The photoalkylation of nitroarenes with benzyl alcohols in one pot at room temperature and 1 atm N 2 was achieved over the Pd/H 1.07 Ti 1.73 O 4 ·H 2 O nanosheets. The sample shows efficient photocatalytic activity with high conversion of nitrobenzene (99%) and selectivity of secondary amine (85%). This flexible photocatalytic system is also applicable to other nitroarenes with high efficiency. Results of in situ FTIR, DRS, and in situ ESR revealed that the benzyl alcohol and nitrobenzene molecules can bind with the surface Lewis and Brønsted acid sites in the catalyst via the H O⋯Ti and NO 2 ⋯H O Ti species. The formation of surface coordination species results in not only the activation of reactant molecules via surface electron transfer, but also the expanded visible light absorption of the catalyst. Moreover, in situ ESR suggested that the surface coordination can also facilitate the formation of oxygen vacancies in catalysts, which can greatly promote the exposure of Lewis sites and enhance the activation of reactant molecules. Finally, a possible hydrogen transfer strategy over the sample is proposed on a molecular level.
The natural alkaloid, tryptanthrin (indolo[2,1-b]quinazoline-6,12-dione), and its analogues are found to exhibit potent antitumor and anti -MRSA activities. An efficient and convenient method has been developed for the synthesis of tryptanthrin D-ring derivatives through the reaction of substituted tryptanthrins and secondary amines in moderate to good yields. Some of the new compounds exhibited antitumor activities against the human tumor cell lines A549, HCT116 and MDA-MB-231, with mean IC 50 values at low micromolar levels. In addition, some of the compounds showed excellent anti -MRSA activities and were more effective than vancomycin , with MIC values of 0.31–1.25 μg/mL for Mu50,RN4220, and Newman strains.