Four new two-dimensional vanadium phosphates, [H2N(C4H8)NH2][(VO)(4)(OH)(4)(PO4)(2)] (1), [(NH3C3H6)NH(C2H4)(2)-NH(C3H6NH3)][(VO)(5)(OH)(2)(PO4)(4)]. 2H(2)O (2) [HN(C2H4)(3)NH](2)[(VO)(8)(HPO4)(3)(PO4)(4)(OH)(2)]. 2H(2)O (3), and [HN(C2H4)(3)-NH][(VO)(3)(OH)(2)] (4), have been synthesized by exploiting the hydrothermal technique. Compound 1 was synthesized from the reaction of a mixture VCl4, H3PO4, piperazine, tetrabutylammonium hydroxide, and H2O in the mole ratio 1:2.2:1.7:1.2:2830 heated at 200 degrees C for 48 h. Phosphate 2 was obtained from the reaction of VCL, H3PO4, 1,4-bis(aminopropyl)piperazine, and water in the mole ratio 1:2.4:6.3:1207 heated for 114 h at 150 degrees C. Compounds 3 and 4 were synthesized from the same reactants, VCl4, H3PO4, 1,4-diazabicyclo[2.2.2]octane (DABCO), and H2O under different reaction conditions. While the preparation of 3 employed the mole ratio 1:8.0:4.0:1375 and a heating time of 72 h at 200 degrees C, the synthesis of 4 required a ratio of 1:6.0:4.0:2268 at 200 degrees C for 48 h. While these four materials share a common motif of inorganic V/P/O layers separated by organic cations, each exhibits highly distinctive structuralfeatures.Phosphate 1 has discrete binuclear {V2O8} edge-sharing units, which give rise to undulations in the inorganic V/P/O layer; while compound 2 possesses similar {V2O} units, the distinctive features of isolated VO5 square pyramids and {V2O4P2} intersecting rings are also present. While compounds 3 and 4 have the same template, 1,4-diazabicyclo[2.2.2]octane, examination of the inorganic layers reveals different structural motifs. Compound 3 possesses two isolated tetrameric units: one composed of two face-sharing VO6 octahedra, each sharing a corner with a {VO5} square pyramid, while the second consists of two pairs of corner-sharing {VO5} square pyramids, linked by mu(4)-phosphate groups. In contrast, compound 4 ntains binuclear units constructed from face-sharing (VO6) dimers linked by corner-sharing interactions into infinite chains.In addition each binuclear unit of 4 exhibits a corner-sharing interaction with a {VO5} square pyramidal site to produce a ribbon of octahedral-square pyramidal vanadium polyhedra; adjacent ribbons are linked through mu(4)-phosphate groups. Crystal data are as follows. C4H16N2O16P4V4 (1): blue plates, monoclinic space group P2(1)/c (No. 14) with a 10.682(2) Angstrom, b = 8.991(2) Angstrom, c = 8.951(2) Angstrom, beta = 110.41(3)degrees, V = 805.7(4) Angstrom(3), Z = 1; refinement based on 1493 reflections gave a final residual of R = 0.0569. C10H34N4O25P4V5 (2): blue plates, triclinic space group P ($) over bar 1 (No. 2) with a = 9.433(3) Angstrom, b = 17.799(3) Angstrom, c = 9.356(1) Angstrom, alpha = 103.83(1)degrees, beta = 91.80(2)degrees, C12H37N2O40P7V8 (3): blue plates, monoclinic space group P2/n (No. 13) with a = 9.559(2) Angstrom, b = 8.840(2) Angstrom, c = 24.309(5) Angstrom, beta = 100.07(2)degrees, V = 2022.5(7) Angstrom(3), Z = 2; 3181 reflections, R = 0.0561. C6H16N2O13P2V3 (4): ink-blue square plates, monoclinic space group P2(1)/n (No. 14) with a = 12.048(2) Angstrom, b = 6.3470(10) Angstrom, c = 20249(4) Angstrom, V = 1493.5(8) Angstrom(3), Z = 4; 1846 reflections, R = 0.0567.