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(CH3OH)(2)(18-crown-6)] (+) [Cu-5((SBu)-Bu-t)(6)](-) (1 . CH3OH) in the chiral space group was prepared, in which the chiral red-emissive anionic [Cu-5((SBu)-Bu-t)(6)](-) cluster was arranged along a twofold screw axis. Interestingly, the release of the coordinated CH3OH of the cationic units turned the chiral 1.CH3OH crystal into a mesomeric crystal [K(18-crown-6)] (+) [Cu-5((SBu)-Bu-t)(6)] (-) (1), which has a centrosymmetric space group, by adding symmetry elements of glide and mirror planes through both disordered [Cu-5((SBu)-Bu-t)(6)] (-) units. The switchable chiral/achiral rearrangement of [Cu-5((SBu)-Bu-t)(6)](-) clusters along with the capture/release of CH3OH 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-5((SBu)-Bu-t)(6)] (-) (d/l-Cu-5V), which display impressive circularly polarized luminescence (CPL) in contrast to the CPL-silent racemic mixture of 1.CH3OH and mesomeric 1.