Versatile Uranyl Germanate Framework Hosting 12 Different Alkali Halide 1D Salt Inclusions.

Single crystals of 13 new uranyl germanate salt-inclusion materials were grown from alkali halide fluxes: [Cs2Cs5F][(UO2)3(Ge2O7)2] (1), [Cs6Ag2Cl2][(UO2)3(Ge2O7)2] (2), [Cs6Ag0.3Na1.7Cl2][(UO2)3(Ge2O7)2] (3), [Cs6Ag0.4Na1.6Cl2][(UO2)3(Ge2O7)2] (4), [Cs6K2Cl2][(UO2)3(Ge2O7)2] (5), [Cs6K1.9Ag0.1Cl2][(UO2)3(Ge2O7)2] (6), [KK6Cl][(UO2)3(Ge2O7)2] (7), [KK6Br0.6F0.4][(UO2)3(Ge2O7)2] (8), [Na0.9Rb6.1F][(UO2)3(Ge2O7)2] (9), [K0.6Na0.4K5CsCl0.5F0.5][(UO2)3(Ge2O7)2] (10), [K0.8Na0.2K4.8Cs1.2Cl0.5F0.5][(UO2)3(Ge2O7)2] (11), [KK1.8Cs4.2F][(UO2)3(Ge2O7)2] (12), and [Cs6Cs0.71Cl0.71][(UO2)3O3(Ge2O7)] (13). Structures 1-12 contain the same [(UO2)3(Ge2O7)2]6- framework whose pores are filled with varied salt species selected by the choice of the specific alkali halide flux used for crystal growth. The size and identity of the salt species also influence whether the [(UO2)3(Ge2O7)2]6- framework adopts a monoclinic or orthorhombic symmetry. The 13th composition, [Cs6Cs0.71Cl0.71][(UO2)3O3(Ge2O7)] (13), crystallizes in a new structure type in the hexagonal crystal system and contains large channels. Optical characterization was performed on [Cs6K1.9Ag0.1Cl2][(UO2)3(Ge2O7)2] (6) and [KK1.8Cs4.2F][(UO2)3(Ge2O7)2] (12), and both exhibit UV-vis absorption and luminescence typical of the uranyl group. The fluorine-containing composition luminesces 10 times as intensely as does the chlorine-containing composition.