K2Na3[{B6O10(OH)}{B3O4(OH)3}] ⋅ H2O: A Layered Borate Built by Mixed Oxoboron Clusters with Nonlinear‐Optical Property.

A new acentric borate, K2Na3[{B6O10(OH)}‐{B3O4(OH)3}] ⋅ H2O (1) has been made under solvothermal condition. 1 has layered structure made by B6O13(OH)‐based chains and B3O5(OH)3‐bridging clusters. Second‐harmonic generation (SHG) measurements reveal that 1 is a phase‐matchable nonlinear optical (NLO) material, showing the SHG signal intensity of 1.8 times that of KDP (KH2PO4). Besides, UV‐Vis diffuse reflectance spectrum shows that 1 has the short deep UV (DUV) absorption cutoff edge of 198 nm. Thermogravimetric analysis reveals it has good thermal stability. Also 1 represents firstly mixed oxoboron clusters‐made 2D layered borate with NLO property. [ABSTRACT FROM AUTHOR]