Synthesis and Characterization of Transition Metal Complexes with Disaccharide-D-Lactose

Maryam Tayebani, Sakine Nematollahi
2017 Journal of Scientific and Engineering Research   unpublished
A series of seven different transition metals Nickle(II), Cobalt(II), Manganese(II), Iron(III), Zinc(II), Copper(II)and Cerium(II)complexes with D-Lactose mono hydrate have been synthesized and characterized by elementary analysis, molar conductivity measurements ,thermo gravimetric analyses, infrared spectra, atomic emission and electronic spectral data. Even though the method for preparation of these compounds have been the same, but different compounds with different structural formula have
more » ... tural formula have been obtained. The infrared spectra spectrums of these complexes have demonstrated the same metal-ion-binding pattern in all these complexes. The electronic spectrums can propose the existence of the d-character of the electron transitions in these complexes to some extent. These stable, water soluble metal carbohydrate complexes can be used as a suitable metal supplements in many biological systems. 1. Introduction In living organisms, transition metal ions have crucial role where they are found to be coordinated to different biomolecules and participating in many biochemical reactions. Interactions between metal ions and nucleosides, nucleotides polyalcohols and other sugar-type ligands are involved in many biochemical processes in living organisms, including immunological events recognition processes, and pathological conditions [1]. Carbohydrates in general, including natural and synthetic possess a manifold of donor atoms which enable them the ability to coordinate metal center and providing some additional advantages over other ligands, e.g., biocompatibility, non-toxicity, enantiomeric purity, water solubility, and well-explored chemistry. In recent years, several examples of carbohydrate compounds have been developed for diverse medicinal applications ranging from compounds with antibiotic, antiviral, or fungicidal activity and anticancer compounds [2-3]. The applications of metal-carbohydrate complexes are not limited into the biological systems. They can be used not only for stoichiometric or catalytic stereo selective synthesis but also for separation and analysis of chiral compounds as well [4-6]. In sugar alcohols, diols, triols, polysaccharides, metal-containing polymers, membranes, gels and fibers, saccharides act as polyolato ligands due to deprotonation of one or more hydroxyl groups [7]. Studying metal saccharides binding sites are not such straight forward task. On one hand, understanding the coordination behavior of sugar molecules is difficult because of their sensitive hygroscopic properties and complicated stereochemistry. On the other hand, due to the low stability of the synthesized metal complexes in neutral or acidic aqueous solutions determining the binding sits of hydroxyl groups to the metal ions are difficult [8]. Besides, in solutions of carbohydrates, existence of anomeric and conformational equilibrium for species makes the situation even more difficult [9]. In neutral environment, water molecules bonded to metal ions do not readily substitute by donor oxygen atoms due to the low electron density of the oxygen atoms. In alkaline solutions after deprotonation of hydroxy groups complexes of the meal ions with