The hydrothermal reactions of NH4VO3 with the aromatic phosphonate ligands 1,4-, 1,3-, and 1,2-phenylenediphosphonic acids (H(4)L1, H(4)L3, H(4)L4, respectively); biphenyl-4,4 '-diyldiphosphonic acid (H(4)L2); and 1,3,5-tris(phenyl)4,4 '-triphosphonic acid (H(6)L5) yielded materials of the VxOy/organophosphonate family [VO(H(2)L1)] (1), [VO(H(2)L2)] (2), [V2O2(H2O)(2)(L-3)]center dot 1.5H(2)O (3 center dot 1.5H(2)O), [V2O2(H2O)(2)(L4)]center dot 2H(2)O (4 center dot 2H(2)O), and [V3O3(OH)(H(3)L5)(2)]center dot 7.5H(2)O (6 center dot 7.5H(2)O). The reactions were carried out in the presence of HF, and in one case, fluoride was incorporated to provide [V2F(OH)(H2O)(3)(L4)]center dot 2.25H(2)O (5 center dot 2.25H(2)O). The materials exhibit diverse structural chemistry, including the prototypical buttressed layer architecture for 1 and 2, a complex three-dimensional structure for 3, and unique two-dimensional structures for 4, 5, and 6. The structures of this oxovanadium-arylphosphonate family are quite distinct from those previously described for the VxOy/alkyldiphosphonate series.