Kinetic Barrier Diagrams to Visualize and Engineer Molecular Nonequilibrium Systems

Abstract

Molecular non-equilibrium systems are appealing for developing artificial life-like systems, holding great promises for the nanotechnology of the future. Yet, their development is slowed by the absence of a straightforward and informative representation under non-equilibrium conditions. Indeed, while potential energy surfaces comprise in principle all the information, they hide the dynamic interplay of multiple reaction pathways underlying non-equilibrium systems, i.e., the degree of kinetic asymmetry. To offer an insightful visual representation of kinetic asymmetry, we extended an approach pertaining to catalytic networks, the energy span model. This advancement becomes possible by implementing a holistic approach to complex networks, which focuses on system dynamics -rather than thermodynamics. This approach encompasses both chemically and photochemically driven systems, ranging from unimolecular motors to simple self-assembly schemes. The obtained kinetic asymmetry profiles give immediate access to information needed to guide experiments, such as states' population, rate of machine operation, maximum work output, and effects of design changes. Kinetic asymmetry profiles offer a unifying framework for disparate non-equilibrium phenomena, facilitating the realization of chemical engines.

Artificial Molecular Ratchets: Tools Enabling Endergonic Processes

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“…Dissipative materials have been developed that rely on energy input to maintain structural integrity and display emerging properties [12,13,14,15] . It has been postulated that non‐equilibrium self‐assembly relies on the same ratchet mechanisms that drive molecular machines [16,17,18,19] . Experimental observations such as catastrophic collapse in supramolecular fibers, [20] oscillations [21,22] and cooperative catalysis [23,24] in the assembled state indeed suggest that ratchet mechanisms are embedded in these systems.…”

“…[12,13,14,15] It has been postulated that non-equilibrium self-assembly relies on the same ratchet mechanisms that drive molecular machines. [16,17,18,19] Experimental observations such as catastrophic collapse in supramolecular fibers, [20] oscillations [21,22] and cooperative catalysis [23,24] in the assembled state indeed suggest that ratchet mechanisms are embedded in these systems. Yet, unequivocal proof for their presence is hampered by the complexity of these systems which complicates a detailed kinetic and thermodynamic analysis of all occurring processes.…”

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