Formation and manipulation of protopolymer chains.

We define "protopolymer" to mean that the monomer units of a polymer are together and aligned, but are not yet reacted to their final form, the polymer. We have created, observed, and manipulated this new chemical state in linear chains of phenylene on Cu[111] at low temperature. We demonstrate that protopolyphenylene forms by manipulating individual monomer units out of the chains using a scanning tunneling microscope. Both the bare and the phenylene-covered Cu[111] surface can serve as an extended catalytic active site to bring together and to align the monomer phenylene units formed from the dissociative chemisorption of p-diiodobenzene. When short segments of protopolymer chains are moved on the phenylene-covered surface, the intermolecular interactions are sufficiently strong to realign the chains in new locations. The alignment due to these interactions may be used in the controlled growth and assembly, as well as for the simplified manipulation of complex, hierarchical structures.