Preparation of pd(0) nanoparticles supported on BD-g-C3N4 (Pd@BD-g-C3N4) and invesitigation of their catalytic performance in the suzuki-miyaura C-C coupling reacti̇ons

C-C cross-coupling reactions that use palladium catalysts are highly preferred for the reaction of adding various functional groups such as aromatic ring, alkyne, and alkene to unsaturated compounds. In these reactions, carbon-carbon bond formation can be achieved by reactions of organometallic compounds such as Grignard and organoboron compounds with aryl/vinyl halides. One of the most important approaches for the formation of the C-C bond is the Palladium-catalyzed Suzuki-Miyaura Coupling Reactions (SMR). Suzuki-Miyaura coupling reactions are widely used in the synthesis of pharmaceutical intermediates, natural products, functional materials, and biomolecules due to many advantages such as low toxicity of reagents and mild reaction conditions. It is known that this coupling process only takes place with catalytic reactions in the presence of an appropriate catalyst. Although coordination compounds containing Pd are generally used in these reactions, colloidal and supported structures containing Pd nanoparticles have also been used as catalysts recently. When we look at the catalytic systems used for C-C coupling reactions, it has been revealed that systems made of nano-sized materials provide much better catalytic performances with their high surface areas and surface-active atom numbers. Furthermore, in C-C coupling reactions, photocatalytic methods have started to take place as an alternative to the classical catalysis method, with low cost and carried out in mild conditions and daylight. In this study, palladium in different percentages by mass (0.1%, 0.5%, 1%, 2%, and 3%) was decorated with benzene-loaded graphytic carbon nitride (BD-g-C3N4) support material by wet impregnation reduction method, and Pd@BD-g-C3N4 catalysts were prepared. Electronic and morphological properties of catalysts were identified by advanced analytical methods such as ICP-MS, Powder X-ray diffraction (P-XRD), Transmissive Electron Microscopy (TEM), Scanning Electron microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-ray Photoelectron spectroscopy (XPS), BET, UV-NIR, and FTIR. Then, the catalytic and photocatalytic efficiency of the prepared Pd@BD-g-C3N4 catalysts in Suzuki-Miyaura C-C Coupling Reactions was investigated. Catalytic conversions were calculated by gas chromatography (GC) method. The average particle size of the prepared Pd@BD-g-C3N4 catalyst was found to be 6.24 ± 0.5nm. The 2% Pd loaded Pd@BD-g- C3N4-35 catalyst showed high conversion (>97%) in the Suzuki-Miyaura C-C coupling reactions, in open air and water as solvent (100 oC). Moreover, the high durability of the 2%-Pd@BD-g-C3N4 nanocatalyst shows that it is a green heterogeneous catalyst that can be reused (<5 cycle counts) in Suzuki-Miyaura C-C coupling reactions. At the end of the photocatalytic investigations carried out with different percentages of Pd@BD-g-C3N4, the highest conversion was measured as 51% in 4 h in daylight at room conditions in the 2%-Pd@BD-g-C3N4 catalyst.