of the material that does not lead to its destruction. It is theoretically shown that in standard fullerite, in the absence of electric and magnetic fields, fullerene rotations occur with an average angular frequency of 0.34·× 1012 rad·s−1, which is consistent with the experimental data obtained using nuclear magnetic resonance. By means of calculations, we found that alternating magnetic fields of a certain configuration wind fullerenes encapsulated by iron. In this case, two temperatures arise in the fullerite crystal: a high rotational temperature and a vibrational temperature close to normal. For the purpose of determining this velocity, as well as the nature of rotations, the present paper suggests a way of integrating the dynamic Euler equations for the projections of a molecule's angular velocity vector onto the coordinate axes associated with the fullerene. The stages of computer simulation of fullerene movements, which was carried out without using previously developed packages of molecular-dynamic modelling, are consistently described. [ABSTRACT FROM AUTHOR]

Oligomers of the low-band-gap PCDTBT polymer, based on either 3,6 or 2,7 carbazole units, were modified with vinyl ω-chain end functionalities. The vinyl-functionalized oligomers were used as comonomers in free radical polymerizations with quinoline-based monomers such as 6-vinylphenyl-(2-pyridinyl)-4-phenyl-quinoline (vinyl-QPy), and 6-vinylphenyl-(2-perfluorophenyl)-4-phenyl quinoline (vinyl-5FQ). The co-polymeric materials bearing the vinyl-QPy moiety were developed as potential compatibilizers in polymer electron donor–fullerene acceptor blends for non-covalent interactions with the fullerene part. The co-polymeric materials bearing the vinyl-5FQ moiety were developed for the covalent attachment of carbon nanostructures; specifically, PC61BM. Both copolymers and hybrids, after thorough purification, were characterized in terms of their spectroscopic and optical properties as well as their ability to form nanophased separated films as such, or as additives at various percentages into PCDTBT: PC71BM blends. [ABSTRACT FROM AUTHOR]

The endohedral fullerene 15N@C60 has narrow electron paramagnetic resonance lines which have been proposed as the basis for a condensed-matter portable atomic clock. We measure the low-frequency spectrum of this molecule, identifying and characterizing a clock transition at which the frequency becomes insensitive to magnetic field. We infer a linewidth at the clock field of 100 kHz. Using experimental data, we are able to place a bound on the clock's projected frequency stability. We discuss ways to improve the frequency stability to be competitive with existing miniature clocks. [ABSTRACT FROM AUTHOR]

The article presents a study about the synthesis of 4-amino-substituted aromatic aldehydes and their condensation with fullerene C60. The study found that N-methyl-1-(4-aminophenyl)fullero-C60[1,9]pyrrolidines were formed due to the reaction of fullerene C60 with N-methylglycine (sarcosine) and 4-N-aminobenzaldehydes. Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry were used to confirm the structure offulleropyrrolidines.