Domino synthesis of quinoxaline derivatives using SBA-Pr-NH2 as a nanoreactor and their spectrophotometric complexation studies with some metals ions

Amino-functionalized SBA-15 (SBA-Pr-NH2) with a pore size of 6 nm has been used as a basic nanocatalyst in the domino one-pot synthesis of quinoxaline derivatives via the four-component reaction of ninhydrin, 1,2-aryl-diamines, malono derivatives, and alpha-methylenecarbonyl compound using microwave irradiation. The solid basic catalyst plays a significant role in catalysis, and enhancing the rate and yield of the reaction, it can be easily handled and removed from the reaction mixture by simple filtration and also reused several times without substantial loss of reactivity. Moreover, the complexation reaction between quinoxaline as a model ligand and some metal ions including Cd2+, Co2+, Cu2+, Fe3+, Hg2+, Ni2+, Pb2+, and Zn2+ ions was examined spectrophotometrically in DMF solution at 25 degrees C. The formation constants of the resulting complexes were calculated from the computer fitting of the molar absorbance measurements in different mole ratios. The obtained data indicated that the stability constant of the resulting complexes varied in the following order Pb2+> Hg2+> Cd2+> Ni2+> Cu2+> Fe3+> Zn2+> Co2+.