On-Surface Synthesis of Heptacene Organometallic Complexes

We report the on-surface formation of Au-directed heptacene organometallic complexes on a Au(111) template in an ultrahigh vacuum environment. Successive thermal annealing steps investigated by means of scanning tunneling microscopy, noncontact atomic force microscopy, temperature-programmed desorption and density functional theory reveal the formation of heptacene organometallic complexes via a selective two-step activation of an alpha-diketone-protected heptacene precursor. Furthermore, we demonstrate the efficiency of tip-induced deprotection experiments as a complementary strategy in the complex formation. Our results provide perspectives for the on-surface synthesis of larger acenes featuring potential use in the fields of organic electronics, spintronics and nonlinear optics.