An uranyl isophthalate has been hydrothermally synthesized at 200 degrees C for 24 h, from a mixture of uranyl nitrate, isophthalic acid, and hydrazine in water. It was characterized by single-crystal analysis [triclinic, P (1) over bar, a = 7.3934(3) angstrom, b = 13.3296(5) angstrom, = 15.4432(5) angstrom, alpha = 111.865(2)degrees, beta = 90.637(2)degrees, gamma = 104.867(2)degrees, V = 1355.49(9) angstrom(3)] and different spectroscopic techniques (Raman, IR-ATR, UV visible), The 3D structure of the phase (UO2)(8)O-2(OH)(4)(H2O)4(1,3-bdc)(4)center dot 4H(2)O (1,3-bdc = 1,3-benzenedicarboxylate) reveals octanuclear units based on the association of 7-fold coordinated uranyl cations (pentagonal bipyramid) involving a rare case of cation cation interaction together with edge-sharing polyhedral connection mode. UV visible absorption spectroscopy confirmed that uranium was only involved in the structure as uranyl forms (excluding the assigning four uranyl presence of tetravalent or pentavalent uranium). Additionally, mu-Raman and IR-ATR experiments allowed contributions to the four types of uranyl entities in the structure, in agreement with the XRD analysis.