Transition metal nanoparticle catalysis in green solvents

Nanoparticle (NP) catalysis in liquid phase, which is usually called “soluble” NP catalysis, is an old topic but is now well advanced due to the great progress in nano-chemistry and nano-technology in green chemistry. After a short introduction of the history, this review describes the current status of NP catalysis in solvents and then discusses the main drawbacks hindering the particles from industrial practice. Efficiency, stability, sustainability, and recyclability (ESSR) criteria were suggested to evaluate NP catalytic systems. A state-of-the-art approach to satisfy ideal ESSR criteria is to produce cohesion over the individual contributions of metal center, stabilizer and solvent (MSS), i.e., a cohesive MSS approach. Based on reported examples, the roles that the metal core, the stabilizer and the solvent play in NP catalysis are discussed in detail. For clarity, a fairly complete list of NP catalytic systems in various green solvents reported in recent decade is provided.