Synthesis and Photochromism of Chloro- and tert-Butyl-Functionalized Terarylene Derivatives for Surface Deposition

In the field of extreme miniaturization of electronic devices, it is necessary to study candidate molecules at the single-molecular level by scanning tunneling microscopy (STM). This necessitates molecules with specific functionalizations to control molecule–surface and molecule–molecule interactions to avoid molecular diffusion on the surface and to prevent the aggregation of molecules, respectively. In this context, we present the synthesis and photochromism of terarylene derivatives with tert-butyl and chloride groups. We show that these groups preserve the photochemical and switching properties of the molecules. DFT calculations on the conformations of the molecules predict the presence of several conformations during vacuum-deposition. Initial STM experiments show that tert-butyl groups result in images with a better contrast to enable the identification of the molecules on the surface without any aggregation.