Efficient synthesis of organic compounds for solar energy conversion by direct arylation reactions

Organic compounds play pivotal roles in various devices for solar energy conversion, in which they may act as light-absorbing components, fluorescent emitters or charge-transporting materials. Clearly, development of sustainable protocols for the synthesis of such compounds will be crucial in favouring the future widespread diffusion of sunlight-harvesting technologies. In the last few years, we described several efficient routes for the preparation of organic photoactive compounds, such as sensitizers for dye-sensitized solar cells [1,2] or emitters for luminescent solar concentrators [3], in which most traditional cross-coupling reactions were replaced with direct arylation processes, leading to shorter synthetic sequences and reduced waste production (Fig. 1, top) [4]. More recently, we studied the use in such processes of biocompatible deep eutectic solvents (DES) in place of common organic volatile solvents, and compared the most relevant green chemistry metrics in the two cases (Fig. 1, bottom) [5]. In this communication, we will describe our most significant findings, highlighting the reactions scope, the properties of the synthesized compounds and our efforts in expanding the range of metal-catalyzed reactions in the new environmentally-friendly reaction media.