Highly efficient chemoselective hydrogenation of unsaturated aldehydes catalyzed by hydrophobically modified core-shell defective ZIFs: Frustrated Lewis pair catalysis.

[Display omitted] • ZIF-67-MW show more defects and better catalytic performance. • Independent metal center and N sites in defective ZIFs construct an FLPs system. • DFT proves that the FLPs sites in defective ZIFs can easily dissociate the H-H bond. • ZIF-67-MW@SiO 2 -DMDES shows brighter prospects in unsaturated aldehydes hydrogenation. Zeolitic imidazolate frameworks (ZIFs) were prepared by different methods for the chemoselective hydrogenation of biomass-derived cinnamaldehyde. It was found that the ZIFs prepared by microwave-assisted method (ZIF-67-MW) shows more defects, and the independent Lewis acid (metal center) and Lewis basic (N in 2-methylimidazole) sites in the defective ZIFs construct a heterogeneous Frustrated Lewis pairs (FLPs) system. The theoretical calculations indicate that the FLPs sites in the defective ZIFs can easily dissociate the H-H bond with a low activation energy of 8.7 kcal/mol. And the silica-coated and hydrophobically modified core–shell structure of ZIF-67-MW@SiO 2 -DMDES is developed to enhance the stability of ZIF-67-MW and the selectivity to cinnamyl alcohol, it gives > 99% cinnamaldehyde conversion and 95.3% selectivity to cinnamyl alcohol. Furthermore, the reaction mechanism was proposed by the combination of experimental results and theoretical calculations. The results of substrate-extending experiments show that ZIF-67-MW@SiO 2 -DMDES presents brighter prospects in the selective hydrogenation of a series of unsaturated aldehydes. [ABSTRACT FROM AUTHOR]