Deciphering Photoluminescence in an Aryl Iodides-Gold Nanoparticles System: Au-Mediated Homocoupling Reaction at a Low Temperature.

The study of photoactive materials often unveils intriguing findings, showcasing the value of an interdisciplinary approach. We examined the purported metal-enhanced luminescence thought to result from the chemisorption of aryl iodides on poly( N -vinylpyrrolidone)-stabilized gold nanoparticles. Our discovery deviates from previous assumptions: the fluorescence observed does not originate from excimers of iodophenols chemisorbed on Au:PVP. Instead, it arises from biphenol products, resulting from a gold-mediated Ullmann homocoupling reaction that occurs within the system. Notably, this reaction, known for its demanding nature, proceeds in methanol under purely ambient conditions: room temperature and air atmosphere, without the need for a base. Therefore, these findings not only offer a complete understanding of the observed luminescence but also provide a substantial contribution to the field of carbon-carbon coupling reactions.