A Hybrid Open-Framework Aluminum Phosphate-Oxalate Possessing Large Circular 12-Membered Channels

A new aluminum phosphate-oxalate, I, $[N_2C_4H_{12}]Al_2(PO_4) (HPO_4)(C_2O_4)]H_2O$, has been synthesized hydrothermally in the presence of structure- irecting amines. The hybrid structure comprises a vertex- inkage of $AlO_6 $octahedra, $PO_4$tetrahedra, and $C_2O_4$units leading to three-dimensional connectivity. The connectivity between $AlO_6 $ and $PO_4$ units are such that it forms double-six rings that are connected to each other via the oxalate units, thereby leading to the formation of a large circular 12-membered channel of width $\sim 9 \AA$ along the c axis. The structure-directing amine along with one water molecule is situated within this channel. The connectivity also forms two different types of 8-membered channels along the a and b axes. The three- imensional structure of I, is very similar to the naturally occurring aluminosilicate zeolite, gmelinite. Crystal data for I are: monoclinic, space group Pccm, a = 9.992(1), b = 11.644(1), $c = 12.231(1) \AA$, V = 1423.0(2), M = 438.9, Z = 4, $R_F = 0.07$