Crystal structure, phase transition and thermal decomposition of a copper (II) sulfate dihydrate containing a chiral organic ammonium cation

The directed synthesis of a new organically templated copper sulfate has been achieved through the use of chiral organic amine. Reaction containing S-2-methylpiperazine, CuSO4 center dot 5H(2)O, H(2)SO4 and H2O were subjected to the slow evaporation conditions, resulting in the growth of single crystals of [(S)-C5H14N2][ Cu(SO4)(2)(H2O)(4)]center dot(H2O)(2). At room temperature, it crystallises in the non-centrosymmetric space group P2(1), Z = 2, a = 7.5583(5), b = 10.1721(6), c = 10.7974(7) angstrom, beta = 94.425(4)degrees and V = 827.67(9) angstrom(3). The structure consists of trimeric units [Cu(SO4)(2)(H2O)(4)](2) , [(S)-C5H14N2](2+) cations and free water molecules, donating hydrogen bonds that stabilize the three-dimensional structure and filling space. The title compound undergoes a reversible phase transition of first-order, which is detected by differential-scanning calorimetry at 347.2 K in the heating cycle and at 318.9 K in the cooling cycle. The evolution of the dielectric constant as a function of frequency and temperature revealed this transition to be ferro-paraelectric. Thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the copper oxide. (C) 2009 Elsevier B. V. All rights reserved.