6TH International Congress on Technology - Engineering - Kuala Lumpur3 - Malaysia (2018-07-19)

Crystallization Of Multifunctional Hybrid Solids

Self-assembly of metal ions and organic ligand in aqueous medium can result in crystallization of a large number of hybrid solids ranging from discrete metal complexes to 3D coordination networks [1]. However, the formation of hybrid solids depends on a large number of synthetic parameters such as concentration and nature of reactants, temperature, solvent and pH of the reaction medium. Moreover, secondary interactions such as hydrogen bonding, ?…? and C-H…? interactions play a crucial role in stabilizing the crystal structure of hybrid solids. On the other hand, a careful selection of metal ions and ligands can manifest or enhance properties such as magnetism, conductivity and gas adsorption. Therefore, herein we have made an attempt to synthesize hybrid solids of transition metals with selected organic ligands and investigate their properties for application as thermochromic, magnetic and anti-bacterial agents. Using solvent evaporation technique, hybrid solids namely (pipH2)[CoCl4] (1), (pipH2)[CuCl4].Cl2.3H2O (2) and [Co(H2O)4(ampyz)2][Co(H2O)6](SO4)2(H2O)2 (3) were synthesized using piperazine (pip) and 2-aminopyrazine (ampyz) as ligands. The structural elucidation of the synthesized solids was carried out using Fourier Transform Infra-Red Spectroscopy (FTIR), Powder X-ray Diffraction (PXRD) and Single Crystal X-ray Diffraction (SXRD). The role of supramolecular interactions in stabilizing the crystal structure of solids 1-3 was investigated using software Mercury and Diamond 4.1. Interestingly, 2 and 3 exhibited chromotropism and all the three solids also exhibited significant anti-bacterial activity and magnetic behaviour. The synthesis of solids 1-3 in ethanol has already been reported in literature [2-4]. However, the present study reveals that ethanol is not required for the synthesis of these solids as they can be easily synthesized in aqueous medium. The results are significant as water or water-alcohol mixture is preferred reaction medium over pure ethanol. In addition, the anti-bacterial activity and magnetic behaviour of these solids has not been reported so far. The anti-bacterial analysis shows that the solids have appreciable anti-bacterial activity against five different bacterial strains tested in the present study. Magnetic susceptibility measurements from 5 to 300 K at 1 kOe for solids 1-3 showed that the solids were paramagnetic in nature which suggests the absence of short-range correlations. The observed magnetic moments of transition metal ions of the solids 1-3 were found to be in good agreement with the values reported in literature [5].
Jency Thomas, Gitto Thomas Kuruthukulangarakoola, Raji CR, Memsy CK, SE Lofland, KV Ramanujachary