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Ma Z, Yan Z, Li X, Chung LW. Quantum Tunneling in Reactions Modulated by External Electric Fields: Reactivity and Selectivity. J Phys Chem Lett 2023; 14:1124-1132. [PMID: 36705472 DOI: 10.1021/acs.jpclett.2c03461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Quantum tunneling and external electric fields (EEFs) can promote some reactions. However, the synergetic effect of an EEF on a tunneling-involving reaction and its temperature-dependence is not very clear. In this study, we extensively investigated how EEFs affect three reactions that involve hydrogen- or (ground- and excited-state) carbon-tunneling using reliable DFT, DLPNO-CCSD(T1), and variational transition-state theory methods. Our study revealed that oriented EEFs can significantly reduce the barrier and corresponding barrier width (and vice versa) through more electrostatic stabilization in transition states. These EEF effects enhance the nontunneling and tunneling-involving rates. Such EEF effects also decrease the crossover temperatures and quantum tunneling contribution, albeit with lower and thinner barriers. Moreover, EEFs can modulate and switch on/off the tunneling-driven 1,2-H migration of hydroxycarbenes under cryogenic conditions. Furthermore, our study predicts for the first time that EEF/tunneling synergy can control the chemo- or site-selectivity of one molecule bearing two similar/same reactive sites.
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Affiliation(s)
- Zhifeng Ma
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Zeyin Yan
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Xin Li
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
| | - Lung Wa Chung
- Shenzhen Grubbs Institute, Department of Chemistry, and Guangdong Provincial Key Laboratory of Catalysis, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen 518055, P. R. China
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Robson B. De novo protein folding on computers. Benefits and challenges. Comput Biol Med 2022; 143:105292. [PMID: 35158120 DOI: 10.1016/j.compbiomed.2022.105292] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 01/05/2023]
Abstract
There has been recent success in prediction of the three-dimensional folded native structures of proteins, most famously by the AlphaFold Algorithm running on Google's/Alphabet's DeepMind computer. However, this largely involves machine learning of protein structures and is not a de novo protein structure prediction method for predicting three-dimensional structures from amino acid residue sequences. A de novo approach would be based almost entirely on general principles of energy and entropy that govern protein folding energetics, and importantly do so without the use of the amino acid sequences and structural features of other proteins. Most consider that problem as still unsolved even though it has occupied leading scientists for decades. Many consider that it remains one of the major outstanding issues in modern science. There is crucial continuing help from experimental findings on protein unfolding and refolding in the laboratory, but only to a limited extent because many researchers consider that the speed by which real proteins folds themselves, often from milliseconds to minutes, is itself still not fully understood. This is unfortunate, because a practical solution to the problem would probably have a major effect on personalized medicine, the pharmaceutical industry, biotechnology, and nanotechnology, including for example "smaller" tasks such as better modeling of flexible "unfolded" regions of the SARS-COV-2 spike glycoprotein when interacting with its cell receptor, antibodies, and therapeutic agents. Some important ideas from earlier studies are given before moving on to lessons from periodic and aperiodic crystals, and a possible role for quantum phenomena. The conclusion is that better computation of entropy should be the priority, though that is presented guardedly.
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Affiliation(s)
- Barry Robson
- Ingine Inc.Cleveland Ohio and The Dirac Foundation, Oxfordshire, UK.
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Condensed-phase isomerization through tunnelling gateways. Nature 2022; 612:691-695. [PMID: 36265512 PMCID: PMC9771804 DOI: 10.1038/s41586-022-05451-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 10/17/2022] [Indexed: 02/05/2023]
Abstract
Quantum mechanical tunnelling describes transmission of matter waves through a barrier with height larger than the energy of the wave1. Tunnelling becomes important when the de Broglie wavelength of the particle exceeds the barrier thickness; because wavelength increases with decreasing mass, lighter particles tunnel more efficiently than heavier ones. However, there exist examples in condensed-phase chemistry where increasing mass leads to increased tunnelling rates2. In contrast to the textbook approach, which considers transitions between continuum states, condensed-phase reactions involve transitions between bound states of reactants and products. Here this conceptual distinction is highlighted by experimental measurements of isotopologue-specific tunnelling rates for CO rotational isomerization at an NaCl surface3,4, showing nonmonotonic mass dependence. A quantum rate theory of isomerization is developed wherein transitions between sub-barrier reactant and product states occur through interaction with the environment. Tunnelling is fastest for specific pairs of states (gateways), the quantum mechanical details of which lead to enhanced cross-barrier coupling; the energies of these gateways arise nonsystematically, giving an erratic mass dependence. Gateways also accelerate ground-state isomerization, acting as leaky holes through the reaction barrier. This simple model provides a way to account for tunnelling in condensed-phase chemistry, and indicates that heavy-atom tunnelling may be more important than typically assumed.
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Litman Y, Rossi M. Multidimensional Hydrogen Tunneling in Supported Molecular Switches: The Role of Surface Interactions. PHYSICAL REVIEW LETTERS 2020; 125:216001. [PMID: 33275002 DOI: 10.1103/physrevlett.125.216001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 10/08/2020] [Indexed: 06/12/2023]
Abstract
The nuclear tunneling crossover temperature (T_{c}) of hydrogen transfer reactions in supported molecular-switch architectures can lie close to room temperature. This calls for the inclusion of nuclear quantum effects (NQEs) in the calculation of reaction rates even at high temperatures. However, computations of NQEs relying on standard parametrized dimensionality-reduced models quickly become inadequate in these environments. In this Letter, we study the paradigmatic molecular switch based on porphycene molecules adsorbed on metallic surfaces with full-dimensional calculations that combine density-functional theory for the electrons with the semiclassical ring-polymer instanton approximation for the nuclei. We show that the double intramolecular hydrogen transfer (DHT) rate can be enhanced by orders of magnitude due to surface fluctuations in the deep-tunneling regime. We also explain the origin of an Arrhenius temperature dependence of the rate below T_{c} and why this dependence differs at different surfaces. We propose a simple model to rationalize the temperature dependence of DHT rates spanning diverse fcc [110] surfaces.
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Affiliation(s)
- Yair Litman
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany and Institute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Mariana Rossi
- Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany and MPI for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
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Dutra M, Wickramasinghe S, Garashchuk S. Multidimensional Tunneling Dynamics Employing Quantum-Trajectory Guided Adaptable Gaussian Bases. J Phys Chem A 2020; 124:9314-9325. [PMID: 33090807 DOI: 10.1021/acs.jpca.0c07168] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An efficient basis representation of time-dependent wavefunctions is essential for theoretical studies of high-dimensional molecular systems exhibiting large-amplitude motion. For fully coupled anharmonic systems, the complexity of a general wavefunction scales exponentially with the system size; therefore, for practical reasons, it is desirable to adapt the basis to the time-dependent wavefunction at hand. Often times on this quest for a minimal basis representation, time-dependent Gaussians are employed, in part because of their localization in both configuration and momentum spaces and also because of their direct connection to classical and semiclassical dynamics, guiding the evolution of the basis function parameters. In this work, the quantum-trajectory guided adaptable Gaussian (QTAG) bases method [ J. Chem. Theory Comput. 2020, 16, 18-34] is generalized to include correlated, i.e., non-factorizable, basis functions, and the performance of the QTAG dynamics is assessed on benchmark system/bath tunneling models of up to 20 dimensions. For the popular choice of initial conditions describing tunneling between the reactant/product wells, the minimal "semiclassical" description of the bath modes using essentially a single multidimensional basis function combined with the multi-Gaussian representation of the tunneling mode is shown to capture the dominant features of dynamics in a highly efficient manner.
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Affiliation(s)
- Matthew Dutra
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sachith Wickramasinghe
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sophya Garashchuk
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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Molecular motor crossing the frontier of classical to quantum tunneling motion. Proc Natl Acad Sci U S A 2020; 117:14838-14842. [PMID: 32541061 DOI: 10.1073/pnas.1918654117] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The reliability by which molecular motor proteins convert undirected energy input into directed motion or transport has inspired the design of innumerable artificial molecular motors. We have realized and investigated an artificial molecular motor applying scanning tunneling microscopy (STM), which consists of a single acetylene (C2H2) rotor anchored to a chiral atomic cluster provided by a PdGa(111) surface that acts as a stator. By breaking spatial inversion symmetry, the stator defines the unique sense of rotation. While thermally activated motion is nondirected, inelastic electron tunneling triggers rotations, where the degree of directionality depends on the magnitude of the STM bias voltage. Below 17 K and 30-mV bias voltage, a constant rotation frequency is observed which bears the fundamental characteristics of quantum tunneling. The concomitantly high directionality, exceeding 97%, implicates the combination of quantum and nonequilibrium processes in this regime, being the hallmark of macroscopic quantum tunneling. The acetylene on PdGa(111) motor therefore pushes molecular machines to their extreme limits, not just in terms of size, but also regarding structural precision, degree of directionality, and cross-over from classical motion to quantum tunneling. This ultrasmall motor thus opens the possibility to investigate in operando effects and origins of energy dissipation during tunneling events, and, ultimately, energy harvesting at the atomic scales.
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Jing C, Zhang B, Synkule S, Ebrahimi M, Riss A, Auwärter W, Jiang L, Médard G, Reichert J, Barth JV, Papageorgiou AC. Snapshots of Dynamic Adaptation: Two-Dimensional Molecular Architectonics with Linear Bis-Hydroxamic Acid Modules. Angew Chem Int Ed Engl 2019; 58:18948-18956. [PMID: 31671244 PMCID: PMC6973039 DOI: 10.1002/anie.201912247] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Indexed: 12/13/2022]
Abstract
Linear modules equipped with two terminal hydroxamic acid groups act as the building block of diverse two-dimensional supramolecular motifs and patterns with room-temperature stability on the close-packed single-crystal surfaces of silver and gold, revealing a complex self-assembly scenario. By combining multiple investigation techniques (scanning tunneling microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and density functional theory calculations), we analyze the characteristics of the ordered assemblies which range from close-packed structures to polyporous networks featuring an exceptionally extended primitive unit cell with a side length exceeding 7 nm. The polyporous network shows potential for hosting and promoting the formation of chiral supramolecules, whereas a transition from 1D chiral randomness to an ordered racemate is discovered in a different porous phase. We correlate the observed structural changes to the adaptivity of the building block and surface-induced changes in the chemical state of the hydroxamic acid functional group.
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Affiliation(s)
- Chao Jing
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
- Key Laboratory for Advanced MaterialsSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai200237P. R. China
| | - Bodong Zhang
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Sabine Synkule
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Maryam Ebrahimi
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
- Department of ChemistryLakehead University955 Oliver RdThunder BayONP7B 5E1Canada
| | - Alexander Riss
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Willi Auwärter
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Li Jiang
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Guillaume Médard
- Chair of Proteomics and BioanalyticsTechnical University of MunichEmil Erlenmeyer Forum 585354FreisingGermany
| | - Joachim Reichert
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
| | - Johannes V. Barth
- Physics Department E20Technical University of MunichJames Franck Straße 185748GarchingGermany
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Jing C, Zhang B, Synkule S, Ebrahimi M, Riss A, Auwärter W, Jiang L, Médard G, Reichert J, Barth JV, Papageorgiou AC. Snapshots of Dynamic Adaptation: Two‐Dimensional Molecular Architectonics with Linear Bis‐Hydroxamic Acid Modules. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912247] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Chao Jing
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
- Key Laboratory for Advanced Materials School of Chemistry and Molecular Engineering East China University of Science and Technology Shanghai 200237 P. R. China
| | - Bodong Zhang
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Sabine Synkule
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Maryam Ebrahimi
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
- Department of Chemistry Lakehead University 955 Oliver Rd Thunder Bay ON P7B 5E1 Canada
| | - Alexander Riss
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Willi Auwärter
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Li Jiang
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Guillaume Médard
- Chair of Proteomics and Bioanalytics Technical University of Munich Emil Erlenmeyer Forum 5 85354 Freising Germany
| | - Joachim Reichert
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Johannes V. Barth
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
| | - Anthoula C. Papageorgiou
- Physics Department E20 Technical University of Munich James Franck Straße 1 85748 Garching Germany
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