Syntheses and Crystal Structures of Three Organically Templated Gallium Phosphates

Three open-framework gallium phosphates [C6H16N2][Ga(HPO4)(PO4)] (1), {H[C6H16N2](2)[Ga-7(OH)(2)(PO4)(8)]} (2), and {H[C4H12N2](2)[Ga-7(OH)(2)(PO4)(8)]<bold></bold>2H(2)O} (3) were solvothermally synthesized in the presence of 2,6-dimethylpyrazine, N-ethylpiperazine, and piperazine as templates, respectively. Compound 1 possesses an infinite one-dimensional chain structure connected by hydrogen-bond interactions to generate a 3D supramolecular framework. Compounds 2 and 3 show similar inorganic framework structures, which may be viewed as the assembly of a secondary building unit (SBU), Ga6P8 containing two GaO4, two GaO5, two GaO6 as well as eight PO4 groups. The SBUs are linked with each other by vertex-sharing oxygen atoms to form 2D sheets, which are further connected by GaO4 tetrahedra to result in the final 3D open-framework with left- and right-handed helical chains. In these materials, the well-ordered organic species reside in the voids of structures and interact with the framework by way of hydrogen bonds.