Self-assembly of nitroxide radicals via halogen bonding—directional NO⋯I interactions

Boubekeur, Kamal; Syssa-Magalé, Jean-Laurent; Palvadeau, P.; Schöllhorn, Bernd

doi:10.1016/j.tetlet.2005.12.088

Cited by 73 publications

(83 citation statements)

References 24 publications

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“…41,42 Considering Bondi's radii, it is 19.6% shorter than the sum of van der Waals radii, 43,44 which indicates that the C-IÁ Á ÁO-N halogen bonding is strong. In the co-crystal structure, one 1,4-DIPFB molecule connected to two TEMPO radicals by XB in a 1 : 2 (1,4-DIPFB : TEMPO) stoichiometry.…”

Section: Crystallographic Studymentioning

confidence: 97%

Exploring the halogen bond specific solvent effects in halogenated solvent systems by ESR probe

Pang

Jin

2015

New J. Chem.

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The halogen bond specific solvent effect in halogenated solvents was investigated by ESR, Raman spectroscopy, X-ray diffraction and unrestricted MP2 calculations using the ESR probe TEMPO. From ESR spectroscopy, 14 N isotropic hyperfine splitting (HFS) constant a N values are higher in halogenated than non-halogenated solvents as solvent polarity is near to each other, and plotting a N values vs. solvent acceptor number (AN) provides a linear correlation. These results could be attributed to the formation of halogen bonding (XB) and indicate that as specific solvent effect halogen bonding does exist in halogenated solvents, particularly in halo-perfluoro-solvents, in which the halogen bonding between the nucleophilic solutes and halogenated solvent molecules is so strong that it must not be ignored. In both halogen-and hydrogen-containing solvents, halogen bonding and hydrogen bonding may co-exist. Calculations show that the strength of hydrogen bond may be slightly stronger than the corresponding halogen bond. However, the halogen bond becomes more competitive going from chlorine(Cl)-substituted to bromine(Br)-substituted to iodine(I)-substituted solvents, and it is possible that XB solvent effects become preponderant in I-substituted solvents. The analysis of Mulliken atomic spin densities on N and O atoms also proved that when the XB is formed, the spin densities on O would transfer to N, further indicating that the increase of a N should be ascribed to XB specific solvent effects. † Electronic supplementary information (ESI) available: Relationship between a N and e (dielectric constant), a N and m (dipole moment), the Raman spectra and the optimised XB or HB structures of TEMPO and solvent molecules. CCDC 1014498. For ESI and crystallographic data in CIF or other electronic format see

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Section: Crystallographic Studymentioning

confidence: 97%

Exploring the halogen bond specific solvent effects in halogenated solvent systems by ESR probe

Pang

Jin

2015

New J. Chem.

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“…15a) [59]. This work was extended by Micallef to isoindoline nitroxide [60,61]: a similar trimeric entity was crystallized (Fig.…”

Section: Nitronyl Radicalsmentioning

confidence: 83%

Organizing Radical Species in the Solid State with Halogen Bonding

Fourmigué

Lieffrig

2014

Topics in Current Chemistry

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The electronic properties (conductivity, magnetism) of radical systems in the solid state essentially depend on (1) the extent of delocalization of the spin density in the molecule and (2) the intermolecular interactions between radicals. The halogen bond has proven very efficient in engineering such magnetic or conducting structures and recent advances along these lines are reviewed here. Three situations are considered: (1) halogenated radical species acting as halogen bond donors, as found in iodotetrathiafulvalene-based chiral conductors or bilayer systems, and in spin crossover (SCO) complexes with halogenated ligands, (2) radical species acting as halogen bond acceptors, such as neutral nitronyl species or anionic, mixed-valence dithiolene complexes, interacting with closed-shell halogen bond donors (iodoperfluoro alkanes and arenes, iodo- or bromo-pyridinium cations), and, finally, (3) charge transfer salts where both halogen bond donor and acceptor are radical species.

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“…The presence of the electron-withdrawing fluorines strongly enhances the electron acceptor ability of the organic iodine and in addition minimizes the interferences from the other weak interactions, the C-F groups being very insensitive to the interaction with other functional groups. This has permitted their application to dictate the arrangement of molecules for topological reactions in the solid state [30], for the creation of binding sites in crosslinked polymers [31], for layer-by-layer assembly of two polymers [32], for the design nonlinear optical materials [33] and liquid crystals [34], as anion receptors [35], for chiral resolution [36], for complex radicals to tune the magnetic interactions [37], and also for the controlled growth of thin films [38]. Nevertheless, the effectiveness of halogen bonds are not restricted to the use of haloperfluorocarbons; activation of the halogens can also be achieved by other means, such as sp hybridization of the carbon atom attached to the halogen or use of positively charged molecules, leading to novel materials with interesting properties.…”

Section: Halogens As Electrophilesmentioning

confidence: 99%

Supramolecular Interactions and Smart Materials: C–X…X′–M Halogen Bonds and Gas Sorption in Molecular Solids

Espallargas

2010

Ideas in Chemistry and Molecular Sciences

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The ultimate goal of a solid-state chemist is the rational design and synthesis of crystalline materials with the presence of specific and tunable chemical or physical properties, the so-called ''smart materials.'' Porosity, magnetism, chirality, conductivity, superconductivity, spin-transition, optical, and photophysical properties can be exploited for a wide variety of applications including gas storage, separations, electronic, catalysis, nonlinear optics, or drug delivery, and are therefore the objectives of intense research activity. The occurrence of these properties in crystalline materials 1) results from the combination of two aspects: (i) the molecular units (building blocks) that compose the crystal and (ii) the arrangement of these building blocks in the crystal. Controlling the former is relatively simple, and essentially it is only limited to the imagination and creativity of the researcher, since molecular chemistry has, over about two centuries, developed a wide range of very powerful procedures for creating even more sophisticated molecules from atoms linked by covalent bonds. On the contrary, organizing the molecules, or building blocks, in a predetermined manner is difficult to accomplish given that the structure of crystalline solids results from a delicate balance between all the intermolecular interactions present in the crystal, maximizing the attractive ones and minimizing the repulsive ones while, although not always, adopting the densest packing [1]. When a single strong interaction dominates in the system other weak intermolecular interactions normally play a secondary role in the crystal packing, providing support to the stronger interactions. In this situation, control over the molecular packing can successfully be achieved [2], although the presence of numerous weak interactions can in some cases overwhelm much stronger interactions as a result of their abundance [3]. Further difficulties can be encountered if the building blocks are 1) It should of course be acknowledged that crystalline products might not always represent the most desirable form of a material with respect to a given application.

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Self-assembly of nitroxide radicals via halogen bonding—directional NO⋯I interactions

Cited by 73 publications

References 24 publications

Exploring the halogen bond specific solvent effects in halogenated solvent systems by ESR probe

Exploring the halogen bond specific solvent effects in halogenated solvent systems by ESR probe

Organizing Radical Species in the Solid State with Halogen Bonding

Supramolecular Interactions and Smart Materials: C–X…X′–M Halogen Bonds and Gas Sorption in Molecular Solids

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