Tetrathiafulvalene (TTF) is a kind of fused ring aromatic compound containing four sulfur atoms in one molecule, which is well known as a charge transport material. In order to calculate the charge mobility of this se...Tetrathiafulvalene (TTF) is a kind of fused ring aromatic compound containing four sulfur atoms in one molecule, which is well known as a charge transport material. In order to calculate the charge mobility of this semiconductor, Marcus electron transfer theory and the embedded model, which can give small intramolecular reorganization energies, were employed. The calculated results were in good agreement with the experimental values, so the above computing model is appropriate to assess the electrical property of TTF. On this basis, we predicted the charge mobility of 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) crystals, for which the molecular structure is similar to TTF. The calculated results indicated that BDH-TTP is a p-type material, which has a better performance than TTF in hole transfer due to larger hole coupling and the smaller hole injection barrier. In addition, the direct coupling (DC) and the site energy correction (SEC) methods were used to calculate the charge transfer integrals. Although the results were slightly different, the qualitative trends were the same. Furthermore we took into account the anisotropic transfer properties of TTF and BDH-TTF, since obviously the mobilities along one dimension are larger than those along three dimensions. Finally, natural bond orbital analysis was used to study the interactions in all of the dimers.展开更多
A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calcu...A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.展开更多
基金supported by the Key Laboratory for New Molecule Material DesignFunction of Tianshui Normal University+3 种基金the Scientific Research Projects of Middle-agedYoung Researchers in Tianshui Normal University (TSA1116)the National Natural Science Foundation of China (21071110)the Fund of the Educational Commission of Gansu Province (1108-03)
文摘Tetrathiafulvalene (TTF) is a kind of fused ring aromatic compound containing four sulfur atoms in one molecule, which is well known as a charge transport material. In order to calculate the charge mobility of this semiconductor, Marcus electron transfer theory and the embedded model, which can give small intramolecular reorganization energies, were employed. The calculated results were in good agreement with the experimental values, so the above computing model is appropriate to assess the electrical property of TTF. On this basis, we predicted the charge mobility of 2,5-bis(1,3-dithiolan-2-ylidene)-1,3,4,6-tetrathiapentalene (BDH-TTP) crystals, for which the molecular structure is similar to TTF. The calculated results indicated that BDH-TTP is a p-type material, which has a better performance than TTF in hole transfer due to larger hole coupling and the smaller hole injection barrier. In addition, the direct coupling (DC) and the site energy correction (SEC) methods were used to calculate the charge transfer integrals. Although the results were slightly different, the qualitative trends were the same. Furthermore we took into account the anisotropic transfer properties of TTF and BDH-TTF, since obviously the mobilities along one dimension are larger than those along three dimensions. Finally, natural bond orbital analysis was used to study the interactions in all of the dimers.
基金supported by the National Natural Science Foundation of China (21172017, 20972013 and 20772005)the specialized Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20110010110011)"CHEMCLOUD COMPUTING " of Beijing University of Chemical Technology
文摘A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.
