Single-atom heterogeneous catalysts for sustainable organic synthesis

Abstract

Single-atom heterogeneous catalysts can be highly selective for organic transformations of value to the pharmaceutical, fine, and specialty chemical industries. Their well-defined nature allows atomically precise control of their properties to potentially match the performance of commercially used organometallic catalysts. The improved metal recovery and reusability enabled through using solid catalysts pave the way for process intensification and minimized work-up in downstream operations. Process optimization requires tailoring the reaction environment, which can cause loss of structural stability, leading to deactivation. The structural and mechanistic understanding provided by computational and experimental interrogation can guide the design and development of next-generation catalysts. Single-atom heterogeneous catalysts (SACs) incorporating isolated metal centers on solid supports demonstrate promise for improving the sustainability of commercial organic transformations. They avoid the issues of metal recovery and reuse associated with conventionally applied organometallic precious metal complexes while delivering highly selective and stable performance. Considering the broad reaction scope of SACs, in this review we explore the potential for activating specific low-energy pathways through tailoring the chemical environment of the active metal for chemo-, regio-, and stereoselective applications while ensuring full accessibility of metal centers. Opportunities and challenges towards their mechanistic understanding and technical implementation, including the influence of the reaction environment, deactivation pathways, and the need for improved sustainability metrics, are discussed. Single-atom heterogeneous catalysts (SACs) incorporating isolated metal centers on solid supports demonstrate promise for improving the sustainability of commercial organic transformations. They avoid the issues of metal recovery and reuse associated with conventionally applied organometallic precious metal complexes while delivering highly selective and stable performance. Considering the broad reaction scope of SACs, in this review we explore the potential for activating specific low-energy pathways through tailoring the chemical environment of the active metal for chemo-, regio-, and stereoselective applications while ensuring full accessibility of metal centers. Opportunities and challenges towards their mechanistic understanding and technical implementation, including the influence of the reaction environment, deactivation pathways, and the need for improved sustainability metrics, are discussed. a catalyst that acts in the same phase as the reactants, most commonly an organometallic complex. the industrially used process to form aldehydes from alkenes. The reaction proceeds via the addition of a formyl group (CHO) and a hydrogen atom to a carbon–carbon double bond. The reaction is performed in the presence of a transition-metal catalyst in the presence of CO and H2 and can be operated in gas or liquid phase. a method for assessing environmental impacts associated with all of the stages of the life cycle of a commercial product. the characterization of the catalyst under reaction conditions involving the simultaneous measurement of conversion or rate. a catalytic material integrating metal atoms spatially isolated on a support. also known as intercalation; the metal atom diffuses into the subsurface of the support and is therefore inaccessible for reaction with the substrates. metric of catalyst activity expressed in moles of product per mole of metal active site.