Homochiral hybrid hexagonal antiperovskite crystals [R- and S-3-chloroquinuclidinium]3(CdCl3)(CdCl4)

Hybrid chiral perovskites with promising optoelectronic and spintronic applications have attracted great attention. However, reports on hybrid chiral antiperovskites have been rare. In this work, we have successfully designed and synthesized a pair of new homochiral hybrid X(3)AB-type hexagonal antiperovskite crystals [R- and S-3-chloroquinuclidinium](3)(CdCl3)(CdCl4) (R-1 and S-1) by a homochiral strategy. Accordingly, the racemic crystal [3-chloroquinuclidinium]CdCl3 has experienced a significant transformation from an ordinary one-dimensional chain-like hybrid framework to an infrequent hybrid hexagonal antiperovskite structural stacking in homochiral crystals. The enantiomeric relationship between R-1 and S-1 verified by circular dichroism spectra and their active nonlinear optical intensity indicates the delivery of chirality from organic cations to the entire molecular level. In addition, the representative R-1 exhibits an evident thermal anomaly and step-like dielectric response around 406 K, pointing to a possible isomorphic phase transition in R-1 and S-1. To our knowledge, this is the first report on homochiral hybrid hexagonal antiperovskite crystals. This finding would inspire the design of a novel chiral antiperovskite family by a homochiral strategy.