Strategies for 1D self-assembly. One-dimensional structures can be templated by substrates, either through anisotropic substrate lattices formed when substrates reconstruct to minimize surface energy, or at atomic step edges. One-dimensional structures can also be self-assembled from anisotropic molecules to form ordered assemblies due to interactions such as directional hydrogen-bonding or interactions between long alkyl chains. Such assemblies can then be polymerized to form covalently bound 1D structures. Finally, intrinsically 1D molecules such as DNA may be patterned on substrates directly. Adapted with permission from refs. 163, 168, 173, 181, and 335.