Hollow nanosphere construction of covalent organic frameworks for catalysis: (Pd/C)@TpPa COFs in Suzuki coupling reaction.

[Display omitted] • COFs (Covalent organic frameworks) was chosen as the shell material in heterogeneous catalyst. • A yolk-shell (Pd/C)@TpPa COFs catalyst was synthesized via a template method. • The catalytic performance was tested in Suzuki reaction. • The heterogeneous catalyst showed a high conversion with only 0.05 mol% Pd loading. • Catalytic selectivity by size exclusion due to COFs was observed, amounting to 100%. • The heterogeneous catalyst also showed good recyclability. • Environment-friendly, stable, and robust nano catalyst for cross-coupling reactions. A novel catalyst with a yolk-shell structure was designed to overcome the leaching of noble metals in heterogeneous catalysis. Through a template method, palladium (Pd) nanoparticles were encapsulated by hollow spherical covalent organic frameworks (COFs) consisting of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) and p-phenylenediamine (Pa). The final catalyst with a yolk-shell structure was denoted as (Pd/C)@TpPa COFs. The unique morphology and chemical structure of this novel composite (Pd/C)@TpPa COFs were confirmed by a transmission electron microscope (TEM), a laser particle analyzer, X-ray diffraction (XRD), and N 2 adsorption and desorption. Subsequently, to demonstrate its catalytic performance brought by structural design, this novel catalyst was applied to catalyze the Suzuki reaction. Interestingly, this catalyst exhibited a brilliant size cutoff efficiency for aryl benzene amounting to 100% and achieved a high conversion with only 0.05 mol% Pd loading. Besides, this catalyst could be readily recovered via filtration and reused for at least five consecutive cycles without any significant loss in its activity. [ABSTRACT FROM AUTHOR]