Chemistry and properties at a sub-nanometer scale

Ultrathin materials at a sub-nanometer scale not only feature atomic scale size, but also possess unprecedented properties compared to conventional nanomaterials. The two aspects endow such materials with great potential. In sub-nanometric (SN) wires, the weak interactions may overwhelm the rigidity of inorganic compounds and dominate behaviours at this regime. Consequently intricate structures and polymer-like rheology can be obtained, shedding new light on chemistry as well as material design. As for 0D or 2D SN materials, clusters are analogous to molecules and SN sheets show unique electronic structures. Taking SN wire as an example, their growth mechanisms are discussed, as well as their applications and potentials. The chemistry at this regime can promote their application-oriented research, however, this is not yet well explored. In short, there is great potential at the sub-nanometer scale, although there are also many challenges ahead.