A Semiconductor Nanocluster Platform with Four Structural Configurations: An Ionic Pair with Tunable Chirality

In chemistry, a cluster refers to an ensemble of a certain number of atoms that exhibit distinct physicochemical properties as a unified entity. Isostructural clusters, with subtle variations in structure or composition, can display opposite charges, behaving like monatomic ions to undergo classical reaction processes like disproportionation. Herein, we report that the semiconductor nanoclusters can be obtained in the form of a co-crystallized ionic pair, [Cu₅₆S₁₂(SAdm)₂₀(PP)₁₀]⁺[S@Cu₅₆S₁₂(SAdm)₂₀(PP)₁₀]^- (abbreviated as [S-Cu₅₆]·[S@S-Cu₅₆] hereafter). This bi-nanocluster system is a derivative of a neutral copper sulfide nanocluster [S-Cu₅₆] with an interesting onion-like structural configuration containing multiple shells. It consists of two nearly isostructural copper sulfide nanoclusters with opposite charges that differ only by the presence of a S^2- ion at the center of the cluster assembly. This represents an interesting ionic bi-nanocluster system within the p-type copper sulfide semiconductor family, offering the potential to exhibit electrical properties not observed in the individual component nanoclusters. Notably, by utilizing different chiral carboxylate ligands, chirality can be concurrently imparted to the inorganic cores of both ionic clusters, thereby enabling distinct chiroptical responses as revealed by circular dichroism spectroscopy. This eventually results in four different structural configurations based on this onion-like semiconductor nanocluster platform.