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 3 OH) 2 (18‐crown‐6)] + [Cu 5 (S t Bu) 6 ] − ( 1⋅CH 3 OH ) in the chiral space group was prepared, in which the chiral red‐emissive anionic [Cu 5 (S t Bu) 6 ] − cluster was arranged along a twofold screw axis. Interestingly, the release of the coordinated CH 3 OH of the cationic units turned the chiral 1⋅CH 3 OH crystal into a mesomeric crystal [K(18‐crown‐6)] + [Cu 5 (S t Bu) 6 ] − ( 1 ), which has a centrosymmetric space group, by adding symmetry elements of glide and mirror planes through both disordered [Cu 5 (S t Bu) 6 ] − units. The switchable chiral/achiral rearrangement of [Cu 5 (S t Bu) 6 ] − clusters along with the capture/release of CH 3 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 5 (S t Bu) 6 ] − ( d / l ‐Cu 5V ), which display impressive circularly polarized luminescence (CPL) in contrast to the CPL‐silent racemic mixture of 1⋅CH 3 OH and mesomeric 1 .