Sigma-holes from iso-molecular electrostatic potential surfaces

Alaminsky, Ryan J; Seminario, Jorge M.

doi:10.1007/s00894-019-4051-2

Cited by 11 publications

(2 citation statements)

References 77 publications

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“…Non-covalent σ- and π-hole interactions have generated a great deal of interest and activity in areas ranging from crystal engineering to pharmacology to molecular biology. There have been numerous reviews of this work as well as analyses of the natures of these interactions. ,,,− …”

Section: Introduction Of the σ-Hole And π-Hole Conceptsmentioning

confidence: 99%

Explicit Inclusion of Polarizing Electric Fields in σ- and π-Hole Interactions

2019

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The interactions between a wide variety of molecules having σ-holes or π-holes and several nitrogen bases have been analyzed computationally. The σand π-hole atoms span groups III−VII of the periodic table. The interaction energies range from quite weak, typical of non-covalent bonding, to unusually strong: from −4.6 to −22.0 kcal/mol for σ-hole bonding and from −4.0 to −42.4 kcal/mol for π-hole bonding. The markedly greater strengths of some bonds does not imply that any new factors or types of bonding are involved; they simply reflect higher degrees of the polarization that is part of any Coulombic interaction. To explain the stronger bonding, this polarization must be explicitly taken into account. We show that the interaction energies can be related quite well to (a) the maximum positive electrostatic potentials associated with the σor πholes on their molecular surfaces, (b) the polarizabilities of the nitrogen bases, and especially (c) the polarizing electric fields of the σor π-hole molecules at the positions of the nitrogens.

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Section: Introduction Of the σ-Hole And π-Hole Conceptsmentioning

confidence: 99%

Explicit Inclusion of Polarizing Electric Fields in σ- and π-Hole Interactions

2019

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“…The molecular electrostatic potential surface (MEPs) [39][40][41] is a useful tool for describing the electrostatic nature of the different areas of the molecule. We have realized here the MEPs of the RR141 molecule to determine the electrostatic nature of each site of the organic molecule and determine the more favored centers of interaction (Fig.…”

Section: Molecular Electrostatic Potential Surfaces (Meps)mentioning

confidence: 99%

Computational study of the interaction between azo dye (RR141) and Hematite α-Fe2 O3 (111) Surface: A DFT and MDs Study

Belghiti

Mizeb

Salah

et al. 2023

Preprint

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The adsorptive removal of azo dye molecules from textile effluents by the powdered mineral hematite has been largely studied in the literature, but this mechanism of interaction with the mineral hematite surface is still to date not revealed, hence the need for a theoretical study. The crystal structure model of Hematite adopted is α − Fe2O3 (111). The DFT method and MDs(Molecular Dynamics simulations) have been employed to elucidate the mechanism of interaction. The azo-dye molecule chosen for this study is the reactive red RR141. Geometry minimization of RR141 was performed at the DFT / B3LYP / 6 −31+ +g(d,p) level of theory. The reactivity and performance of RR141-vacuum and RR141-aqueous media in isolated state were evaluated on basis of their planarity, global and local electronic properties as well as deformation ability to adhesion to the mineral surface. The Azo (> N− −N <) and hydroxyl (-O--H) groups are the main active centers for the adsorption of RR141 in a vacuum and aqueous media. Azo and hydroxyl groups of RR141 dye are electron donors, while the sulphonic acid (-SO3--Na+) group is an electron acceptor. The RR141 is found more reactive in the vacuum than in an aqueous medium. The interfacial interaction is the combined effect of the hydrogen bond and the interactions between Fe & −O−, C, −S−,= N− atoms. The whole system is interacting on the first layer through (π-π)-bonds in the nearly parallel adsorption geometries and through the single pair electrons of the heteroatoms.

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Influence of Halogen Substituents on the Photophysical Properties of 7‐Hydroxycoumarin: Insights from Experimental and Theoretical Studies

Hawkins,

Adair,

Ryder

et al. 2024

ChemPhysChem

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Benzopyrone is a popular fluorescent scaffold, but how chemical modifications affect its properties is less understood. We investigated this using halogenated 7‐hydroxycoumarin, unsubstituted 4‐methylumbiliferone, and ortho‐chloro and bromo substitutions on the phenolic ring. Experimental charge density data and computational methods revealed that halogenation at the ortho position significantly reduced quantum yield (QY). Specifically, 7‐hydroxycoumarin (1) had a QY of 70%, while ortho‐chloro (2) and ortho‐bromo (3) had QYs of 61% and 30%, respectively. Experimental data showed that all probes excited similarly, but the electrostatic potential and dipole moments indicated that 2 and 3 dissipated excitation energy more easily due to charge separation. The heavy‐atom effect of Cl and Br did not fully explain the QY reductions, suggesting other radiative decay processes were involved. By incorporating spin‐orbit coupling (SOC) effects, we estimated intersystem crossing (ISC) and phosphorescence rates, providing theoretical QYs of 78% for 1, 59% for 2, and 15% for 3. The large deviation for 3 was attributed to its higher SOC potential. Our findings indicate that 3’s reduced QY results from a mix of SOC‐induced ISC and charge dissipation, while 2’s reduction is primarily due to charge separation. Further studies are needed to validate this approach with other scaffolds.

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Sigma-holes from iso-molecular electrostatic potential surfaces

Cited by 11 publications

References 77 publications

Explicit Inclusion of Polarizing Electric Fields in σ- and π-Hole Interactions

Explicit Inclusion of Polarizing Electric Fields in σ- and π-Hole Interactions

Computational study of the interaction between azo dye (RR141) and Hematite α-Fe2 O3 (111) Surface: A DFT and MDs Study

Influence of Halogen Substituents on the Photophysical Properties of 7‐Hydroxycoumarin: Insights from Experimental and Theoretical Studies

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