Adsorption of helical and saddle-shaped oligothiophenes on solid surface

Abstract

The arrangement of oligothiophenes is essential for understanding the relationship between structure and properties particularly in the organic electronic field. The self-assembly behaviors of helical (TMS)2-[7]helicene ( T1 ), naphthalene-cored double (TMS)2-[7]helicene ( T2 ), and saddle-shaped cyclooctatetrathiophene ( T3 ), its derivative α , α , α , α -tetraphenyl-cyclooctatetrathiophene ( T4 ) on solid surface are firstly investigated by using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) calculation. 1,3,5-Tris(10-carboxydecyloxy)-benzene (TCDB) is selected to build flexible host networks to immobilize these oligothiophenes in order to capture their molecular adsorption images successfully. The observed monodisperse or polydisperse filling and long-range alignment of oligothiophenes are described based on the non-covalent interactions and commensurate structure between olihothiophene and cavity. We speculate that those molecularly defined alignments could lead to significantly understanding the application of such ordered monolayer in organic electronic devices.