Variable-Temperature X-ray Crystallographic and DFT Computational Study of the NH···O/N···HO Tautomeric Competition in 1-(Arylazo)-2-naphthols. Outline of a Transiton-State Hydrogen-Bond Theory

2005 ◽  
Vol 127 (13) ◽  
pp. 4943-4953 ◽  
Author(s):  
Paola Gilli ◽  
Valerio Bertolasi ◽  
Loretta Pretto ◽  
Liudmil Antonov ◽  
Gastone Gilli
Keyword(s):  
Hydrogen Bond ◽  
Computational Study ◽  
Variable Temperature ◽  
X Ray ◽  
Bond Theory

A Solid-State NMR, X-ray Diffraction, and ab Initio Computational Study of Hydrogen-Bond Structure and Dynamics of Pyrazole-4-Carboxylic Acid Chains

2001 ◽  
Vol 123 (32) ◽  
pp. 7898-7906 ◽  
Author(s):  
Concepción Foces-Foces ◽  
Aurea Echevarría ◽  
Nadine Jagerovic ◽  
Ibon Alkorta ◽  
José Elguero ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Carboxylic Acid ◽  
Ab Initio ◽  
Solid State Nmr ◽  
Computational Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Dynamics

Structural characterization of p-benzosemiquinone radical in a solid state: the radical stabilization by a low-barrier hydrogen bond

2006 ◽  
Vol 62 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Mario Roboz
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Variable Temperature ◽  
Organic Radical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Packings ◽  
Dynamical Disorder ◽  
Benzenoid Ring

Semiquinone (p-benzosemiquinone), a transient organic radical, was detected in the solid state by EPR spectroscopy revealing four symmetrically equivalent protons. A variable-temperature X-ray diffraction analysis (293 and 90 K) and EPR data support a dynamical disorder of the proton. A low-barrier O—H···O hydrogen bond stabilizes the radical. The C—O bond length is 1.297 (4) Å, corresponding to a bond order of ca 1.5. The geometry of the radical implies an electron delocalization throughout the benzenoid ring. Two polymorphs of semiquinone, monoclinic and triclinic, were observed and their structures determined. Their crystal packings were compared with those of quinhydrone polymorphs.

Variable temperature and high-pressure crystal chemistry of perovskite formamidinium lead iodide: a single crystal X-ray diffraction and computational study

2017 ◽  
Vol 53 (54) ◽  
pp. 7537-7540 ◽  
Author(s):  
Shijing Sun ◽  
Zeyu Deng ◽  
Yue Wu ◽  
Fengxia Wei ◽  
Furkan Halis Isikgor ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Low Temperature ◽  
Tetragonal Phase ◽  
Computational Study ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
X Ray ◽  
Tetragonal Phase Transition

Single crystals of [(NH2)2CH]PbI3 undergo a cubic-to-tetragonal phase transition at low temperature and high pressure.

scholarly journals Single crystal synchrotron X-ray diffraction for imaging hydrogen bond evolution

2014 ◽  
Vol 70 (a1) ◽  
pp. C559-C559
Author(s):  
Lucy Saunders ◽  
Harriott Nowell ◽  
Lynne Thomas ◽  
Paul Raithby ◽  
Chick Wilson
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Atom Position ◽  
Proton Disorder ◽  
Atom Position

Hydrogen bonding is a valuable intermolecular interaction in "engineering" solid-state materials. This is because of the directionality and relative strength (1) of these bonds. Hydrogen bonds enable charge and energy transfer, via H-bond evolution, in a range of biological and chemical systems (2). Recent work has demonstrated that single crystal X-ray diffraction can be used to image the evolution of hydrogen bonds, including variable temperature proton migration and proton disorder processes. In particular, in a recent study of the temperature dependent proton disorder in hydrogen bonded 3,5-dinitrobenzoic acid (3,5-DNBA) dimers, the proton disorder deduced from data collected on an X-ray laboratory source is in agreement with that found from neutron data (3). This work focuses on variable temperature single crystal synchrotron X-ray diffraction, for the imaging of evolving hydrogen bonds. The development of appropriate methodology is important here, particularly as previous studies have involved laboratory X-ray sources only. Results will be presented from variable temperature data collections on I19, at the Diamond Light Source, and on beamline 11.3.1, at the Advanced Light Source (ALS), on systems such as 3,5-DNBA and co-crystals of benzimidazole, both exhibiting proton disorder across hydrogen bonding interactions. Synchrotron X-ray diffraction measurements have also been used to follow the change in the position of a proton within an intramolecular [N–H···N]+ hydrogen bond across a range of proton-sponge molecular complexes. Importantly, it has been possible to visualise the evolving hydrogen atom position in Fourier difference electron density maps generated from the synchrotron data. In particular, for the 35-DNBA study, the clearest picture of the evolving hydrogen atom position is observed in those generated from data collected at the ALS; even clearer than that observed in X-ray laboratory and neutron measurements on the same system.

Variable-temperature X-ray diffraction study of structural parameters of NH---S hydrogen bonds in triethylammonium and pyridinium silanethiolates

2016 ◽  
Vol 72 (5) ◽  
pp. 763-770 ◽  
Author(s):  
Agnieszka Mielcarek ◽  
Marek Daszkiewicz ◽  
Katarzyna Kazimierczuk ◽  
Anna Ciborska ◽  
Anna Dołęga
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Potential Energy ◽  
Variable Temperature ◽  
Structural Parameters ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Range ◽  
Ft Ir ◽  
Thermochemical Parameters

Two hydrogen-bonded, well defined compounds were synthesized from tris(2,6-diisopropyl)phenoxysilanethiol (TDST) and triethylamine (TDST–TEA) or pyridine (TDST–py). The crystalline compounds were characterized in the solid state by variable-temperature X-ray diffraction measurements and ATR FT–IR spectroscopy. The toluene solutions of TDST–TEA and TDST–py were studied by NMR spectroscopy. The total hydrogen-bond energies and FT–IR spectra were calculated with the use of BLYP-D/TZP and B3LYP/6-31G(d,p)/GD3BJ methods. Thermochemical parameters and potential energy scans were calculated at the B3LYP/6-31G(d,p)/GD3BJ level. All results point to the higher energy of bonding in TDST–TEA both in the solid state and in solution. At the same time the potential energy scan reveals a very broad double-well hydrogen bond in TDST-py, indicating good stabilization of the system for a wide range ofD—H...Adistances.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

Crystal structure of ziprasidone hydrochloride monohydrate, C21H22Cl2N4OS(H2O)

2015 ◽  
Vol 30 (3) ◽  
pp. 192-198
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Powder Diffraction ◽  
Density Functional ◽  
Minimum Energy ◽  
Strong Hydrogen Bond ◽  
Powder Diffraction File ◽  
X Ray ◽  
Hydrochloride Monohydrate ◽  
Positively Charged

The crystal structure of ziprasidone hydrochloride monohydrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Ziprasidone hydrochloride monohydrate crystallizes in space group P-1 (#2) with a = 7.250 10(3), b = 10.986 66(8), c = 14.071 87(14) Å, α = 83.4310(4), β = 80.5931(6), γ = 87.1437(6)°, V = 1098.00(1) Å3, and Z = 2. The ziprasidone conformation in the solid state is very close to the minimum energy conformation. The positively-charged nitrogen in the ziprasidone makes a strong hydrogen bond with the chloride anion. The water molecule makes two weaker bonds to the chloride, and acts as an acceptor in an N–H⋯O hydrogen bond. The powder pattern is included in the Powder Diffraction File™ as entry 00-064-1492.

scholarly journals Powder study of 3-azabicyclo[3.3.1]nonane-2,4-dione form 2

2006 ◽  
Vol 62 (7) ◽  
pp. o3046-o3048 ◽  
Author(s):  
Ashley T Hulme ◽  
Philippe Fernandes ◽  
Alastair Florence ◽  
Andrea Johnston ◽  
Kenneth Shankland
Keyword(s):  
Crystal Structure ◽  
Simulated Annealing ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Title Compound ◽  
Variable Temperature ◽  
Polycrystalline Sample ◽  
Asymmetric Unit ◽  
X Ray ◽  
Compound C

A polycrystalline sample of a new polymorph of the title compound, C8H11NO2, was produced during a variable-temperature X-ray powder diffraction study. The crystal structure was solved at 1.67 Å resolution by simulated annealing from laboratory powder data collected at 250 K. Subsequent Rietveld refinement yielded an R wp of 0.070 to 1.54 Å resolution. The structure contains two molecules in the asymmetric unit, which form a C 2 2(8) chain motif via N—H...O hydrogen bonds.

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