Superatom-assembled boranes,carboranes,and low-dimensional boron nanomaterials based on aromatic icosahedral B_(12)and C_(2)B_(10)

Using the experimentally known aromatic icosahedral superatoms I_(h)B_(12)H_(12)2−and D_(5d)1,12-C_(2)B_(10)H_(12)as building blocks and based on extensive density functional theory calculations,we predict herein a series of core–shell superpolyhedral boranes and carboranes in a bottom-up approach,including the high-symmetry Th B_(12)@B_(152)H_(72)2−(2),C2h C_(2)B_(10)@B_(152)H_(72)(3),D_(3d)B_(12)@B_(144)H_(66)(4),I_(h)B_(12)@C_(24)B_(12)0H_(72)2−(6),and D_(5d)C_(2)B_(10)@C_(24)B_(12)0H_(72)(7).More interestingly,the superatom-assembled linear D2h B_(36)H_(32)^(2−)(8),close-packed planar D_(3d)B_(84)H_(60)^(2−)(10),and nearly close-packed core−shell D_(3d)B_(12)@B144H_(6)6(4)can be extended periodically to form the one-dimensional(1D)α-rhombohedral borane nanowire B_(12)H_(10)(Pmmm)(9),two-dimensional(2D)α-rhombohedral monolayer borophane B_(12)H_(6)(P m1)(11),and the experimentally known three-dimensional(3D)α-rhombohedral boron(R m)(12)which can be viewed as an assembly of the monolayer B_(12)H_(6)(11)staggered in vertical direction,setting up a bottom-up strategy to form low-dimensional boron-based nanomaterials from their borane“seeds”via partial or complete dehydrogenations.Detailed bonding analyses indicate that the high stability of these nanostructures originates from the spherical aromaticity of their icosahedral B_(12)or C_(2)B_(10)structural units which possess the universal skeleton electronic configuration of 1S21P61D101F8 following the Wade’s n+1 rule.The infrared(IR)and Raman spectra of the most-concerned neutral B_(12)@B144H_(6)6(4)and C_(2)B_(10)@C_(24)B_(12)0H_(72)(7)are computationally simulated to facilitate their experimental characterizations.

Organic ligand mediated evolution from superalkalis to superatomic molecules and 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(CNC_(6)H_(4)NC)ligand could dramatically reduce the adiabatic ionization potentials(AlPs)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 XAl_(12)(CNC_(6)H_(4)NC)(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 CNC_(6)H_(4)NC-based superatoms to superatomic molecules and nanomaterials.