A complex of type [Cu6Na4(mu-O)(4)(NTA)(2)(bpy)(6)(H2O)(4)(NO3)(2)]center dot 3H(2)O 1 was allowed to react separately with tetrabutylammonium salts (TBAX), X = F-, Cl-, Br-, I-, AcO-, NO3-, and H2PO4-. The color of complex 1 changed immediately on the addition of TBAI (tetrabutylammonium iodide) only. However, keeping the corresponding solution for 2 months at room temperature, four complexes of compositions [Cu-6(mu-OH)(4)(NTA)(2)(bpy)(6)]2I(-)center dot 5H(2)O 2, [Cu-2(bpy)(2)(OH)(2)(I)](2)(NO3)(2)(H2O) 3, [Cu(bpy)(2)I]I-3(-) 4, and [Cu(bpy)(2)I]I center dot TBAI 5 (bpy = 2,2'-bipyridyl, H(3)NTA = nitrilotriacetic acid) together with some residues of TBAI and complex 1 were isolated in one-pot synthesis. These complexes were characterized using elemental analysis, spectroscopic (IR, UV-vis) and single crystal X-ray diffraction techniques. Colorimetric response of complex 1 with iodide anions was further supported by the changes in its UV-vis spectra recorded in methanol. The results indicated that 1 exhibits a strong affinity for iodide anions.