Two layered galloborates from centric to acentric structures: syntheses and NLO properties

Two layered galloborates (GBOs), Na3GaB4O9 (1) and Na5Ga[B7O12(OH)]2·2B(OH)3 (2), have been solvothermally made. 1 exhibits an unprecedented layer built by GaO4 tetrahedra and B4O9 clusters. 2 was made by raising the ratio of B/Ga and the reaction temperature of 1, featuring a 2D acentric layer built by GaO4 groups and B7O13(OH) clusters. 2 shows the highest second-harmonic generation (SHG) response of 4.6 times that of KDP (KH2PO4) among main group metal borates (MBOs).