Kinetics and Stoichiometry of the Reaction of Ozone with Fullerene C60 in a CCl4 Solution

The stoichiometry (1 : 1) and the numerical value of the rate constant of the reaction of a fullerene with ozone (1.2 × 10³ l mol^–1 s^–1) at 0°C were determined. A kinetic study of the reaction revealed the presence of an active impurity in high-purity samples. Suggestions as to the structure of this impurity were proposed based on the rate constant of its reaction with ozone. In contrast to simple aromatic compounds, the reaction of the fullerene with the first molecule of ozone dramatically (by several orders of magnitude) decreased the reactivity of the other C=C bonds in the molecule.     

Fullerene-silica complexes for medical chemistry

A quantum-chemical study of the interaction of C₆₀ fullerene with nanosized silica was performed. It was demonstrated that a fullerene molecule forms a weakly bound complex with a pyrogenic silica (Aerosil) particle only via the interaction with the silanediol groups of the hydroxyl covering on the particle. By contrast, a fullerene molecule is not bonded to an individual siloxane cycle, and, therefore, fullerosilica gel is formed due to the retention of fullerene molecules in pores of silica gel as a result cooperative action of the siloxane cycles comprising the pore. In both cases, the predicted medico-biological action of medicinal preparations is due to the radical-like and donor-acceptor characteristics of the C₆₀ molecule.     

Heating a bowl of single-molecule-soup: structure and desorption energetics of water-encapsulated open-cage [60] fullerenoid anions in the gas-phase

The gas-phase unimolecular decay kinetics of an anionic, open-cage [60] fullerene derivative encapsulating one water molecule is studied by means of black-body IR radiation induced dissociation (BIRD) in the temperature programmable ion trap of a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer. The primary reaction channel observed is escape of the water molecule from the fullerenoid bowl. The rate constants for this water loss as a function of temperature are evaluated using the Arrhenius equation to yield an activation energy of 104 ± 4 kJ mol(-1). A complementary ion mobility spectrometry study contrasting the water-encapsulated and the empty fullerene cages finds identical collision cross sections to within experimental error-supporting the structural assignment of this gas-phase anion as an endohedral (i.e. encapsulated) species. Both experiments were compared with quantum-chemical computations which well-describe the transition state for water desorption and the concomitant binding and activation energies.     

Solvent free mechanochemical oxygenation of fullerene under oxygen atmosphere

Oxygenation of fullerene took place under mechanical stressing by a simple vibration mill in an oxygen atmosphere at 1 atm. Milled products were mixtures of poly-oxidized fullerene, C₆₀O_n, containing C-O-C and CO bonds. We observed a concurrent reaction as well, that is, polymerization of C₆₀ and C₆₀O. The average number of oxygen, n, of the overall products obtained by milling for 5 h was 8.6 per molecule of C₆₀. We confirmed generation of singlet oxygen during the present mechanochemical reaction by an ESR spin trapping method. Trapping of ¹O₂ was completely inhibited the oxygenation of fullerene. Formation of ¹O₂ is attributed to the energy transfer from mechanically excited state of fullerene and plays a decisive role on the present oxygenation of fullerene under mechanical stressing in O₂. In contrast, no ¹O₂ was observed by mechanically stressing the conventional photo-sensitizer, rosebengal. The difference in the behavior of C₆₀ and rosebengal is interpreted in terms of molecular deformation, being much easier for a 3D molecule, C₆₀, than a planar molecule, in line with the concept of inverse Jahn-Teller effects.     

Energetics and Electronic Properties of a Neutral Diuranium Molecule Encapsulated in C90 Fullerene

Scientists have found that the size of the cavity of endohedral metallofullerenes (EMFs) can influence the properties of the inner molecule. In this work, the neutral diuranium molecule was encapsulated into the C90 fullerene. The neutral U-U dissociation potential energy surfaces of different electronic states confined in the C90 fullerene were scanned and the quintuple and the septuplet of these states were found to be low-lying. In the fullerene cage, the U2 molecule easily disintegrates along the axis of the fullerene, and then is chemically adsorbed on the both ends of the fullerene. The charge distribution and the molecular orbit properties of the complex were also uncovered.     

C60负离子化学的研究进展

中性的C60是很强的缺电子体,主要和亲核试剂进行化学反应.与之不同的是C60经还原生成负离子后,由缺电子变为富含电子,具有很强的亲核性质,可与亲电试剂进行反应.由于这种电子结构的变化,C60负离子进行的反应从机理至产物均有可能与中性富勒烯不同.从而丰富了富勒烯的反应方式和富勒烯产物的类型.结合我们的工作综述了C60负离子化学的研究进展,对丰富富勒烯化学、扩展富勒烯衍生物的种类及制备方法具有一定意义.     

Using cyanide to put noble gases inside C60

After fullerenes are heated in the presence of a noble gas or an unreactive molecule at 650 degrees C and 3000 atm pressure, a small fraction of the fullerene molecules contain the atom or molecule. The incorporation fraction is greatly enhanced by adding potassium cyanide to the reaction mixture. The details of the preparation are described here.     

Stereoanalysis of fullerenes with a chiral molecular framework

Stereoanalysis of three fullerene molecules with a chiral molecular framework C₃₂, C₇₆, and C₇₈ and achiral fullerene C₆₀ molecule was carried out. Comparative quantitative analysis of the degree of chirality showed topology to be the major factor governing the chirality of fullerenes. A procedure for determining the relative contribution of topological chirality to the total chirality of the molecule is proposed. Structural fragments responsible for chirality are found. The title fullerenes are assigned to the corresponding subclasses of homochirality. A classification system of isomeric fullerenes is proposed.     

Radical reaction of [60]fullerene with phosphorus compounds mediated by manganese(III) acetate

Radical reaction of [60]fullerene with phosphonates or phosphine oxide mediated by manganese(III) acetate dihydrate in chlorobenzene under three different conditions afforded three different types of phosphorylated fullerenes: singly bonded fullerene dimers 2, hydrophosphorylated fullerenes 3, and acetoxylated fullerene derivatives 4. In addition, interconversions among the three types of phosphorylated fullerene derivatives have also been investigated. A possible reaction mechanism was proposed to explain experimental results.     

Synthesis of a Fullerene Derivative of Benzo[18]crown-6 by Diels-Alder Reaction: Complexation Ability,Amphiphilic Properties,and X-Ray Crystal Structure of a Dimethoxy-1,9-(methano[1,2]benzenomethano)fullerene[60] Benzene Clathrate

A fullerene derivative 1 of benzo[18]crown-6 was obtained by Diels-Alder addition of fullerene[60](C₆₀) to the ortho-quinodimethane prepared in situ from 4,5-bis(bromomethyl)benzo[18]crown-6 ( 3 ) with Bu₄NI in toluene. Extraction experiments show that the complexation of K⁺ ions strongly increases the solubility of 1 in protic solvents like MeOH. Using Langmuir-Blodgett techniques, monolayers of the highly amphiphilic fullerene-derived crown ether 1 and its K⁺ ion complex were prepared. An X-ray crystal structure was obtained from a benzene clathrate of comparison compound 2 , synthesized by Diels-Alder reaction of C₆₀ with the ortho-quinodimethane derived from 1,2-bis(bromomethyl)-4,5-dimethoxybenzene ( 4 ). Both the fullerene molecule 2 and the benzene molecule are fully ordered in a crystal packing which is stabilized by intermolecular van-der-Waals contacts between the benzene ring and the C-spheres, intermolecular C…?C contacts between the C₆₀ moieties, and intermolecular O…?C contacts between the O-atoms of the veratrole moieties and fullerene C-atoms.     

C60Pt(CO)(Pph3)配合物的合成及氧化还原性能研究

采用配体取代法,即在惰性气氛下以C60取代Pt(CO)2(Pph3)2中的CO及Pph3,合成了C60Pt(CO)(Pph3)富勒烯金属配合物,利用元素分析、红外光谱、紫外可见光谱、光电子能谱等手段对产物进行鉴定和表征,结果表明,C60以σ-π配位方式与Pt形成了稳定的η2型C60配合物.由于该分子存在超共轭作用,分子内电子流动性大,因而该配合物可能具有良好的光电转化性能及催化性能.氧化还原性能研究表明,C60在与金属有机基团Pt(CO)(Pph3)形成配合物后,其还原电位向负方向发生了移动.     

Regioselective oxygenative tetraamination of [60]fullerene. Fullerene-mediated reduction of molecular oxygen by amine via ground state single electron transfer in dimethyl sulfoxide

The reaction of [60]fullerene with a variety of a secondary aliphatic amines in 20% v/v dimethyl sulfoxide in chlorobenzene under an atmospheric pressure of molecular oxygen allows regioselective introduction of four amino groups and one epoxide group around one pentagon of the fullerene molecule in good to high yield. This new synthesis of tetraaminofullerene expoxide can be carried out with a simple procedure on a multigram scale at room temperature and affords a variety of functionalized fullerene derivatives. Near-infrared analysis of a mixture of [60]fullerene and piperidine in a deaerated dimethyl sulfoxide/chlorobenzene mixture indicated equilibrium formation of [60]fullerene radical anion (C60*-) that persists at least for 2 weeks at room temperature but reacts immediately with molecular oxygen to give the tetraaminofullerene expoxide. The Benesi-Hildebrand analysis of the concentration dependency of the near-infrared absorption indicated that a [C60*- piperidine*+] radical ion pair is formed with an equivalent constant of K = 0.62 +/- 0.02 M(-1) at 25 degrees C. This and other lines of evidence suggest that the oxygenative amination reaction involves C60-mediated reduction of molecular oxygen by the amine.     

The Influence of Chemical Composition of Fullerenes on the Structural Features and Conformational Preference of Encapsulated Disilane Molecule

The study of the structure and conformational properties of the disilane molecule in the C₈₀ and B₄₇N₃₃ fullerene cavities using the PBE/3ζ DFT method showed that the encapsulated molecule contains a shortened Si–Si bond, carries a certain electric charge, and exhibits a noticeable increase in the potential barrier to rotation around the Si–Si bond. At the same time, in the case of fullerene Si₆₀, the observed effects, with the exception of the electric charge on the guest molecule, do not appear. For the Si₂H₆@C₆₀ system, in the course of geometry optimization, a virtual reaction of disilane with the carbon skeleton of the nanoobject occurs with Si–Si bond cleavage and the formation of two SiH₃ fragments bonded to fullerene carbon atoms.     

An Electron Acceptor with Porphyrin and Perylene Bisimides for Efficient Non‐Fullerene Solar Cells

A star‐shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non‐fullerene organic solar cells. The new conjugated molecule exhibits aligned energy levels, good electron mobility, and complementary absorption with a donor polymer. These advantages facilitate a high power conversion efficiency of 7.4 % in non‐fullerene solar cells, which represents the highest photovoltaic performance based on porphyrin derivatives as the acceptor.     

Porphyrin–Fullerene Dyad Based on Indium(III) Complex. Donor–Acceptor Complex Formation Equilibrium

Formation kinetics and spectral properties of the donor–acceptor complexes of (5,10,15,20- tetra(2-methoxyphenyl)porphinato)chloroindium(III) with 2′-(pyridin-4-yl)-5′-(pyridin-2-yl)-1′-(pyridin- 2-yl)methylpyrrolidinyl[3′,4′:1,2][60]fullerene were studied. The formation of the donor–acceptor dyad [(Py₃F)InTPP(2-OCH₃)₄]⁺Cl^– occurs as a two-step reaction, including fast reversible coordination of the fullerene base molecule and slow irreversible displacement of the axial chloride ion to the second coordination sphere. Quantitative characteristics for the reaction rate and equilibrium were obtained. The reaction products were identified by IR and ¹H NMR spectroscopy. The most important electron optical and stability parameters of the porphyrin–fullerene dyads with inner- and outer-sphere chloride ions were determined. These results are important for studies of the photophysics of porphyrin–fullerene dyads and development of photoconverters based on them.     

Anhydride-functionalized fullerene: a versatile precursor for fullerene-based materials

Soluble phthalic anhydride-functionalized fullerene was generated via simple pyrolysis of the corresponding di-t-butyl phthalate precursor at 200 °C for 120 min. This non-chemical method for generating electrophilic fullerene may be advantageous for the preparation of various fullerene-containing materials. The utility of the resulting fullerene anhydride was demonstrated by solution coupling reaction with PEG-amine, surface reaction with amine-functionalized glass, and hydrolysis reaction to form amphiphilic fullerene.     

Synthesis of [60]fullerene acetals and ketals: reaction of [60]fullerene with aldehydes/ketones and alkoxides

The reaction of C(60) with propionaldehyde (butyraldehyde or phenylacetaldehyde) and MeONa-MeOH or EtONa-EtOH in anhydrous chlorobenzene in the presence of air at room temperature unexpectedly gave rare fullerene acetals 2aa-cb, while the reaction of C(60) with acetone (acetophenone, cyclohexanone, or cyclopentanone) and MeONa-MeOH or EtONa-EtOH under the same conditions afforded the uncommon fullerene ketals 4aa-db. A possible reaction mechanism for the formation of the fullerene acetals and ketals is proposed based on further experimental results.     

Quantum transition theory and dynamics of ionic molecule formation in cluster collisions

We apply the quantum transition theory of chemical reactions to ionic molecule formation in collisions between alkali-metal clusters and two types of reactive species: halogens and fullerenes. We show that the probability of a sticking collision is strongly dependent upon the nuclear dynamics. It turns out that although both halogens and fullerenes have a high electron affinity and appear promising for a harpooning reaction, this process is inhibited in the fullerene case by unfavorable Franck-Condon factors. This conclusion is in agreement with experimental observations. We predict that a strong reactive channel should reappear if the bare fullerene is replaced by a fullerene-rare gas complex. The product translational and vibrational energy distribution for such a collision is evaluated.     

Organic and organometallic derivatives of dihydrogen-encapsulated [60]fullerene

Regioselective multi-addition reaction of organocopper and amine compounds onto dihydrogen-encapsulated [60]fullerene, H2@C60, produced a variety of organic and organometallic derivatives of H2@C60. The X-ray crystallographic analysis of dihydrogen-encapsulated bucky ferrocene, Fe(H2@C60Ph5)C5H5, showed the presence of the dihydrogen molecule located almost in the center but slightly away from the ferrocene moiety. The 1H NMR chemical shift values for the encapsulated molecular hydrogen indicated that these values are susceptible to the magnetic environment of the inside as well as the outside of the fullerene cage.     

Conformationally constrained macrocyclic diporphyrin-fullerene artificial photosynthetic reaction center

Photosynthetic reaction centers convert excitation energy from absorbed sunlight into chemical potential energy in the form of a charge-separated state. The rates of the electron transfer reactions necessary to achieve long-lived, high-energy charge-separated states with high quantum yields are determined in part by precise control of the electronic coupling among the chromophores, donors, and acceptors and of the reaction energetics. Successful artificial photosynthetic reaction centers for solar energy conversion have similar requirements. Control of electronic coupling in particular necessitates chemical linkages between active component moieties that both mediate coupling and restrict conformational mobility so that only spatial arrangements that promote favorable coupling are populated. Toward this end, we report the synthesis, structure, and photochemical properties of an artificial reaction center containing two porphyrin electron donor moieties and a fullerene electron acceptor in a macrocyclic arrangement involving a ring of 42 atoms. The two porphyrins are closely spaced, in an arrangement reminiscent of that of the special pair in bacterial reaction centers. The molecule is produced by an unusual cyclization reaction that yields mainly a product with C(2) symmetry and trans-2 disubstitution at the fullerene. The macrocycle maintains a rigid, highly constrained structure that was determined by UV-vis spectroscopy, NMR, mass spectrometry, and molecular modeling at the semiempirical PM6 and DFT (B3LYP/6-31G**) levels. Transient absorption results for the macrocycle in 2-methyltetrahydrofuran reveal photoinduced electron transfer from the porphyrin first excited singlet state to the fullerene to form a P(?+)-C(60)(?-)-P charge separated state with a time constant of 1.1 ps. Photoinduced electron transfer to the fullerene excited singlet state to form the same charge-separated state has a time constant of 15 ps. The charge-separated state is formed with a quantum yield of essentially unity and has a lifetime of 2.7 ns. The ultrafast charge separation coupled with charge recombination that is over 2000 times slower is consistent with a very rigid molecular structure having a small reorganization energy for electron transfer, relative to related porphyrin-fullerene molecules.