Cations Controlling the Chiral Assembly of Luminescent Atomically Precise Copper(I) Clusters.

Chiral assembly and asymmetric synthesis are critically important for the generation of chiral metal clusters with chiroptical activities. Here, a racemic mixture of [K(CH OH) (18-crown-6)] [Cu (S Bu) ] (1⋅CH OH) in the chiral space group was prepared, in which the chiral red-emissive anionic [Cu (S Bu) ] cluster was arranged along a twofold screw axis. Interestingly, the release of the coordinated CH OH of the cationic units turned the chiral 1⋅CH OH crystal into a mesomeric crystal [K(18-crown-6)] [Cu (S Bu) ] (1), which has a centrosymmetric space group, by adding symmetry elements of glide and mirror planes through both disordered [Cu (S Bu) ] units. The switchable chiral/achiral rearrangement of [Cu (S Bu) ] clusters along with the capture/release of CH OH were concomitant with an intense increase/decrease in luminescence. We also used cationic chiral amino alcohols to induce the chiral assembly of a pair of enantiomers, [d/l-valinol(18-crown-6)] [Cu (S Bu) ] (d/l-Cu ), which display impressive circularly polarized luminescence (CPL) in contrast to the CPL-silent racemic mixture of 1⋅CH OH and mesomeric 1.