Abstract
This paper aimed to synthesis, spectroscopic characterizations, and antioxidant assessment of two new selenium complexes with nicotinamide (Nic) and riboflavin (RF) as drug chelates. The speculated structures of the synthetic selenium complexes have been discussed by using different tools of spectroscopic analyses like infrared, the Raman, electronic, H-1-NMR, and mass. Accordingly, the Fourier transform infrared and H-1-NMR spectra, the mode of complexation is supported, as four molecules of nicotinamide drug act as a monodentate chelate through the N-atom of the pyridine ring with [Se(Nic)(4)]center dot H2O formula. The two riboflavin drug molecules coordinated to selenium metal as a bidentate chelate through azomethine nitrogen of pyrazine ring and O-atom of C=O pyrimidine-2,4-dione group with general formula [Se(RF)(2)]. Both of Nic and RF chelates act as neutral charge ligands. The conductivity measurements indicated that the selenium complexes are non-electrolytes behaviors. Thermal analyses (thermal gravimetric-differential thermal analysis) of the studied complexes show that the decomposition process takes place in one broadening step with a wide temperature range. The surface morphology of the mentioned complexes was studied by scanning electron microscope and the particle size is calculated using X-ray powder diffraction. Thermodynamic kinetic parameters are calculated by using the Coats and Redfern equation. Screening of antioxidant activities of selenium complexes in vitro are assessed. The antioxidant activity is studied by three methods (DPPH assay, beta-carotene/linoleic acid bleaching assay, and ferric reducing power assay), the studied complexes have a significant antioxidant activity compared to synthetic antioxidants like trolox and BHT.