Reversible adsorption and desorption of water in nanoporous copper(II) metal-organic nanocapsules

Nanocapsule of [Cu-2(bda)(2)(bpy)(2)]center dot 4H(2)O (1) with nanoparticle morphology (bda(2-) = 2,2E(1)-biphenyl dicarboxylate and bpy = 2,2E(1)-bipyridine), was synthesized by sonochemical process. Guest water molecules can be removed from the nanopores of 1 by thermal treatment at 200 A degrees C. The color of this compound changed from blue to deep green during this process. This process is reversible and compound [Cu-2(bda)(2)(bpy)(2)] (2) with the pore size of 4.3 x 5.5 can absorb water again. Thus nanoparticles of compound 2 with 1.53% weight absorption of water/compound 2 at room temperature could be used as water adsorption material like silica gel. Adsorption and desorption of water in these copper(II) metal-organic nanocapsules were studied by IR spectroscopy, thermo gravimetric analyses (TGA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM).