Bioinspired Catalyst Design Principles: Progress in Emulating Properties of Enzymes in Synthetic Catalysts

Abstract

Catalysis enables many aspects of modern life, including fuels, products, plastics, and medicines. Recent advances in catalysis have enabled us to realize higher efficiencies and new processes. Ideally, we seek to achieve high rates of selective conversions using catalysts derived from abundantly available elements and operating under mild conditions, specifically lower reaction temperatures and pressures. Such catalysts could enable decentralized, on-demand synthesis of chemicals and energy carriers. Nature has demonstrated the feasibility of this approach with enzymes, which showcase catalytic processes at low temperatures and pressures with nonprecious metals. Current thinking holds that in addition to the active site, the complexity of the enzyme structure, specifically the protein scaffold, is also critical to achieving this performance. Recreating this environment has been a long-standing scientific goal. However, we still understand the functions of enzymes better than we understand the de novo design of catalysts that mimic enzymes features, while also retaining their activity and selectivity under more demanding conditions. In this Perspective, we will critically examine four key areas of catalyst design that incorporate the chemical and structural properties of enzymes into synthetic catalysts: (i) the use of confinement to enhance catalytic activity, (ii) tailoring the environment around the active site, (iii) proton transport, and (iv) bifunctionality and cooperativity.

Challenges and Opportunities for Exploiting the Role of Zeolite Confinements for the Selective Hydrogenation of Acetylene

“…This fascinating difference in the mechanism was attributed to the smaller pores having a stronger local electric field, thereby allowing for the direct dissociation and activation of dihydrogen molecules. Recently, Lercher and co-workers and Surendranath and co-workers have attempted to develop a framework to elucidate and enumerate the effect of electric fields on reaction kinetics. − Specifically, Lercher and co-workers have suggested that the influence of electric fields center around the modulation of ground and transition states inside the confined environments of zeolites. − The influence of electric field on ground and transition state energies can be enumerated as the product of the relative difference in the dipole moments of the transition state and the ground state and the local electric field, in line with recent work by Shetty et al, and Deshlahra et al , Surendranath and co-workers probed the spontaneous local electric field at the solid–liquid interfaces of a Pt catalyst through vibrational Stark effect and the open circuit potential (OCP) established as an electric double layer is formed at the metal-liquid interface . In addition, the OCP is correlated to the metal work-function and the ionic strength in the double layer suggesting that they may be important indicators in probing electric field effects inside the confined environment of the zeolites …”

Regulating Access to Active Sites via Hydrogen Bonding and Cation–Dipole Interactions: A Dual Cofactor Approach to Switchable Catalysis

“…In biological systems, catalytic reactions are often modulated by “gating” mechanisms that regulate substrate access to active sites based on allosteric interactions between enzymes and small molecule or ion cofactors. − Synthetic chemists have long sought to replicate allosteric gating to achieve controlled or switchable catalysis in artificial systems. − The most common gating mechanisms involve physical blocking groups, such as supramolecular constructs with switchable steric bulk or supramolecular cages with switchable access, catalyst solubility, and configurational changes like cis/trans isomerization or metal–ligand bond-breaking reactions. ,− These designs have enabled breakthroughs in copolymer synthesis, established methods for switching product selectivity in small-molecule synthesis without needing to synthetically modify the catalyst, and enhanced capabilities for multicatalyst cascades. , …”

Regulating Access to Active Sites via Hydrogen Bonding and Cation-Dipole Interactions: A Dual Cofactor Approach to Switchable Catalysis

“…[2][3][4][5] Synthetic chemists have long sought to replicate the function of allosteric control over substrate gating to achieve controlled or switchable catalysis. [6][7][8][9] The most common gating mechanisms involve physical blocking groups, such as supramolecular constructs with switchable steric bulk or supramolecular cages with switchable access, catalyst solubility, and configurational changes like cis/trans isomerization or metal-ligand bond breaking reactions. 6,[10][11][12][13][14] One important gating mechanism employed by enzymes is tunable hydrogen bonding (Hbonding) networks.…”