Co-ordination chemistry is undoubtedly the most active research area in inorganic chemistry. Investigations about the transition metal cations interacting with the heterocyclic molecules are essential for a better assessment of the role and effects of metal ions in biological systems. Heterocyclic compound is one which posseses a cyclic structure with at least two different kinds of heteroatoms in the ring. Nitrogen, oxygen and sulphur are the most important heteroatoms. Azoles played a significant role in the history of heterocyclic chemistry and also been used as remarkable synthons in organic reactions. The presence of –NH2 group at 2-positin of the azole and azine ring compounds make them more efficient in pharmacological field. Substituted benzothiazoles have been studied and found to have various chemical reactivity and biological activities. Its aromaticity makes it stable, although as a heterocycle, it has reactive sites which allow for functionalization. Thiourea derivatives and their structures can be considered as good chelating agents due to their ability to encapsulate metal ions into their co-ordination moiety. Various thiourea derivatives are well known for their complexation capacity. These ligands are of interest because they have two potential co-ordination sites i.e. sulphur and nitrogen atoms. The interaction of these donor ligands and copper soap (copper palmitate) gives complexes of different geometries. These complexes are potentially more biologically active. Owing to their multifold applications we synthesized complexes of copper(II) palmitate having 4-nitrophenylthiourea and 2-amino-6-nitro-benzothiazole. Densities of these complexes in varying concentration in non-aqueous benzene-propanol solvent mixture were studied. Using density data, critical micelle concentration was elucidated. This study clearly indicates that solute-solvent interaction decreases with increase in ring strain and size of synthesized complexes.
