Thermochemical stabilities, electronic structures, and optical properties of C₅₆X₁₀ (X = H, F, and Cl) fullerene compounds

Abstract

Stimulated by the recent isolation and characterization of C₅₆Cl₁₀ chlorofullerene (Tan et al., J Am Chem Soc 2008, 130, 15240), we perform a systematic study on the geometrical structures, thermochemistry, and electronic and optical properties of C₅₆X₁₀ (X = H, F, and Cl) on the basis of density functional theory (DFT). Compared with pristine C₅₆, the equatorial carbon atoms in C₅₆X₁₀ are saturated by X atoms and change to sp³ hybridization to release the large local strains. The addition reactions C₅₆ + 5X₂ --> C₅₆X₁₀ are highly exothermic, and the optimal temperature for synthesizing C₅₆X₁₀ should be ranged between 500 and 1000 K. By combining 10 X atoms at the abutting pentagon vertexes and active sites, C₅₆Cl₁₀ molecules exhibit large energy gaps between the highest occupied and lowest unoccupied molecular orbitals (from 2.84 to 3.00 eV), showing high chemical stabilities. The C₅₆F₁₀ and C₅₆Cl₁₀ could be excellent electron acceptors for potential photonic/photovoltaic applications in consequence of their large vertical electron affinities. The density of states is also calculated, which suggest that the frontier molecular orbitals of C₅₆X₁₀ are mainly from the carbon orbitals of two separate annulene subunits, and the contributions derived from X atoms are secondary. In addition, the ultraviolet-visible spectra and second-order hyperpolarizabilities of C₅₆X₁₀ are calculated by means of time-dependent DFT and finite field approach, respectively. Both the average static linear polarizability <α> and second-order hyperpolarizability <γ> of these compounds are larger than those of C₆₀ due to lower symmetric structures and high delocalization of π electron density on the two separate annulene subunits.

Theoretical studies on the structural and spectral properties of two specific C54 isomers and the chlorinated species C54Cl8

“… 36 The final UV-Vis spectrum is obtained by a Gaussian functional convolution with FWHM set at 3000 cm −1 , which constitutes an average width for an absorption band observed in the UV-Vis range. 37 …”

Topology-Based Approach to Predict Relative Stabilities of Charged and Functionalized Fullerenes

“…92−98 The enhanced electron affinity makes halogenated fullerenes excellent electron acceptors for novel charge-transfer complexes, 99 donor−acceptor dyads, 100,101 and photonic/photovoltaic devices. 102,103 Perfluoroalkylated fullerenes have also been intensively studied, 104 with practical applications as powerful and tunable acceptors in the field of organic electronics. 104−106 One of the fundamental aspects of the chemistry of neutral, charged, and functionalized fullerenes is the relationship between stability and structure, due to the huge number of possible isomers.…”

Static polarization of the supramolecular dyads of fullerene C60 with porphyrin derivatives

“…It has been shown earlier that this level of theory predicts the linear polarizability of C 60 fullerene close to the experimental value [27]. To correctly describe the intermolecular interaction between the two parts of the dyads the Grimme D3 dispersion correction was used [28].…”