A series of combinations of thiophene and vinyl/butadiene were investigated by ab initio and DFT methods to explore their electronic structures and charge transfer properties. The results show that increasing thiophene ring and vinyl number is a rational strategy to raise the HOMO energy levels and lower the LUMO energy levels. Mov- ing the vinyl from the periphery to the core has the slight effect on the HOMO and LUMO energy levels. Further- more, replacing the middle vinyl and end-capped vinyl of 3b （T5V4） with the butadiene can lower LUMO energy levels and then facilitate the electron injection. Above all, the close hole and electron reorganization energies （2h and λ-e） are observed from these compounds. However, the λes are smaller than their respective λhs in some com- pounds, which is relatively rare in organic materials. Especially, the promising ambipolar material 3c （T5B4） is recommended theoretically for possessing the equivalent minimum Ah （0.24 eV） and 2e （0.24 eV）. The absorption wavelengths exhibit red shifts with the increasing of the thiophene ring and the vinyl number under the same con- figuration, which correspond to the reverse order of AEH_L and Eg. The linear relationships are found between experimental lowest singlet excited energies （Eexp） with theoretical values AEH-L and Eg.
The isomerization of CH3S（OH）CH2 to CH3S（O）CH3 in the absence and presence of water has been investigated at the G3XMP2//B3LYP/6-311 ＋ G（2df, p） level. The naked isomerization, the reaction without water, gives the high barrier height （21.56 kcal.mol^-1）. Three models are constructed to describe the water influence on the isomerization, that is, water molecules are the catalyst and the microsolvation, and water molecules act as the catalyst and microsolvation simultaneously. Our results show that the isomerization barrier heights of CH3S（OH）CH2 to CH3S（O）CH3 are reduced by 12.32, 11.04, and 7.80 kcal.mol^-1, respectively, when one, two, and three water molecules are performed as catalyst, in contrast to the naked isomerization. Moreover, the rate constants of the isomerization are calculated using the transition state theory with the Wigner tunneling correction over the temperature range of 240-425 K. We find that the rate constant of a single water molecule as the catalyst is 1.58 times larger than the naked isomerization at 325 K, whereas it is slower by 6 orders of magnitude when water molecule serves as the microsolvation at 325 K, compared to naked reaction. So the water-catalyzed isomerization of CH3S（OH）CH2 to CH3S（O）CH3 is predicted to be the key role in lowering the activation energy. The isomerization involving water molecules acting as mierosolvation is unfavorable under atmospheric conditions.
Cao JiaWenliang WangTianlei ZhangLoujun GaoFeng FuDanjun Wang
