A Sustainable Approach for Graphene Oxide-supported Metal N-Heterocyclic Carbenes Catalysts

Sustainable noble metal-N-heterocyclic carbenes (NHC's) are a topic of arising concern in both the chemical industry and the academic community due to a growing consciousness of environmental pollution and scarcity. Recovering and reusing homogeneous catalysts from the reaction mixture requires a tremendous amount of capital investment in the chemical manufacturing industry. Heterogeneous catalysts are proved to have better functional groups tolerance; however, catalysts support largely influences the active catalyst sites to affect catalyst efficiency and selectivity. Thus the, choice of catalyst supports plays an almost decisive role in this emerging area of catalysis research. Graphene oxide (GO)/reduced graphene oxide (rGO) support has a potential growth in heterogeneous catalysis owing to their commercial availability, considerably larger surface area, inert towards chemical transformations, and easy surface functionalization to attached metal complexes via covalent and non-covalent aromatic pi-conjugates. To take advantage of two independently well-established research areas of noble metal-N-heterocyclic carbenes and GO/rGO support via covalent or non-covalent interactions approach would offer novel heterogeneous complexes with improved catalytic efficiency without sacrificing product selectivity. This unique concept of marrying metal-N-heterocyclic carbenes with GO/rGO support has potential growth in the chemical and pharmaceutical industry, however, limited examples are reported in the literature. In this perspective, a comprehensive summary of metal-NHC synthesis on GO/rGO support and synthetic strategies to graft M-NHC onto GO/rGO surface, catalytic efficiency, for the catalytic transformation are critically reviewed. Furthermore, a plausible mechanism for non-covalent grafting methodology is summarized to direct readers to give a better understanding of M-NHC@rGO complexes. This would also allow the designing of engineered catalysts for unexplored catalytic applications.

Automated summary

Sustainable noble metal-N-heterocyclic carbenes (NHC's) have gained significant attention in both the chemical industry and academic community due to environmental concerns and resource scarcity. The choice of catalyst supports plays a crucial role in heterogeneous catalysis, with graphene oxide (GO)/reduced graphene oxide (rGO) support showing great potential due to their larger surface area, inertness towards chemical transformations, and easy surface functionalization. Marrying metal-N-heterocyclic carbenes with GO/rGO support offers novel heterogeneous complexes with improved catalytic efficiency without sacrificing product selectivity, presenting opportunities for the chemical and pharmaceutical industry. However, limited examples of this approach are reported in the literature, highlighting the need for comprehensive reviews on metal-NHC synthesis on GO/rGO support and synthetic strategies for grafting M-NHC onto GO/rGO surface, as well as understanding the catalytic efficiency and mechanisms of non-covalent grafting methodology to design engineered catalysts for unexplored catalytic applications.