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According to our search of the Cambridge Structural Database, a huge number of crystal structures involving intramolecular C S⋯O S(C) interactions were extracted. The largest proportion of these interactions in the crystals shows rather good linearity and short interatomic S⋯O distances. Then, intramolecular C S⋯O S(C) interactions in three representative organic molecules, i.e. sulfamethizole, thioindirubin, and thiazolo-pyridinium methide, were investigated using density functional theory calculations at the M06-2x level. The effects of different substituents and intermolecular hydrogen bonds on these interactions were also examined. The presence of both electron-withdrawing and electron-donating substituents into the donor moiety tends to strengthen intramolecular S⋯O bonds, while the formation of intermolecular hydrogen bonds has a complex influence. To gain a deeper understanding of the nature and strength of these interactions, the analyses of atom in molecules, noncovalent interaction index, and natural bond orbital were undertaken. Intramolecular chalogen bonds are weak electrostatic interactions and play a key role in controlling the crystal forms of relevant organic compounds, frequently supported by intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

To elucidate the efficient removal and reliable storage of radioactive iodine for ionic liquids, halogen bonds in the complexes of I 2 with a series of ion pairs were investigated at the M06-2x level of theory in this work. Albeit halogen bonds in these complexes are somewhat weaker than those in the systems of bare anions, these interactions still belong to strong halogen bonds and show some covalent character. The strength of these interactions deceases in the following order: [Cl] − ≈ [Br] − ≈ [I] − > [Ac] − ≈ [NO 3 ] − > [BF 4 ] − , consistent with the experimentally determined trend of the removal efficiency for corresponding ionic liquids. In addition, the electrostatic potential, atoms in molecules, and charge transfer analyses were also undertaken for the complexes under study, to gain a deeper understanding of the nature of these interactions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Substituents in electron donors have a slight effect on halogen bonding. [•] The presence of transition metals leads to much stronger halogen bonds. [•] Crystallographic evidence has been obtained from the CSD. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electron-donating substituents lead to stronger halogen bonds. [•] X⋯N interactions play a key role in XB-based crystal engineering. [•] Experimental evidence of the interactions was obtained from CSD. [ABSTRACT FROM AUTHOR]

Highlights: [•] Weak energetic effects are observed in the studied crystal structures. [•] Calculated energetic results agree well with the geometric features. [•] Energetic effects are much more complicated in crystal structures. [Copyright &y& Elsevier]

[Display omitted] • A number of X-ray crystals containing double pentavalent PnBs were gathered. • These interactions are principally electrostatic and enhance as the Pn size grows. • A two-parameter model was established to assess the strength of such interactions. Hypervalent pnictogen bonding (PnB) involving a pnictogen(V) atom as an electrophilic center has attracted far less interest to date compared with conventional trivalent PnB. In this work, we firstly collected a number of crystal structures, which contain a four-membered interaction motif with two pentavalent Pn∙∙∙O contacts in the dimer units, from the Cambridge Structural Database. Then, a set of homodimers of pnictogenoxide species were selected to model such interactions detected in the crystals. Double pentavalent PnBs are principally electrostatic in character and strengthen with the increasing atomic polarizability of pnictogens. Particularly, a two-parameter model containing the electrostatic potential maxima of the Pn atoms and the minima of the O atoms was established to predict the strength of these interactions. The introduction of powerful electron-withdrawing substituents into the scaffold leads to much enhanced double PnBs, as a result of the pronounced influence of these substituents on the σ-hole intensity of pnictogens. [ABSTRACT FROM AUTHOR]

Abstract: Anion recognition by the combination of different kinds of intermolecular forces has been evidenced in recent years. In this work, the binding behaviors of three urea-based receptors 1–3 towards several anions (Cl−, Br−, I−, ) have been investigated using density functional theory calculations. Distinct noncovalent interactions, involving halogen bonding, hydrogen bonding, and anion–π interactions, in the host–guest complexes under study are characterized. For the iodide receptor 1 composed of halogen- and hydrogen-bond donor groups (Ce:glyph name="sbnd" />H), the anions are held by bidentate halogen and hydrogen bonds, while Nanion and anion–π interactions are presented in the complexes of the perfluorinated receptor 2. On the other hand, multiple hydrogen bonding interactions (Nyph name="sbnd" />H⋯anion) occur between the host benzoate ester 3 and anionic guests. The introduction of iodine atoms into the phenyl groups of the receptor also leads to highly improved binding affinity of anions. The results presented here would provide a basis for the design and synthesis of new and functional host molecules exhibiting specific anion recognition. [Copyright &y& Elsevier]

[Display omitted] • Several complexes in which double ChB and XB interactions coexist were studied. • Weak energetic effects are found between the two kinds of interactions. • Many computational tools were used to characterize these σ-hole interactions. The interplay between double chalcogen-bonding interactions and halogen bonds that coexist in the complexes of ditopic chalcogenazolo-pyridine modules was investigated through the analysis of the crystal structures collected and theoretical calculations. Weak energetic effects are observed in the studied complexes, and these two interactions thus show some additive characters, which can be ascribed to the formation of double interactions with a cyclic motif. The computational tools of atoms in molecules, noncovalent interaction index, and natural bond orbital were also used to characterize the interactions as well as to analyze how these two interactions mutually influence each other. [ABSTRACT FROM AUTHOR]