Breaking Symmetry\nfor SHG Response: Lanthanide Acetate\nCrystals via Water Molecule Regulation Strategy

In the field of nonlinear optical\n(NLO) materials research,\nthe\ndesign and synthesis of novel materials are crucial for advancing\nmodern scientific and technological development. This study employs\nan innovative coordination strategy, building upon the existing structure\nof [Ln<sub>2</sub>(CH<sub>3</sub>COO)<sub>6</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (Ln = Tb, Sm), to successfully synthesize\na series of acetate rare-earth metal compounds [Ln<sub>2</sub>(CH<sub>3</sub>COO)<sub>6</sub>(H<sub>2</sub>O)]<i><sub>n</sub></i> [Ln = Tb(<b>1</b>), Er(<b>2</b>), Y(<b>3</b>)]\nby regulating the number of water molecules. This approach achieved\na structural transition from centrosymmetric (CS) to noncentrosymmetric\n(NCS), endowing these compounds with significant nonlinear optical\nresponses. We discovered that reducing the coordinated water molecules\nand introducing acetate as a bidentate ligand is an effective method\nfor modulating crystal structure and realizing NLO performance. This\nfinding not only deepens the understanding of the structure of acetate\nsalts but also provides important theoretical and experimental support\nfor the development of materials with potential NLO propeties.