Nanoconfined spaces for Sustainable Catalysis: Soy Protein-Based Cryogels for Cross-Coupling Reactions

The green synthesis approach offers an efficient route for converting waste into valuable chemicals while minimising energy consumption and environmental impact. In this context, the pivotal roles of heterogeneous catalysis and nanocatalysis are evident, as they provide stable and tunable active sites that enable selective and sustainable transformations in industrial processes. In order to develop more environmentally friendly catalytic systems, novel palladium-based catalysts have been immobilised within soy protein cryogels. These bio-based materials address the major drawbacks of traditional palladium catalysts, including limited reusability, structural instability, and metal leaching. The porous cryogel matrix creates a confined microenvironment that ensures homogeneous dispersion and stabilisation of palladium species at a concentration of 2 mmol%, thereby enabling effective nanocatalysis in Suzuki–Miyaura, Sonogashira, and Heck reactions.

A diverse library of C–C coupled products was synthesised under mild conditions (80 °C) in alcoholic and aqueous media, achieving excellent yields of up to 99%. The findings of the recyclability studies demonstrated the remarkable structural integrity and reusability of the catalyst over multiple cycles, with only minimal reductions in efficiency after ten runs. The protein network within the cryogel facilitates facile recovery of the catalyst, whilst also modulating its activity through spatial confinement effects. A series of computational investigations were conducted in order to further elucidate the structural and electronic characteristics that underpin the performance of the catalyst. The system's low-cost synthesis, high stability, and scalability make it a promising green alternative for industrial heterogeneous catalysis and nanocatalysis.