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A unified approach to the synthesis of the series of higher acenes up to previously unreported undecacene has been developed through the on‐surface dehydrogenation of partially saturated precursors. These molecules could be converted into the parent acenes by both atomic manipulation with the tip of a scanning tunneling and atomic force microscope (STM/AFM) as well as by on‐surface annealing. The structure of the generated acenes has been visualized by high‐resolution non‐contact AFM imaging and the evolution of the transport gap with the increase of the number of fused benzene rings has been determined on the basis of scanning tunneling spectroscopy (STS) measurements.

Present-day electronic technology, based to a large extent on silicon fabricated devices, is surely approaching size limitations arising from quantum effects. The effort to achieve rapid development of electronic devices requires implementation of entirely new ideas that will allow existing technological constraints to be overcome. Among a wide range of concepts, utilization of single organic molecules, acting as active blocks performing logic operations, appears as one of the most appealing and is based on the state-of-the-art use of modern nanotechnology. In this short review, we offer a selection of recent experiments addressing milestones of single-molecule computing devices technology. Along with discussion of the latest achievements in atomic- and molecular-scale technologies, we discuss their future perspectives, challenges, and still unsolved issues standing in the way of practical implementation of single-molecule devices. Concept of a single-molecule electronic device. The molecule is equipped with various functional groups responsible for logic operations and bonding to an underlying surface and metallic nanoelectrodes. The monomolecular nanodevice is deposited on a thin buffer layer assuring the decoupling from a (semi-)conducting substrate.

The adsorption of individual Violet Lander molecules self-assembled on the c(8x2) reconstructed InSb(001) surface in its native form and on the surface passivated with one to three monolayers of KBr is investigated by means of low-temperature scanning tunneling microscopy (STM). Preferred adsorption sites of the molecules are found on flat terraces as well as at atomic step edges. For molecules immobilized on flat terraces, several different conformations are identified from STM images acquired with submolecular resolution and are explained by the rotation of the 3,5-di-tert-butylphenyl groups around sigma bonds, which allows adjustment of the molecular geometry to the anisotropic substrate structure. Formation of ordered molecular chains is found at steps running along substrate reconstruction rows, whereas at the steps oriented perpendicularly no intermolecular ordering is recorded. It is also shown that the molecules deposited at two or more monolayers of the epitaxial KBr spacer do not have any stable adsorption sites recorded with STM. Prospects for the manipulation of single molecules by using the STM tip on highly anisotropic substrates are also explored, and demonstrate the feasibility of controlled lateral displacement in all directions.

Molecular reorientation: Copper (II) phthalocyanines are investigated on the rutile TiO2(011)-(2×1) surface. At first, a quasi-ordered wetting monolayer is formed, after which well-ordered islands composed of flat-lying molecules appear (picture, left). Post-deposition thermal annealing at 200 °C leads to a complete reorientation of the second layer so that the molecules adopt an upright configuration (picture, right).