Manipulating Chiroptical Activities in 0D Chiral Hybrid Manganese Bromides by Solvent Molecular Engineering

Abstract 0D hybrid metal halides (0D HMHs) with fully isolated inorganic units provide an ideal platform for studying the correlations between chiroptical activities and crystal structures at atomic levels. Here, through the incorporation of different solvent molecules, a series of 0D chiral manganese bromides ( RR/SS ‐C 20 H 28 N 2 ) 3 MnBr 8 ·2X (X = C 2 H 5 OH, CH 3 OH, or H 2 O) are synthesized to elucidate their chiroptical properties. They show negligible circular dichroism signals of Mn absorptions due to C 2v ‐symmetric MnBr 4 2− tetrahedra. However, they display distinct circularly polarized luminescence (CPL) signals with continuously increased luminescence asymmetry factors ( g lum ) from 10 −4 (X = C 2 H 5 OH) to 10 −3 (X = H 2 O). The increased g lum value is structurally revealed to originate from the enhancement of MnBr 4 2‐ tetrahedral bond‐angle distortions, due to the presence of different solvent molecules. Furthermore, ( RR/SS ‐C 20 H 28 N 2 )MnBr 4 ·H 2 O enantiomers with larger bond‐angle distortions of MnBr 4 2− tetrahedra are synthesized based on hydrobromic acid‐induced structural transformation of ( RR/SS ‐C 20 H 28 N 2 ) 3 MnBr 8 ·2H 2 O enantiomers. Therefore, such ( RR/SS ‐C 20 H 28 N 2 )MnBr 4 ·H 2 O enantiomers exhibit enhanced CPL signals with | g lum | up to 1.23 × 10 −2 . This work provides unique insight into enhancing chiroptical activities in 0D HMH systems.