Abstract
In this study, Pd(II)/TCH@SBA-15 nanocomposites were synthesized by the grafting of 3-chloropropyltriethoxysilane and thiocarbohydrazide on SBA-15 and subsequent deposition of palladium acetates through the ligand-metal coordination method. The structure and morphology of this nanoporous nanocomposite was thoroughly identified by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis, atomic absorption spectroscopy, and Brunauer-Emmett-Teller instrumental analyses. Furthermore, the catalytic activity of this nanocomposite was investigated in the three-component synthesis of 3-benzimidazolyl or benzothiazoleyl-1,3-thiazolidin-4-ones via a reaction of 2-aminobenzimidazole or 2-aminobenzothiazole, aromatic aldehydes, and thioglycolic acid in an acetone-H2O mixture under green conditions. The Pd/TCH@SBA-15 nanocatalyst is demonstrated to exhibit a high catalyzing activity in the three-component reaction of the synthesis of N-heterocyclic thiazolidinones with good to excellent yields. One of the advantages of the suggested method is the direct application of the thiocarbohydrazide ligand to stabilize Pd nanoparticles through formation of a stable ring complex without creating an additional Schiff base step. Moreover, this organometallic nanocatalyst can be recycled several times with no notable leaching or loss of performance.