Synthesis of a metal–dicarboxylate hybrid with three dimensional Na–O–Cu connectivity: structure, magnetic property and controlled solid state thermolysis leading to CuO nanorod

A one-pot reaction of CuCl2 · 2H2O and malonic acid leads to a novel three dimensional inorganic–organic hybrid framework, [Na2Cu(mal)2(H2O)2]n, (1) (mal = malonate dianion). Single crystal X-ray structure of 1 reveals that it is a novel heterometallic three dimensional coordination-polymeric network which consists of interlocked anionic Cu–malonate and cationic Na–water–malonate sheets, where malonate dianion functions as an unprecedented heptadentate ligand. Low temperature magnetic study reveals that the compound is weak ferromagnetically coupled and this is supported by magneto-structural correlation. Thermogravimetric analyses are performed and it is observed that complex 1 upon heating finally transforms to CuO, which is evident by X-ray powder diffraction technique. Controlled solid state thermolysis of complex 1 at ∼850 °C for 24 h leads to the formation of CuO nanorods, which is confirmed by scanning electron microscopy and X-ray powder diffraction technique. The nanorods formed here have average diameters of ca. 40–200 nm and lengths up to 13 μm.