Herein, a novel and environmentally benign solid catalyst was fabricated by grafting WO3 active species onto the ZnCo2O4@CeO2 support for efficient levulinic acid production from corncob waste biomass. The morphological, compositional, and textural properties of the designed catalyst were investigated using different characterization techniques to identify suitable catalyst formulation with enhanced catalytic activity and stability. The results demonstrated that WO3 active species were successfully loaded with uniform distribution onto the support to develop a robust catalyst with both acidic and basic sites. The experimental investigation showed that among the catalysts, WO3(10 wt %)/ZnCo2O4@CeO2 exhibited the best catalytic activity, providing a maximum levulinic acid yield of 78.49% at the optimal conditions of 6 wt % catalyst dosage, reaction temperature of 180 °C, and reaction time of 200 min. The presence of an optimum number of both acid and base active sites on the catalyst surface could lead to the highest catalytic activity of the synthesized catalyst. Finally, the reusability investigation indicated that the synthesized catalyst possessed sufficient recyclability of up to four times for the levulinic acid production from the selected biomass with negligible drop in the catalytic activity.
The bidentate N-(1-Alkylpyridin-4(1H)-ylidene)amide (PYA) pro-ligands [H2LBn][Cl]2 (2), and [H2LMe][TfO]2 (3) were prepared by simple alkylation reactions of the known compound, N,N-di(pyridin-4-yl)oxalamide (H2L, 1). The Pd(II) complexes, [Pd(LBn)2][Cl]2 (4), [Pd(LMe)2][Cl][TfO] (5), Pd(LBn)Cl2 (6) and Pd(LMe)Cl2 (7) were synthesized through reactions between these pro-ligands and suitable Pd(II) substrates in the presence of base. The molecular structures of 3 and 6 were obtained by single crystal X-ray structure determinations. Studies of the experimental and computational DNA binding interactions of the compounds 1-7 revealed that overall 4 and 6 have the largest values for the binding parameters Kb and ΔGbo. The results showed a good correlation with the steric and electronic parameters obtained by quantitative structure activity relationship (QSAR) studies. In-vitro cytotoxicity studies against four different cell lines showed that the human breast cancer cell lines MCF-7, T47D and cervical cancer cell line HeLa had either higher or similar sensitivities towards 4, 6 and 2, respectively, compared to cisplatin. In general, the cytotoxicity of the compounds, represented by IC50 values, decreased in the order 4 > 6 > 2 > 5 > 3 > 1 > 7 in cancer cell lines. Apoptosis contributed significantly to the cytotoxic effects of these anticancer agents as evaluated by apoptosis studies.