Chiral Separation of Copper Sulfide [S-Cu₃₆] Nanocluster Using a Chiral Adaptive Counterion

This work presents a new strategy to achieve the growth of copper sulfide nanoclusters with high nuclearity. Through a phosphine-assisted C-S reductive cleavage approach, an intrinsically chiral [Cu₄] cluster passes through a [S-Cu₉] cluster and transforms into a higher-nuclearity [S-Cu₃₆] cluster, which features a core-shell structure with a [Cu₄]⁴⁺ core encapsulated by a chiral [Cu₂₀S₁₂] shell. Interestingly, the spiral arrangement of the bidental ligands on the surface of the [S-Cu₃₆] cluster leads to the L-/R-enantiomeric configurations. Moreover, by utilization of [Na(THF)₆]⁺ as a chiral adaptive counterion, [S-Cu₃₆] can be interlocked separately, thus enabling the isolation of homochiral clusters. Theoretical calculation suggests that the configuration transition between two enantiomeric [Na(THF)₆]⁺ species is favorable at room temperature, thereby promoting the cocrystallization of resulting chiral products. This study introduces a novel perspective on the synthesis of chiral copper sulfide nanoclusters and presents an innovative approach to achieving the chiral separation of nanoclusters.