New 1,3,4-oxadiazole containing materials with the effective leading substituents: The electrochemical properties, optical absorptions, and the electronic structures
| 作者: Zhang P, Xia BH, Zhang QX, Yang B, Li M, Zhang G, Tian WJ* |
| 來(lái)源出版物: SYNTHETIC METALS 卷: 156 期: 9-10 頁(yè): 705-713 出版年: MAY 5 2006 |
摘要: The electrochemical and optical absorption properties as well as the thermal stabilities of a series of 1,3,4-oxadiazole dimers 1,3-bis[2-(4-methylphenyl)-1,3,4-oxadiazol-5-yl]benzene (OXD-X) and its derivatives with the different alkoxy substituents on the central benzene ring such as -O(CH2)(n-1)CH3 (OXD-An, n = 3, 7, 10, 16), -O(CH2)(n)OC6H5CH3 (OXD-Bn, n = 6), and -O(CH2)(n)OC6H4N=NC6H4OCH3 (OXD-Cn, n = 3, 6, 10) are studied. The DSC measurements exhibit dramatically elevated glass transition temperatures for OXD-X and OXD-An (120-245 degrees C) in contrast to the well-known PBD (similar to 60 degrees C), indicating the better thermal stabilities. From OXD-X to OXD-An, OXD-Bn or OXD-Cn, the cyclic voltammograms and UV-vis absorption spectroscopy display significant variation, in which the later three species show additional lower energy absorptions at lambda > 330 nm compared with OXD-X and particularly, both of OXD-Bn and OXD-Cn display an oxidation peak at similar to+1.0 V and two successive redox reactions occur for OXD-Cn. Theoretically, the B3LYP/6-31g calculations explore that these extraordinary properties are due to the influence of the substituents on the benzene ring to the frontier molecular orbital distribution, especially the -O(CH2)(n)OC6H4N=NC6H4OCH3 groups in OXD-Cn deduce the new pictures of the frontier molecular orbitals, causing the electron-transporting behavior originally happening on the molecular skeleton transferred to the side chain.