研究目的

Investigating the therapeutic effects of a specific herbal medicine on a particular disease.

研究成果

In summary, copper loaded ZnO (S-1) was synthesized from Zn-Na-acetate complex (C32H48O34Na8Zn4, C-1), which is responsive to O2/light and showed highly reversible switching activity between its oxidized (S-2) and reduced (S-1) state. The reduced state (S-1) showed higher reactivity for the selective aerial oxidation of alkyl arenes/heteroarenes to corresponding aldehyde/ketone under light as compared to its oxidized state (S-2). On the contrary, oxidized state (S-2) is found to be much more efficient for the selective photo reduction of nitro aromatics to corresponding amines as compared to its reduced state (S-1). Furthermore, by changing the stimuli (light and O2/N2), the reaction could be turned ‘off’ and ‘on’ for both the cases. The switching efficiency between the states and their relative reactivity were found to be consistent under variety of reaction conditions. The relative reactivity of in-situ generated states were found to be similar with the ex-situ generated states and remain unaltered irrespective of oxidation-reduction (or vice versa) sequence and substrates used in the reaction. The mechanistic studies suggest that the presence of copper not only improves the spectral response for suppressing the hole?electron pair recombination process but also facilitate the formation of reactive superoxo (O2-) species responsible for oxidation. While, adsorbed hydrogen on catalyst surface followed by electron transfer is responsible for reduction reaction. The photo catalysts (S-1 and S-2) are found to be reusable and showed its quality performance in a large-scale-set-up for the synthesis of aldehydes/ketones and amino aromatics/heteroaromatics in multi-gram scale. Finally, the system was utilized in an assisted tandem catalysis set-up for the synthesis of benzyl amines utilizing both oxidation and reduction reactions followed by reduction of imines from the condensation between the two products by stimuli responsive switching between the states of the catalyst.

研究不足

The technical and application constraints of the experiments, as well as potential areas for optimization.