Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ): the first fluoride-containing iodate-phosphate with a 1D [Ga 2 F 6 (IO 3 )(PO 4 )] 4- helix chain.

Herein, the first F-containing iodate-phosphate, namely Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ), was prepared via a hydrothermal reaction, in which HPF 6 (70 wt% solution in water) was used as the source of both fluoride and phosphate anions for the first time. Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ) features an unprecedented 1D [Ga 2 F 6 (IO 3 )(PO 4 )] 4- helix chain, composed of a 1D Ga(1)(IO 3 )O 4 F chain via the bridging of 0D Ga(2)(PO 4 )F 5 . The UV-Vis spectrum shows that Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ) has a wide bandgap with a short-UV absorption edge (4.35 eV; 253 nm). Birefringence measurement under a polarizing microscope shows that Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ) displays a moderate birefringence of 0.072@550 nm, which is consistent with the value (0.070@550 nm) obtained by DFT calculations, indicating that Ba 2 Ga 2 F 6 (IO 3 )(PO 4 ) has potential applications as a short-UV birefringent material. This study highlights the crucial role played by the incorporation of specific functional groups into compounds, shedding light on their contribution to promising inorganic functional materials.