Well-defined nanomagnetic nitrilotriacetic acid complex of Cu(ii) supported on silica-coated nanosized magnetite: a new highly efficient and magnetically separable catalyst for C–N bond formation

Abstract

A nitrilotriacetic acid (NTA) complex of Cu(II) supported on silica-coated nanosized magnetite Fe₃O₄@SiO₂-Pr-DEA-[NTA-Cu(II)]₂ was prepared as a new well-defined magnetically separable nanomaterial and fully characterized via IR, XRD, FESEM, TEM, TGA, DLS, BET, VSM, solid-state UV-vis spectroscopy, EDX, ICP-OES, and FESEM-EDX map analyses. Thereafter, it was successfully applied as a new easily magnetically separable and reusable heterogeneous nanocatalyst for the Buchwald–Hartwig C–N bond formation reaction in DMF at 110 °C. Using this method, various kinds of nitrogen heterocycles, such as imidazoles, 2-methyl-1H-imidazole, benzimidazole, indole, and 10H-phenothiazine as well as aliphatic secondary amines such as piperidine, piperazine, morpholine, dimethylamine, and diethylamine, were reacted with aryl halide compounds, and the desired products were obtained with good to excellent yields. In all cases, the applied catalyst could be recovered easily and rapidly using an external magnet and reused 7 times without significant loss of catalytic activity.