Thiazoline-Iridium (III) Complexes and Immobilized Nanomaterials as Selective Catalysts inN-Alkylation of Amines with Alcohols

In this research, a new series of thiazoline-iridium (III) complexes (4-7) derived from cysteine were prepared and fully characterized by conventional methods. The molecular structure of complex5was also determined by single-crystal X-ray diffraction. These complexes were evaluated as catalysts for hydrogen-borrowing reactions of amines with alcohols. In particular, complex5showed the best activity as catalyst. Various amines have been alkylated with alcohols affording moderate to good yield (33-99%). Moreover, the immobilized nanomaterials (M-1,M-2) were fabricated by sonication process from the best catalyst5with the multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO), respectively, and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and inductively coupled plasma-mass spectrometry (ICP-MS). TheM(1,2)nanomaterials were also tested as catalysts in model catalytic reaction forN-alkylation. TheM(1)nanomaterial showed significantly higher activity than theM(2)nanomaterial. TheM(1)catalyst was recovered by filtration and reused for four catalytic cycles with high conversion (99%, 97%, 96%, and 86%).