On-surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building-blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On-surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π-extended two-dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single-active site character of their single-molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom-up constructed covalent nanomeshes.

On-surface chemistry holds the potential for ultimate miniaturization of functional devices. Porphyrins are promising building-blocks in exploring advanced nanoarchitecture concepts. More stable molecular materials of practical interest with improved charge transfer properties can be achieved by covalently interconnecting molecular units. On-surface synthesis allows to construct extended covalent nanostructures at interfaces not conventionally available. Here, we address the synthesis and properties of covalent molecular network composed of interconnected constituents derived from halogenated nickel tetraphenylporphyrin on Au(111). We report that the π-extended two-dimensional material exhibits dispersive electronic features. Concomitantly, the functional Ni cores retain the same single-active site character of their single-molecule counterparts. This opens new pathways when exploiting the high robustness of transition metal cores provided by bottom-up constructed covalent nanomeshes.

No abstract

Topological insulators (TIs) form a class of materials whose properties are associated with nongeneric quantum effects. Phenomenologically, TIs are semiconductors in the bulk, but possess metallic surface states of a distinctive quality. These surface states are protected by the topology of the bulk electronic structure. [1] Their momentum (propagation direction) and their spin are locked orthogonally. This stabilization can only be broken by strong perturbation, e.g., by an energy exceeding the topologically nontrivial bandgap of the bulk. As a result, these surface electrons are protected against backscattering from nonmagnetic impurities, [2] leading to dissipation-free charge transport and preservation of spin orientation under suitable conditions. [3] Therefore, TIs are envisioned as promising materials for high-performance spin field-effect transistors [4] and as quantum bits in quantum computing. [5] Despite the strong interest in TIs, the number of TIs experimentally proven as well as useable under "real" conditions is still quite limited.