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Nanoporous metals (NPMs) with diversified shapes and compositions can be readily fabricated by dealloying monolithic alloys through chemical or electrochemical processes. Benefited from their high surface area, high density of low‐coordinated sites on the ligament surface, and unsupported character, NPMs have attracted increasing attentions as a new class of heterogeneous catalysts with high activity, selectivity, and long‐term stability, reminiscent of the great success of Raney nickel. In the present minireview, we summarize the recent advances in this exciting field and provide a critical discussion of the nature of their active sites and the structure–property correlation.

The transfer hydrogenation of levulinic acid to γ‐valerolactone using an equimolar mixture of formate/formic acid in water was investigated using Ru/ZrO2 catalysts. Ru/ZrO2 with < 3 wt. % loading were more active than those with higher loadings. The stability of the catalysts is of concern as the reaction occurs under acidic and hydrothermal conditions. To minimize metal leaching, the Ru/ZrO2 catalysts were prepared by a sol‐gel process to entrap the ruthenium nanoparticles within the support. Despite insignificant leaching of Ru, the used catalyst was deactivated after the first run. No agglomeration of Ru particles could be observed by TEM and XRD. However, the zirconia support had transformed from a predominantly tetragonal crystal phase to the monoclinic form. X‐ray photoelectron spectroscopy revealed a decrease in the surface Ru/Zr ratio. Doping with 0.1 wt. % SiO2 successfully stabilized the tetragonal phase of zirconia and the recycled catalyst maintained its high activity in reuse.

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Six new dibenzo[b,e]oxepinone metabolites, chaetones A-F (1-6), as well as three known compounds, 1-hydroxy-6-methyl-8-hydroxymethylxanthone (7), citreorosein (8), and emodin (9), were obtained from a freshwater-derived fungal strain Chaetomium sp. YMF 1.02105. Their structures were established on the basis of extensive spectroscopic data analysis and comparison with spectroscopic data reported. Compounds 1-6 are further additions to the small group of dibenzo[b,e]oxepinones represented by arugosins A-H. Compounds 1-7 were tested for their cytotoxic activities against A549, Raji, HepG2, MCF-7, and HL-60 cell lines. The results showed that compound 3 had significant cytotoxicity with IC50 values of 1.2, 1.8, 1.9, 2.3, and 1.6 µg/mL, respectively, against the five cancer cell lines. All compounds showed modest antimicrobial activity against Staphylococcus aureus (ATCC 6538) in standard disk assays.

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