Isomeric and Structural Impacts on Electron Acceptability of Carbon Cages in Atom-Bridged Fullerene Dimers

Abstract

The electrochemical properties of the carbon-bridged fullerene dimers C 121 (I), C 121 (II), C 121 (III), C 131 , and C 141 were characterized systematically for the first time in this study. Cyclic voltammogram and differential pulse voltammogram analyses revealed that they first underwent three reversible fullerene-unit-based reduction processes where each of the two carbon cages accepted one electron in each step and then possessed a different deep reduction sequence from the fourth to sixth reduction potentials of the fullerene cages. The electronic interactions between cages in the atom-bridged dimers (e.g., C 60 -C-C 60 ) were found to be different from those of dimers in which two cages were connected directly. Comparison studies of the redox properties of the five dimers revealed that the C 60 dimerization via [5.6]-[6.6] connection influenced the cage electron acceptability much more than that of [5.6]-[5.6] or [6.6]-[6.6] connections and the dimerization with C 70 cages influenced the reduction potentials of dimerized products more potently than that with C 60 cages. Further results from controlled potential electrolysis, high-performance liquid chromatography, matrix-assisted laser desorption and ionization time-of-flight mass spectrometry, ultraviolet absorption spectral analyses demonstrated the reduction processes and a dissociation of the dimers based on reductions. The theoretical understanding of the experiments was investigated by using time-dependent density functional calculations for the ionic states of C 121 (I, II, III) n-with n ) 0, 1, 2, 3, or 4. IntroductionElectrochemical characterization, as one of the most useful tools in the study of electronic properties, has been successfully performed on a lot of fullerenes and their derivatives. The properties, stability, mechanism, and reactivity of fullerene derivatives could be deduced from the experiment. 1-6 Many kinds of fullerene-cage-based derivatives have been synthesized for the purpose of developing electrochemically or optically active systems with different applications, whose basic constructing units are dimer, carbon-bridged dimer, or trimer structures. Their electronic properties are mostly dominated by the electronic interactions between the neighboring fullerene cages of the dimerized units. How the dimerization influences the electronically functional properties is of particular interest for developing as well as understanding the ultimate materials of fullerene derivatives with the desired functions and expected applications such as photovoltaic conversion materials and alloptical switch or optical limiting materials. 7,8 In this work, electrochemical analyses were performed on a series of fullerene dimers, in which the two fullerene cages were

Electrochemistry of symmetrical fullerene dimer C121 film modified electrodes

“…The three reduction peaks appear at about E pR1 = À1.00 V, E pR2 = À1.33 V and E pR3 = À1.58 V vs. Fc/Fc + . Compared with our previous results of C 121 in the mixed solution of toluene and acetonitrile (v:v = 4:1) containing 0.1 M TBAP [34], the first two reduction peak potentials of C 121 in the films seem to correlate very well with the reduction peak potentials in solution, so we presume that the three reduction peaks correspond to three two-electron transfer processes involving reduction of two fullerene units in the dimers. These two electrons are assigned to each of the two cages, but splitting of the peaks is not observed, which indicates that each of the two C 60 monomers can be reduced at the same potential.…”

“…All the peaks almost disappeared after several cyclic scans. Based on the experimental results of C 121 in the mixed solution of toluene and acetonitrile (v:v = 4:1) containing 0.1 M TBAP [34], we presume that rearrangement or dissociation of the dimer after the fourth reduction resulting in formation of different fullerene-based species leads to great suppression of the electrochemical activity on the second scan and disappearance after several scans.…”

First Endohedral Metallofullerene-Containing Polymer: Preparation and Characterization of Gd@C82-Polystyrene

“…To confirm this conclusion, we investigated the electrochemical behavior of C 60 -PS (0.37 wt % C 60 ). It is worth mentioning that the characteristic six couples of reversible reduction/oxidation peaks of the C 60 cage cannot be observed at all. Similar to those of Gd@C 82 -PS, a negative shift of the broad peak was observed obviously.…”

Resistance Switch in a Minimal-Fullerene Chain in Vertically Stacked Electrodes

“…Fullerene devices, which are intermediate materials between inorganic and organic materials, have been developed. − The individual C 60 molecule is a rigid spherical shell composed of carbon atoms and can be functionalized like organic molecules. , Although fullerene surfaces can be chemically functionalized for various applications, the intrinsic structure of fullerene is stable even in conventional device fabrication processes. − Fullerene C 60 can accept up to six electrons into the lowest unoccupied molecular orbital (LUMO) at a low energy level, providing excellent electron acceptor characteristics in n-type semiconductors. − Furthermore, intermolecular bonds between fullerenes can be connected to form a polymer chain in the film or bulk, allowing the electrical function of a device to be controlled by bond connections. Based on these properties, fullerene has been proposed as a material in electrical devices.…”