Polymorphism in high-crystalline-stability metal-organic nanotubes.

By application of mixed organic ligands of 5-amino-2,4,6-triiodoisophthalic acid (H(2)ATIBDC) and 4,4'-bipyridine (bpy) to assemble with Zn ions at room temperature, two novel polymorphic structures, Zn(ATIBDC)(bpy).3H(2)O (denoted as MONT-1 and MONT-2), possessing one-dimensional metal-organic nanotubular structures have been synthesized and characterized. MONT-1 was generated by connection of the zero-dimensional Zn-bpy squares through the bridging ATIBDC ligands, while MONT-2 was formed by connection of the one-dimensional Zn-bpy helix through the ATIBDC ligands. Both nanotubes possess highly crystalline stabilities and can absorb the uncoordinated water molecules reversibly.