New divalent metal ion complexes with 1,8-diaminonapthalene-2-thione: Synthesis, Spectroscopic, anti-bacterial and anticancer activity studies

Abstract Treatment of two molar equivalents of 1,8-diaminonaphthalene-2-thione with one molar equivalent of the metal's(II) salt (Pd, Pt, Hg, Cd, Zn) afforded both neutral thione complexes and thionate derived complexes. The prepared ligand and its complexes (1-8) were characterized via different spectroscopic technics including: FT-IR, 1H, 13C-NMR, and mass spectroscopy. The spectroscopic data analysis suggested that these compounds adopt different structural geometries. For instance, Pd(II) and Pt(II) complexes show square planar geometry. Whereas, thione complexes of Hg(II), Zn(II), and Cd(II) showed probable tetrahedral structure. However, thionate derived complexes of Hg, and Ph-Hg are expected to be linear. The thionato-Cd(II) complex show bidentate chelating mode through its N and S donor atoms. Furthermore, the newly prepared complexes exhibit nano-structural characteristics, which were measured by SEM and X-Ray diffraction of the powder. SEM data showed that complexes from (3, 5) and (8) gave irregular nano-structure, nano-rod structure, and nano-sphere structural pattern respectively. On the other hand, Complexes (1) and (2) were tested against MCF-7 (breast) and LoVo (colon) cancer cells using MTT assay. It was found that the palladium complex showed a promising antiproliferative activity against colon (LoVo) and breast (MCF-7) cancer cells with IC50 values 21.13 and 22.25 µM respectively. In addition the anti-bacterial activity was study against two different pathogenic bacteria, and the Pd(II) complex displayed highest activity compared with other complexes.