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

Five organic-inorganic hybrid gallium oxalate-phosphates, [Ga{sub 2}(PO{sub 4}){sub 2}(H{sub 2}O)(C{sub 2}O{sub 4}){sub 0.5}](C{sub 3}N{sub 2}H{sub 12}){sub 0.5}(H{sub 2}O) (1), [Ga{sub 2}(PO{sub 4}){sub 2}(C{sub 2}O{sub 4}){sub 0.5}](C{sub 2}N{sub 2}H{sub 10}){sub 0.5}(H{sub 2}O) (2), [Ga{sub 2}(PO{sub 4}){sub 2}(C{sub 2}O{sub 4}){sub 0.5}](C{sub 3}N{sub 2}H{sub 12}){sub 0.5} (3), [Ga{sub 2}(PO{sub 4}){sub 2}(H{sub 2}PO{sub 4}){sub 0.5}(C{sub 2}O{sub 4}){sub 0.5}](C{sub 4}N{sub 3}H{sub 16}){sub 0.5} (H{sub 2}O){sub 1.5} (4) and [Ga{sub 2.5}(PO{sub 4}){sub 2.5}(H{sub 2}O){sub 1.5}(C{sub 2}O{sub 4}){sub 0.5}](C{sub 4}N{sub 3}H{sub 15}){sub 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{sub 4}(PO{sub 4}){sub 4}(C{sub 2}O{sub 4}) building unit made up from Ga{sub 2}O{sub 8}(C{sub 2}O{sub 4}) oxalate-bridging dimer and alternating PO{sub 4} and GaO{sub 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{sub 2}PO{sub 4} group and Ga(PO{sub 4})(H{sub 2}O){sub 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. - Graphical abstract: Compound 4 contains layers where the Ga{sub 4}(PO{sub 4}){sub 4}(C{sub 2}O{sub 4}) building units are connected to each other in an opposite orientation. The phosphorous atom sits on a twofold axis, is positioned between the layers and joins the GaO{sub 4}(C{sub 2}O{sub 4}) group from adjacent layers, generating two types of alternating 8MR and 12MR channels along the [001] direction.