2,568 results on '"London dispersion force"'
Search Results
2. Understanding the Nature and Strength of Noncovalent Face‐to‐Face Arene–Fullerene Interactions.
- Author
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Yamada, Michio, Kurihara, Yukiyo, Koizumi, Masaaki, Tsuji, Kasumi, Maeda, Yutaka, and Suzuki, Mitsuaki
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- *
DIPOLE moments , *PHARMACEUTICAL chemistry , *AZULENE , *FULLERENES , *TORSION , *INTERMOLECULAR forces - Abstract
Face‐to‐face noncovalent arene−fullerene interactions are important in several research fields such as synthetic chemistry, materials chemistry, and medicinal chemistry; however, their nature and strength are still poorly understood. In this study, we prepare a fullerene‐based torsion balance containing thioanisole, phenol, naphthalene, azulene, and pyrene moieties as a unimolecular model system. Moreover, we compare the folding free energies between the folded and the unfolded conformers of a series of the molecular torsion balances to quantify noncovalent interactions between arenes and the fullerene surface. This work demonstrates that the contributions of polarizabilities, anionic charges, electronic dipole moments, and the number of arene rings to the interactions can be experimentally measured by analyzing the folding equilibrium of the molecular torsion balances. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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3. Nucleosides and Oligonucleotides Incorporating 2-Thiothymine or 2-Thiouracil Derivatives as Modified Nucleobases
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Seio, Kohji, Sekine, Mitsuo, Obika, Satoshi, editor, and Sekine, Mitsuo, editor
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- 2018
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4. High-Resolution THz Spectroscopy and Solid-State Density Functional Theory Calculations of Polycyclic Aromatic Hydrocarbons.
- Author
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Zhang, Feng, Wang, Houng-Wei, Tominaga, Keisuke, Hayashi, Michitoshi, and Sasaki, Tetsuo
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- *
DENSITY functional theory , *ISOTOPE shift , *SPECTRUM analysis , *ACENES , *TERAHERTZ spectroscopy , *BENZENE , *POLYCYCLIC aromatic hydrocarbons - Abstract
High-resolution and broadband THz spectra of the crystals of nine polycyclic aromatic hydrocarbons (PAHs) are presented. Five PAHs are comprised of ortho-fused benzene rings and the other four of peri-fused benzene rings. THz mode assignment is performed by using the anthracene and pyrene crystals as examples. The performance of the PBE functional augmented by Grimme's two dispersion correction terms, D* and D3, respectively, are rigorously evaluated against the experimental criteria of frequency and isotope shift (IS). The D* and D3 terms use empirical and semi-classical approach for correcting the London-type dispersion interactions, respectively. The nature of each THz mode simulated by PBE-D* and that by PBE-D3 is quantitatively compared in terms of the percentage contributions of the intermolecular and the intramolecular vibrations to the vibrational energy. We find that the two methods have equivalent performance in reproducing the frequencies, ISs, and nature of THz modes of both the anthracene and pyrene crystals. [ABSTRACT FROM AUTHOR]
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- 2020
- Full Text
- View/download PDF
5. A Fullerene‐Based Molecular Torsion Balance for Investigating Noncovalent Interactions at the C60 Surface.
- Author
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Yamada, Michio, Narita, Haruna, and Maeda, Yutaka
- Subjects
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TORSION balances , *INTERMOLECULAR forces , *SURFACE interactions , *ELECTROSTATIC interaction , *MOIETIES (Chemistry) , *FULLERENES - Abstract
To investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C60 and organic moieties connected through a biphenyl linkage were synthesized. NMR and computational studies show that the unimolecular system remains in equilibrium between well‐defined folded and unfolded conformers owing to restricted rotation around the biphenyl C−C bond. The energy differences between the two conformers depend on the substituents and is ascribed to differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Fullerenes favor interacting with the π‐faces of benzenes bearing electron‐donating substituents. The correlation between the folding free energies and corresponding Hammett constants of the substituents in the arene‐containing torsion balances reflects the contributions of the electrostatic interactions and dispersion force to face‐to‐face arene–fullerene interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
6. Dispersion force engineering. The long path from hooked atoms to next-generation spacecraft
- Author
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Fabrizio Pinto
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Spacecraft ,Series (mathematics) ,Computer science ,business.industry ,General purpose technology ,Intermolecular force ,Path (graph theory) ,Miniaturization ,Aerospace engineering ,business ,Space vehicle ,London dispersion force - Abstract
This paper presented as a Keynote talk is one of a series by the author analyzing in depth different interrelated aspects of the evolution of our understanding of intermolecular forces from a key speculation within early atomistic philosophy to applications in modern industry products, such as the atomic force microscope (AFM), non-volatile memory elements (NRAM), and “gecko-glue” adhesives. The manner in which dispersion force engineering as an emerging general purpose technology is enabling breakthrough advances in spacecraft performance and extreme space vehicle miniaturization is the overall topic of this paper series.
- Published
- 2022
7. Van der Waals Forces
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Bruylants, Gilles, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Cleaves, Henderson James (Jim), II, editor, Pinti, Daniele L., editor, Quintanilla, José Cernicharo, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor
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- 2015
- Full Text
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8. Tris[triphenylantimony(V)]hexa(μ-oxido)tellurium(VI): a molecular complex with six Te—O—Sb bridges
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Ganna A. Senchyk and Kostiantyn V. Domasevitch
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crystal structure ,hirshfeld surface ,hexaoxidotellurate(VI) ,Stacking ,chemistry.chemical_element ,Crystal structure ,London dispersion force ,Research Communications ,Ion ,polyoxoanions ,General Materials Science ,polyoxoanions ,hexaoxidotellurate(vi) ,triorganoantimony(V) ,triorganoantimony(v) ,Crystallography ,Chemistry ,Hydrogen bond ,oxide clusters ,General Chemistry ,Condensed Matter Physics ,HEXA ,QD901-999 ,Polyoxometalate ,Tellurium - Abstract
The structure of (C18H15Sb)3TeO6, contains a [TeO6] octahedral unit linked to three trigonal–bipyramidal [SbC3O2] units via pairs of bridging O atoms to form a discrete molecular unit. The packing of the units is dominated by C—H⋯O hydrogen bonding and weak dispersion forces, with a minor contribution from C—H⋯π bonds and π–π stacking interactions., In the structure of the title compound [systematic name hexa-μ-oxido-1:2κ4 O:O;1:3κ4 O:O;1:4κ4 O:O-nonaphenyl-2κ3 C,3κ3 C,4κ3 C-triantimony(V)tellurium(VI)], [Sb3Te(C6H5)9O6], the hexaoxidotellurate(VI) ion is coordinated to three SbV ions via pairs of cis-positioned O atoms to form a discrete molecular unit. The TeVI and SbV central ions exhibit distorted octahedral [TeO6] and distorted trigonal–bipyramidal [SbC3O2] coordination geometries, respectively. The linking of these polyhedra, by sharing the dioxide edges, results in the Te-based octahedron having a mer-configuration. The packing of the molecules is dominated by C—H⋯O hydrogen bonding and weak dispersion forces, with a minor contribution from C—H⋯π bonds and π–π stacking interactions. According to the Hirshfeld surface analysis, the contributions of the H⋯H, H⋯C/C⋯H and H⋯O/O⋯H contacts are 58.0, 32.6 and 7.8%, respectively. The title structure provides a model for the bonding of triorganoantimony dications to octahedral oxoanions, and the observed doubly bridged motifs, Te(μ-O)2Sb, may find application in the functionalization of polyoxometalate species.
- Published
- 2021
9. London Dispersion Helps Refine Steric A-Values: Dispersion Energy Donor Scales
- Author
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Peter R. Schreiner, Ephrath Solel, and Marcel Ruth
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Steric effects ,Scale (ratio) ,Chemistry ,General Chemistry ,Biochemistry ,London dispersion force ,Catalysis ,symbols.namesake ,Colloid and Surface Chemistry ,Pauli exclusion principle ,Chemical physics ,Steric factor ,Dispersion (optics) ,symbols ,A value ,Conformational isomerism - Abstract
We suggest a scale of dispersion energy donors (DEDs) that allows for direct comparisons with steric effects. This scale is based on the classic A-values and allows groups to reorient to minimize strain, thereby providing an advantage over raw group polarizabilities. The A-value can no longer be considered purely a steric factor. Even for groups that do not participate in charge transfer or electrostatic interactions, the A-value includes Pauli repulsion (steric hindrance) and attractive London dispersion (LD) interactions. Although the common assumption is that, at the distances found in monosubstituted cyclohexanes, steric demands are the key factors influencing conformer preferences, we show in this computational study that there is a non-negligible LD part. We use this system to build a DED scale and a complementary steric scale. These scales are quantitatively comparable, as they are based on the same system, and allow for comparison of the two competing interactions in experimentally relevant settings. In addition, we show that LD interactions can be used to explain puzzling data regarding relative group sizes.
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- 2021
10. Noncovalent Interactions in Organometallic Chemistry: From Cohesion to Reactivity, a New Chapter
- Author
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Yann Cornaton and Jean-Pierre Djukic
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chemistry.chemical_classification ,Agostic interaction ,010405 organic chemistry ,Ab initio ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Chemical physics ,symbols ,Non-covalent interactions ,Molecule ,Cohesion (chemistry) ,van der Waals force ,Organometallic chemistry - Abstract
Noncovalent interactions (NCIs) have long interested a vast community of chemists who investigated their "canonical categories" derived from descriptive crystallography, e.g., H-bonds, π-π interactions, halogen/chalcogen/tetrel bonds, cation-π and C-H-π interactions, metallophilic interactions in the broad sense, etc. Recent developments in theoretical chemistry have enabled the treatment of noncovalent interactions under new auspices: dispersion-force-inclusive density functionals have emerged, which are reliable for modeling small to large molecular systems. It is possible to perform the full analysis of the contributions of London, Debye, and Keesom forces, i.e., the main components of van der Waals forces, by the DFT-D and ab initio methods at a reasonable computational cost. Our research has been focusing for now 15 years on the role of NCIs in the cohesion of organometallic complexes. NCIs are not only effective in Werner's secondary coordination sphere but also in the metal's primary one. The stabilization of electron-unsaturated transition metal complexes by hemichelation, metal-metal donor-acceptor complexes, and self-aggregation of cationic Rh(I) chromophores have indeed outlined the significance of the London dispersion force as an attractive force operating throughout the whole molecule or molecular assembly. The recent outburst of interest in C-H bond functionalization led us to address the broader question of reaction and catalyst engineering: although one can now satisfactorily analyze bonding and molecular cohesion in transition-metal-based organometallic systems, can modern theoretical methods guide reactivity exploration and the engineering of novel catalytic systems? We addressed this question by investigating the ambiphilic metal-ligand activation/concerted metalation-deprotonation mechanism involved in transition-metal-catalyzed directed C-H bond functionalization. This endeavor was initiated having in scope the construction of a rationale for the transposition of 4-5d metal chemistry to earth-abundant 3d metals. In this base-assisted mechanism of C-H bond metalation, agostic interactions are necessary but not sufficient because C-H bond breaking actually relies on the attractive NCI coding of a proton-transfer step and the minimization of metal-H repulsion. This Account introduces the recent shift of our research toward the construction of an NCI-inclusive paradigm of chemical reactivity engineering based on experimental efforts propped up by state-of-the-art theoretical tools.
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- 2021
11. Competition between Hydrogen Bonding and Dispersion Force in Water Adsorption and Epoxy Adhesion to Boron Nitride: From the Flat to the Curved
- Author
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Kazunari Yoshizawa and Yuta Tsuji
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Materials science ,Hydrogen bond ,Surfaces and Interfaces ,Orbital overlap ,Adhesion ,Condensed Matter Physics ,London dispersion force ,chemistry.chemical_compound ,Adsorption ,chemistry ,Boron nitride ,Chemical physics ,Electrochemistry ,Molecule ,General Materials Science ,Lone pair ,Spectroscopy - Abstract
Hexagonal boron nitride (h-BN) is a material with excellent thermal conductivity and electrical insulation, used as an additive to various matrices. To increase the affinity of h-BN to them, hydrogen bonds should be formed at the interface. In reality, however, they are not formed; the N atoms are not capable of accepting hydrogen bonds due to the delocalization of their lone pair electrons over the B-N π bonds. To make it form hydrogen bonds, one may need to break the planarity of h-BN so that the orbital overlap in the B-N π bonds can be reduced. This idea is verified with first-principles calculations on the adsorption of a water molecule on hypothetical h-BN surfaces, the planarity of which is broken. One can do it in silico but not in vitro. BN nanotubes (BNNTs) are considered as a more realistic BN surface with nonplanarity. The hydrogen bond is shown to become stronger as the curvature of the tube increases. On the contrary, the strength of the dispersion force acting at the interface becomes weaker. In water adsorption, these two interactions are in competition with each other. However, in epoxy adhesion, the interaction due to dispersion forces is overwhelmingly stronger than that due to hydrogen bonding. The smaller the curvature of the surface, the smaller the distance between more atoms at the interface; thus, the interaction due to dispersion forces maximized.
- Published
- 2021
12. Microkinetic modeling of DME synthesis from methanol over H-zeolite catalyst: Associative vs. dissociative pathways
- Author
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Myung-June Park, Jiyeong Cho, Jongmin Park, and Won Bo Lee
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Reaction mechanism ,Chemistry ,Reaction formation ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,London dispersion force ,Catalysis ,Transition state ,0104 chemical sciences ,Reaction rate ,chemistry.chemical_compound ,Computational chemistry ,Methanol ,0210 nano-technology ,Zeolite - Abstract
In this study, the reaction pathways of DME synthesis by methanol dehydration over a H-zeolite catalyst were analyzed through both computational chemistry and microkinetic modeling methods. The reaction mechanisms consisted of nine forward and backward elementary-step reactions for both associative and dissociative pathways. Based on the second-order Moller–Plesset perturbation theory (MP2), to determine the effects of dispersion forces that were important in our reaction system, the structures of all related reaction species were optimized, and the transition states of the associative and dissociative pathways were elucidated. Also, the energies and activation barriers of the optimized structures and transition states were calculated. Then, a microkinetic model was developed using the energies and activation barriers obtained from the MP2 calculations. Meanwhile, the pre-exponential factors of the kinetic parameters were not calculated theoretically but estimated by fitting the experimental data, which enhanced the reliability of the microkinetic model. By comparing the relative elementary-step reaction rates calculated using the developed model, the dissociative pathway was suggested as a dominant pathway of DME synthesis, while the DME formation reaction of the dissociative pathway (CH3OH-CH3-Z → CH3OCH3-H-Z) was found to be the rate-determining step. The developed model was also used to evaluate the effects of temperature on the site fractions over the catalyst.
- Published
- 2021
13. Effect of External Electric Field on Tetrel Bonding Interactions in (FTF3···FH) Complexes (T = C, Si, Ge, and Sn)
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Fouad Taha, Mahmoud Moustafa, Afnan A. K. Kamel, Mahmoud A. A. Ibrahim, Nayra A. M. Moussa, Lamiaa A. Mohamed, Mahmoud E. S. Soliman, and H. R. Abd El-Mageed
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Quantum chemical ,Work (thermodynamics) ,Chemistry ,General Chemical Engineering ,Supramolecular chemistry ,General Chemistry ,Interaction energy ,Decomposition analysis ,London dispersion force ,Article ,Chemical physics ,Electric field ,Perturbation theory ,QD1-999 - Abstract
A quantum chemical study was accomplished on the σ-hole interactions of the barely explored group IV elements, for the first time, in the absence and presence of the positively and negatively directed external electric field (EEF). The analyses of molecular electrostatic potential addressed the occurrence of the σ-hole on all the inspected tetrel atoms, confirming their salient versatility to engage in σ-hole interactions. MP2 energetic findings disclosed the occurrence of favorable σ-hole interactions within the tetrel bonding complexes. The tetrel bonding interactions became stronger in the order of C < Si < Ge < Sn for F-T-F3···FH complexes with the largest interaction energy amounting to -19.43 kcal/mol for the optimized F-Sn-F3···FH complex under the influence of +0.020 au EEF. The interaction energy conspicuously evolved by boosting the magnitude of the positively directed EEF value and declining the negatively directed EEF one. The decomposition analysis for the interaction energies was also executed in terms of symmetry-adapted perturbation theory, illuminating the dominant electrostatic contribution to all the studied complexes' interactions except carbon-based interactions controlled by dispersion forces. The outcomes that emerged from the current work reported significantly how the direction and strength of the EEF affect the tetrel-bonding interactions, leading to further improvements in the forthcoming studies of supramolecular chemistry and materials science.
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- 2021
14. On the control of dispersion interactions between biological membranes and protein coated biointerfaces
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Andreas Baer, Kheya Sengupta, Arnaud Hemmerle, Matthias Späth, Robert Blackwell, Wolfgang Peukert, Ana-Sunčana Smith, Drew F. Parsons, Centre Interdisciplinaire de Nanoscience de Marseille (CINaM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
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Biointerface ,02 engineering and technology ,Polyethylene glycol ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Polyethylene Glycols ,Biomaterials ,chemistry.chemical_compound ,symbols.namesake ,Colloid and Surface Chemistry ,[PHYS.COND]Physics [physics]/Condensed Matter [cond-mat] ,Bovine serum albumin ,ComputingMilieux_MISCELLANEOUS ,biology ,Chemistry ,Physics ,Vesicle ,Adhesiveness ,Serum Albumin, Bovine ,Biological membrane ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Membrane ,biology.protein ,symbols ,Biophysics ,Glass ,van der Waals force ,Biointerfaces ,Dispersion forces ,Lifshitz theory ,Van der Waals interactions ,Reflection interference contrast microscopy (RICM) ,0210 nano-technology - Abstract
Hypothesis Interaction of cellular membranes with biointerfaces is of vital importance for a number of medical devices and implants. Adhesiveness of these surfaces and cells is often regulated by depositing a layer of bovine serum albumin (BSA) or other protein coatings. However, anomalously large separations between phospholipid membranes and the biointerfaces in various conditions and buffers have been observed, which could not be understood using available theoretical arguments. Methods Using the Lifshitz theory, we here evaluate the distance-dependent Hamaker coefficient describing the dispersion interaction between a biointerface and a membrane to understand the relative positioning of two surfaces. Our theoretical modeling is supported by experiments where the biointerface is represented by a glass substrate with deposited BSA and protein layers. These biointerfaces are allowed to interact with giant unilamellar vesicles decorated with polyethylene glycol (PEG) using PEG lipids to mimic cellular membranes and their pericellular coat. Results We demonstrate that careful treatment of the van der Waals interactions is critical for explaining the lack of adhesiveness of the membranes with protein-decorated biointerfaces. We show that BSA alone indeed passivates the glass, but depositing an additional protein layer on the surface BSA, or producing multiple layers of proteins and BSA results in repulsive dispersion forces responsible for 100 nm large equilibrium separations between the two surfaces.
- Published
- 2021
15. <scp>Water‐mediated</scp> interactions destabilize proteins
- Author
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Tomonari Sumi and Hiroshi Imamura
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Models, Molecular ,Protein Folding ,Leucine zipper ,Saccharomyces cerevisiae Proteins ,Full‐Length Papers ,Saccharomyces cerevisiae ,Biochemistry ,London dispersion force ,Hydrophobic effect ,Full‐Length Paper ,water‐mediated interactions ,Native state ,Molecular Biology ,intramolecular and intermolecular dispersion forces ,Protein Stability ,Chemistry ,Critical question ,Solvation ,Water ,hydrophobic interactions ,Folding (chemistry) ,Basic-Leucine Zipper Transcription Factors ,solvation‐free energy ,Chemical physics ,Density functional theory ,protein folding stability - Abstract
Proteins are folded to avoid exposure of the non-polar groups to water because water-mediated interactions between nonpolar groups are a promising factor in the thermodynamic stabilities of proteins-which is a well-accepted view as one of the unique effects of hydrophobic interactions. This paper poses a critical question for this classical view by conducting an accurate solvation free-energy calculation for a thermodynamic cycle of a protein folding using a liquid-state density functional theory. Here, the solvation-free energy for a leucine zipper formation was examined in the coiled-coil protein GCN4-p1, a typical model for hydrophobic interactions, which demonstrated that water-mediated interactions were unfavorable for the association of nonpolar groups in the native state, while the dispersion forces between them were, instead, responsible for the association. Furthermore, the present analysis well predicted the isolated helical state stabilized by pressure, which was previously observed in an experiment. We reviewed the problems in the classical concept and semiempirical presumption that the energetic cost of the hydration of nonpolar groups is a driving force of folding. This article is protected by copyright. All rights reserved.
- Published
- 2021
16. In‐Fjord Substitution in Expanded Helicenes: Effects of the Insert on the Inversion Barrier and Helical Pitch
- Author
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Martin Simon, Christopher Golz, Xaiza Aniban, Samuel Suárez-Pantiga, Manuel Alcarazo, Ricardo A. Mata, and Pablo Redero
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Steric effects ,hydroarylation ,Electronic structure ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,racemization barriers ,Inversion barrier ,Polycyclic Compounds ,Racemization ,Full Paper ,polycyclic aromatic compounds ,010405 organic chemistry ,Chemistry ,expanded helicenes ,Organic Chemistry ,Substitution (logic) ,Stereoisomerism ,General Chemistry ,Full Papers ,Transition state ,Au catalysis ,0104 chemical sciences ,Characterization (materials science) ,Chemical physics ,Estuaries - Abstract
A series of expanded helicenes of different sizes and shapes incorporating phenyl‐ and biphenyl‐substituents at the deepest part of their fjord have been synthesized via sequential Au‐catalyzed hydroarylation of appropriately designed diynes, and their racemization barriers have been calculated employing electronic structure methods. These show that the overall profile of the inversions (energies, number of transition states and intermediates, and their relative position) is intensively affected by the interplay of steric and attractive London dispersion interactions. Hence, in‐fjord substitution constitutes an additional tool to handle the mechanical properties in helicenes of uncommonly large diameter. The photochemical characterization of the newly prepared helical structures is also reported., Deep in‐fjord substitution is presented as a new tool to control the mechanical properties of expanded helicenes. The syntheses of a series of these compounds containing internal inserts is described and their overall inversion profile is calculated. Interestingly, the interplay between steric and dispersion interactions play a major role in shape of the inversion profiles (energies, number of transition states and intermediates).
- Published
- 2021
17. Hexaphenylditetrels – When Longer Bonds Provide Higher Stability
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Peter R. Schreiner, Lars Rummel, and Jan M. Schümann
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bond strength ,Bond strength ,Communication ,bond dissociation energy ,Organic Chemistry ,General Chemistry ,Stability (probability) ,London dispersion force ,Bond-dissociation energy ,Catalysis ,Dissociation (chemistry) ,Communications ,chemistry.chemical_compound ,C−H-π-interactions ,chemistry ,Pauli repulsion ,Chemical physics ,Hexaphenylethane ,Very Important Paper ,Chemical stability ,London dispersion ,Perturbation theory - Abstract
We present a computational analysis of hexaphenylethane derivatives with heavier tetrels comprising the central bond. In stark contrast to parent hexaphenylethane, the heavier tetrel derivatives can readily be prepared. In order to determine the origin of their apparent thermodynamic stability against dissociation as compared to the carbon case, we employed local energy decomposition analysis (LED) and symmetry‐adapted perturbation theory (SAPT) at the DLPNO‐CCSD(T)/def2‐TZVP and sSAPT0/def2‐TZVP levels of theory. We identified London dispersion (LD) interactions as the decisive factor for the molecular stability of heavier tetrel derivatives. This stability is made possible owing to the longer (than C−C) central bonds that move the phenyl groups out of the heavily repulsive regime so they can optimally benefit from LD interactions., Carbon‐Carbon bonds are exceptional as demonstrated for the hexaphenylditetrels where attractive London dispersion interactions are the decisive factor for the thermodynamic stabilities of tetrels other than carbon. Structural and energetic comparisons show that even though hexaphenylethane displays the largest dispersion energy between the two molecular halves, it has remained elusive because of even larger Pauli repulsion of the phenyl moieties that are forced in close contact due to the C−C bond that is the shortest in this series.
- Published
- 2021
18. Assessing the Applicability of the Geometric Counterpoise Correction in B2PLYP/Double-ζ Calculations for Thermochemistry, Kinetics, and Noncovalent Interactions
- Author
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Lars Goerigk and Nisha Mehta
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Set (abstract data type) ,chemistry.chemical_classification ,Superposition principle ,Basis (linear algebra) ,Chemistry ,Thermochemistry ,Non-covalent interactions ,Counterpoise ,General Chemistry ,Statistical physics ,London dispersion force ,Basis set - Abstract
We present a proof-of-concept study of the suitability of Kruse and Grimme’s geometric counterpoise correction (gCP) for basis set superposition errors (BSSEs) in double-hybrid density functional calculations with a double-ζ basis set. The gCP approach only requires geometrical information as an input and no orbital/density information is needed. Therefore, this correction is practically free of any additional cost. gCP is trained against the Boys and Bernardi counterpoise correction across a set of 528 noncovalently bound dimers. We investigate the suitability of the approach for the B2PLYP/def2-SVP level of theory, and reveal error compensation effects—missing London dispersion and the BSSE—associated with B2PLYP/def2-SVP calculations, and present B2PLYP-gCP-D3(BJ)/def2-SVP with the reparametrised DFT-D3(BJ) and gCP corrections as a more balanced alternative. Benchmarking results on the S66x8 benchmark set for noncovalent interactions and the GMTKN55 database for main-group thermochemistry, kinetics, and noncovalent interactions show a statistical improvement of the B2PLYP-gCP-D3(BJ) scheme over plain B2PLYP and B2PLYP-D3(BJ). B2PLYP-D3(BJ) shows significant overestimation of interaction energies, barrier heights with larger deviations from the reference values, and wrong relative stabilities in conformers, all of which can be associated with BSSE. We find that the gCP-corrected method represents a significant improvement over B2PLYP-D3(BJ), particularly for intramolecular noncovalent interactions. These findings encourage future developments of efficient double-hybrid DFT strategies that can be applied when double-hybrid calculations with large basis sets are not feasible due to system size.
- Published
- 2021
19. Understanding the Nature and Properties of Hydrogen–Hydrogen Bonds: The Stability of a Bulky Phosphatetrahedrane as a Case Study
- Author
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Giovanni Bistoni, Martin-Louis Y. Riu, and Christopher C. Cummins
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Crystallography ,Hydrogen ,chemistry ,Hydrogen bond ,chemistry.chemical_element ,Thermal stability ,Reaction intermediate ,Physical and Theoretical Chemistry ,Dispersion (chemistry) ,Stability (probability) ,London dispersion force ,Decomposition - Abstract
Recently, the first mixed C/P phosphatetrahedranes (tBuC)3P and (tBuCP)2 were reported. Unlike (tBuCP)2, (tBuC)3P exhibits remarkable thermal stability, which can be partially attributed to a network of nine hydrogen-hydrogen bonds (HHBs) localized between the tert-butyl substituents. The stabilizing contribution arising from this network of HHBs was obtained from local energy decomposition (LED) analysis calculated at the domain-based local pair natural orbital CCSD(T) (DLPNO-CCSD(T)) level of theory. These calculations suggest that each HHB contributes approximately -0.7 kcal/mol of stabilization; however, the net stabilization energy likely lies between -0.25 and -0.5 kcal/mol because of steric repulsion. Spatial analysis of the London dispersion energy via a dispersion interaction density (DID) plot reveals that the DID surface is localized at key C-H groups involved in HHBs, consistent with London dispersion interactions predominantly arising from HHBs. In addition, we present a computed mechanism that supports a phosphinidenoid species as a key reaction intermediate in the synthesis of (tBuC)3P.
- Published
- 2021
20. Theoretical Derivation of a Prediction Model for CO2 Adsorption by Coal
- Author
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Ren Lifeng, Fei Jinbiao, Jianchi Hao, Hu Wen, and Li Ma
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Materials science ,business.industry ,General Chemical Engineering ,technology, industry, and agriculture ,Coal mining ,Thermodynamics ,Langmuir adsorption model ,General Chemistry ,complex mixtures ,London dispersion force ,Article ,Isothermal process ,respiratory tract diseases ,Chemistry ,symbols.namesake ,Adsorption ,Volume (thermodynamics) ,Phase (matter) ,otorhinolaryngologic diseases ,symbols ,Coal ,business ,QD1-999 - Abstract
Adsorption characteristics of CO2 by coal are an important reservoir parameter to determine the CO2 storage capacity of the coal seam. The Langmuir isotherm adsorption model is commonly used to describe the isothermal adsorption line of coal. However, we cannot predict the CO2 adsorption capacity at other temperatures by using the Langmuir model based on the experimental data at a fixed temperature. This paper analyzes the ε–Vad adsorption characteristic curves of three coal samples over a range of temperatures and pressures. The study demonstrates that the adsorption characteristic curves of CO2 gas are independent of temperature and depend mainly on the dispersion force between coal and the CO2 molecules. In addition, the adsorption potential of CO2 gas has a negative correlation with the volume of the adsorbed phase. Hence, the CO2 adsorption characteristic curve of coal conforms to the logarithmic function. Based on the adsorption potential theory, the prediction model of CO2 adsorption by coal is derived. The deviation analysis from measured data shows that the average relative deviation of the three coal samples is ∼5%, and the prediction results are accurate and reliable. Under different temperature and pressure conditions of the three coal samples, the results from the prediction model of CO2 adsorption by coal and the Langmuir model have a strong correlation with the experimental results. In comparison with the Langmuir model, the prediction model of CO2 adsorption by coal can predict the adsorption capacity under different temperature and pressure conditions. Hence, it has a wide range of applications when compared to that of the Langmuir model. In practical applications, better results are achieved with a significant reduction in experimental time and labor.
- Published
- 2021
21. Molecular Structure‐Property Relationships of the Asymmetric Thienoacenes: Naphtho[2,3‐ b ]thieno[2,3‐ d ]thiophene, Anthra[2,3‐ b ]thieno[2,3‐ d ]thiophene, and their Thienyl Derivatives
- Author
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Kazuhiro Yamamoto, Amane Matsunaga, Shigeki Tamura, Hiroshi Katagiri, and Yuta Ogawa
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Organic semiconductor ,chemistry.chemical_compound ,Crystallography ,Materials science ,chemistry ,Thiophene ,Molecule ,General Chemistry ,Crystal structure ,London dispersion force - Published
- 2021
22. Dispersion‐Bound Isolated Dimers in the Gas Phase: Observation of the Shortest Intermolecular CH⋅⋅⋅H−C Distance via Stimulated Raman Spectroscopy
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Patrick H. Strebert, Peter R. Schreiner, Markus Gerhards, Sören Rösel, Dominique Maué, and Dominic Bernhard
- Subjects
molecular beam experiments ,Materials science ,Infrared spectroscopy ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,Crystal ,chemistry.chemical_compound ,combined IR/UV experiments ,Spectroscopy ,density functional theory ,Triphenylmethane ,010405 organic chemistry ,Communication ,Intermolecular force ,General Chemistry ,Communications ,vibrational spectroscopy ,0104 chemical sciences ,Crystallography ,chemistry ,non-covalent interactions ,Intermolecular Forces | Very Important Paper ,Dispersion (chemistry) ,Molecular beam - Abstract
The triphenylmethane and all‐meta tert‐butyl triphenylmethane dimers, (TPM)2 and (T tBuPM)2, respectively, were studied with ionization loss stimulated Raman spectroscopy in molecular beam experiments to resolve structure sensitive vibrations. This answers the question whether the recently reported linear head‐to‐head arrangement in (T tBuPM)2 results from crystal packing or prevails also in the gas phase, and therefore must result from extraordinarily strong London dispersion (LD) interactions. Our study clearly demonstrates that the head‐to‐head arrangement is maintained even under isolated molecular beam conditions in the absence of crystal packing effects. The central Raman‐active aliphatic C−D vibration of appropriately deuterated (T tBuPM)2 associated with an unusually short C−D⋅⋅⋅D−C distance exhibits a strong blue‐shift compared to the undisturbed case. As the LD stabilizing tert‐butyl groups are absent in (TPM)2, it displays an approximately S 6‐symmetric tail‐to‐tail arrangement., Head‐on Collision: Isolated gas phase triphenylmethane based dimers containing dispersion energy donors form a head‐to‐head structure with an extremely short C−H⋅⋅⋅H−C distance with a collinear arrangement of atoms. This surprising result from molecular beam experiments indicates that it is London dispersion but not crystal packing, responsible for this peculiar structural arrangement.
- Published
- 2021
23. RETRACTED ARTICLE: A novel biosensor for gabapentin drug detection based on the Pd-decorated aluminum nitride nanotube
- Author
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Ajit Kumar, Saeideh Ebrahimiasl, Sheida Ahmadi, Abdol Ghaffar Ebadi, Akram Hosseinian, and Semih Yaşar
- Subjects
Nanotube ,010405 organic chemistry ,Chemistry ,Nitride ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,Drug detection ,Desorption ,Atom ,Molecule ,Physical chemistry ,Density functional theory ,Physical and Theoretical Chemistry - Abstract
Density functional theory calculations were performed to inspect the potential application of pristine AlN nanotube (AlNNT) as well as Pd-decorated AlNNT (Pd@AlNNT) in recognition of gabapentin (GB) drug. The sensing response of AlNNT to the GB drug is very small (~ 5.2 at 298 K) attributed to the small adsorption energy (AE) of −0.16 eV. Molecular orbital energy decomposition method (EDA) showed that the contributions of electrostatic attraction, Pauli repulsion, orbital relations, and dispersion forces in the AE are about −0.21, 0.19, −0.11, and −0.09 eV, respectively. A Pd atom preferentially adsorbed over an Al–N bond of the AlNNT, releasing the energy of 2.93 eV. We found that the GB strongly adsorbed on the Pd@AlNNT with AE of −1.29 eV and the sensing response increased to 524.6 by the Pd decoration. Based on the results, the main stabilization contribution to the AE of GB on the Pd@AlNNT comes from the electrostatic attraction based on the EDA analysis. The recovery time was achieved to be 1.8 s for the GB desorption from the Pd@AlNNT surface. Finally, we concluded that the Pd@AlNNT can transform the presence of GB molecules into electrical signal, and it may potentially be applied as an electronic sensor for GB drug detection.
- Published
- 2021
24. Beyond Chemical Accuracy for Alkane Thermochemistry: The DHthermo Approach
- Author
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Bernardino Tirri, Éric Brémond, Carlo Adamo, Hanwei Li, Juan Carlos Sancho-García, Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL), Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS (UMR_7086)), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universidad de Alicante, Universidad de Alicante. Departamento de Química Física, and Química Cuántica
- Subjects
Isodesmic reaction ,Basis (linear algebra) ,010405 organic chemistry ,Chemistry ,Chemical accuracy ,Alkane thermochemistry ,Organic Chemistry ,010402 general chemistry ,DHthermo ,01 natural sciences ,Stability (probability) ,London dispersion force ,0104 chemical sciences ,Intramolecular force ,Thermochemistry ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Density functional theory ,Química Física ,Statistical physics ,Basis set - Abstract
The so-called protobranching phenomenon, that is the greater stability of branched alkanes with respect to their linear isomers, represents an interesting challenge for approaches based on density functional theory (DFT), since it requires a balanced description of several electronic effects, including (intramolecular) dispersion forces. Here, we investigate this problem using a protocol recently developed based on double-hybrid functionals and a small basis set, DH-SVPD, suited for noncovalent interactions. The energies of bond separation reactions (BSR), defined on the basis of an isodesmic principle, are taken as reference properties for the evaluation of 15 DFT approaches. The obtained results show that error lower than the so-called “chemical accuracy” (
- Published
- 2021
25. Interplay between London Dispersion, Hubbard U, and Metastable States for Uranium Compounds
- Author
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Matthew S. Christian, Erin R. Johnson, and Theodore M. Besmann
- Subjects
Actinide chemistry ,010304 chemical physics ,Condensed matter physics ,Field (physics) ,Chemistry ,chemistry.chemical_element ,Actinide ,Uranium ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,London dispersion force ,0104 chemical sciences ,Dipole ,Metastability ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Physical and Theoretical Chemistry ,Dispersion (chemistry) - Abstract
High-throughput computational studies of lanthanide and actinide chemistry with density-functional theory are complicated by the need for Hubbard U corrections, which ensure localization of the f-electrons, but can lead to metastable states. This work presents a systematic investigation of the effects of both Hubbard U value and metastable states on the predicted structural and thermodynamic properties of four uranium compounds central to the field of nuclear fuels: UC, UN, UO2, and UCl3. We also assess the impact of the exchange-hole dipole moment (XDM) dispersion correction on the computed properties. Overall, the choice of Hubbard U value and inclusion of a dispersion correction cause larger variations in the computed geometric properties than result from metastable states. The weak dependence of structure optimization on metastable states should simplify future high-throughput calculations on actinides. Conversely, addition of the dispersion correction is found to offset the repulsion introduced by the Hubbard U term and provides greatly improved agreement with experiment for both cell volumes and heats of formation. The XDM dispersion correction is largely invariant to the chosen U value, making it a robust dispersion correction for actinide systems.
- Published
- 2021
26. Reactivity of Single Transition Metal Atoms on a Hydroxylated Amorphous Silica Surface: A Periodic Conceptual DFT Investigation
- Author
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Frederik Tielens, Stefaan Cottenier, Mercedes Alonso, Bert M. Weckhuysen, Paul W. Ayers, Frank De Proft, Xavier Deraet, Jan Turek, General Chemistry, Chemistry, and Faculty of Sciences and Bioengineering Sciences
- Subjects
010405 organic chemistry ,Chemistry ,Organic Chemistry ,Fermi level ,General Chemistry ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,0104 chemical sciences ,symbols.namesake ,Chemical physics ,Atom ,symbols ,Density of states ,Oxophilicity ,Reactivity (chemistry) ,Density functional theory ,van der Waals force - Abstract
The drive to develop maximal atom-efficient catalysts coupled to the continuous striving for more sustainable reactions has led to an ever-increasing interest in single-atom catalysis. Based on a periodic conceptual density functional theory (cDFT) approach, fundamental insights into the reactivity and adsorption of single late transition metal atoms supported on a fully hydroxylated amorphous silica surface have been acquired. In particular, this investigation revealed that the influence of van der Waals dispersion forces is especially significant for a silver (98 %) or gold (78 %) atom, whereas the oxophilicity of the Group 8–10 transition metals plays a major role in the interaction strength of these atoms on the irreducible SiO2 support. The adsorption energies for the less-electronegative row 4 elements (Fe, Co, Ni) ranged from −1.40 to −1.92 eV, whereas for the heavier row 5 and 6 metals, with the exception of Pd, these values are between −2.20 and −2.92 eV. The deviating behavior of Pd can be attributed to a fully filled d-shell and, hence, the absence of the hybridization effects. Through a systematic analysis of cDFT descriptors determined by using three different theoretical schemes, the Fermi weighted density of states approach was identified as the most suitable for describing the reactivity of the studied systems. The main advantage of this scheme is the fact that it is not influenced by fictitious Coulomb interactions between successive, charged reciprocal cells. Moreover, the contribution of the energy levels to the reactivity is simultaneously scaled based on their position relative to the Fermi level. Finally, the obtained Fermi weighted density of states reactivity trends show a good agreement with the chemical characteristics of the investigated metal atoms as well as the experimental data.
- Published
- 2021
27. Quantification of Noncovalent Interactions in Azide–Pnictogen, –Chalcogen, and –Halogen Contacts
- Author
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Amol M. Vibhute, Stefan Grimme, Lukas Kunze, Markus Bursch, Daniel B. Werz, Peter G. Jones, Andreas Hansen, and Kana M. Sureshan
- Subjects
Density Functional Calculations ,010402 general chemistry ,01 natural sciences ,London dispersion force ,azides ,Catalysis ,noncovalent interactions ,Chalcogen ,chemistry.chemical_compound ,Non-covalent interactions ,Pnictogen ,chemistry.chemical_classification ,Full Paper ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Intermolecular force ,General Chemistry ,Full Papers ,0104 chemical sciences ,Crystallography ,Intramolecular force ,Halogen ,local energy decomposition ,London dispersion ,Azide - Abstract
The noncovalent interactions between azides and oxygen‐containing moieties are investigated through a computational study based on experimental findings. The targeted synthesis of organic compounds with close intramolecular azide–oxygen contacts yielded six new representatives, for which X‐ray structures were determined. Two of those compounds were investigated with respect to their potential conformations in the gas phase and a possible significantly shorter azide–oxygen contact. Furthermore, a set of 44 high‐quality, gas‐phase computational model systems with intermolecular azide–pnictogen (N, P, As, Sb), –chalcogen (O, S, Se, Te), and –halogen (F, Cl, Br, I) contacts are compiled and investigated through semiempirical quantum mechanical methods, density functional approximations, and wave function theory. A local energy decomposition (LED) analysis is applied to study the nature of the noncovalent interaction. The special role of electrostatic and London dispersion interactions is discussed in detail. London dispersion is identified as a dominant factor of the azide–donor interaction with mean London dispersion energy‐interaction energy ratios of 1.3. Electrostatic contributions enhance the azide–donor coordination motif. The association energies range from −1.00 to −5.5 kcal mol−1., The interactions that bind: The noncovalent interactions between azides and oxygen‐containing moieties are investigated through a computational study based on experimental findings. A set of 44 high‐quality, gas‐phase computational model systems with intermolecular azide–pnictogen, –chalcogen, and –halogen contacts are compiled and investigated through semiempirical quantum mechanical methods, density functional approximations, and wave function theory.
- Published
- 2021
28. Tactile Models for the Visualization, Conceptualization, and Review of Intermolecular Forces in the College Chemistry Classroom
- Author
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Grace A. Beggs and Deborah C. Bromfield Lee
- Subjects
Molecular interactions ,Conceptualization ,010405 organic chemistry ,education ,05 social sciences ,Intermolecular force ,050301 education ,Survey result ,General Chemistry ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,Education ,Visualization ,Human–computer interaction ,Concept learning ,Chemistry (relationship) ,0503 education - Abstract
The authors describe the construction and use of tactile models for demonstrating intermolecular forces. These models are composed of inexpensive materials and can be used in college chemistry classrooms of varying levels including general and organic chemistry. The models were designed to be paired with an accompanying activity to encourage students to compare and contrast the three types of intermolecular forces (hydrogen bonding, dipole–dipole forces, and London dispersion forces) as well as determine the relationship between intermolecular forces and the physical properties of specific molecules. More importantly, the handheld models allow for visualization of molecular interactions to promote multisensory learning. In this work, the authors discuss the development, implementation, and survey results of a modeling activity for conceptualization and review of intermolecular forces in introductory, general, and organic chemistry classrooms.
- Published
- 2021
29. London Dispersion Interactions Rather than Steric Hindrance Determine the Enantioselectivity of the Corey–Bakshi–Shibata Reduction
- Author
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Christian Eschmann, Lijuan Song, and Peter R. Schreiner
- Subjects
Steric effects ,CBS reduction ,borane reduction ,010402 general chemistry ,01 natural sciences ,London dispersion force ,steric repulsion ,Catalysis ,noncovalent interactions ,Computational chemistry ,Non-covalent interactions ,Research Articles ,chemistry.chemical_classification ,010405 organic chemistry ,Organocatalysis ,Enantioselective synthesis ,Substrate (chemistry) ,asymmetric catalysis ,General Chemistry ,General Medicine ,0104 chemical sciences ,chemistry ,Dispersion (chemistry) ,Selectivity ,Research Article - Abstract
The well‐known Corey–Bakshi–Shibata (CBS) reduction is a powerful method for the asymmetric synthesis of alcohols from prochiral ketones, often featuring high yields and excellent selectivities. While steric repulsion has been regarded as the key director of the observed high enantioselectivity for many years, we show that London dispersion (LD) interactions are at least as important for enantiodiscrimination. We exemplify this through a combination of detailed computational and experimental studies for a series of modified CBS catalysts equipped with dispersion energy donors (DEDs) in the catalysts and the substrates. Our results demonstrate that attractive LD interactions between the catalyst and the substrate, rather than steric repulsion, determine the selectivity. As a key outcome of our study, we were able to improve the catalyst design for some challenging CBS reductions., London dispersion (LD) interactions facilitate the enantioselectivity in the Corey–Bakshi–Shibata (CBS) reduction. Employing a combination of computational and experimental studies, we provide a modern view on the origin of enantioselectivity in this powerful organocatalyzed reaction. The results demonstrate that attractive LD interactions between the catalyst and the substrate rather than steric repulsion determine the selectivity.
- Published
- 2021
30. Ion-pairing π-electronic systems: ordered arrangement and noncovalent interactions of negatively charged porphyrins
- Author
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Yoshifumi Sasano, Nobuhiro Yasuda, Yukihide Ishibashi, Yoichi Kobayashi, Yasuteru Shigeta, Hiroki Tanaka, Yohei Haketa, Tsuyoshi Asahi, Tatsuki Morimoto, Hiromitsu Maeda, and Ryuma Sato
- Subjects
chemistry.chemical_classification ,Absorption spectroscopy ,Stacking ,General Chemistry ,Porphyrin ,London dispersion force ,Photoinduced electron transfer ,Ion ,Chemistry ,chemistry.chemical_compound ,Crystallography ,Deprotonation ,chemistry ,Non-covalent interactions - Abstract
In this study, charged π-electronic species are observed to develop stacking structures based on electrostatic and dispersion forces. iπ–iπ Interaction, defined herein, functions for the stacking structures consisting of charged π-electronic species and is in contrast to conventional π–π interaction, which mainly exhibits dispersion force, for electronically neutral π-electronic species. Establishing the concept of iπ–iπ interaction requires the evaluation of interionic interactions for π-electronic ion pairs. Free base (metal-free) and diamagnetic metal complexes of 5-hydroxy-10,15,20-tris(pentafluorophenyl)porphyrin were synthesized, producing π-electronic anions upon the deprotonation of the hydroxy unit. Coexisting cations in the ion pairs with porphyrin anions were introduced as the counter species of the hydroxy anion as a base for commercially available cations and as ion-exchanged species, via Na+ in the intermediate ion pairs, for synthesized π-electronic cations. Solid-state ion-pairing assemblies were constructed for the porphyrin anions in combination with aliphatic tetrabutylammonium (TBA+) and π-electronic 4,8,12-tripropyl-4,8,12-triazatriangulenium (TATA+) cations. The ordered arrangements of charged species, with the contributions of the charge-by-charge and charge-segregated modes, were observed according to the constituent charged building units. The energy decomposition analysis (EDA) of single-crystal packing structures revealed that electrostatic and dispersion forces are important factors in stabilizing the stacking of π-electronic ions. Furthermore, crystal-state absorption spectra of the ion pairs were correlated with the assembling modes. Transient absorption spectroscopy of the single crystals revealed the occurrence of photoinduced electron transfer from the π-electronic anion in the charge-segregated mode., π-Electronic ion pairs comprising porphyrin-based π-electronic anions have exhibited characteristic assembling modes and resulting electronic properties such as solid-state absorption and photoinduced electron transfer.
- Published
- 2021
31. Understanding liquid–liquid equilibria in binary mixtures of hydrocarbons with a thermally robust perarylphosphonium-based ionic liquid
- Author
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Kevin N. West, Brooks D. Rabideau, Jimmie L. McGehee, Albaraa D. Mando, James H. Davis, Santosh R. P. Bandlamudi, C. Heath Turner, and Mohammad Soltani
- Subjects
chemistry.chemical_classification ,General Chemical Engineering ,Mixing (process engineering) ,General Chemistry ,London dispersion force ,Toluene ,Molecular dynamics ,chemistry.chemical_compound ,Hydrocarbon ,chemistry ,Chemical physics ,Phase (matter) ,Ionic liquid ,Absorption (chemistry) - Abstract
Binary mixtures of hydrocarbons and a thermally robust ionic liquid (IL) incorporating a perarylphosphonium-based cation are investigated experimentally and computationally. Experimentally, it is seen that excess toluene added to the IL forms two distinct liquid phases, an “ion-rich” phase of fixed composition and a phase that is nearly pure toluene. Conversely, n-heptane is observed to be essentially immiscible in the neat IL. Molecular dynamics simulations capture both of these behaviours. Furthermore, the simulated composition of the toluene-rich IL phase is within 10% of the experimentally determined composition. Additional simulations are performed on the binary mixtures of the IL and ten other small hydrocarbons having mixed aromatic/aliphatic character. It is found that hydrocarbons with a predominant aliphatic character are largely immiscible with the IL, while those with a predominant aromatic character readily mix with the IL. A detailed analysis of the structure and energetic changes that occur on mixing reveals the nature of the ion-rich phase. The simulations show a bicontinuous phase with hydrocarbon uptake akin to absorption and swelling by a porous absorbent. Aromatic hydrocarbons are driven into the neat IL via dispersion forces with the IL cations and, to a lesser extent, the IL anions. The ion–ion network expands to accommodate the hydrocarbons, yet maintains a core connective structure. At a certain loading, this network becomes stretched to its limit. The energetic penalty associated with breaking the core connective network outweighs the gain from new hydrocarbon–IL interactions, leaving additional hydrocarbons in the neat phase. The spatially alternating charge of the expanded IL network is shown to interact favourably with the stacked aromatic subphase, something not possible for aliphatic hydrocarbons.
- Published
- 2021
32. On the physical mechanisms underlying single molecule dynamics in simple liquids
- Author
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Peter T. Tkacik, Russell G. Keanini, and Jerry L. Dahlberg
- Subjects
Materials science ,Phonon ,Science ,FOS: Physical sciences ,02 engineering and technology ,Electron ,01 natural sciences ,London dispersion force ,Article ,Viscosity ,Engineering ,Atomic orbital ,Distortion ,0103 physical sciences ,Molecule ,010306 general physics ,Multidisciplinary ,Physics ,Fluid Dynamics (physics.flu-dyn) ,Physics - Fluid Dynamics ,021001 nanoscience & nanotechnology ,Chemical physics ,Drag ,Medicine ,0210 nano-technology - Abstract
Physical arguments and comparisons with published experimental data suggest that in simple liquids: i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, ii) viscosity decay with increasing temperature reflects electron cloud compression and attendant suppression of electron screening, produced by increased nuclear agitation, and iii) temperature-dependent self-diffusion is driven by a narrow band of phonon frequencies lying at the low-frequency end of the solid-state-like phonon spectrum. The results suggest that collision-induced electron cloud distortion plays a decisive role in single molecule dynamics: i) electron cloud compression produces short-lived repulsive states and single molecule, self-diffusive hops, while ii) shear-induced distortion generates viscosity and single-molecule-scale viscous drag. The results provide new insight into nonequilibrium molecular dynamics in nonpolar, nonmetallic liquids., Comment: 23 pages, 7 figures
- Published
- 2021
33. Local energy decomposition analysis and molecular properties of encapsulated methane in fullerene (CH4@C60)
- Author
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Niklas Hedin and Aleksander Jaworski
- Subjects
Coupling constant ,Fullerene ,Coupled cluster ,Ionization ,Intermolecular force ,Potential energy surface ,Physics::Atomic and Molecular Clusters ,General Physics and Astronomy ,Trimer ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,London dispersion force ,Molecular physics - Abstract
Methane has been successfully encapsulated within cages of C60 fullerene, which is an appropriate model system to study confinement effects. Its chemistry and physics are also relevant for theoretical model descriptions. Here we provide insights into intermolecular interactions and predicted spectroscopic responses of the CH4@C60 complex and compared them with results from other methods and with data from the literature. Local energy decomposition analysis (LED) within the domain-based local pair natural orbital coupled cluster singles, doubles, and perturbative triples (DLPNO-CCSD(T)) framework was used, and an efficient protocol for studies of endohedral complexes of fullerenes is proposed. This approach allowed us to assess energies in relation to electronic and geometric preparation, electrostatics, exchange, and London dispersion for the CH4@C60 endohedral complex. The calculated stabilization energy of CH4 inside the C60 fullerene was −13.5 kcal mol−1 and its magnitude was significantly larger than the latent heat of evaporation of CH4. Evaluation of vibrational frequencies and polarizabilities of the CH4@C60 complex revealed that the infrared (IR) and Raman bands of the endohedral CH4 were essentially “silent” due to the dielectric screening effect of C60, which acted as a molecular Faraday cage. Absorption spectra in the UV-vis domain and ionization potentials of C60 and CH4@C60 were predicted. They were almost identical. The calculated 1H/13C NMR shifts and spin–spin coupling constants were in very good agreement with experimental data. In addition, reference DLPNO-CCSD(T) interaction energies for complexes with noble gases (Ng@C60; Ng = He, Ne, Ar, Kr) were calculated. The values were compared with those derived from supramolecular MP2/SCS-MP2 calculations and estimates with London-type formulas by Pyykko and coworkers [Phys. Chem. Chem. Phys., 2010, 12, 6187–6203], and with values derived from DFT-based symmetry-adapted perturbation theory (DFT-SAPT) by Hesselmann & Korona [Phys. Chem. Chem. Phys., 2011, 13, 732–743]. Selected points at the potential energy surface of the endohedral He2@C60 trimer were considered. In contrast to previous theoretical attempts with the DFT/MP2/SCS-MP2/DFT-SAPT methods, our calculations at the DLPNO-CCSD(T) level of theory predicted the He2@C60 trimer to be thermodynamically stable, which is in agreement with experimental observations.
- Published
- 2021
34. Comparison of ±σ-hole and ±R˙-hole interactions formed by tetrel-containing complexes: a computational study
- Author
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Ebtisam M. Z. Telb and Mahmoud A. A. Ibrahim
- Subjects
Symmetry-adapted perturbation theory ,Chemistry ,General Chemical Engineering ,Radical ,02 engineering and technology ,General Chemistry ,Interaction energy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,Monomer ,Lewis acids and bases ,0210 nano-technology ,Quantum - Abstract
For the first time, unconventional ±R˙-hole interactions were unveiled in tetrel-containing complexes. The nature and characteristics of ±R˙-hole interactions were explored relative to their ±σ-hole counterparts for ˙TF3⋯ and W–T–F3⋯B/R˙/A complexes (where T = C, Si, and Ge, W = H and F, B = Lewis bases, R˙ = free radicals, and A = Lewis acids). In an effort to thoroughly investigate such interactions, a plethora of quantum mechanical calculations, including molecular electrostatic potential (MEP), maximum positive electrostatic potential (Vs,max), point-of-charge (PoC), interaction energy, symmetry adapted perturbation theory (SAPT), and reduced density gradient–noncovalent interaction (RDG–NCI) calculations, were applied. The most notable findings to emerge from this study are that (i) from the electrostatic perspective, the molecular stabilization energies of ˙TF3 and W–T–F3 monomers became more negative as the Lewis basicity increased, (ii) the most stable complexes were observed for the ones containing Lewis bases, forming −σ-hole and −R˙-hole interactions, and the interaction energies systematically increased in the order H–T–F3⋯B < ˙TF3⋯B < F–T–F3⋯B, (iii) contrariwise, the +σ-hole and +R˙-hole interactions with Lewis acids are more energetically favorable in the order F–T–F3⋯A < ˙TF3⋯A < H–T–F3⋯A, and (iv) generally, the dispersion force plays a key role in stabilizing the tetrel-containing complexes, jointly with the electrostatic and induction forces for the interactions with Lewis bases and acids, respectively. Concretely, the findings presented in this paper add to our understanding of the characteristics and nature of such intriguing interactions.
- Published
- 2021
35. Determination of the dispersion forces in the gas phase structures of ionic liquids using exclusively thermodynamic methods
- Author
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Dzmitry H. Zaitsau, Ralf Ludwig, and Sergey P. Verevkin
- Subjects
chemistry.chemical_classification ,Activity coefficient ,Materials science ,010405 organic chemistry ,Hydrogen bond ,General Physics and Astronomy ,Ionic bonding ,Thermodynamics ,010402 general chemistry ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Ionic liquid ,Vaporization ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,Dispersion (chemistry) ,Alkyl - Abstract
Ionic liquids are described by a delicate balance of Coulomb interaction, hydrogen bonding and dispersion forces. Dissecting the different types of interactions from thermodynamic properties is still a challenge. Here, we show that comparison of vaporization enthalpies of tetra-alkyl-ammonium ionic liquids with bis(trifluoromethylsulfonyl)imide [NTf2]− anions and the related molecular liquids, trialkylamines, allows for determining dispersion interactions in the gas phase ion-pairs. For this purpose, we measured vapor pressures and vaporization enthalpies of these ionic and molecular liquids by using a quartz-crystal microbalance. For supporting these data, we determined the vaporization enthalpies additionally from experimental activity coefficients at infinite dilution. Characteristic alkyl chain length dependences of the vaporization enthalpies have been established and were used for quantifying the dispersion forces in the gas phase species. The dissected dispersion contributions suggest that the alkyl chains do not show star-like topologies but embrace the anion maximizing the dispersion interactions. For the longest alkyl chains with eight carbon atoms, the dispersion interaction is as strong as two and a half hydrogen bonds. The proportion of dispersion in the gas phase species depending on the number of methylene groups in the ammonium cations is strongly supported by quantum chemical calculations.
- Published
- 2021
36. Dispersion forces in chirality recognition – a density functional and wave function theory study of diols
- Author
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Axel Wuttke, Beppo Hartwig, Xaiza Aniban, and Ricardo A. Mata
- Subjects
chemistry.chemical_classification ,Steric effects ,Physics ,010304 chemical physics ,Hydrogen bond ,Biomolecule ,General Physics and Astronomy ,010402 general chemistry ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,chemistry ,Chemical physics ,0103 physical sciences ,Dispersion (optics) ,Molecule ,Physical and Theoretical Chemistry ,Chirality (chemistry) ,Wave function - Abstract
In the discussion of chirality recognition, steric considerations and strongly directed interactions such as hydrogen bonds are primarily discussed. However, given the sheer size of biomolecules, it is expected that dispersion forces could also play a determining role for aggregate formation and associated chirality recognition. With the example of diol molecules, we explore different factors in the formation of homo- and hetero-dimers as well as their relative stability. By comparing density functional results with the analysis of local correlation methods, we infer the impact of dispersion not only on the energies but also on the structures of such chiral aggregates. A local orbital based scheme is used to calculate wave function dispersion-free gradients and compare to uncorrected density functional structures.
- Published
- 2021
37. Arylene–hexaynylene and –octaynylene macrocycles: extending the polyyne chains drives self-association by enhanced dispersion force
- Author
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Yosuke Nakamura, Ryo Kumagai, Takashi Hirose, Nobutaka Takahashi, Tsukasa Abe, Shin-ichiro Kato, Chisa Higuchi, Yoshihito Shiota, Koji Yamamoto, Kazuhiro Hayashi, Zakir Hossain, and Kazunari Yoshizawa
- Subjects
Polyyne ,Materials science ,Self association ,Arylene ,Metals and Alloys ,General Chemistry ,London dispersion force ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Crystallography ,Chain (algebraic topology) ,Materials Chemistry ,Ceramics and Composites - Abstract
Tetraalkoxyphenanthrylene-hexaynylene and -octaynylene macrocycles, which represent the first examples of isolable arylene-alkynylene macrocycles (AAMs) that contain polyyne chains longer than tetrayne, were synthesized and their self-association behavior was examined. Extending the polyyne chain from diyne to tetrayne, hexayne, and octayne exponentially increased the self-association constant of the macrocycles.
- Published
- 2021
38. London Dispersion in Alkane Solvents
- Author
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Hermann A. Wegner and Marcel A. Strauss
- Subjects
molecular probe ,Alkane ,chemistry.chemical_classification ,spectroscopy ,General Chemistry ,London dispersion force ,Catalysis ,chemistry.chemical_compound ,azobenzene ,chemistry ,Azobenzene ,Chemical physics ,Intramolecular force ,London dispersion ,Solvent effects ,Dispersion (chemistry) ,Isomerization ,Research Articles ,Alkyl ,Research Article ,Solvent Effects - Abstract
The importance of London dispersion interactions in solution is an ongoing debate. Although the significance of dispersion for structure and stability is widely accepted, the degree of its attenuation in solution is still not properly understood. Quantitative evaluations are derived mostly from computations. Experimental data provide guidelines to include London dispersion in solution phase design. Herein, dispersive interactions were examined with an azobenzene probe. Alkyl substituents in meta positions of the azobenzene core were systematically varied and the effect on the half‐lives for the thermally induced Z to E isomerization in several alkane solvents was determined. The results show that intramolecular dispersion is only marginally influenced. In solvents with low surface tension, reduced destabilizing solvent‐solvent interactions increase the half‐life up to 20 %. Specific individual interactions between alkyl chains on the azobenzene and those of the solvent lead to additional fluctuations of the half‐lives. These presumably result from structural changes of the conformer ensemble., The degree of attenuation of London dispersion in solution is evaluated. Dispersive interactions were examined with azobenzene probes. The effect on half‐lives for the thermally induced Z to E isomerization in several alkane solvents was determined. The results show only a marginally influence on intramolecular dispersion. In solvents with low surface tension, reduced destabilizing solvent‐solvent interactions increase the half‐life up to 20 %.
- Published
- 2020
39. DFT study of the hydrogen adsorption and storage on Ni4 cluster embedded in multivacancy graphene
- Author
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M.E. Pronsato, Jorge Mario Marchetti, V. Orazi, and R.E. Ambrusi
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Graphene ,Energy Engineering and Power Technology ,02 engineering and technology ,Electronic structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,London dispersion force ,0104 chemical sciences ,law.invention ,Hydrogen storage ,symbols.namesake ,Fuel Technology ,Adsorption ,Chemical physics ,law ,symbols ,Molecule ,Density functional theory ,van der Waals force ,0210 nano-technology - Abstract
Hydrogen adsorption stability, geometry, electronic structure and mechanism has been investigated on Ni4 cluster embedded in graphene with three, four and six vacancies by density functional theory (DFT) calculations. An energetic analysis of hydrogen adsorption by addition of one to four H2 molecules was performed for each system in order to determine their hydrogen storage capacity. Dispersion force contribution to the adsorption energy is quantitative evaluated to know whether H2 molecules adsorption behavior is dominated by chemical or van der Waals interactions. A further analysis of this type of interactions is also addressed by total and partial density of states. Bonding and charge transfer characteristics for the different steps involved in the adsorption mechanism are also included. Special attention is given to the effects caused by this new Ni/graphene interface to the hydrogen adsorption behavior.
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- 2020
40. Comparison of Theory and Experiments on van der Waals Forces in Media—A Survey
- Author
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Friedrich Anton Burger, Stefan Yoshi Buhmann, Johannes Fiedler, and Robert W. Corkery
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Physics ,symbols.namesake ,General Energy ,Classical mechanics ,symbols ,Physical and Theoretical Chemistry ,van der Waals force ,London dispersion force ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
We present a critical overview comparing theoretical predictions and measurements of van der Waals dispersion forces in media on the basis of the respective Hamaker constants. To quantify the agree...
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- 2020
41. Unusual chalcogen⋯chalcogen interactions in like⋯like and unlike YCY⋯YCY complexes (Y = O, S, and Se)
- Author
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Mohamed Shehata, Mahmoud Moustafa, Nayra A. M. Moussa, Mahmoud A. A. Ibrahim, H. R. Abd El-Mageed, and Mahmoud E. S. Soliman
- Subjects
Crystallography ,Chalcogen ,Atomic radius ,Atoms in molecules ,Binding energy ,General Physics and Astronomy ,Molecule ,Physical and Theoretical Chemistry ,Perturbation theory ,Decomposition analysis ,London dispersion force - Abstract
Chalcogen∙∙∙Chalcogen interactions were investigated within four types of like∙∙∙like and unlike Y=C=Y∙∙∙Y=C=Y complexes (where Y = O, S, and Se). A plethora of quantum mechanical calculations, including molecular electrostatic potential (MEP), maximum surface electrostatic potential (Vs,max), point-of-charge (PoC), quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI), and symmetry-adapted perturbation theory-based energy decomposition analysis (SAPT-EDA) calculations, were executed. The energetic findings revealed a preferential tendency of the studied chalcogen-bearing molecules to engage in type I, II, III, and IV chalcogen∙∙∙chalcogen interactions. Notably, the selenium-bearing molecules exhibited the most potent ability to favorably participate in all the explored chalcogen∙∙∙chalcogen interactions. Among like∙∙∙like complexes, type IV interactions showed the most favorable negative binding energies, whereas type III interactions exhibited the scrawniest binding energies. Unexpectedly, oxygen-containing complexes within type IV interactions showed an alien pattern of binding energies that decreased along with the chalcogen atomic size level up. QTAIM analysis provided a solo BCP, via chalcogen∙∙∙chalcogen interactions, with no clues for any secondary ones. SAPT-EDA outlined the domination of the explored interactions by the dispersion forces and indicated to the pivotal shares of the electrostatic forces, except type III σ-hole∙∙∙σ-hole and di σ-hole interactions. These observations demonstrate in better detail all types of chalcogen∙∙∙chalcogen interactions, leading to a persuasive intensification for versatile fields related to materials science and drug design.
- Published
- 2022
42. Attraction between Permanent Dipoles and London Dispersion Forces Dominate the Thermodynamics of Organic Crystallization
- Author
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Rajshree Chakrabarti and Peter G. Vekilov
- Subjects
Materials science ,010405 organic chemistry ,Thermodynamics ,General Chemistry ,Contrast (music) ,010402 general chemistry ,Condensed Matter Physics ,01 natural sciences ,Attraction ,London dispersion force ,0104 chemical sciences ,law.invention ,Dipole ,law ,General Materials Science ,Crystallization - Abstract
Organic crystallization controls natural and pathological processes and technologies to produce pharmaceuticals, fine chemicals, and electronic and optical devices. In contrast to water-based cryst...
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- 2020
43. DFT <scp>‐D4</scp> counterparts of leading <scp>meta‐</scp> generalized‐gradient approximation and hybrid density functionals for energetics and geometries
- Author
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Lars Goerigk and Asim Najibi
- Subjects
Models, Molecular ,Molecular Conformation ,Thermodynamics ,Random hexamer ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,Turn (biochemistry) ,Coordination Complexes ,0103 physical sciences ,Organometallic Compounds ,Thermochemistry ,Non-covalent interactions ,Computer Simulation ,Wave function ,Conformational isomerism ,Density Functional Theory ,chemistry.chemical_classification ,010304 chemical physics ,Water ,General Chemistry ,0104 chemical sciences ,Computational Mathematics ,chemistry ,Density functional theory ,Peptides ,Databases, Chemical - Abstract
Previously, we introduced DFT-D3(BJ)ωB97X-V and ωB97M-V functionals and assessed them for the GMTKN55 database [Najibi and Goerigk, J Chem. Theory Comput. 2018, 14, 5725]. In this study, we present DFT-D4 damping parameters to build the DFT-D4 counterparts of these functionals and assess these in comparison. We extend our analysis beyond GMTKN55 and especially turn our attention to enzymatically catalyzed and metal-organic reactions. We find that B97M-D4 is now the second-best performing meta-generalized-gradient approximation functional for the GMTKN55 database and it can provide noticeably better organometallic reaction energies compared to B97M-D3(BJ). Moreover, the aforementioned DFT-D3(BJ)-based functionals have not been thoroughly assessed for geometries and herein we close this gap by analyzing geometries of noncovalently bound dimers and trimers, peptide conformers, water hexamers and transition-metal complexes. We find that several of the B97(M)-based methods-particularly the DFT-D4 versions-surpass the accuracy of previously studied methods for peptide conformer, water hexamer, and transition-metal complex geometries, making them safe-to-use, cost-efficient alternatives to the original methods. The DFT-D4 variants can be easily used with ORCA4.1 and above.
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- 2020
44. Unconventional Type III Halogen···Halogen Interactions: A Quantum Mechanical Elucidation of σ-Hole···σ-Hole and Di-σ-Hole Interactions
- Author
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Nayra A. M. Moussa and Mahmoud A. A. Ibrahim
- Subjects
Physics ,Work (thermodynamics) ,General Chemical Engineering ,Binding energy ,General Chemistry ,Crystal structure ,Crystal engineering ,London dispersion force ,Article ,Chemistry ,Chemical physics ,Halogen ,Perturbation theory ,QD1-999 ,Quantum - Abstract
Herein, two unconventional type III halogen···halogen interactions, namely, σ-hole···σ-hole and di-σ-hole interactions, were reported in a series of halogenated complexes. In type III, the A-halogen···halogen angles are typically equal to 180°, and the occurrence of σ-hole on halogen atoms is mandatory. Using diverse quantum mechanical calculations, it was demonstrated that the occurrence of such interactions with binding energies varied from −0.35 to −1.30 kcal/mol. Symmetry-adapted perturbation theory-based energy decomposition analysis (SAPT-EDA) revealed that type III interactions are dominated by dispersion forces, while electrostatic forces are unfavorable. Cambridge Structure Database (CSD) survey unveiled the experimental evidence for the manifestation of σ-hole···σ-hole interactions in crystal structures. This work might be deemed as a foundation for a vast number of forthcoming crystal engineering and materials science studies.
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- 2020
45. The crystal structures, Hirshfeld surface analyses and energy frameworks of two hexathiapyrazinophane regioisomers; 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane
- Author
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Helen Stoeckli-Evans and Tokouré Assoumatine
- Subjects
crystal structure ,Pyrazine ,m-bis ,regioisomers ,Crystal structure ,thiapyrazinophanes ,010402 general chemistry ,010403 inorganic & nuclear chemistry ,Ring (chemistry) ,01 natural sciences ,London dispersion force ,Research Communications ,energy frameworks ,Crystal ,chemistry.chemical_compound ,hirshfeld surface analysis ,Structural isomer ,General Materials Science ,hexathiapyrazinophanes ,Crystallography ,Chemistry ,Hydrogen bond ,thiapyrazinophanes ,p-bis ,General Chemistry ,hexathiapyrazinophanes ,Condensed Matter Physics ,HEXA ,fingerprint plots ,0104 chemical sciences ,QD901-999 ,m-bis ,p-bis - Abstract
The title hexathiapyrazinophanes are regioisomers, having a central tetra-2,3,5,6-methylenepyrazine unit with two –S—CH2—CH2—S—CH2—CH2—S– chains linking the methylene C atoms at positions 2 and 6 and 3 and 5 in the m-bis regioisomer, but linking the methylene C atoms at positions 2 and 5 and 3 and 6 in the p-bis regioisomer., The title thiapyrazinophanes, 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane, C16H24N2S6, (I), and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane, C16H24N2S6, (II), are regioisomers; m-bis L1 and p-bis L1, respectively. Both compounds have a central tetra-2,3,5,6-methylenepyrazine unit with two –S—CH2—CH2—S—CH2—CH2—S– chains, linking the methylene C atoms at positions 2 and 6 and 3 and 5 on the pyrazine ring of I, but linking the methylene C atoms at positions 2 and 5 and 3 and 6 on the pyrazine ring of II. Both compounds crystallize with half a molecule in the asymmetric unit. The whole molecule of I is generated by inversion symmetry, with the pyrazine ring being located about a center of symmetry. The whole molecule of II is generated by twofold rotation symmetry, with the pyrazine N atoms being located on the twofold rotation axis. In compound I, there are pairs of intramolecular C—H⋯S contacts present, but none in compound II. In the crystal of I, there are no significant intermolecular interactions present, while in the crystal of II, molecules are linked by pairs of C—H⋯S hydrogen bonds, forming corrugated layers lying parallel the ac plane. The Hirshfeld surfaces and the energy frameworks of the two regioisomers indicate little difference in the interatomic contacts, which are dominated by dispersion forces.
- Published
- 2020
46. Angular Dependence of the Pressure Tensor in a Wedge-Shaped Cavity of a Solid
- Author
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A. I. Rusanov and Elena N. Brodskaya
- Subjects
Physics ,Work (thermodynamics) ,Mechanical equilibrium ,business.product_category ,Surfaces and Interfaces ,Function (mathematics) ,Mechanics ,London dispersion force ,Wedge (mechanical device) ,law.invention ,Colloid and Surface Chemistry ,Planar ,law ,Angular dependence ,Tensor ,Physical and Theoretical Chemistry ,business - Abstract
In addition to our previous work [1], a detailed analysis has been carried out for the angular dependences of all components of the pressure tensor in a wedge-shaped cavity of a solid with dispersion forces. It has been shown that the pressure tensor components satisfy the conditions of mechanical equilibrium as a function of the distance from the walls of the wedge-shaped cavity and the angular variable. Additional contributions to the pressure tensor relative to the tensor in a planar slit have been obtained in the case of small angles.
- Published
- 2020
47. London Dispersion and Hydrogen‐Bonding Interactions in Bulky Molecules: The Case of Diadamantyl Ether Complexes
- Author
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Peter R. Schreiner, Pablo Pinacho, Cristobal Perez, Melanie Schnell, María Mar Quesada Moreno, and Marina Šekutor
- Subjects
Ether ,Alcohol ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,chemistry.chemical_compound ,molecular complexes ,rotational spectroscopy ,Non-covalent interactions ,Molecule ,chemistry.chemical_classification ,diadamantyl ether ,dispersion ,non-covalent interactions, quantum chemical calculations ,Full Paper ,010405 organic chemistry ,Hydrogen bond ,Organic Chemistry ,General Chemistry ,quantum chemical computations ,Full Papers ,0104 chemical sciences ,Crystallography ,Monomer ,chemistry ,non-covalent interactions ,ddc:540 ,Non‐Covalent Interactions | Hot Paper ,Dispersion (chemistry) - Abstract
Chemistry - a European journal 26(47), 10817 - 10825 (2020). doi:10.1002/chem.202001444, Diadamantyl ether (DAE, C20H30O) represents a good model to study the interplay between London dispersion and hydrogen‐bond interactions. By using broadband rotational spectroscopy, an accurate experimental structure of the diadamantyl ether monomer is obtained and its aggregates with water and a variety of aliphatic alcohols of increasing size are analyzed. In the monomer, C−H⋅⋅⋅H−C London dispersion attractions between the two adamantyl subunits further stabilize its structure. Water and the alcohol partners bind to diadamantyl ether through hydrogen bonding and non‐covalent Owater/alcohol⋅⋅⋅H−CDAE and C−Halcohol⋅⋅⋅H−CDAE interactions. Electrostatic contributions drive the stabilization of all the complexes, whereas London dispersion interactions become more pronounced with increasing size of the alcohol. Complexes with dominant dispersion contributions are significantly higher in energy and were not observed in the experiment. The results presented herein shed light on the first steps of microsolvation and aggregation of molecular complexes with London dispersion energy donor (DED) groups and the kind of interactions that control them., Published by Wiley-VCH, Weinheim
- Published
- 2020
48. A Fullerene‐Based Molecular Torsion Balance for Investigating Noncovalent Interactions at the C60Surface
- Author
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Yutaka Maeda, Haruna Narita, and Michio Yamada
- Subjects
Biphenyl ,chemistry.chemical_classification ,Quantitative Biology::Biomolecules ,Fullerene ,010405 organic chemistry ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,London dispersion force ,Catalysis ,0104 chemical sciences ,Folding (chemistry) ,chemistry.chemical_compound ,chemistry ,Computational chemistry ,Intramolecular force ,Physics::Atomic and Molecular Clusters ,Non-covalent interactions ,Pi interaction ,Physics::Chemical Physics ,Conformational isomerism - Abstract
To investigate the nature and strength of noncovalent interactions at the fullerene surface, molecular torsion balances consisting of C60 and organic moieties connected through a biphenyl linkage were synthesized. NMR and computational studies show that the unimolecular system remains in equilibrium between well-defined folded and unfolded conformers owing to restricted rotation around the biphenyl C-C bond. The energy differences between the two conformers depend on the substituents and is ascribed to differences in the intramolecular noncovalent interactions between the organic moieties and the fullerene surface. Fullerenes favor interacting with the π-faces of benzenes bearing electron-donating substituents. The correlation between the folding free energies and corresponding Hammett constants of the substituents in the arene-containing torsion balances reflects the contributions of the electrostatic interactions and dispersion force to face-to-face arene-fullerene interactions.
- Published
- 2020
49. Microscopic mechanism for effect of sodium on NO heterogeneous reduction by char
- Author
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Ri-yi Lin, Xiu-xia Zhang, Miao Xie, Xiao-xue Lu, Zhi-jun Zhou, and Hui-xi Wu
- Subjects
inorganic chemicals ,010405 organic chemistry ,Chemistry ,02 engineering and technology ,Activation energy ,01 natural sciences ,Bond order ,London dispersion force ,0104 chemical sciences ,Reaction coordinate ,020401 chemical engineering ,Atom ,Molecule ,Physical chemistry ,Density functional theory ,Char ,0204 chemical engineering - Abstract
A thorough theoretical exploration of microscopic mechanism for effect of sodium (Na) on nitric oxide (NO) heterogeneous reduction by char was performed based on density functional theory with consideration of London dispersion interaction. Calculation results show that the Na atom could migrate at edge of char and prefers to be incorporated into a five-atom ring forming a pentagon with 174.2 kJ/mol released. A strong electrostatic attraction between the Na atom and carbon atoms at the edge is found by reduced density gradient analysis. Electrons transfer from the Na atom to char, resulting in electron rearrangement on char. It is the most stable mode for adsorption of the first NO molecule when O atom in NO molecule is adjacent to the Na atom. The doping of Na could promote adsorption of the first NO molecule, but has little effect on that of the second NO molecule. The intrinsic reaction coordinate calculations and Mayer bond order analyses suggest that the Na atom affects heterogeneous reduction through “oxidized-reduced” cycle via “combination-separation” with the O atom. Desorption of N2 molecule is the rate-determining step in the whole reaction channel. The canonical variational theory was used for kinetic analyses, considering the tunneling effect along the reaction coordinate with Wigner method. It is found that the reaction is accelerated by doping Na atom. Although the addition of Na would not significantly reduce activation energy of the rate-determining step, but would increase activation sites at the edge of char.
- Published
- 2020
50. An Update on Multiple Bonding between Heavier Main Group Elements: The Importance of Pauli Repulsion, Charge-Shift Character, and London Dispersion Force Effects
- Author
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Philip P. Power
- Subjects
Field (physics) ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Charge (physics) ,010402 general chemistry ,01 natural sciences ,Multiple bonds ,London dispersion force ,0104 chemical sciences ,Inorganic Chemistry ,symbols.namesake ,Pauli exclusion principle ,Character (mathematics) ,Main group element ,Quantum mechanics ,symbols ,Physical and Theoretical Chemistry - Abstract
An update on some recent developments in the bonding of compounds with multiple bonds between heavier main group elements is the major theme of this review. A brief historical summary of the field ...
- Published
- 2020
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