hybrid perovskites (HOIPs) with noticeable circular dichroism (CD) in 2017. [7] (2). It opens up new possibilities to advance our materials functionalities. For example, the chirality transfer from organic ligands to inorganic structures provides a synthetic design paradigm toward Rashba-Dresselhaus spin-polarization for spintronics. [8] In conventional cases, the incorporation of (S-or R-) chiral organic ligands will not affect the resulting metal halide composite structure as compared with the incorporation of racemic (mixed equal ratio of S-and R-) organic ligands because of indistinguishable composition, similar chemical bonding and similar tethering group packing characteristics between enantiomers of chiral materials. This is widely demonstrated by nearidentical X-ray diffraction (XRD) patterns and photo luminescence (PL) spectra observed for chiral and racemic materials. [9][10][11][12][13][14][15] However, Zhao and his co-workers observed different photoluminescent behaviors between chiral and racemic metal halide perovskites. The optical difference was ascribed to the distinction of weak interactions existing in the perovskite crystal structure such as the hydrogen bonding and van der Waals force. [16] Moreover, recent experimental results by Mitzi and co-workers also demonstrated that the asymmetric hydrogen bonding in the chiral organic ligand (1-(1-naphthyl) ethylammonium) can induce more distorted PbBr 6 octahedra than the racemic one (without asymmetric hydrogen bonding), resulting in a difference in the corresponding perovskite XRD patterns. [8,17] These findings point out a new possibility that incorporating chiral ligands in metal halide composites can change the resulting structure, an effect though not been demonstrated previously.In the present work, by introducing MBA (methylbenzylamine) into manganous bromide frameworks, we discover a significant difference in the crystal structure between chiral and racemic metal halide composites. The XRD patterns indicate that the crystal structure is switched from octahedron of one-dimensional (chain-like) in racemic composites to tetrahedron of one-dimensional (chain-like) in chiral composites. Consistently, significantly different PL results are also observed in these composites. Specifically, the chiral composites exhibit bright green emissions while the racemic composite shows bright red emissions in low-humidity conditions. In addition, the green emission in chiral composite turns red with increasing humidity, suggesting the moisture induced crystal structure transformation. In contrast, the racemic composite shows no moisture response. The different moisture response might result from the difference in hydrogen bonding in these Incorporating chiral organic compounds into metal halide frames is a common and useful method to introduce chirality in metal halide composites. The structures of resulting racemic and chiral composites are usually considered to be nearly identical owing to similar chemical bonding. In this work, by incorporating chiral MBAB...

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