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

Two layered galloborates (GBOs), Na 3 GaB 4 O 9 (1) and Na 5 Ga[B 7 O 12 (OH)] 2 ·2B(OH) 3 (2), have been solvothermally made. 1 exhibits an unprecedented layer built by GaO 4 tetrahedra and B 4 O 9 clusters. 2 was made by raising the ratio of B/Ga and the reaction temperature of 1, featuring a 2D acentric layer built by GaO 4 groups and B 7 O 13 (OH) clusters. 2 shows the highest second-harmonic generation (SHG) response of 4.6 times that of KDP (KH 2 PO 4 ) among main group metal borates (MBOs).