A new three-dimensional open-framework aluminophosphate (NH4)(2)Al-4(PO4)(4)(HPO4)-H2O (denoted AIPO-CJ19) with an Al/P ratio of 4/5 has been synthesized, using pyridine as the solvent and 2-aminopyridine as the structure-directing agent, under solvothermal conditions. The structure was determined by single-crystal X-ray diffraction and further characterized by solid-state NMR techniques. The alternation of the Al-centered polyhedra (including AlO4, AlO5, and AlO6) and the P-centered tetrahedra (including PO4 and PO3OH) results in an interrupted open-framework structure with an eight-membered ring channel along the [100] direction. This is the first aluminophosphate containing three kinds of Al coordinations (AlO4, AlO5, and AlO6) with all oxygen vertexes connected to framework P atoms. Al-27 MAS NMR, P-31 MAS NMR, and H-1 -> P-31 CPMAS NMR characterizations show that the solid-state NMR techniques are an effective complement to XRD analysis for structure elucidation. Furthermore, all of the possible coordinations of Al and P in the aluminophosphates with an Al/P ratio of 4/5 are summarized. Crystal data: (NH4)(2)Al-4(PO4)(4)(HPO4)-H2O, monoclinic P2(1) (No. 4), a = 5.0568(3) angstrom, b = 21.6211(18) angstrom, c = 8.1724(4) angstrom, 91,361(4)degrees, V = 893.27(10) angstrom(3), Z = 2, R-1 = 0.0456 (I > 2 sigma(I), and wR(2) = 0.1051 (all data).