New organically templated gallium oxalate-phosphate structures based on Ga 4(PO 4) 4(C 2O 4) building unit

Five organic-inorganic hybrid gallium oxalate-phosphates, [Ga ₂(PO ₄) ₂(H ₂O)(C ₂O ₄) _0.5](C ₃N ₂H ₁₂) _0.5(H ₂O) ( 1), [Ga ₂(PO ₄) ₂(C ₂O ₄) _0.5](C ₂N ₂H ₁₀) _0.5(H ₂O) ( 2), [Ga ₂(PO ₄) ₂(C ₂O ₄) _0.5](C ₃N ₂H ₁₂) _0.5 ( 3), [Ga ₂(PO ₄) ₂(H ₂PO ₄) _0.5(C ₂O ₄) _0.5](C ₄N ₃H ₁₆) _0.5 (H ₂O) _1.5 ( 4) and [Ga _2.5(PO ₄) _2.5(H ₂O) _1.5(C ₂O ₄) _0.5](C ₄N ₃H ₁₅) _0.5 ( 5), have been synthesized by using 1,3-diaminopropane, ethylenediamine and diethylene triamine as structure-directing agents under hydrothermal condition. The structures of 1- 5 are based on Ga ₄(PO ₄) ₄(C ₂O ₄) building unit made up from Ga ₂O ₈(C ₂O ₄) oxalate-bridging dimer and alternating PO ₄ and GaO ₄ tetrahedral units. Compound 1 is layered structure where the building units link together in the same orientation. Corner sharing of these similar layers result in three-dimensional (3-D) structure 2. However, in compound 3, the building units arrange in a wave-like way to generate two types of eight member ring (8MR) channels. Both 4 and 5 contain the layers where the building units have an opposite orientation. Those layers are linked by H ₂PO ₄ group and Ga(PO ₄)(H ₂O) ₃ cluster, respectively, to form 3-D frameworks with 12MR large pore channels. Compounds 2- 5 exhibit intersecting 3-D channels where the protoned amines are located.