Palladium Schiff base complex-modified Cu(BDC-NH2) metal–organic frameworks for C–N coupling

Abstract

In this study, the synthesis of a novel functionalized metal–organic-framework (MOF) [Cu(BDC-NH₂)@Schiff-base-Pd(II)] catalyst via post-synthetic modification of Cu(BDC-NH₂) is reported. The targeted complex was prepared by chemically attaching N,N′-bis(5-formylpyrrol-2-ylmethyl) homopiperazine via a Schiff base reaction followed by complexation with Pd ions. Afterwards, the synthesized solid was applied as a very effective multifunctional catalyst in C–N coupling reactions. The synthesized compounds were identified by suitable techniques including N₂ isotherms, EDX spectroscopy, FT-IR spectroscopy, XRD, SEM, ICP-OES and TG-DTA. This nanocatalyst was used in C–N cross-coupling reactions, and it showed its usage in a diverse range of different functional groups with good efficiency. The reasons for introducing this catalyst system are its advantages such as considerably high selectivity, almost complete conversion of products, high yields, and convenient separation of catalysts and products. The results indicate that the highest efficiency of the product in the reaction was obtained in the shortest possible time with the use of [Cu(BDC-NH₂)@Schiff-base-Pd(II)] catalysts. Overall, the high catalytic activity of the [Cu(BDC-NH₂)@Schiff-base-Pd(II)] catalyst may be due to the obtained high surface area and the synergistic features created between Lewis acidic Cu nodes and Pd ions.