Symmetry breaking in the solid state of 9,10-anthracene amino acid conjugates as seen by X-ray diffraction and NMR spectroscopy

The preparation and characterization of tris-pyridyl bispidine (3,7-diazabicyclo[3.3.1]nonane) derivatives with benzimidazole and imidazole donor groups at the N-3 position of the bispidine skeleton and their copper(II) complexes are reported. The impact of the hetaryl substituents on the configurational isomerism of piperidones and their corresponding bispidones has been studied by NMR spectroscopy, revealing the exclusive appearance in the enol form for the piperidones in solution and the trans-configuration regarding the two pyridyl substituents, as well as the sole formation of the unsymmetric exo-endo isomers for the corresponding bispidones. Thus, the bispidones are preorganized ligands for building pentacoordinated complexes, confirmed by the preparation and characterization of the corresponding Cu(II) complexes. Of the di-pyridyl piperidones with benzimidazole and imidazole substituents, and of the Cu(II) complex of the benzimidazole-containing bispidone, crystals have become available for the analysis by X-ray diffraction, showing that the piperidones form the enol tautomers also in the solid state.

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Investigation of the disorder of dibromo- and dichloromethane in their tri-ortho-thymotide clathrates using X-ray diffraction and solid-state 2H NMR spectroscopy

Canadian Journal of Chemistry ◽

10.1139/v10-178 ◽

2011 ◽

Vol 89 (7) ◽

pp. 854-862

Author(s):

Glenn A. Facey ◽

Ilia Korobkov

Keyword(s):

Solid State ◽

Nmr Spectroscopy ◽

Guest Molecule ◽

Type B ◽

X Ray Diffraction ◽

Guest Molecules ◽

X Ray ◽

Twofold Axis ◽

H Nmr ◽

Heavy Atoms

The tri-ortho-thymotide (TOT) clathrates of dibromo- and dichloromethane were characterized by single crystal X-ray diffraction at 200 K and solid-state 2H NMR spectroscopy as a function of temperature. The host structure was found to be typical of other cage-type TOT clathrates. The X-ray results showed a substantial amount of disorder among the guest molecules. In both clathrates, multiple guest molecule positions could be modeled. The heavy atoms of all the guest molecule positions lie approximately in the same plane, with some out-of-plane distortion. The guest molecules were of two different types in positions symmetric about the crystallographic twofold rotation axis: type A guests, with carbon atoms well removed from the crystallographic twofold axis, and type B guests, with carbon atoms very close to the twofold axis. The 2H NMR spectra for the guests confirmed that the disorder was dynamic. The experimental results could be accounted for by the presence of three simultaneous types of molecular motion, all fast with respect to the 2H quadrupolar interaction: (i) twofold molecular flips about the molecular C2 symmetry axis, (ii) exchange between the type A and type B sites in a single plane, and (iii) a two-site libration of the plane containing the heavy atoms of the A and B guest sites with a temperature-dependent amplitude.

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Sila-Pharmaka, 26. Mitt. [1]. Darstellung und Eigenschaften potentiell curarewirksamer Silicium-Verbindungen, III / Sila-Pharmaca, 26th Communication [1]. Preparation and Properties of Silicon Compounds with Potential Curare-Like Activity, III

Zeitschrift für Naturforschung B ◽

10.1515/znb-1982-1119 ◽

1982 ◽

Vol 37 (11) ◽

pp. 1461-1471 ◽

Cited By ~ 4

Author(s):

Reinhold Tacke ◽

Haryanto Linoh ◽

Moayad T. Attar-Bashi ◽

William S. Sheldrick ◽

Ludger Ernst ◽

...

Keyword(s):

Solid State ◽

Nmr Spectroscopy ◽

Neuromuscular Blocking ◽

Neuromuscular Blocking Agents ◽

X Ray Diffraction ◽

Silicon Compounds ◽

X Ray ◽

Structure Activity Relationships ◽

H Nmr ◽

Structure Activity

The potentially curare-like silicon compounds 8a-8f wore synthesized and investigated with respect to their structure-activity relationships. The conformations of the compounds in the solid state and in solution were studied by X-ray diffraction analysis (8a-8e) and 1H NMR spectroscopy (8a-8f), respectively. The muscle relaxing properties of 8a-8f were investigated on the mouse. The observed structure-activity relationships are not in accordance with the classical “14 Å model” for neuromuscular blocking agents.

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