Short, strong halogen bonding in co-crystals of pyridyl bis-urea macrocycles and iodoperfluorocarbons

Geer, Michael F.; Mazzuca, James W.; Smith, Mark D.; Shimizu, Linda S.

doi:10.1039/c3ce41413b

Cited by 8 publications

(8 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is more contracted than previously reported C-I···O halogen bonds with A10, 53,54,55 A15 56 and electron rich carbonyl compounds. 57 A much shorter C-I···O halogen bond is reported with t-BuOK which is presumably due to high ionic character of the oxygen atom. 58 The increased reductions in combined van der Waals radii and short C- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 aakeroy@ksu.edu.…”

Section: Resultsmentioning

confidence: 96%

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

Aakeröy

Wijethunga

Desper

et al. 2015

Crystal Growth & Design

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 96%

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

Aakeröy

Wijethunga

Desper

et al. 2015

Crystal Growth & Design

View full text Add to dashboard Cite

show abstract

“…Prior work focused on slow evaporation methods, which were unsuccessful with 1. 8 Water was vapour diffused into these solutions. X-ray quality crystals of 1·(o-DITFB) 2 , 1 ·(m-DITFB) 2 ·DMSO and 1·p-DITFB were obtained from multiple solutions; however, despite the different ratios each donor only formed one type of co-crystal with 1.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, a protected derivative of 1 cocrystallized with pentafluoroiodobenzene, exhibiting unusually short I⋯O distances (2.719(2) Å, 78% of the sum of vdw radii); however, this compound lacked the urea hydrogen bonding sites and could not assemble into columns. 8 In this manuscript, we investigate strong pillars of self-assembled 1 as a co-crystal former for ditopic halogen bond donors (Fig. 1c) to test the robustness of this synthon and probe its ability to form co-crystals with three regioisomers of diiodotetrafluorobenzene:…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…The alternative approach is to increase the electron density of the halogen bond acceptor by the introduction of electron donating substituents . A stronger halogen bond is often presumed to be reflected by a shorter distance between the halogen bond donor and the acceptor. ,, Computational studies revealed that the Hammett substituent constants of pyridine-based halogen bond acceptors correlate to the strength of their halogen bond. , Strategic tuning of halogen bond strength is expected to facilitate the development of halogen transfer reagents and of supramolecular systems, , for example.…”

Section: Resultsmentioning

confidence: 99%

Substituent Effects on the [N–I–N]⁺ Halogen Bond

et al. 2016

View full text Add to dashboard Cite

We have investigated the influence of electron density on the three-center [N–I–N]+ halogen bond. A series of [bis(pyridine)iodine]+ and [1,2-bis((pyridine-2-ylethynyl)benzene)iodine]+ BF4– complexes substituted with electron withdrawing and donating functionalities in the para-position of their pyridine nitrogen were synthesized and studied by spectroscopic and computational methods. The systematic change of electron density of the pyridine nitrogens upon alteration of the para-substituent (NO2, CF3, H, F, Me, OMe, NMe2) was confirmed by 15N NMR and by computation of the natural atomic population and the π electron population of the nitrogen atoms. Formation of the [N–I–N]+ halogen bond resulted in >100 ppm 15N NMR coordination shifts. Substituent effects on the 15N NMR chemical shift are governed by the π population rather than the total electron population at the nitrogens. Isotopic perturbation of equilibrium NMR studies along with computation on the DFT level indicate that all studied systems possess static, symmetric [N–I–N]+ halogen bonds, independent of their electron density. This was further confirmed by single crystal X-ray diffraction data of 4-substituted [bis(pyridine)iodine]+ complexes. An increased electron density of the halogen bond acceptor stabilizes the [N···I···N]+ bond, whereas electron deficiency reduces the stability of the complexes, as demonstrated by UV-kinetics and computation. In contrast, the N–I bond length is virtually unaffected by changes of the electron density. The understanding of electronic effects on the [N–X–N]+ halogen bond is expected to provide a useful handle for the modulation of the reactivity of [bis(pyridine)halogen]+-type synthetic reagents.

show abstract

Short, strong halogen bonding in co-crystals of pyridyl bis-urea macrocycles and iodoperfluorocarbons

Cited by 8 publications

References 33 publications

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

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

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

Substituent Effects on the [N–I–N]⁺ Halogen Bond

Contact Info

Product

Resources

About

Short, strong halogen bonding in co-crystals of pyridyl bis-urea macrocycles and iodoperfluorocarbons

Cited by 8 publications

References 33 publications

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

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

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

Substituent Effects on the [N–I–N]+ Halogen Bond

Contact Info

Product

Resources

About

Substituent Effects on the [N–I–N]⁺ Halogen Bond