Theoretic Study of Sulfur-Doped Graphdiynes by X-ray Spectroscopy.

Sulfur-doped graphdiyne at different sites has a tremendous impact on its electronic structure and properties. Due to the large number of S-doping sites, there is no comprehensive and systematic experimental and theoretical study regarding the identification of S-doped graphdiyne configurations. In this paper, X-ray photoelectron (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra as well as geometries of 10 sulfur-doped graphdiyne molecules have been simulated at the density functional theory (DFT) level. Different types of carbon spectra were theoretically modeled to analyze the contribution of the spectra. Calculated results show that the NEXAFS spectra exhibit a clear dependence on the local structure. The theoretically simulated XPS spectra are in good agreement with the experimental spectra. The XPS spectra combined with the NEXAFS spectra can provide effective information for identifying the 10 S-doped conformations. Our research results provide further theoretical prediction and guidance for the experimental synthesis of S-doped graphdiyne, which solves the difficult problem of identification of S-doped carbon-based materials.

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

The ground-state electronic/geometrical structures of the three classical isomers Cs(15)-C84, C2(13)-C84, and C2(8)-C84 as well as the corresponding embedded derivatives U@Cs(15)-C84, YCN@C2(13)-C84, and U@C2(8)-C84 have been calculated at the density functional theory (DFT) level. Then, the isomers of C84 were theoretically identified by X-ray photoelectron spectroscopy (XPS) and near X-ray absorption fine-structure spectroscopy (NEXAFS). The spectral components of total spectra for carbon atoms in various local environments have been investigated. The ultraviolet-visible (UV-vis) absorption spectroscopies of U@Cs(15)-C84, YCN@C2(13)-C84, and U@C2(8)-C84 have also been performed utilizing time-dependent (TD) DFT calculations. The UV-vis spectra are in good agreement with the experimental results. These spectra provide an effective method for the identification of isomers. The results of this study can offer useful data for further experimental and theoretical studies using X-ray and UV-vis spectroscopy methods on freshly synthesized fullerene isomers and their derivatives.

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.

Structural and Spectral Properties of a Nonclassical C66 Isomer with Its Hydrogenated Derivative C66H4 in Theory.

X-ray photoelectron and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of a newly discovered nonclassical isomer C 2v -C66(NC), and two classical fullerene isomers C 2-#4466C66 and C s -#4169C66 with their hydrogenated derivatives [C 2v -C66H4(NC), C 2-#4466C66H4, and C s -#4169C66H4] have been calculated at the density functional theory (DFT) level. Significant differences were observed in the electronic structures and simulated X-ray spectra after hydrogenation. Simultaneously, both X-ray photoelectron and NEXAFS spectra reflected conspicuous isomer dependence, indicating that the "fingerprints" in the X-ray spectra can offer an effective method for identifying the above-mentioned fullerene isomers. The simulated ultraviolet-visible (UV-vis) absorption spectroscopy of C 2v -C66H4(NC) has also been generated by means of the time-dependent DFT method, and the calculations are well consistent with the experimental results. Consequently, this work reveals that X-ray and UV-vis spectroscopy techniques can provide valuable information to help researchers explore the fullerene electronic structure and isomer identification on the future experimental and theoretical fullerene domains.

Spinel Zn3V3O8 nanosheets via a one-step hydrothermal synthesis with peroxidase-like activity for high sensitivity glucose colorimetric detection in synthetic perspiration.

Due to their specific spinel structure, ternary oxides with multi-catalytic sites on a highly active exposed surface are recommended as alternative bio-catalysts. Spinel zinc vanadate with two-dimensional nanosheets (Zn3V3O8 NSs) was synthesised using a one-step hydrothermal route with CTAB and glycine as a bi-surfactant, where each NS has a thin thickness (25 nm) and wide cross section (2 µm). As a key parameter for peroxidase-like activity, the Michaelis-Menten constant (Km) for Zn3V3O8 NSs was calculated to be 0.271 mM with TMB and 1.317 mM with H2O2 at optimum conditions, indicating a higher affinity for the exposed (011) facet towards horseradish peroxidases. This affinity is related to the geometric matching between V4+ active sites and the terminal amino groups of TMB. The V4+ ions on the (011) facet act as dangling bonds and readily react with H2O2 in a Fenton-like reaction. The peroxidase-like activity for Zn3V3O8 NSs is verified by the formation of [V(IV)-OO˙] by the ˙O2- and V5+ near V4+ sites, but oxidase activity for Zn3V3O8 NSs. Based on the peroxidase-like activity, Zn3V3O8 NSs were used as a colorimetric glucose sensor with a wide linear range from 0.01 to 0.5 mM and a detection limit (LOD = 3σ/S) of 2.81 × 10-7 M. The colorimetric sensor also exhibited high accuracy and selectivity in synthetic perspiration samples.

Structural and spectral properties of a non-classical C58 isomer and its fluorinated derivatives in theory.

The traditional classical fullerene is only composed of pentagons and hexagons, with many different topologies, of which only a few structures conform to the isolated pentagon rule (IPR), which means all five-membered rings are separated by hexagons, whereas isomers that violate the rule are called non-IPR isomers. In contrast, the non-classical fullerene consists of other kinds of polygons such as squares and heptagons in addition to pentagons and hexagons. X-ray photoelectron spectra (XPS), near-edge X-ray absorption fine structure (NEXAFS) spectra and X-ray emission spectra (XES), as well as the ground-state electronic/geometrical structures of the important non-IPR isomers C 3v-#1205C58 and C 2-#1078C58, and the remarkable non-classical isomer C s-C58(NC) with its two fluorides C s-C58(NC)F18(A) and C s-C58(NC)F18(B), have been computed at the density functional theory (DFT) level. Significant differences in the electronic structures and simulated X-ray spectra have been observed after fluorination. Meanwhile, strong isomer dependence has been shown in these spectra, which means the "fingerprint" in the X-ray spectra can effectively identify the above-mentioned fullerene isomers. As a consequence, the work can provide useful information especially isomer identification for experimental and theoretical research in fullerene science.

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

X-ray photoelectron (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra as well as the ground-state electronic/geometrical structures of #540C54 captured in experiment and the most controversial isomer #369C54 (C 2v- and C s-symmetry, respectively) have been calculated at the density functional theory (DFT) level. After chlorination, significant changes were observed in the electronic structure and X-ray spectra. Both XPS and NEXAFS spectra showed strong isomer dependence. The results indicated that the "fingerprints" in the X-ray spectra afforded an effective way to identify the fullerene isomers mentioned above. Ultraviolet-visible (UV-Vis) absorption spectroscopy of C54Cl8 was also simulated at the time-dependent (TD) DFT level, and the simulated UV-Vis spectrum was in accordance with the experimental result. The results of this study can provide valuable information for further experimental and theoretical studies of new fullerenes and their derivatives through X-ray and ultraviolet spectroscopy. The study of newly synthesized fullerene isomers and their derivatives using X-ray and UV-Vis spectra offers valuable information for further experimental and theoretical exploration.

First-principles studies on the structural and spectral properties of C72 isomers and the chlorinated derivative C72Cl4.

X-ray photoelectron (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra, as well as the ground-state electronic/geometrical structures of two important isomers of the elusive C72 fullerene family (C2v- and D6d-symmetry, respectively) and the corresponding chlorinated derivative C72Cl4, which are newly captured in the experiment, have been simulated at the density functional theory (DFT) level. Effective changes in the electronic structure and simulated X-ray spectra have been observed after chlorination. Both spectra show strong isomer dependence, therefore the "fingerprints" in the X-ray spectra offer a useful method for isomer identification of the above-mentioned fullerenes. The ultraviolet-visible (UV-vis) absorption spectroscopy of C72Cl4 has also been performed by means of time-dependent (TD) DFT calculations. The simulated UV-vis spectrum is in good agreement with the experimental results. The results of this work can provide valuable information for further experimental and theoretical studies on newly synthesized fullerene isomers and their derivatives by means of X-ray and UV-vis spectroscopy techniques.