Theoretical Study on Polynuclear Superalkali Cations with Various Functional Groups as the Central Core

A new series of polynuclear superalkali cations YLi₃⁺ (Y = CO₃, SO₃, SO₄, O₄, and O₅) has been created when the central group is surrounded by alkali atoms. The structural characteristics and stabilities of these systems are provided on the basis of ab initio methods. In the lowest-energy structure of the CO₃Li₃⁺, SO₃Li₃⁺, and SO₄Li₃⁺ cations, the central Y (Y = CO₃, SO₃, and SO₄) group features a slight distortion. The global minima of O₄Li₃⁺ and O₅Li₃⁺ are of the forms O₂^–(Li⁺)₃O₂^– and O₂^–(Li⁺)₃O₃^–, respectively, both of which contain two monovalent ion units. The structural integrity of the central Y group and the arrangement of the lithium ligands are two influencing factors on the vertical electron affinities (EA_vert) for the YLi₃⁺ species. The YLi₃⁺ cation, with its lithium ligands being distributed evenly or far from each other, tends to exhibit a low EA_vert value, whereas a greater extent of cleavage of the central Y group leads to a higher EA_vert value and even makes some species lose their superalkali nature

Supramolecular Motors on Graphite Surface Stabilized by Charge States and Hydrogen Bonds

Molecular motors are nanoscale machines that convert external energies into controlled mechanical movements. In supramolecular motors, the rotator and stator are held together mechanically, and thus the rotation can be essentially barrier free when molecular conformation is negligible. However, nearly all the supramolecular motors appeared in solutions or host–guest complexes. Surface-mounted supramolecular motors have rarely been addressed, even though they are easily manipulated by external fields. Here we report a surface-mounted supramolecular motor assembled by charge states and hydrogen bonds. On a graphite surface, individual ethanol clusters can be charged with a scanning tunneling microscopy tip and then trap the ethanol chains with a permanent dipole moment. Serving as a rotator, the trapped ethanol chains rotate around a charged cluster driven by the inelastic tunneling electrons. Random rotation in clockwise or anticlockwise direction occurs in the chiral molecular chains through chiral flipping. Directional rotation with clockwise chirality can be realized by introducing a chiral branch to the near end of ethanol chains to suppress the chiral flipping with steric hindrance