Pd(0) nanocatalyst stabilized on a novel agar/pectin composite and its catalytic activity in the synthesis of biphenyl compounds by Suzuki-Miyaura cross coupling reaction and reduction of o-nitroaniline.

The most important parameters for the fabrication of metallic nanoparticles are their synthesis method and the selection of stabilizer. These properties influence durability, shape, size, distribution, and catalytic performance of metallic nanoparticles. Therefore, a novel agar/pectin composite (APC) was designed in this study as a stabilizer, and then palladium nanocatalyst (Pd NPs@APC) was synthesized using green protocol which contains no hazardous reducing agents. The results of the thermal analysis showed that Pd NPs@APC had highly thermal durability (239 °C). Palladium nanoparticles were in spherical shape and homogeneously dispersed on APC surface. In addition, the particle sizes of palladium nanoparticles were determined as 34-54 nm. Catalytic activity of Pd NPs@APC was investigated in (i) Suzuki-Miyaura cross coupling reactions by using microwave irradiation to decrease high reaction time and energy as well as to provide clean synthesis and (ii) the reduction of o-nitroaniline to 1,2-benzenediamine at room temperature in water. Catalytic tests showed that Pd NPs@APC had high activity and sustainability performance against both Suzuki-Miyaura reactions and the reduction of o-nitroaniline.