Organic ligand mediated evolution from aluminum-based superalkalis to superatomic molecules and one-dimensional nanowires

Superatoms are considered as promising building blocks for customizing superatomic molecules and cluster-assembly nanomaterials due to their tunable electronic structures and functionalities. Electron counting rules, which mainly adjust the shell-filling of clusters, are classical strategies in designing superatoms. Here, by employing the density functional theory (DFT) calculations, we proved that the 1, 4-phenylene diisocyanide (CNC₆H₄NC) ligand could dramatically reduce the adiabatic ionization potentials (AIPs) of the aluminum-based clusters, which have 39, 40, and 41 valence electrons, respectively, to give rise to superalkali species without changing their shell-filling. Moreover, the rigid structure of the ligand can be used as a bridge firmly linking the same or different aluminum-based clusters to form superatomic molecules and nanowires. In particular, the bridging process was observed to enhance their nonlinear optical (NLO) responses, which can be further promoted by the oriented external electric field (OEEF). Also, the stable cluster-assembly XAl₁₂(CNC₆H₄NC) (X = Al, C, and P) nanowires were constructed, which exhibit strong absorption in the visible light region. These findings not only suggest an effective ligand-field strategy in superatom design but also unveil the geometrical and electronic evolution from the CNC₆H₄NC-based superatoms to superatomic molecules and nanomaterials.