One-pot synthesis of unsubstituted and methyl substituted-pyrazinyl diselenides and monoselenides: structural, optical property characterization and DFT calculations

Organoselenium compounds have long been fascinated researchers owing to their wide range of applications, such as in anticancer, in catalysis, and as molecular precursors for metal selenides. In this view, herein, the one-pot synthesis of dimethyl substituted and unsubstituted dipyrazinyl monoselenides, [(2-pyz)2Se] and [(2,5-Me2-3-pyz)2Se], and the corresponding dipyrazinyl disenides, [(2-pyzSe)2] and [(2,5-Me2-3-pyzSe)2], is demonstrated by the reduction of selenium metal using sodium borohydride at room temperature and a subsequent alkylation using the corresponding pyrazinyl halide in ethanol. All the diselenides and monoselenides were characterized using IR, UV-vis, photoluminescence, and NMR (1H, 13C{1H}, and 77Se{1H}) spectroscopy. The molecular structures of the diselenides and monoselenides were unambiguously determined by single-crystal X-ray diffraction (SC-XRD). The optical properties, including absorption, excitation, emission, and quantum yield, of these organoselenium compounds were examined. Additionally, DFT calculations were performed to determine the HOMO and LUMO orbitals, band gap, and oscillator strength of these ligands. A facile synthesis of selenopyrazine compounds is demonstrated at room temperature. The molecular structures are unambiguously determined using SC-XRD. Additionally, the optical properties of these compounds are studied.