NH2-MIL-125(Ti)-derived porous cages of titanium oxides to support Pt-Co alloys for chemoselective hydrogenation reactions.

The change of atom density induced structural collapse in the transformation process from metal-organic frameworks (MOFs) to their inorganic counterparts is a major challenge to the achievement of porous hollow structures. Herein, we develop an amino acid-mediated strategy for transformation of NH2-MIL-125(Ti) to successfully synthesize well-defined porous cages of titanium oxides (PCT) due to sheets serving as structural scaffolds. On this basis, PCT supported Pt-based nanoparticles are generated via a similar synthetic route, and are utilized to study the selective hydrogenation of carbonyl groups in α,ß-unsaturated aldehydes, benefiting from the specific structures of PCT and tunable electronic structures of Pt mainly affected by doping with metal species such as Co. In this case, Pt-Co/PCT composites give 96% selectivity for cinnamyl alcohol at 100% conversion of cinnamaldehyde under 0.2 MPa H2 and 80 °C for 3 h. This research would offer a promising strategy for important organic transformations in academic and industrial research to selectively synthesize high-value-added products.