Hydroxyfluorooxoborate (NH 4 )[C(NH 2 ) 3 ][B 3 O 3 F 4 (OH)] for exploring the effects of cation substitution on structure and optical properties.

Cation substitution is a straightforward but effective technique for improving the structure and properties; however, controlling directed substitution still poses significant difficulties. Herein, a metal-free hydroxyfluorooxoborate (NH 4 )[C(NH 2 ) 3 ][B 3 O 3 F 4 (OH)] has been synthesized using the strategy of heterologous substitution based on the template of A 2 [B 3 O 3 F 4 (OH)]. Tunable structure and optical properties have been achieved via varied A-site cation substitution. The intrinsic mechanism for this tunability was established by crystallography and theoretical research.