Dendrimer assisted synthesis of bimetallic nanoparticles and their catalytic applications

Abstract

The development of nanotechnology for the preparation of metal nanoparticles (NPs) creates new opportunities for a catalytic revolution. Bimetallic nanoparticles have gained significant attention because of their promising properties, unique features, and novel applications in catalysis significantly in various carbon-carbon cross-coupling reactions, oxidation, and reduction reactions under mild conditions. Conversely, an innovative and facile approach is still scarce to implement the formation of a dendritic ligand supported stabilized heterogeneous bimetallic NPs and catalytic application in coupling reactions, oxidation, and reduction reactions. Hence, triazine and diazine-based dendrimer-assisted Pd/Cu, Pd/Co, Pd/Ni, Ni/Cu, and Zn/Cu bimetallic nanoparticles have been synthesized via sequential reduction method and co-complexation method successfully. These bimetallic nanoparticles were characterized by SEM, EDX, XRF, TEM, XRD, TG, and DSC methods. The SEM, EDX, and XRF results showed the nanosized aggregated dendritic leaf and globular surface morphology, and the presence of required metal ions of the prepared nanoparticles respectively. Similarly, the phase of these nanoparticles was detected as the Face Centered Cubic (FCC) structure by XRD analysis, and the average particle size below 30 nm of these nanoparticles was identified by TEM analysis. Furthermore, the good thermal stability of these nanoparticles was determined by TG and DSC experiments. The Pd-metallodendrimer has also been characterized by FTIR, 1HNMR, 13CNMR, SEM, EDX, Mass, TG, and DSC techniques. These Pd/Cu, Pd/Co, and Pd/Ni bimetallic nanoparticles were successfully applied as a heterogeneous catalyst for the Heck reactions, Glaser reactions, Sonogashira reactions, Suzuki-Miyaura reactions, and ynones preparation reactions in excellent yields. Alcohol oxidation and nitro group reduction by using Ni/Cu and Zn/Cu bimetallic nanoparticles in water under green conditions have been performed successfully and the Ni/Cu (3:1) and Zn/Cu (2:1) were found more effective than other molar ratios of these bimetallic nanoparticles. The recoverability and reusability of these nanoparticles reveal the heterogeneous nature of these catalysts. Moreover, these bimetallic nanoparticles can be investigated as a catalyst not only in the various carbon-carbon cross-coupling reactions but also in the carbon-nitrogen, carbon-sulfur, carbon-oxygen bond formation reactions in the heterocyclic compounds. Therefore, these dendritic ligands assisted bimetallic nanoparticles will open up a new era in the field of catalysis.