Synthesis and Electrochemistry of Novel Dumbbell-Shaped Bis-pyrazolino[60]fullerene Derivatives Formed Using Microwave Radiation

Covalently linked thieno[2,3-b]thiophene-fullerene dimers: synthesis and physical characterization

Thienothiophene (TT) has received great attention in the fields of electronics and optoelectronics. Here we report a synthesis and characterization of fullerene-donor-fullerene triads linked to thieno[2,3-b]thiophene as a donor. The photophysical and electrochemical properties of the new dumbbells were investigated using UV-vis spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and square wave voltammetry. The results showed that both compounds have higher LUMO energy levels than PC61BM, indicating that they can be used in photovoltaic applications. Furthermore, the powder was structurally and morphologically characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). The SEM revealed the morphological characterization of the two derivatives as globular and urchin-like supramolecular assemblies.

Distributed Polarizability Model for Covalently Bonded Fullerene Nanoaggregates: Origins of Polarizability Exaltation

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.

Pyrazole-, isoxazole- and pyrrole-ring fused derivatives of C60: synthesis and electrochemical properties as well as morphological characterization

Pyrazole-, isoxazole- and pyrrole-ring fused derivatives of C60.