Nonequilibrium thermodynamics of light-induced reactions.
15 Sep 2021-Journal of Chemical Physics (AIP Publishing LLCAIP Publishing)-Vol. 155, Iss: 11, pp 114101
TL;DR: In this article, the authors extend the theory of nonequilibrium thermodynamics to include incoherent light as a source of free energy and derive the chemical potential of photons relative to the system they interact with.
Abstract: Current formulations of nonequilibrium thermodynamics of open chemical reaction networks only consider chemostats as free-energy sources sustaining nonequilibrium behaviors. Here, we extend the theory to include incoherent light as a source of free energy. We do so by relying on a local equilibrium assumption to derive the chemical potential of photons relative to the system they interact with. This allows us to identify the thermodynamic potential and the thermodynamic forces driving light-reacting chemical systems out-of-equilibrium. We use this framework to treat two paradigmatic photochemical mechanisms describing light-induced unimolecular reactions—namely, the adiabatic and diabatic mechanisms—and highlight the different thermodynamics they lead to. Furthermore, using a thermodynamic coarse-graining procedure, we express our findings in terms of commonly measured experimental quantities, such as quantum yields.
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TL;DR: In this article , the authors extend the scope of information thermodynamics to deterministic bipartite chemical reaction networks, composed of two coupled subnetworks sharing species but not reactions.
Abstract: Information thermodynamics relates the rate of change of mutual information between two interacting subsystems to their thermodynamics when the joined system is described by a bipartite stochastic dynamics satisfying local detailed balance. Here, we expand the scope of information thermodynamics to deterministic bipartite chemical reaction networks, namely, composed of two coupled subnetworks sharing species but not reactions. We do so by introducing a meaningful notion of mutual information between different molecular features that we express in terms of deterministic concentrations. This allows us to formulate separate second laws for each subnetwork, which account for their energy and information exchanges, in complete analogy with stochastic systems. We then use our framework to investigate the working mechanisms of a model of chemically driven self-assembly and an experimental light-driven bimolecular motor. We show that both systems are constituted by two coupled subnetworks of chemical reactions. One subnetwork is maintained out of equilibrium by external reservoirs (chemostats or light sources) and powers the other via energy and information flows. In doing so, we clarify that the information flow is precisely the thermodynamic counterpart of an information ratchet mechanism only when no energy flow is involved.
12 citations
TL;DR: A variety of artificial molecular machines operated by light have been constructed by implementing photochemical processes within appropriately designed (supra)molecular assemblies as mentioned in this paper, which could open up new routes for the realization of nanostructured devices and materials capable to harness, convert, and store light energy.
Abstract: The exploitation of sunlight as a clean, renewable, and distributed energy source is key to facing the energetic demand of modern society in a sustainable and affordable fashion. In the past few decades, chemists have learned to make molecular machines, that is, synthetic chemical systems in which energy inputs cause controlled movements of molecular components that could be used to perform a task. A variety of artificial molecular machines operated by light have been constructed by implementing photochemical processes within appropriately designed (supra)molecular assemblies. These studies could open up new routes for the realization of nanostructured devices and materials capable to harness, convert, and store light energy.
12 citations
TL;DR: In this article , the authors provide a design perspective for catalysis-driven molecular machines, using a rotary motor and a kinesin walker as illustrative examples, and pinpoints both chemical gating and power strokes as tunable design elements that can affect kinetic asymmetry.
Abstract: Chemically fueled autonomous molecular machines are catalysis-driven systems governed by Brownian information ratchet mechanisms. One fundamental principle behind their operation is kinetic asymmetry, which quantifies the directionality of molecular motors. However, it is difficult for synthetic chemists to apply this concept to molecular design because kinetic asymmetry is usually introduced in abstract mathematical terms involving experimentally inaccessible parameters. Furthermore, two seemingly contradictory mechanisms have been proposed for chemically driven autonomous molecular machines: Brownian ratchet and power stroke mechanisms. This Perspective addresses both these issues, providing accessible and experimentally useful design principles for catalysis-driven molecular machinery. We relate kinetic asymmetry to the Curtin–Hammett principle using a synthetic rotary motor and a kinesin walker as illustrative examples. Our approach describes these molecular motors in terms of the Brownian ratchet mechanism but pinpoints both chemical gating and power strokes as tunable design elements that can affect kinetic asymmetry. We explain why this approach to kinetic asymmetry is consistent with previous ones and outline conditions where power strokes can be useful design elements. Finally, we discuss the role of information, a concept used with different meanings in the literature. We hope that this Perspective will be accessible to a broad range of chemists, clarifying the parameters that can be usefully controlled in the design and synthesis of molecular machines and related systems. It may also aid a more comprehensive and interdisciplinary understanding of biomolecular machinery.
11 citations
TL;DR: In this paper , the energy span model is extended to provide a visual representation of kinetic asymmetry in nonequilibrium systems, including both chemically and photochemically driven systems, ranging from unimolecular motors to simple self-assembly schemes.
Abstract: Molecular nonequilibrium systems hold great promises for the nanotechnology of the future. Yet, their development is slowed by the absence of an informative representation. Indeed, while potential energy surfaces comprise in principle all the information, they hide the dynamic interplay of multiple reaction pathways underlying nonequilibrium 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, by focusing on system dynamics - rather than thermodynamics. Our approach encompasses both chemically and photochemically driven systems, ranging from unimolecular motors to simple self-assembly schemes. The obtained diagrams 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. The proposed kinetic barrier diagrams offer a unifying graphical tool for disparate nonequilibrium phenomena.
4 citations
TL;DR: In this paper , steady-state reaction networks are inspected from the viewpoint of individual tagged molecules jumping among their chemical states upon the occurrence of reactive events, where the focus is on how an ideal spatial compartmentalization may affect the dynamical features of the tagged molecule.
Abstract: Here, steady-state reaction networks are inspected from the viewpoint of individual tagged molecules jumping among their chemical states upon the occurrence of reactive events. Such an agent-based viewpoint is useful for selectively characterizing the behavior of functional molecules, especially in the presence of bimolecular processes. We present the tools for simulating the jump dynamics both in the macroscopic limit and in the small-volume sample where the numbers of reactive molecules are of the order of few units with an inherently stochastic kinetics. The focus is on how an ideal spatial "compartmentalization" may affect the dynamical features of the tagged molecule. Our general approach is applied to a synthetic light-driven supramolecular pump composed of ring-like and axle-like molecules that dynamically assemble and disassemble, originating an average ring-through-axle directed motion under constant irradiation. In such an example, the dynamical feature of interest is the completion time of direct/inverse cycles of tagged rings and axles. We find a surprisingly strong robustness of the average cycle times with respect to the system's size. This is explained in the presence of rate-determining unimolecular processes, which may, therefore, play a crucial role in stabilizing the behavior of small chemical systems against strong fluctuations in the number of molecules.
3 citations
References
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TL;DR: In el marco del Proyecto subvencionado by the Fundación Antorchas (FAN) as mentioned in this paper, el material was digitalizado, e.g., en la Biblioteca del Departamento de Fisica de la Facultad de Ciencias Exactas de la Universidad Nacional de La Plata.
Abstract: Este material fue digitalizado en el marco del Proyecto subvencionado por la Fundacion Antorchas y se encuentra en la Biblioteca del Departamento de Fisica de la Facultad de Ciencias Exactas de la Universidad Nacional de La Plata.
2,623 citations
TL;DR: In this article, the authors report repetitive, monodirectional rotation around a central carbon-carbon double bond in a chiral, helical alkene, with each 360° rotation involving four discrete isomerization steps activated by ultraviolet light or a change in the temperature of the system.
Abstract: Attempts to fabricate mechanical devices on the molecular level1,2 have yielded analogues of rotors3, gears4, switches5, shuttles6,7, turnstiles8 and ratchets9. Molecular motors, however, have not yet been made, even though they are common in biological systems10. Rotary motion as such has been induced in interlocked systems11,12,13 and directly visualized for single molecules14, but the controlled conversion of energy into unidirectional rotary motion has remained difficult to achieve. Here we report repetitive, monodirectional rotation around a central carbon–carbon double bond in a chiral, helical alkene, with each 360° rotation involving four discrete isomerization steps activated by ultraviolet light or a change in the temperature of the system. We find that axial chirality and the presence of two chiral centres are essential for the observed monodirectional behaviour of the molecular motor. Two light-induced cis-trans isomerizations are each associated with a 180° rotation around the carbon–carbon double bond and are each followed by thermally controlled helicity inversions, which effectively block reverse rotation and thus ensure that the four individual steps add up to one full rotation in one direction only. As the energy barriers of the helicity inversion steps can be adjusted by structural modifications, chiral alkenes based on our system may find use as basic components for ‘molecular machinery’ driven by light.
1,494 citations
TL;DR: Can PSII be exploited through increased use of biomass as an energy source and, more importantly, can the energy/CO2 problem be addressed by developing new photochemical technologies which mimic the natural system?
Abstract: Photosystem II (PSII) is the water splitting enzyme of photosynthesis. Its appearance during evolution dramatically changed the chemical composition of our planet and set in motion an unprecedented explosion in biological activity. Powered by sunlight, PSII supplies biology with the ‘hydrogen’ needed to convert carbon dioxide into organic molecules. The questions now are can we continue to exploit this photosynthetic process through increased use of biomass as an energy source and, more importantly, can we address the energy/CO2 problem by developing new photochemical technologies which mimic the natural system? (Critical review, 82 references)
1,494 citations
21 Feb 2006
TL;DR: In this article, the triplet-state Energies of a triplet state were investigated in the context of low-temperature photophysics of organic molecules in solution.
Abstract: Photophysics of Organic Molecules in Solution Introduction Electronic States Radiative Transitions Nonradiative Transitions Excited State Kinetics Acknowledgments Bibliography Transition Metal Complexes Electronic Structure Types of Excited States and Electronic Transitions Absorption and Emission Bands Jablonski Diagram Photochemical Reactivity Electrochemical Behavior Polynuclear Metal Complexes Photophysical Properties of Organic Compounds Photophysics of Organic Molecules in Solution Triplet-State Energies: Ordered Flash Photolysis: Designing Experiments Low-Temperature Photophysics of Organic Molecules Absorption and Luminescence Spectra of Organic Compounds ESR and ODMR Parameters of the Triplet State Photophysical Properties of Transition Metal Complexes Photophysical Parameters Absorption and Emission Spectra Abbreviations Rate Constants of Excited-State Quenching Ionization Energies, Electron Affinities, and Reduction Potentials Ionization Energies and Electron Affinities Reduction Potentials Bond Dissociation Energies Solvent Properties Donor Number Luminescence Spectroscopy Measurements Correction of Luminescence Intensity Measurements in Solution Fluorescence Quantum Yield Standards Phosphorescence Quantum Yield Standards Luminescence Lifetime Standards Light Sources and Filters Spectral Distribution of Photochemical Sources Transmission Characteristics of Light Filters and Glasses Chemical Actinometry Ferrioxalate Actinometer Photochromic Actinometers Reinecke's Salt Actinometer Uranyl Oxalate Actinometer Other Actinometers Miscellaneous Spin-Orbit Coupling Hammett ? Constants Fundamental Constants and Conversion Factors Index *References included in each chapter
1,464 citations
TL;DR: In this article, a new set of Spekfralmessungen von O. Lummer, E. Pringsheim and E. Kurlbaum was gezeigt, das das zuerst von W. Wien aus molekularkinetischen Betrachtungen und spater von mir aus der Theorie der elektromagnetischen Strahlung abgeleitete Gesetz der Energieverteilung im Normalspektrum keine allgemeine G
Abstract: Die neueren Spekfralmessungen von O. Lummer und E. Pringsheim 4) und noch auffalliger diejenigen von H. Rubens und F. Kurlbaum 5), welche zugleich ein frUher von H. Beckmann 1) erhaltenes Resultat bestatigten, haben gezeigt, das das zuerst von W. Wien aus molekularkinetischen Betrachtungen und spater von mir aus der Theorie der elektromagnetischen Strahlung abgeleitete Gesetz der Energieverteilung im Normalspektrum keine allgemeine GUltigkeit besitzt.
1,170 citations