Substituent Effect on the Circularly Polarized Luminescence of C1-Symmetric Carbene-Copper(I) Complexes

The substituent effect on the magnitude of the circularly polarized luminescence (CPL) of (Ment)CAAC-Cu-X (X=F, Cl, Br, I, BH4, B3H8; CAAC=cyclic (alkyl)(amino)carbenes) complexes is experimentally investigated. This study examines seven pairs of enantiomeric complexes with small anionic substituents (halides, borohydrides, hydride). The complexes are fully characterized, including single crystal X-ray diffraction studies, and chiroptical measurements show that small covalent anions induce a larger CPL magnitude. These results demonstrate that the magnitude of the CPL can be manipulated without making any modifications to the chiral ligand.