Synthesis of a covalent square grid

摘要

For quite a few years, the area of atomic and molecular scale technology has been the subject of intense speculation. There has also been considerable interest in the actual synthesis of various more or less complex single-molecule devices, both electrical (e.g. switches and wires) and mechanical (e.g., brakes, turnstiles, levers, and even a mousetrap). However, it is often not very clear how any of these devices would be used in practice when they float about freely in a solution. Some degree of control over their location in space and absolute orientation would appear highly desirable, particularly if several devices are to work together. One possibility is to adsorb them on a surface in an oriented fashion, perhaps singly for work with an STM tip or in a periodic array dictated by a surface lattice, or attached to the outside of a self-assembled monolayer. Still, the degree of control over their location in space and absolute orientation would remain rather limited. Another possibility is to allow the devices to form a three-dimensionally periodic lattice of a crystal. Usually, they will then be packed in a manner over which one has limited control, if any. Such regular arrays could still be quite useful, e.g., as quantum dots, if one had complete control over the separations, the nature of the material that separates them, and the geometry of the lattice. Much progress in crystal engineering has been made by numerous research groups, and this type of control may be available in the future.