Compostos orgânicos perfluorados (POCs), tais como perfluoroctanossulfonato (PFOS) e perfluoralquilsulfonamida (PFASA), são compostos que, recentemente, têm atraído considerável atenção mundial, devido à sua alta persistência e ampla distribuição no ambiente. Entre os métodos espectroscópicos usados para estudar PFASA, ressonância magnética nuclear de 19 F (RMN 19 F) é muito eficiente devido à sua habilidade para determinar concentrações de PFASA em amostras biológicas e para medir poluição em amostras de água. Por esta razão, um estudo teórico das propriedades de RMN 19 F foi realizado. Neste estudo, determinamos a constante de blindagem (σ) para diferentes núcleos de flúor das 18 moléculas em estudo, usando teoria do funcional de densidade (DFT) e o método GIAO no nível B3PW91/6-31+G(d,p). Os cálculos de σ foram realizados no vácuo e na presença de solvente. Os valores dos deslocamentos químicos (d) foram também calculados num nível diferente da teoria. Os melhores resultados foram obtidos com o nível de cálculo DFT-GIAO/B3PW91/6-31+G(d,p), considerando solventes como dimetilsulfóxido (DMSO), clorofórmio (CHCl 3), acetona (CH 3 COCH 3) e metanol (CH 3 OH). Os resultados foram interpretados em termos de dureza calculada no nível DFT/B3PW91/6-31+G(d, p). O comportamento da dureza foi maior nas moléculas de quatro carbonos PFASA do que nas de oito carbonos. Isto explica, teoricamente, a resistência de quatro carbonos PFASA para serem transformados em perfluorobutanossulfonato (PFBS). Perfluorinated organic compounds (POCs), such as perfluorooctanesulfonate (PFOS) and perfluoroalkylsulfonamide (PFASA) are compounds that have recently attracted considerable attention worldwide because of its high persistence and wide distribution in the environment. Among the spectroscopic methods used to study the PFASA, 19 F nuclear magnetic resonance (NMR 19 F) is very effective, due to its ability to determine concentrations of PFASA in biological samples and measure pollution in water samples. For this reason, a theoretical study of the properties of 19 F NMR was performed. In this study we have determined the shielding constant (σ) for different fluorine nucleus of the 18 molecules under study, using density functional theory (DFT) and GIAO method with the B3PW91/6-31+G(d,p) level of calculation. The σ calculations were made at vacuum and in presence of a solvent. The values of chemical shifts (d), were also calculated in a different level of theory. The best results were obtained with the level of calculation DFT-GIAO/B3PW91/6-31+G(d,p) by considering the solvent such as dimethylsulfoxide (DMSO), chloroform (CHCl 3), acetone (CH 3 COCH 3) and methanol (CH 3 OH). The results were interpreted in terms of calculated hardness at DFT/B3PW91/6-31+G(d, p) level. The behaviour of the hardness was higher in the molecules of four carbons PFASA than eight carbons. This explain theoretically resistance of four carbons PFAS to be transformed into perfluorobutanesulfonate (PFBS).
In this contribution, a complete study of Triarylamine-Oxadiazole derivatives for organic light emitting diodes (OLED) applications is presented. Our purpose in this article is the establishment of correlations between the computational calculations based on density functional theory (DFT) and the experimental results with some electronic and reactivity properties. The geometries of the Triarylamine-Oxadiazole molecules are discussed in terms of the substituents groups (CF3A, t-Bu-, CNA, and CH3A) and the electronics structures are described in detail in terms of the distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). We also calculate the ionization potential and electron affinity with to gain insights into the nature of nucleophilic and electrophilic interactions in the studied molecules. To study the global and local reactivities use make use suitable reactivity descriptors defined on the framework of DFT. The descriptors involved in the model are global and local electrophilicity index (x), chemical hardness (g) and softness (S), Fukui functions (f(r)), local softness (s). Correlation between the values of these quantities and the electron-withdrawing and electron-donor effects of triarylamine-Oxadiazole derivatives is addressed.
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