Multi-Emission Regulated by Coordination Bonding and Protonation in Chiral Hybrid Zinc(II) Halides for Circularly Polarized Luminescence and Anticounterfeiting

Abstract Luminescent hybrid metal halides (HMHs) have emerged as promising platforms for circularly polarized luminescence (CPL); however, their rational design remains challenging due to the limited understanding of the relationship between structural chirality and the luminescence dissymmetry factor (glum). Herein, using chiral 2,2′-bipyridine-based enantiomers and by modulating the synthesis pathways, two pairs of chiral Zn(II) hybrids ([Zn(R/S-L)3][ZnBr4] (R-HH-1/S-HH-1) and [H2R/S-L][ZnBr4] (R-HH-2/S-HH-2)) were synthesized. In R-HH-1/S-HH-1, [Zn(R/S-L)3] node adopts Λ- and Δ-enantiomorphic configurations, R-HH-1/S-HH-1 exhibited blue fluorescence and green room-temperature phosphorescence (RTP). The luminescence of R-HH-2/S-HH-2 is dominated by green self-trapped exciton (STE) emission. Importantly, these two pairs of chiral HMHs have high glum values; especially, the glum values of R-HH-2/S-HH-2 are +12.23 × 10–3 and −11.68 × 10–3, improved by the hierarchical chiral hydrogen-bonding networks. Meanwhile, these HMHs exhibit photochromic properties for anticounterfeiting. This work provides an approach for the design of high-performance chiroptical HMHs.