| Autor: |
Enrique Ortí, Pedro M. Viruela, Juan Aragó |
| Rok vydání: |
2009 |
| Předmět: |
|
| Zdroj: |
Journal of Molecular Structure: THEOCHEM. 912:27-31 |
| ISSN: |
0166-1280 |
| DOI: |
10.1016/j.theochem.2009.03.021 |
| Popis: |
In this paper, we report a theoretical study of four types of thiophene-based oligomers showing the same number of C C double bonds and very different molecular structures. The comparative study has been performed on the basis of B3LYP/6-31G∗∗ calculations. The way the thiophene rings are linked together has a remarkable influence on the molecular and electronic properties. Linear quaterthiophene and heptathienoacene show similar aromatic structures but a loss of π-conjugation is detected for the latter due to the condensation of thiophene rings. A blue shift of the most intense electronic transition is predicted for fused heptathienoacene compared with non-fused quaterthiophene. Cyclic quaterthiophene exhibits quinoid thiophene rings folded in an envelope shape and should be visualized as a sulphur-bridged, cis-transoid polyenic chain. Circularly-fused sulflower presents a loss of π-conjugation with respect to linear systems due to its highly-branched conjugated backbone. The loss of conjugation and the high symmetry of the molecule determine that sulflower shows no optical absorption in the visible or near-UV. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect