Self-assembled nanostructures of a series of linear oligothiophene derivatives adsorbed on surfaces

Many previous studies have shown that the molecular structures of oligothiophene derivatives includ-ing molecular skeleton and alkyl chains have a significant effect on their self-assemblies on the surface. In this work, a series of linear oligothiophene derivatives (DCV-nT-Hex, n = 3-11) modified with termi-nal dicyanovinyls and alkyl chains were adopted to further investigate the different assembly behaviors at liquid-solid interface by scanning tunneling microscopy (STM). Interestingly, via the hydrogen bond-ing and van der Waals interactions, DCV-3T-Hex formed zigzag and flower structures while DCV-nT-Hex ( n = 4-11) formed lamellar structures. Density functional theory (DFT) calculations show that for the most energetically favorable configurations of DCV-nT-Hex, the different distribution of alkyl chains af-fected intermolecular interactions, and ultimately led to the different assembled structures. The zigzag and flower structures of DCV-3T-Hex had preferential thermodynamic stability compared to other struc-tures of DCV-nT-Hex ( n = 4-11). In addition, self-assembled nanostructures of DCV-nT-Hex molecules with even numbers ( n = 4, 6, 8, 10) were overall more stable than those with odd numbers ( n = 5, 7, 9, 11), and the stability of the self-assembled structure was weakened with the extension of the molecular backbone, individually. The orientation of molecular alkyl chains was found to greatly affect the inter-molecular interactions and thus leading to various self-assembly structures of DCV-nT-Hex ( n = 3-11).(c) 2022 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.