β-Cyclodextrin–TiO2: Green Nest for reduction of nitroaromatic compounds†
In this paper, highly efficient photocatalytic reduction of nitroaromatic compounds was investigated using β-cyclodextrin (β-CD) and commercial nano-TiO2 as a host–guest system in water under sunlight irradiation. The nitroaromatic compounds solubilized in water through encapsulation in β-CD formed an inclusion complex which was attached to TiO2 under sunlight irradiation. This ‘guest–host system’ that we call ‘Green Nest’ showed high efficiency for the reduction of nitro compounds to the corresponding amines, and more interestingly, one pot reductive N-formylation and N-acylation from nitroaromatic compounds can be carried out in the presence of triethyl orthoformate, acetic and benzoic anhydride. The β-CD–TiO2 was characterized by transmission electron microscopy, UV-visible spectra, thermogravimetric analysis, Brunauer–Emmett–Teller measurements, UV-visible diffuse reflectance spectroscopy, and Raman spectroscopy.