Abstract
Mixed-ligand complexes of selenium(IV) ion chelating with caffeine (cat) molecule as a primary ligand and N,O donors (L-valine (L-val); L-proline (L-pro); 2,4-diaminophenol (dap)), or nitrogen-base donors (2,2'-bipyridine (bpy) and bathophenanthroline (bphen)) as secondary ligand were prepared. These complexes were assigned based on different techniques like molar conductance, UV-Visible (UV-Vis), infrared (FT-1R), H-1-NMR spectroscopy, thermal analysis (TGA-DTG), X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopes (TEM). The FT-IR and H-1-NMR spectra deduced that the caf chelate is acts as a monodentate with Se(IV) through the nitrogen atom N9, while secondary ligands (L-val, L-pro, dap, bpy and bphen) coordinated as bi-dentate ligand towards Se(IV) via NO or NN donating atoms. Dependent on the spectroscopic results, it can be confirmed that Se(IV) complexes have an octahedral geometry with general formulas [Se(cat)(L)(Cl)(3)] (where L = L-val, L-pro and dap) I-III and [Se(cat)(L')(Cl)(3)]Cl (where L' = bpy and bphen) IV and V. The conductance data of the synthesized complexes revealed that the [Se(cat)(L)(Cl)(3)] complexes have a non-electrolyte properties, while [Se(cat)(L')(Cl)(3)]Cl complex has a 1:1 electrolyte nature. TGA-DTG analysis shows that the degradation of complexes occurs between 30 - 800 degrees C. SEM, TEM, and XRD analyses revealed the particle size of synthesized complexes. All the five complexes in this study were evaluated for their anticancer effect towards two colorectal adenocarcinoma (Caco-2) and breast cancer (Mcf-7) cell lines.