All elementary steps of a chemical reaction have been successfully induced on individual molecules with a scanning tunneling microscope (STM) in a controlled step-by-step manner utilizing a variety of manipulation techniques. The reaction steps involve the separation of iodine from iodobenzene by using tunneling electrons, bringing together two resultant phenyls mechanically by lateral manipulation and, finally, their chemical association to form a biphenyl molecule mediated by excitation with tunneling electrons. The procedures presented here constitute an important step towards the assembly of individual molecules out of simple building blocks in situ on the atomic scale.

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The design of networks of organic molecules at metal surfaces, highly attractive for a variety of applications ranging from molecular electronics to gas sensors to protective coatings, has matured to a degree that patterns with multinanometre unit cells and almost any arbitrary geometry can be fabricated. This Review provides an overview of vacuum-deposited organic networks at metal surfaces, using intermolecular hydrogen bonding, metal-atom coordination and in situ polymerization. Recent progress in these areas highlights how the design of surface patterns can benefit from the wealth of information available from solution- and bulk-phase chemistry, while at the same time providing novel insights into the nature of such bonds through the applicability of direct scanning probe imaging at metal surfaces.

A reliable procedure for controlled vertical transfer of single CO molecules between a Cu(111) surface and a scanning tunneling microscope tip and vice versa is demonstrated. It is shown that with a tip having a single CO molecule at its apex, chemical contrast is achieved allowing distinction of adsorbed CO molecules and oxgen atoms, which look very similar to the bare metal tip.

MoS2(1-x) Se2x single-layer films are prepared using a mixture of organic selenium and sulfur precursors as well as a solid molybdenum source. The direct bandgaps are found to scale nearly linearly with composition in the range of 1.87 eV (pure single-layer MoS2 ) to 1.55 eV (pure single-layer MoSe2 ) permitting straightforward bandgap engineering.