Search results for "halogen bonding"
showing 10 items of 35 documents
Tunable Interaction Strength and Nature of the S···Br Halogen Bonds in [(Thione)Br2] Systems
2015
The strength and nature of the S···Br and Br···Br interactions were systematically tuned by altering the electron donor properties of the thione group. Three new halogen-bonded compounds, [(N-methylbenzothiazole-2-thione)Br2]·0.5CH2Cl2 (1), [(2(3H)-benzothiazolethione)Br2] (2), and [(2-benzimidazolethione)Br]·[Br3] (3), were synthesized and studied structurally by using X-ray crystallography and computationally by using charge density analysis based on QTAIM calculations. Analysis of the interaction strength indicated a formation of surprisingly strong S···Br halogen bonds in 1 (−104 kJ mol–1, and RBrS = 0.64) and 2 (−116 kJ mol–1, and RBrS = 0.63) with a substantial covalent contribution. …
Efficient light-induced phase transitions in halogen-bonded liquid crystals
2016
Here, we present a new family of light-responsive, fluorinated supramolecular liquid crystals (LCs) showing efficient and reversible light-induced LC-to-isotropic phase transitions. Our materials design is based on fluorinated azobenzenes, where the fluorination serves to strengthen the noncovalent interaction with bond-accepting stilbazole molecules, and increase the lifetime of the cis-form of the azobenzene units. The halogen-bonded LCs were characterized by means of X-ray diffraction, hot-stage polarized optical microscopy, and differential scanning calorimetry. Simultaneous analysis of light-induced changes in birefringence, absorption, and optical scattering allowed us to estimate tha…
Iodine Clathrated : A Solid-State Analog of the Iodine-Starch Complex
2019
Co-crystallizing iodine with a simple dicationic salt (1,8- diammoniumoctane chloride) results in the clathration of the iodine (I2) molecules inside trigonal and hexagonal helical channels of the crystal lattice with 72 wt% overall I2 loading. The I2 inside the bigger trigonal channel forms a I-I•••I-I•••I-I halogen-bonded infinite helical chain, while the I2 in the smaller hexagonal channel is disordered. In both channels the I2 interaction with the channel wall happens through I-I•••Cl- halogen bonds. The helical channels in the crystal lattice are constructed via the strong charge-assisted H2N+ -H•••Cl- hydrogen bonds between the dications and the chloride anions. The structure shows a …
Halogen bonding stabilizes a cis-azobenzene derivative in the solid state : A crystallographic study
2017
Crystals oftrans- andcis-isomers of a fluorinated azobenzene derivative have been prepared and characterized by single-crystal X-ray diffraction. The presence of F atoms on the aromatic core of the azobenzene increases the lifetime of the metastablecis-isomer, allowing single crystals of thecis-azobenzene to be grown. Structural analysis on thecis-azobenzene, complemented with density functional theory calculations, highlights the active role of the halogen-bond contact (N...I synthon) in promoting the stabilization of thecis-isomer. The presence of a long aliphatic chain on the azobenzene unit induces a phase segregation that stabilizes the molecular arrangement for both thetrans- andcis-i…
Halogen bonding and host-guest chemistry between
2019
Single crystal X-ray structures of halogen-bonded assemblies formed between host N-hexylammonium resorcinarene bromide (1) or N-cyclohexylammonium resorcinarene chloride (2), and 1,4-diiodooctafluorobutane and accompanying small solvent guests (methanol, acetonitrile and water) are presented. The guests’ inclusion affects the geometry of the cavity of the receptors 1 and 2, while the divalent halogen bond donor 1,4-diiodooctafluorobutane determines the overall nature of the halogen bond assembly. The crystal lattice of 1 contains two structurally different dimeric assemblies A and B, formally resulting in the mixture of a capsular dimer and a dimeric pseudo-capsule. 1H and 19F NMR analyses …
Concerted Halogen-Bonded Networks with N-Alkyl Ammonium Resorcinarene Bromides: From Dimeric Dumbbell to Capsular Architectures
2015
N-Alkyl ammonium resorcinarene bromides and 1,4-diiodooctafluorobutane via multiple intermolecular halogen bonds (XB) form different exotic supramolecular architectures through subtle changes of the upper rim substituents. Dimeric dumbbell-like assembly with encapsulated guest molecules is generated with N-benzyl substituents. The N-hexyl groups engender an XB-induced polymeric pseudocapsule and an XB-induced dimeric capsule with entrapped 1,4-dioxane guest molecules. The N-propyl and N-cyclohexyl groups generate deep cavity cavitands. The deep cavity cavitands possess cavities for self-inclusion leading to polymeric herringbone arrangement in one direction and that pack into 3D polymeric a…
Supramolecular Assembly of Metal Complexes by (Aryl)I⋯dz2[PtII] Halogen Bond
2020
The theoretical data for the half‐lantern complexes [Pt(C^N)(μ‐S^N)] 2 ( 1 – 3 ; С^N is cyclometalated 2‐Ph‐benzothiazole; S^N is 2‐SH‐pyridine 1 , 2‐SH‐benzoxazole 2 , 2‐SH‐tetrafluorobenzothiazole 3 ) indicate that the Pt···Pt orbital interaction leads to an increment of the nucleophilicity of the outer d z 2 ‐orbitals to provide assembly with electrophilic species. 1 – 3 were co‐crystallized with bifunctional halogen bond (XB) donors to give adducts ( 1 – 3 ) 2 ∙(1,4‐diiodotetrafluorobenzene) and infinite polymeric [ 1 ·1,1’‐diiodoperfluorodiphenyl] n . X‐ray crystallography revealed that the supramolecular assembly is achieved via (Aryl)I∙∙∙ d z 2 [Pt II ] XB between iodine σ‐holes and …
Surface-relief gratings in halogen-bonded polymer-azobenzene complexes A concentration-dependence study
2017
In recent years, supramolecular complexes comprising a poly(4-vinylpyridine) backbone and azobenzene-based halogen bond donors have emerged as a promising class of materials for the inscription of light-induced surface-relief gratings (SRGs). The studies up to date have focused on building supramolecular hierarchies, i.e., optimizing the polymer–azobenzene noncovalent interaction for efficient surface patterning. They have been conducted using systems with relatively low azobenzene content, and little is known about the concentration dependence of SRG formation in halogen-bonded polymer–azobenzene complexes. Herein, we bridge this gap, and study the concentration dependence of SRG formation…
Dissecting the packing forces in mixed perfluorocarbon/aromatic co-crystals
2021
We carried out a systematic evaluation of the packing forces in co-crystals featuring monoiodo- and diiodo-perfluoroalkanes and 1,2,4-oxadiazoles through single crystal X-ray diffraction and theoretical analysis. The molecules assemble via a combination of halogen bonding and specific dispersive interactions involving the perfluorinated units. We quantitatively elucidated the nature and strength of such interactions through solid-state calculations and Hirshfeld surface analysis. One of the co-crystals, formed by two monoiodoperfluorodecane molecules, the longest perfluorinated chain ever solved at the atomic level, allowed us to fully highlight the role of fluorous interactions.
Halogen-bonded photoresponsive materials
2015
The aim of the present review is to illustrate to the reader the state of the art on the construction of supramolecular azobenzene-containing materials formed by halogen bonding. These materials include several examples of polymeric, liquid crystalline or crystalline species whose performances are either superior to the corresponding performances of their hydrogen-bonded analogues or simply distinctive of the halogen-bonded species. submittedVersion Peer reviewed