Theoretical Study on the Structure and Spectral Properties of Several Classical and Non-Classical C₇₆ Isomers and Their Newly Synthesized Derivatives

Abstract

X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of the newly discovered two non-classical isomers C2–C76(NC2) and C1–C76(NC3) with their derivatives C2–C76(NC2)­(CF3)14 and C1–C76(NC3)­Cl24, as well as the non-IPR­(isolated pentagon rule) isomer C1–#17418C76 with its embedded metal fullerene U@C1–#17418C76 have been calculated at the density functional theory (DFT) level. The electronic structure after chlorination is significantly different in the simulated X-ray spectrum. Both XPS and NEXAFS spectra reflect obvious isomer dependence, indicating that the “fingerprint” in X-ray spectroscopy can provide an effective means for the identification of the above-mentioned fullerene isomers. Time-dependent DFT was used to simulate the ultraviolet–visible absorption spectrum of U@C1–#17418C76. The calculated results are in good agreement with the experimental consequence. This work reveals that theoretically simulated X-ray and UV–vis spectroscopy techniques can provide valuable information to help researchers explore the electronic structure of fullerenes and the identification of isomers in future experimental and theoretical fields.

Theoretical Study on the Structure and Spectral Properties of Several Classical C84 Isomers and Their Newly Synthesized Derivatives

“…The results show that when the TD-DFT method is used to simulate the UV–vis spectra, there are some phenomena of peak shift in some systems. The phenomena have been reported in the previous literature, ,,, and earlier studies demonstrated that the slight peak shift was within a reasonable range. , In general, the simulated spectra are in good agreement with the experimental spectra.…”

“…Although the B3LYP functional is not a good representation of the weak interaction, the effect of this work on the system is small and can be reasonably ignored. According to our calculations, the energy trends and the relative stability between the isomers agree well with the results of previous studies. , The lanthanide and actinide complexes are more complex to calculate and have a higher probability of convergent to unstable wave functions. PBE0 , functional has been used in many papers for metal-containing systems and obtained good results. − In order to make our computational results more reasonable and reliable, for the embedded fullerene derivatives U@ C s (15)-C 84 , YCN@ C 2 (13)-C 84 , and U@ C 2 (8)-C 84 , the structures were optimized at the PBE0 level.…”

“…This indicates that in some cases there is a strong interaction between the embedded metal and the carbon cage. 84 According to prior research, 41,85,86 the triplet states of U@ C s (15)-C 84 and U@C 2 (8)-C 84 are the most energetically beneficial, while the singlet states of the other systems are more common in energy. Table 1 shows the statistics over bond lengths, the HOMO−LUMO gaps of studied species, the relative energies of the three fullerene isomers and endohedral fullerenes as well as the sum of Mulliken charges on all carbon Compared with the original carbon cage and the shortest bond length of the C−C bond of the embedded derivatives increased, the longest bond length decreased, while the bond length of the YCN derivative changed more significantly.…”

“…According to our calculations, the energy trends and the relative stability between the isomers agree well with the results of previous studies. 41,59 The lanthanide and actinide complexes are more complex to calculate and have a higher probability of convergent to unstable wave functions. PBE0 60,61 functional has been used in many papers for metalcontaining systems and obtained good results.…”

“…At the same time, gradient-corrected Beck88 (BE88) exchange and Perdew (PD86) correlation functions were used at the DFT level. It has been verified by many systems that BE88 and PD86 functions are reliable when simulating spectrum, especially for carbon-based materials such as fullerenes and graphene. − ,, In order to promote the self-consistent field convergence of the nuclear pore state, the C atoms in the excited state were calculated using the triple-ζ quality individual gauge for localized orbital (IGLO-III) basis set of Kutzelnigg et al and nonexcited carbon atoms are described by the standard nuclear potential energy. In addition, the full core-hole (FCH) potential method combined with a double basis set method was used to calculate the NEXAFS spectra.…”