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The impact of halogens on chiral crystal structures and properties has been a significant focus. In this study, we utilize protonated R/S-tetrahydro-2H-pyran-3-ammonium (R/S-3ATHP) as an organic cation to synthesize four pairs of one-dimensional (1D) helical chiral hybrid metal halides. The replacement of the halogen anions (X = Cl−, Br−, and I−) and variation of the cation/anion ratio induce changes in the 1D chain packing mode and helicity of the inorganic components in the crystals. Notably, the Br-based chiral hybrid metal halides exhibit two structures, analogous to the Cl (zigzag, z-) and I (linear, l-) counterparts. Structural variations resulting from halogen adjustments further modulate the chiroptical activity, semiconducting, and photoluminescence properties of the crystals. Particularly noteworthy is the helicity of the [PbX6] octahedral-based chains that is significantly influenced by the asymmetric hydrogen bonding interactions which are determined by the halogens and the number of organic cations. The regular change observed in gCD values: z-(R/S-3ATHP)3PbBr5 > z-(R/S-3ATHP)3PbCl5 > l-(R/S-3ATHP)PbI3 > l-(R/S-3ATHP)PbBr3, is correlated with helicity of the helical 1D chains in the crystals, indicating that more helicity corresponds to stronger chiroptical activity. This work establishes a model system for comprehending the interplay between halogens and structural diversity as well as helicity and chiroptical activity, contributing to a deeper understanding of these relationships in related fields. [ABSTRACT FROM AUTHOR]

Multiferroics refer to materials with two or more ferroic orders in one phase within a specific temperature range, including ferroelectricity, ferroelasticity, and ferromagnetism which have been widely used in sensors, actuators, and memory devices. Among them, hybrid perovskites exhibiting multiferroicity are generally limited to low dimensions (0D–2D). Designing 3D lead‐free perovskite multiferroics remains a challenge due to Goldschmidt's tolerance factor limitation. Here, a multiferroic perovskite (R‐3AP)RbBr3 (1; 3AP = 3‐ammoniopyrrolidinium) is successfully synthesized by introducing homochirality to the 3D ferroelectric (Rac‐3AP)RbBr3, achieving both ferroelasticity and ferroelectricity. Compound 1 undergoes a structure phase transition at 401 K belonging to Aizu notation 432F2(s), which has 12 ferroelectric equivalent polarization directions and 6 polar axes. Furthermore, 1 exhibits reversible second harmonic generation switching effects. Moreover, while the temperature varies, the reversible and rapid changes of ferroelastic domains in 1 are observed using a polarizing microscope, indicating that it is a ferroelastic material. This work provides a practical method for designing and synthesizing molecule‐based multiferroics. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead‐free HMHs (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains. [ABSTRACT FROM AUTHOR]

Poor stability is a significant challenge to organic–inorganic hybrid perovskites for practical optoelectronic applications, which results from their inherent ionic nature and soft structures. The coordination bonding strategy is supposed to be a valid approach by enhancing the interaction between the cations and inorganic frameworks. Herein, the first pair of cation‐coordinated perovskites with high stability, achieved through coordination bonds between the cations and [PbXn] anions instead of the weak hydrogen bonds and van der Waals force presented in conventional ionic perovskites, is reported. In L/R‐(4HOPD)PbBr3 (4HOPD = 4‐hydroxypiperidine cation) (L/R=Left/Right–handed), one of the six halogen atoms is replaced by an oxygen atom from the cation. The PbO bond contributes to the high stability under a double 85 test. L/R‐(4HOPD)PbBr3 crystallizes in the tetragonal system, belonging to one of 11 enantiomorphic space group types, P41212 and P43212. Similar to quartz, the chirality originates from the helical assembly of achiral units. The chirality‐induced optical rotatory power is 16.84° mm−1 at 404 nm. Moreover, the uniaxial negative birefringent property with a comparable Δn value makes it a good alternative to quartz. The remarkable stability of this new perovskite presents significant potential for further investigation into stable perovskites and their applications in optical rotation and polarizing optics. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) with polychromatic colors has been widely studied due to its great applications in chiroptical, optoelectronics, and spintronics. However, the realization of white CPL in single‐component solid‐state materials remains a great challenge and suffers from the incompatibility between high efficient luminescence and large asymmetric discrimination. Here, by exploiting self‐trapped exciton mechanism and chirality induction strategy, a pair of 1D chiral perovskites, (RR/SS‐DMPZ)PbBr4 (where DMPZ = cis‐2,5‐dimethylpiperazine divalent cation), is reported to achieve white CPL with both high quantum yield of 28.4% and large photoluminescence asymmetry factor |glum| of 2.32 × 10−2. The crystal structures are featured by 1D double‐chain structure composed of distorted octahedra with short PbPb distances as the structural origin of the high photoluminescence yield. The high |glum| value is caused by efficient chiral induction due to the multiple hydrogen bonds between the chiral host composed of the enantiopure organic cations containing two stereocenters and the inorganic emitting guest. The self‐trapped exciton emission mechanism is demonstrated by density functional theory calculations and variable‐temperature photoluminescence and femtosecond‐transient absorption spectroscopy studies. The photo‐luminescent white light‐emitting diodes exhibit good stability and can be used as single‐component white light emitters. This work provides applicable strategies to explore single‐component white CPL emitters. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead-free HMHs (R-3FP) 2 SbCl 5 (1; 3FP=3-fluoropyrrolidinium) and (R-3FP) 2 SbBr 5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains., (© 2023 Wiley-VCH GmbH.)