KCs₂[GaB₅O₁₀](OH): A Zeolitic Galloborate Framework with a Nonlinear Optical Property

An acentric 3D zeolitic galloborate (GBO) KCs2[GaB5O10](OH) (1) has been successfully synthesized by a hydrothermal method. The alternation of GaO4 and B5O10 clusters constructs the 3D zeolitic framework of 1, exhibiting the unique and topology with different 8-/12-MR and open channels along different directions, which were first observed in zeolitic borates. Second-harmonic generation (SHG) measurements reveal that 1 is a phase-matchable nonlinear optical material with an SHG response of about 1.4 times that of KDP (KH2PO4). A UV–vis spectrum shows that 1 has a cutoff edge of 199 nm, indicating its potential applications in deep-UV regions.