2 Pure Liquids: Data

Wohlfahrt, Ch.

doi:10.1007/10047452_2

Cited by 10 publications

(8 citation statements)

References 459 publications

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“…The effects of the solvent are described within the self-consistent reaction field (SCRF) framework employing the polarizable continuum model (PCM) . In this case, the dielectric constant ε of trichlorobenzene (TCB) in our calculations is set to be 3.98, consistent with the experimental value …”

Section: Methodsmentioning

confidence: 94%

Does a Blatter Radical Retain Its Open-Shell Character When Incorporated into Gold–Molecule–Gold Junctions?

Jiang

Wang

et al. 2023

J. Phys. Chem. C

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One of the key issues for the use of organic radicals in high-performance molecular electronic, spintronic and thermoelectric devices is the retention, at room temperature, of their open-shell character when they are in contact with the metal electrodes of a junction. By means of first-principles quantum transport calculations, we have investigated the stability and the electronic transport properties of single-molecule junctions incorporating a Blatter radical (BR) with thiomethyl linker groups. Our calculations suggest that the BR can unequivocally retain its open-shell nature even when bound to gold electrodes through undercoordinated gold adatoms. Such a state cannot be destroyed by the surrounding solvent molecules and the applied bias. The calculated low-bias conductance values of junctions with BR, an oxidized BR derivative, and a closed-shell stilbene molecule are in quantitative agreement with the available experimental measurements. The small conductance of the BR can be associated with the localization of its π-type singly occupied and singly unoccupied molecular orbitals (SOMO and SUMO), leading to an asymmetrically weak electronic coupling to the two gold electrodes, even though these two orbitals lie very close to the Fermi energy. Furthermore, the nonmonotonic modulation of the junction conductance controlled by a charge gate can be used in experiments to further verify the presence of the unpaired electron. This proof may be realized in practice with an electrostatic solidstate or an electrochemical gate. Our findings deepen the current understanding of the radical−metal interfacial properties and facilitate the design of future radical-based multifunctional molecular devices.

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Section: Methodsmentioning

confidence: 94%

Does a Blatter Radical Retain Its Open-Shell Character When Incorporated into Gold–Molecule–Gold Junctions?

Jiang

Wang

et al. 2023

J. Phys. Chem. C

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“…A reaction‐field correction [128][129] was applied to account for the mean effect of electrostatic interactions beyond the long‐range cutoff distance, using a relative dielectric permittivity of 4.81. The latter value, appropriate for chloroform, was also used for toluene (experimental value 2.40) as an effective way to avoid the occurrence of cutoff artifacts (a similar increase for low‐permittivity solvents was also adopted in previous GROMOS studies [120][132] ).…”

Section: Computational Proceduresmentioning

confidence: 99%

Vase‐Kite Equilibrium of Resorcin[4]arene Cavitands Investigated Using Molecular Dynamics Simulations with Ball‐and‐Stick Local Elevation Umbrella Sampling

Hahn

Milić

Hünenberger

2019

Helvetica Chimica Acta

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A key feature of resorcin[4]arene cavitands is their ability to switch between a closed/contracted (Vase) and an open/expanded (Kite) conformation. The mechanism and dynamics of this interconversion remains, however, elusive. In the present study, the Vase‐Kite transitions of a quinoxaline‐based and of a dinitrobenzene‐based resorcin[4]arene are investigated using molecular dynamics (MD) simulations in three environments (vacuum, chloroform, and toluene) and at three temperatures (198.15, 248.15, and 298.15 K). The challenge of sampling the Vase‐Kite transition, which occurs experimentally on the millisecond time scale, is overcome by calculating relative free energies using ball‐and stick local elevation umbrella sampling (B&S‐LEUS) to enhance the statistics on the relevant states and to promote interconversion transitions. Associated unbiased MD simulations also evidence for the first time a complete Vase‐to‐Kite transition, as well as transitions between degenerate Kite1 and Kite2 forms and solvent‐exchange events. The calculated Vase‐to‐Kite free‐energy changes ΔG are in qualitative agreement with the experimental magnitudes and trends. The level of quantitative agreement is, however, limited by the force‐field accuracy and, in particular, by the approximate treatment of intramolecular interactions at the classical level. The results are in line with a less stable Vase state for the dinitrobenzene compared to the quinoxaline compound, and a negative entropy change ΔS for the Vase‐to‐Kite transition of the latter compound. Relative free energies calculated for intermediates also suggest that the Vase‐Kite transition does not follow a concerted mechanism, but an asynchronous one with sequential opening of the flaps. In particular, the conformation involving two adjacent flaps open in a parallel direction (cis‐p) represents a likely intermediate, which has not been observed experimentally to date.

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“…Simulating systems with increased l B may be of physicochemical relevance due to the fact that l B /σ = 3, 4, 5, and 6 correspond to solvent relative dielectric constants ε r ≃ 53, 40, 31, and 26, which are typical values for commonly employed organic solvents. The l B = σ case, which corresponds to ε r ≃ 158, is additionally included to gain physical insights for both the l B → 0 and l B → ∞ limits, despite the fact that solvent with such high screening power (e.g., HCN) are hardly used.…”

Section: Resultsmentioning

confidence: 99%

Tuning Knotted Copolyelectrolyte Conformations via Solution Properties

2022

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We used Langevin dynamics simulations to study coarse-grained knotted copolyelectrolytes, composed by a neutral and a charged segment, in solutions of different salt concentrations, valency, and solvent screening power. We show that the facile variation of these parameters allows for tuning the length and position of the knotted region, which in turn controls the overall metric properties. Specifically, adding either monovalent or divalent ions causes the knot to swell at the expense of the copolyelectrolyte overall size. However, the knot typically straddles the charged–neutral interface in the presence of monovalent counterions, whereas it is attracted on the charged segment with divalent ones. Notably, similar modulations of knot size and position can also be achieved by varying the dielectric constant of the solvent. Our results demonstrate the feasibility of harnessing the solution-mediated balance of electrostatics and conformational entropy toward a facile external tuning of the conformational properties of knotted polymers.

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2 Pure Liquids: Data

Cited by 10 publications

References 459 publications

Does a Blatter Radical Retain Its Open-Shell Character When Incorporated into Gold–Molecule–Gold Junctions?

Does a Blatter Radical Retain Its Open-Shell Character When Incorporated into Gold–Molecule–Gold Junctions?

Vase‐Kite Equilibrium of Resorcin[4]arene Cavitands Investigated Using Molecular Dynamics Simulations with Ball‐and‐Stick Local Elevation Umbrella Sampling

Tuning Knotted Copolyelectrolyte Conformations via Solution Properties

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