Electrostatic Potential Differences and Halogen-Bond Selectivity

Aakeröy, Christer B.; Wijethunga, Tharanga K.; Desper, John; Đaković, Marijana

doi:10.1021/acs.cgd.5b01770

Cited by 72 publications

(58 citation statements)

References 76 publications

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“…Similar calculations done by Aakeröy and co-workers have shown that p-DITFB isomer has the highest surface electrostatic potential when compared to its other two isomers. 15 Since halogen bonds are largely electrostatic in nature, the strength of this interaction is expected to be greatest between 1 and p-DITFB. 16 We turned to solid-state FT-IR spectroscopy to probe the hydrogen and halogen bonding interactions in these systems further.…”

Section: Resultsmentioning

confidence: 99%

Pillars of assembled pyridyl bis-urea macrocycles: a robust synthon to organize diiodotetrafluorobenzenes

et al. 2017

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Columnar assembled pyridyl bis-urea macrocycles 1 provide a strong 1D supramolecular synthon to construct hierarchical assemblies. These 1D pillars contain ditopic symmetrical acceptors in the form of basic oxygen lone pairs. Herein, we probe this synthon with a series of activated halogen bond donors, the regio-isomers of diiodotetrafluorobenzenes, which vary the relative orientation of the halogen bond formers. Irrespective of the initial stoichiometry, each donor only formed one type of co-crystal with 1. In each case, similar strong pillars of assembled 1 were observed that organize the donors through the CO⋯I interaction, which were significantly shorter than the sum of the van der Waals radii of the atoms involved and among the shortest reported for neutral organic molecules. X-ray photoelectron spectroscopy characteristic core level shifts strongly indicated the formation of halogen bonding interactions.These studies suggest that this synthon can utilize both hydrogen and halogen bonding orthogonally to build complex structures.

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Section: Resultsmentioning

confidence: 99%

Pillars of assembled pyridyl bis-urea macrocycles: a robust synthon to organize diiodotetrafluorobenzenes

et al. 2017

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“…Iodoethynylnitrobenzenes, bromoethynylnitrobenzenes and chloroethynylnitrobenzenes were synthesized according to literature procedures. 37,38 A8 -A10 and A13 -A15 were synthesized following previously reported procedures, 39 as were A7 40 and A12. 41 Infrared spectra were recorded with a Nicolet 380 FT-IR.…”

Section: Methodsmentioning

confidence: 99%

Crystal Engineering with Iodoethynylnitrobenzenes: A Group of Highly Effective Halogen-Bond Donors

Aakeröy

Wijethunga

Desper

et al. 2015

Crystal Growth & Design

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The benefits of employing a 'double activation' strategy for promoting effective practical cocrystal synthesis through halogen bonding was explored in a systematic supramolecular synthetic study of iodoethynylnitrobenzenes, where the positive electrostatic potential on the iodine atom was enhanced through a combination of an sp-hybridized carbon atom and one or more electronwithdrawing nitro groups. Three model compounds, 1-(iodoethynyl)-4-nitrobenzene (4N-I), 1-(iodoethynyl)-3-nitrobenzene (3N-I) and 1-(iodoethynyl)-3,5-dinitrobenzene (3,5DN-I) were synthesized and characterized, and calculated molecular electrostatic surface potential values on the halogen-bond donor site were about 20-40 kJ/mol higher than those observed for previously well-established halogen-bond donors. The ability of these molecules to drive co-crystal formation was evaluated through a total of 45 co-crystallization experiments with 15 different acceptor molecules. IR spectroscopic data for the resulting products showed that each reaction in the formation of a co-crystal driven by either C-I···N or C-I···O halogen bonds. The analogues bromo-compounds displayed a 60% success rate whereas the chloro-analogues did not yield any co-crystals, emphasizing the importance of the magnitude of the electrostatic aspects of halogen bonding for practical supramolecular synthesis. Ten new crystal structures are presented and the outcome (in terms of stoichiometry and connectivity) is largely predictable. A comparison of I···acceptor distances found in these structures with relevant data from the CSD shows that iodoethynylnitrobenzenes consistently give rise to a larger reduction of combined van der Waals radii (for C-X···acceptor) than do other well-known halogen bond donor moieties.

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“…The bond strength is shown to be energetically competitive and sometimes stronger than the hydrogen bond, which increases with the increase size of the halogen donor atom, that is, F < Cl < Br < I. With superior strength and directionality, the halogen bond would also promote the construction of robust and reproducible cocrystal structures . Extensive functional groups could engage in the recognition and coassembly processes, wherein plenty of electron‐rich species have been explored as halogen‐bond acceptors, i.e., π systems, N‐, S‐, or Se‐based acceptors .…”

Section: Rational Design and Controllable Preparation Of Organic Cocrmentioning

confidence: 99%

Cocrystal Engineering: A Collaborative Strategy toward Functional Materials

et al. 2019

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materials, [9][10][11][12] which are crystalline singlephase materials composed of two or more different compounds generally in a stoichiometric ratio, [13] providing a platform for unveiling the structure-property relationships at a molecular level. [14] The building blocks are assembled via noncovalent interactions, offering the opportunity to achieve noncovalent synthesis of functional molecules. [15] Compared with the traditional covalent synthesis, cocrystal engineering offers numerous advantages, including: 1) avoiding complicated synthesis procedures, and cocrystal assemblies have been successfully fabricated by the vapor methods and solution-processing methods in a facile and low-cost way; 2) manipulating intermolecular interactions through selecting suitable conformers from a plentiful supply of raw materials, resulting in tunable structures, morphologies, and sizes; 3) achieving rare and multifunctional properties through a collaborative strategy in distinct constituent units, which are difficult to realize for individual components. [16][17][18] Cocrystal engineering began to draw much attention since the exploration of the metal conductive tetrathiafulvalene-7,7,8,8-tetracyanoquinodimethane (TTF-TCNQ) cocrystals in 1973. [19] The peculiar conductivity in organic materials makes it possible for cocrystals to serve as organic electrodes, which can effectively lower the contact resistance and further improve device performance. Encouraged by this, cocrystals can serve as a breakthrough and provide an opportunity to discover novel physicochemical properties, which are far beyond the performance of single materials. In this respect, dielectric response [20] and nonlinear optics [21,22] are also realized through rational design of each component, which is absent in their constitute components. Even more, the bottom-up supramolecular assembly provides the opportunity to equip them with the individual properties of the donor or acceptor to create multifunctional materials. [23] Typically, ambipolar charge transport can be generated by coassembling p-type semiconductors and n-type ones, and the charge-carrier mobility is now up to 1.57 cm 2 V −1 s −1 for holes and 0.47 cm 2 V −1 s −1 for electrons. [24] To date, these exciting results accelerate the investigations of organic functional cocrystals, such as room-temperature ferroelectricity, [25][26][27] optical waveguide properties, [28,29] pure organic room-temperature phosphorescent properties, [30][31][32] stimulusresponse (e.g., mechanical stress, [33,34] heat, [35,36] or solvent [37] ) characteristics, photovoltaics, [38] and near-infrared photothermal (PT) conversion and imaging, [39] etc.Cocrystal engineering with a noncovalent assembly feature by simple constituent units has inspired great interest and has emerged as an efficient and versatile route to construct functional materials, especially for the fabrication of novel and multifunctional materials, due to the collaborative strategy in the distinct constituent units. Meanwhile, the precise crystal a...

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Electrostatic Potential Differences and Halogen-Bond Selectivity

Cited by 72 publications

References 76 publications

Pillars of assembled pyridyl bis-urea macrocycles: a robust synthon to organize diiodotetrafluorobenzenes

Pillars of assembled pyridyl bis-urea macrocycles: a robust synthon to organize diiodotetrafluorobenzenes

Crystal Engineering with Iodoethynylnitrobenzenes: A Group of Highly Effective Halogen-Bond Donors

Cocrystal Engineering: A Collaborative Strategy toward Functional Materials

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