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NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals.
- Source :
-
Solid state nuclear magnetic resonance [Solid State Nucl Magn Reson] 2006 Feb; Vol. 29 (1-3), pp. 104-12. Date of Electronic Publication: 2005 Oct 05. - Publication Year :
- 2006
-
Abstract
- Oriented inclusion complexes of chloroform@cryptophane-A and chloroform@bis-cryptophane were prepared using a nematic thermotropic liquid crystal (ZLI 1132), and the alignment and magnetic resonance properties of these host-guest systems were studied via (13)C NMR of the labeled guests. Large (1)H-(13)C dipolar splittings for (13)CHCl(3) guests indicated significantly enhanced (approximately 2-fold) ordering for the trapped vs. free ligands under all conditions studied, with similar ordering observed for the two complexes-despite significant differences in size and motional freedom between the hosts. For each environment, variable-temperature studies permitted the sign and magnitude of the order parameter for chloroform's C-H bond to be independently determined from the (13)C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored (1)H-(13)C dipolar couplings. In both systems, the results are consistent with overall alignment of the complexes such that the cage principal axis lies roughly perpendicular to the LC director.
- Subjects :
- Binding Sites
Carbon Radioisotopes
Macromolecular Substances analysis
Macromolecular Substances chemistry
Materials Testing
Molecular Conformation
Phase Transition
Temperature
Chloroform analysis
Chloroform chemistry
Crystallography methods
Liquid Crystals analysis
Liquid Crystals chemistry
Magnetic Resonance Spectroscopy methods
Subjects
Details
- Language :
- English
- ISSN :
- 0926-2040
- Volume :
- 29
- Issue :
- 1-3
- Database :
- MEDLINE
- Journal :
- Solid state nuclear magnetic resonance
- Publication Type :
- Academic Journal
- Accession number :
- 16213691
- Full Text :
- https://doi.org/10.1016/j.ssnmr.2005.08.012