scholarly journals Stoichiomorphic Halogen-Bonded Cocrystals. A Case Study of 1,4-Diiodotetrafluorobenzene and 3-Nitropyridine

2021 ◽  
Author(s):  
Christelle Hajjar ◽  
Tamali Nag ◽  
Hashim Al Sayed ◽  
Jeffrey S. Ovens ◽  
David L. Bryce
Keyword(s):  
Halogen Bond ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Halogen Bonds ◽  
X Ray Diffraction ◽  
Pyridyl Nitrogen ◽  
Space Group ◽  
X Ray ◽  
Variable Stoichiometry

The concept of variable stoichiometry cocrystallization is explored in halogen-bonded systems. Three novel cocrystals of 1,4-diiodotetrafluorobenzene and 3-nitropyridine with molar ratios of 1:1, 2:1, and 1:2, respectively, are prepared by slow evaporation methods. Single-crystal X-ray diffraction analysis reveals key differences between each of the nominally similar cocrystals. For instance, the 1:1 cocrystal crystallizes in the P21/n space group and features a single chemically and crystallographically unique halogen bond between iodine and the pyridyl nitrogen. The 2:1 cocrystal crystallizes in the P1- space group and features a halogen bond between iodine and one of the nitro oxygens in addition to an iodine-nitrogen halogen bond. The 1:2 cocrystal crystallizes with a large unit cell (V = 9896 Å3) in the Cc space group and features 10 crystallographically distinct iodine-nitrogen halogen bonds. Powder X-ray diffraction experiments carried out on the 1:1 and 2:1 cocrystals confirm that gentle grinding does not alter the crystal forms. 1H → 13C and 19F → 13C cross-polarization magic angle spinning (CP/MAS) NMR experiments performed on powdered samples of the 1:1 and 2:1 cocrystals are used as spectral editing tools to select for either the halogen bond acceptor or donor, respectively. Carbon-13 chemical shifts in the cocrystals are shown to change only very subtly relative to pure solid 1,4-diiodotetrafluorobenzene, but the shift of the carbon directly bonded to iodine nevertheless increases, consistent with halogen bond formation (e.g., a shift of +1.6 ppm for the 2:1 cocrystal). This work contributes new examples to the field of variable stoichiometry cocrystal engineering with halogen bonds.

scholarly journals Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil

2017 ◽  
Vol 73 (3) ◽  
pp. 149-156 ◽  
Author(s):  
Ann-Christin Pöppler ◽  
Emily K. Corlett ◽  
Harriet Pearce ◽  
Mark P. Seymour ◽  
Matthew Reid ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Crystallography

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile–4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N—H...O and C—H...O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.

13C and 19F solid-state NMR and X-ray crystallographic study of halogen-bonded frameworks featuring nitrogen-containing heterocycles

2017 ◽  
Vol 73 (3) ◽  
pp. 157-167 ◽  
Author(s):  
Patrick M. J. Szell ◽  
Shaina A. Gabriel ◽  
Russell D. D. Gill ◽  
Shirley Y. H. Wan ◽  
Bulat Gabidullin ◽  
...  
Keyword(s):  
Solid State ◽  
Density Functional ◽  
Halogen Bond ◽  
Chemical Shifts ◽  
Halogen Bonding ◽  
Structural Features ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray ◽  
Donor And Acceptor

Halogen bonding is a noncovalent interaction between the electrophilic region of a halogen (σ-hole) and an electron donor. We report a crystallographic and structural analysis of halogen-bonded compounds by applying a combined X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) approach. Single-crystal XRD was first used to characterize the halogen-bonded cocrystals formed between two fluorinated halogen-bond donors (1,4-diiodotetrafluorobenzene and 1,3,5-trifluoro-2,4,6-triiodobenzene) and several nitrogen-containing heterocycles (acridine, 1,10-phenanthroline, 2,3,5,6-tetramethylpyrazine, and hexamethylenetetramine). New structures are reported for the following three cocrystals, all in the P21/c space group: acridine–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C6F3I3·C13H9N, 1,10-phenanthroline–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C6F3I3·C12H8N2, and 2,3,5,6-tetramethylpyrazine–1,3,5-trifluoro-2,4,6-triiodobenzene (1/1), C6F3I3·C8H12N2. 13C and 19F solid-state magic-angle spinning (MAS) NMR is shown to be a convenient method to characterize the structural features of the halogen-bond donor and acceptor, with chemical shifts attributable to cocrystal formation observed in the spectra of both nuclides. Cross polarization (CP) from 19F to 13C results in improved spectral sensitivity in characterizing the perfluorinated halogen-bond donor when compared to conventional 1H CP. Gauge-including projector-augmented wave density functional theory (GIPAW DFT) calculations of magnetic shielding constants, along with optimization of the XRD structures, provide a final set of structures in best agreement with the experimental 13C and 19F chemical shifts. Data for carbons bonded to iodine remain outliers due to well-known relativistic effects.

scholarly journals A systematic structural study of halogen bondingversushydrogen bonding within competitive supramolecular systems

IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 498-510 ◽  
Author(s):  
Christer B. Aakeröy ◽  
Christine L. Spartz ◽  
Sean Dembowski ◽  
Savannah Dwyre ◽  
John Desper
Keyword(s):  
Molecular Electrostatic Potential ◽  
Halogen Bond ◽  
Supramolecular System ◽  
Materials Chemistry ◽  
Halogen Bonds ◽  
X Ray Diffraction ◽  
Supramolecular Systems ◽  
X Ray ◽  
Practical Guidelines ◽  
Primary Interaction

As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

scholarly journals High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages

2015 ◽  
Vol 112 (46) ◽  
pp. 14156-14161 ◽  
Author(s):  
Seung Bin Baek ◽  
Dohyun Moon ◽  
Robert Graf ◽  
Woo Jong Cho ◽  
Sung Woo Park ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Temperatures ◽  
Direct Detection ◽  
Variable Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamic Motion

Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π–π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use.

scholarly journals Structure of nanocrystalline calcium silicate hydrates: insights from X-ray diffraction, synchrotron X-ray absorption and nuclear magnetic resonance

2016 ◽  
Vol 49 (3) ◽  
pp. 771-783 ◽  
Author(s):  
Sylvain Grangeon ◽  
Francis Claret ◽  
Cédric Roosz ◽  
Tsutomu Sato ◽  
Stéphane Gaboreau ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Calcium Silicate ◽  
Electron Probe ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Silicate Hydrates ◽  
Angle Spinning ◽  
X Ray Absorption

The structure of nanocrystalline calcium silicate hydrates (C–S–H) having Ca/Si ratios ranging between 0.57 ± 0.05 and 1.47 ± 0.04 was studied using an electron probe micro-analyser, powder X-ray diffraction,29Si magic angle spinning NMR, and Fourier-transform infrared and synchrotron X-ray absorption spectroscopies. All samples can be described as nanocrystalline and defective tobermorite. At low Ca/Si ratio, the Si chains are defect free and the SiQ3andQ2environments account, respectively, for up to 40.2 ± 1.5% and 55.6 ± 3.0% of the total Si, with part of theQ3Si being attributable to remnants of the synthesis reactant. As the Ca/Si ratio increases up to 0.87 ± 0.02, the SiQ3environment decreases down to 0 and is preferentially replaced by theQ2environment, which reaches 87.9 ± 2.0%. At higher ratios,Q2decreases down to 32.0 ± 7.6% for Ca/Si = 1.38 ± 0.03 and is replaced by theQ1environment, which peaks at 68.1 ± 3.8%. The combination of X-ray diffraction and NMR allowed capturing the depolymerization of Si chains as well as a two-step variation in the layer-to-layer distance. This latter first increases from ∼11.3 Å (for samples having a Ca/Si ratio <∼0.6) up to 12.25 Å at Ca/Si = 0.87 ± 0.02, probably as a result of a weaker layer-to-layer connectivity, and then decreases down to 11 Å when the Ca/Si ratio reaches 1.38 ± 0.03. The decrease in layer-to-layer distance results from the incorporation of interlayer Ca that may form a Ca(OH)2-like structure, nanocrystalline and intermixed with C–S–H layers, at high Ca/Si ratios.

Synthesis, X-ray diffraction and solid-state 31P magic angle spinning NMR study of ?-tricalcium orthophosphate

1996 ◽  
Vol 7 (7) ◽  
pp. 457-463 ◽  
Author(s):  
M. Bohner ◽  
J. LeMa�tre ◽  
A. P. LeGrand ◽  
J.-B. D'Espinose de la Caillerie ◽  
P. Belgrand
Keyword(s):  
Solid State ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nmr Study ◽  
Angle Spinning

Synthesis and characterization of montmorillonite-type phyllosilicates in a fluoride medium

Clay Minerals ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 177-190 ◽  
Author(s):  
M. Reinholdt ◽  
J. Miehé-Brendlé ◽  
L. Delmotte ◽  
R. Le Dred ◽  
M.-H. Tuilier
Keyword(s):  
Atomic Ratio ◽  
Magic Angle Spinning ◽  
Crystallization Time ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Angle Spinning ◽  
Mg Content ◽  
Fluoride Medium

AbstractThe fluorine route is thoroughly investigated for the hydrothermal synthesis of montmorillonite in the Na2O-MgO-Al2O3-SiO2-H2O system. Using the optimal conditions suggested by Reinholdt et al. (2001) for the crystallization of pure montmorillonites with the formula Na2x(Al2(1-x)Mg2x☐)Si4O10(OH)2, several parameters (x, Mg content, duration of crystallization, F/Si atomic ratio, pH, nature of counterbalance cation) are varied independently from their ideal values. The products are analysed by various techniques (X-ray diffraction, thermogravimetric analysis-differential thermal analysis, 29Si, 27Al and 19F magic angle spinning-nuclear magnetic resonance). It appears that a pure montmorillonite can only be obtained within a narrow x range (0.10 ≤ x ≤ 0.20). The presence of F in the starting hydrogel and the crystallization time also have significant effects on the purity of the final products. It is shown that a small amount of fluorine is needed for the crystallization of pure montmorillonite phyllosilicates.

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