Chirality\nand Solvent Coassist the Structural Evolution\nof Hybrid Manganese Chlorides with Second-Harmonic-Generation Response

Chiral hybrid metal halides have shown great potential\nin optoelectronics,\nincluding for spin splitting, circularly polarized luminescence, and\nnonlinear-optical properties. However, despite their inherent inversion\nsymmetry breaking, studies on second harmonic generation (SHG) of\nchiral hybrid manganese(II) halides remain relatively rare. Here,\nwe report a series of structurally diverse hybrid manganese(II) chlorides:\n(Rac-MBA)<sub>2</sub>[MnCl<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>1</b>), (S-MBA)<sub>2</sub>[MnCl<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>] (<b>2</b>), (S-MBA)<sub>2</sub>[Mn<sub>2</sub>Cl<sub>6</sub>(H<sub>2</sub>O)<sub>4</sub>] (<b>3</b>), and\n(S-MBA)[MnCl<sub>3</sub>(MeOH)] (<b>4</b>), where MBA = α-methylbenzylammonium,\nproviding tunability of the coordination environment and structural\ndimensionality via fine control of the MBA cation chiral state and\ncrystal preparation process, thereby enabling modulation of the SHG\neffects. Specifically, as the amount of methanol increases during\nthe crystal preparation process, the structures of the chiral compounds\nvary from a 0D structure consisting of isolated octahedra to a 0D\nstructure composed of octahedra dimers and to 1D chains of edge-sharing\nMn-centered octahedra. In contrast, the structure of the racemic compound\nremains unchanged, independent of the crystal preparation pathway.\nThe structural details, including the coordination environment, H-bonding,\ndimensionality, and lattice distortion, are described. The SHG response\nof the racemic compound derives only from the inorganic lattice, while\nthe responses of the chiral compounds are attributed to the synergetic\neffect of the chiral cations and inorganic moieties.