Special Issue "σ- and π-Hole Interactions in Crystals"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystal Engineering".

Deadline for manuscript submissions: 31 August 2019

Special Issue Editors

Guest Editor
Dr. Drahomir Hnyk

Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., Rez, Czech Republic
Website | E-Mail
Interests: gas-phase electron diffraction; computational chemistry; NMR spectroscopy; noncovalent interactions; σ- and π-hole interactions; inhibitors
Co-Guest Editor
Dr. Jindřich Fanfrlík

Institute of Organic Chemistry and Biochemistry of the Academy of Sciences of the Czech Republic, Prague, Czech Republic
Website | E-Mail
Interests: computational chemistry; noncovalent interactions; σ- and π-hole interactions; molecular dynamics; inhibitors; protein-ligand complexes
Co-Guest Editor
Dr. Tiddo J. Mooibroek

University of Amsterdam, Van’t Hoff Institute for Molecular Sciences, Amsterdam, Netherlands
Website | E-Mail
Interests: non-covalent interaction; intermolecular interaction; intramolecular interaction; σ-hole interaction; π-hole interaction; directionality; predictability; crystal structure

Special Issue Information

Dear Colleagues,

Both σ- and π-holes are very effective models that enable us to underestand, and even predict, various chemical observations. For example, they can explain various modes of crystal packing, depending on which element(s) the crystal consists of. These concepts can even explain various chemical reactivities. On the σ-hole front, we can give insight intochalcogen bonding, pnictogen bonding, halogen bonding, etc. Many recent examples nicely account for sometimes unusual crystal packing, which could hardly be explained without taking the σ-hole and π-holes concepts into account.

We invite investigators to submit papers which discuss the development of crystal engineering in terms of σ- and π-hole concepts but the topics are rather flexible and submissions that consider either concept to any extent would be welcome.

Dr. Drahomir Hnyk
Dr. Jindřich Fanfrlík
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Crystal packing
  • Crystal engineering
  • Noncovalent interactions
  • σ- and π-hole interactions
  • Quantum-chemical computations

Published Papers (3 papers)

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Research

Open AccessArticle
An Overview of Strengths and Directionalities of Noncovalent Interactions: σ-Holes and π-Holes
Crystals 2019, 9(3), 165; https://doi.org/10.3390/cryst9030165
Received: 12 March 2019 / Revised: 14 March 2019 / Accepted: 16 March 2019 / Published: 21 March 2019
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Abstract
Quantum mechanics, through the Hellmann–Feynman theorem and the Schrödinger equation, show that noncovalent interactions are classically Coulombic in nature, which includes polarization as well as electrostatics. In the great majority of these interactions, the positive electrostatic potentials result from regions of low electronic [...] Read more.
Quantum mechanics, through the Hellmann–Feynman theorem and the Schrödinger equation, show that noncovalent interactions are classically Coulombic in nature, which includes polarization as well as electrostatics. In the great majority of these interactions, the positive electrostatic potentials result from regions of low electronic density. These regions are of two types, designated as σ-holes and π-holes. They differ in directionality; in general, σ-holes are along the extensions of covalent bonds to atoms (or occasionally between such extensions), while π-holes are perpendicular to planar portions of molecules. The magnitudes and locations of the most positive electrostatic potentials associated with σ-holes and π-holes are often approximate guides to the strengths and directions of interactions with negative sites but should be used cautiously for this purpose since polarization is not being taken into account. Since these maximum positive potentials may not be in the immediate proximities of atoms, interatomic close contacts are not always reliable indicators of noncovalent interactions. This is demonstrated for some heterocyclic rings and cyclic polyketones. We briefly mention some problems associated with using Periodic Table Groups to label interactions resulting from σ-holes and π-holes; for example, the labels do not distinguish between these two possibilities with differing directionalities. Full article
(This article belongs to the Special Issue σ- and π-Hole Interactions in Crystals)
Figures

Figure 1

Open AccessArticle
Noncovalent Interactions between 1,3,5-Trifluoro-2,4,6-triiodobenzene and a Series of 1,10-Phenanthroline Derivatives: A Combined Theoretical and Experimental Study
Crystals 2019, 9(3), 140; https://doi.org/10.3390/cryst9030140
Received: 16 January 2019 / Revised: 23 February 2019 / Accepted: 4 March 2019 / Published: 8 March 2019
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Abstract
How many strong C−I⋯N halogen bonds can one 1,3,5-trifluoro-2,4,6-triiodobenzene molecule form in a crystal structure? To answer this question, we investigated in detail the noncovalent interactions between 1,3,5-trifluoro-2,4,6-triiodobenzene and a series of 1,10-phenanthroline derivatives by employing a combined theoretical and experimental method. The [...] Read more.
How many strong C−I⋯N halogen bonds can one 1,3,5-trifluoro-2,4,6-triiodobenzene molecule form in a crystal structure? To answer this question, we investigated in detail the noncovalent interactions between 1,3,5-trifluoro-2,4,6-triiodobenzene and a series of 1,10-phenanthroline derivatives by employing a combined theoretical and experimental method. The results of the quantum chemical calculations and crystallographic experiments clearly show that there is a structural competition between a C−I⋯N halogen bond and π⋯π stacking interaction. For example, when there are much stronger π⋯π stacking interactions between two 1,10-phenanthroline derivative molecules or between two 1,3,5-trifluoro-2,4,6-triiodobenzene molecules in the crystal structures, then one 1,3,5-trifluoro-2,4,6-triiodobenzene molecule forms only one C−I⋯N halogen bond with one 1,10-phenanthroline derivative molecule. Another example is when π⋯π stacking interactions in the crystal structures are not much stronger, one 1,3,5-trifluoro-2,4,6-triiodobenzene molecule can form two C−I⋯N halogen bonds with two 1,10-phenanthroline derivative molecules. Full article
(This article belongs to the Special Issue σ- and π-Hole Interactions in Crystals)
Figures

Figure 1

Open AccessArticle
Dihalogen and Pnictogen Bonding in Crystalline Icosahedral Phosphaboranes
Crystals 2018, 8(10), 390; https://doi.org/10.3390/cryst8100390
Received: 6 September 2018 / Revised: 4 October 2018 / Accepted: 9 October 2018 / Published: 13 October 2018
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Abstract
Noncovalent interactions in the single crystal of 3,6-Cl2-closo-1,2-P2B10H8 and in the crystal of closo-1,7-P2B10Cl10•toluene were analyzed by means of quantum chemical computations. The crystal packing in the [...] Read more.
Noncovalent interactions in the single crystal of 3,6-Cl2-closo-1,2-P2B10H8 and in the crystal of closo-1,7-P2B10Cl10•toluene were analyzed by means of quantum chemical computations. The crystal packing in the second crystal was dominated by numerous B-Cl···Cl-B dihalogen and strong B-P···π pnictogen bonds, the latter of which were characterized by a small length of 3.08 Å and a large interaction energy value, exceeding −10 kcal mol−1. Full article
(This article belongs to the Special Issue σ- and π-Hole Interactions in Crystals)
Figures

Graphical abstract

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