Mixed cobalt/nickel metal–organic framework, an efficient catalyst for one-pot synthesis of substituted imidazoles

Abstract

In the present work, a three-dimensional bimetallic metal–organic framework, [CoNi(µ3-tp)2(µ2-pyz)2] (tp = terephthalic acid, pyz = pyrazine) was applied as a highly efficient and recoverable heterogeneous catalyst. The catalyzed reaction was the one-pot three-component condensation reaction between benzil or benzoin with various substituted aromatic aldehydes and ammonium acetate to synthesize the corresponding imidazoles in solvent-free conditions and high to quantitative yields. The catalyst can be recycled at least five times without significant loss in the catalytic activity. To the best of our knowledge, 2,4,5-trisubstituted 1H-imidazoles were not previously synthesized using MOFs as heterogeneous catalyst. The structure of previously reported cobalt/nickel MOF has been confirmed by various techniques, such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller.