Revealing Pd Nanoparticles Formation from PEG-Mediated Decomposition of Organometallic Precursor and Their Application as Catalyst for the Synthesis of n-Extended Carbazoles

Synthesis of well-controlled palladium nanoparticles (PdNPs) by spontaneous decomposition of tris(dibenzylideneacetone)dipalladium(0) in polyethylene glycol Mw 300 (PEG 300) in the absence of reductant atmosphere or thermal effect is reported. The Pd nanoparticles exhibited a spherical pattern with 2- to 4-nm diameter and low standard deviation according to scanning transmission electron microscopy (STEM) analysis. UV-vis electronic spectroscopy, dynamic light scattering (DLS) and diffusion ordered spectroscopy (DOSY) mode of H-1 nuclear magnetic resonance (NMR) suggested that PEG acts as a template for the formation of PdNPs. These nanoparticles were efficient towards the Suzuki-Miyaura reaction for the synthesis of 3,6-diaryl carbazoles. Indeed, the whole catalyst system demonstrated an efficient recyclability (ten consecutive runs) without significant interference of the N-H moiety. Since diaryl carbazoles are the core of a number of compounds contained within components of organic solar cells and photovoltaics, this method should allow additional organic materials substrates under relatively inexpensive catalytic conditions.