Elucidating the Role of Electron-Donating Groups in Halogen Bonding

The Journal of Physical Chemistry A, Journal Year: 2024, Volume and Issue: 128(8), P. 1477 - 1490

Published: Feb. 19, 2024

Computational quantum chemical techniques were utilized to systematically examine how electron-donating groups affect the electronic and spectroscopic properties of halogen bond donors their corresponding complexes. Unlike majority studies on bonding, where electron-withdrawing are utilized, this work investigates influence substituents within donors. Statistical analyses performed descriptors in a prescribed set archetype, halo-alkyne, halo-benzene, halo-ethynyl benzene systems. The σ-hole magnitude, binding interaction energies, vibrational X···N local force constant (where X = Cl, Br, I, At) found correlate very well monotonic linear manner with all other studied. In addition, enhanced bonds when systems contained that could form intramolecular hydrogen electronegative belt atom adjacent linker features.

Language: Английский

---

What can Blyholder teach us about PFAS degradation on metal surfaces?

Environmental Science Advances, Journal Year: 2024, Volume and Issue: 3(3), P. 383 - 401

Published: Jan. 1, 2024

The C–F bond in PFAS has been shown to have an anti-bonding orbital that can interact with metal surfaces, allowing for its degradation.

Language: Английский

---

Halogen Bond Strength in Solids Quantified via Zeeman-Perturbed Nuclear Quadrupole Resonance Spectroscopy

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: March 4, 2025

Proton NMR is a ubiquitous and valuable probe of hydrogen bonds. Conversely, 127I strong halogen bond (XB) donors hopeless due to quadrupolar coupling constants (CQ) on the order GHz. We report here an innovative implementation Zeeman-perturbed nuclear quadrupole resonance (Zp-NQR) spectroscopy, employing adjustable magnetic fields mT, which renders possible acquisition analysis spectra 79Br nuclei subject couplings up 2.3 GHz in solid powders. This approach demonstrated three series halogen-bonded cocrystals based so-called "iconic" XB p-diiodotetrafluorobenzene, sym-trifluorotriiodobenzene, p-dibromotetrafluorobenzene (27 compounds). Analysis using diagonalization Zeeman-quadrupolar Hamiltonian provides CQ values asymmetry parameters, thereby overcoming various limitations encountered pure NQR. Inspection data reveals correlations with geometrical structural features bond, including its length. Dispersion-corrected zeroth-order regular approximation relativistic DFT computations interaction energies donor are strongly correlated experimental computed CQ(127I) CQ(79Br). It concluded that electric field gradient at site useful metric for quantifying strength solids. The range from ∼5 10 kcal mol-1 systems studied herein. Zp-NQR amenable widespread application diverse problems chemical materials sciences related energy materials, crystal engineering, many comprising isotopes.

Language: Английский

---

Enhancement of Halogen Bond Strength by Intramolecular H-Bonds

The Journal of Physical Chemistry A, Journal Year: 2023, Volume and Issue: 127(21), P. 4695 - 4703

Published: May 20, 2023

Quantum calculations study the potential of an intramolecular H-bond between halogen atom (X) a halobenzene and substituent placed ortho to it, amplify ability X engage in bond (XB) with Lewis base. H-bonding substituents NH2, CH2CH2OH, CH2OH, OH, COOH were added halobenzenes (X = Cl, Br, I). The amino group had little effect, but those containing OH increased CX···N XB energy NH3 nucleophile by about 0.5 kcal/mol; increment associated is larger, nearly 2 kcal/mol. These increments approximately doubled if two such are present. Combining pair groups electron-withdrawing NO2 para position has particularly large raising 4 kcal/mol, which can amount as much 4-fold magnification.

Language: Английский

---

Relation between Halogen Bond Strength and IR and NMR Spectroscopic Markers

Molecules, Journal Year: 2023, Volume and Issue: 28(22), P. 7520 - 7520

Published: Nov. 10, 2023

The relationship between the strength of a halogen bond (XB) and various IR NMR spectroscopic quantities is assessed through DFT calculations. Three different Lewis acids place Br or I atom on phenyl ring; each paired with collection N O bases varying electron donor power. weakest XBs display C–X contraction coupled blue shift in associated frequency, whereas reverse trends occur for stronger bonds. best correlations XB interaction energy are observed shielding C directly bonded to X coupling constants involving C–H/F that lies ortho substituent, but these not accurate enough quantitative assessment energy. These tend improve as acid becomes more potent, which makes wider range strengths.

Language: Английский

---

Does a halogen bond require positive potential on the acid and negative potential on the base?

Physical Chemistry Chemical Physics, Journal Year: 2023, Volume and Issue: 25(10), P. 7184 - 7194

Published: Jan. 1, 2023

It is usually expected that formation of a halogen bond (XB) requires region positive electrostatic potential associated with σ or π-hole on the Lewis acid will interact negative base, either lone pair π-bond region. Quantum calculations model systems suggest this not to be necessary. The placement electron-withdrawing substituents base can reverse sign in its positive, and nonetheless engage XB σ-hole acid. scenario also possible certain circumstances, as negatively charged form base. Despite these classical Coulombic repulsions, overall interaction attractive XBs, albeit only weakly so. strengths bonds are surprisingly insensitive changes partner molecule. For example, even wide range depth approaching yields minimal change strength potential.

Language: Английский

---

Halogen bonds with carbenes acting as Lewis base units: complexes of imidazol-2-ylidene: theoretical analysis and experimental evidence

Physical Chemistry Chemical Physics, Journal Year: 2023, Volume and Issue: 25(13), P. 9636 - 9647

Published: Jan. 1, 2023

Complexes of imidazol-2-ylidene with X 2 , HCCX and XCN (X is a halogen centre) are linked by bonds which possess partly covalent character. In extreme cases complexes the halonium cation transfer to Lewis base observed.

Language: Английский

---

Nanodiamond Reinforced Shape Memory Nanocomposites— Versatile Features and Promises

Polymer-Plastics Technology and Materials, Journal Year: 2024, Volume and Issue: 64(1), P. 88 - 104

Published: Aug. 8, 2024

This state-of-the-art overview highlights the significance of high performance shape memory polymer/nanodiamond nanocomposites. Nanodiamond reinforced polymeric nanocomposites have been designed and advantageously studied for design, microstructure, physical properties, structure–property relation/phenomenon, effects, possible technical advancements. filled polymer matrices effects include polyesters, polyurethane, poly(N-isopropylacrylamide), epoxy, polyaniline, chitosan, etc. Addition nanodiamond especially functional nanoparticles may develop and/or covalent interactions with to form interlinking/cross-linking network responsible active fixing/recovery behavior. Noteworthy thermo-responsive, electroactive, photoactive, photothermal, magnetic sensitive observed. Application areas observed so far are smart strain sensing wearable electronics, antibacterial biosensing, civil engineering related areas.

Language: Английский

---

Shape memory polymers: mechanism, structure, and properties

Elsevier eBooks, Journal Year: 2024, Volume and Issue: unknown, P. 1 - 19

Published: Jan. 1, 2024

Language: Английский

---

Halogen Bonding to the π‐Systems of Polycyclic Aromatics

ChemPhysChem, Journal Year: 2024, Volume and Issue: 25(18)

Published: June 26, 2024

Abstract The propensity of the π‐electron system lying above a polycyclic aromatic to engage in halogen bond is examined by DFT calculations. Prototype Lewis acid CF 3 I placed planes benzene, naphthalene, anthracene, phenanthrene, naphthacene, chrysene, triphenyl, pyrene, and coronene. atom positions itself some 3.3–3.4 Å plane, associated interaction energy about 4 kcal/mol. This quantity little smaller for but roughly equal larger polycyclics. only oscillates as slides across face polycyclic, preferring regions higher density over minima electrostatic potential. binding dominated dispersion which contributes half total energy.

Language: Английский

---