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

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.