NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals

Kathleen E. Chaffee; Malgorzata Marjanska; Boyd M. Goodson

doi:10.1016/j.ssnmr.2005.08.012

NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals

Kathleen E. Chaffee, Malgorzata Marjanska, Boyd M. Goodson

Center for Magnetic Resonance Research

Research output: Contribution to journal › Article › peer-review

6 Scopus citations

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 ¹³C NMR of the labeled guests. Large ¹H-¹³C dipolar splittings for ¹³CHCl₃ guests indicated significantly enhanced (∼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 ¹³C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored ¹H-¹³C 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.

Original language	English (US)
Pages (from-to)	104-112
Number of pages	9
Journal	Solid State Nuclear Magnetic Resonance
Volume	29
Issue number	1-3
DOIs	https://doi.org/10.1016/j.ssnmr.2005.08.012
State	Published - Feb 2006

Bibliographical note

Funding Information:
It is a pleasure to acknowledge our colleagues, Prof. Jean-Pierre Dutasta and Dr. Thierry Brotin (ENS Lyon), for their assistance, and for generously providing samples of cryptophane-A and bis -cryptophane. We thank Prof. Jukka Jokisaari (U. Oulu) for helpful correspondence concerning the use of the gradient method, and Prof. Cynthia Jameson (UIC) for helpful discussions. B.M.G. is a Cottrell Scholar of Research Corporation. Work at SIUC is supported by the National Science Foundation (CAREER Award, Grant No. CHE-03492550), the ACS Petroleum Research Fund, Research Corporation, the Oak Ridge Associated Universities (ORAU), and SIUC's Materials Technology Center and Office of Research Development and Administration (ORDA).

Keywords

Chloroform
Cryptophane-A
Dipolar couplings
Dynamic coupling
Gradient method
Inclusion complexes
Liquid crystals
NMR
ZLI 1132
bis-cryptophane

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@article{64c836ff7dea4cea9eace6bbb48d2700,

title = "NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals",

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 13C NMR of the labeled guests. Large 1H-13C dipolar splittings for 13CHCl3 guests indicated significantly enhanced (∼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 13C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored 1H-13C 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.",

keywords = "Chloroform, Cryptophane-A, Dipolar couplings, Dynamic coupling, Gradient method, Inclusion complexes, Liquid crystals, NMR, ZLI 1132, bis-cryptophane",

author = "Chaffee, {Kathleen E.} and Malgorzata Marjanska and Goodson, {Boyd M.}",

note = "Funding Information: It is a pleasure to acknowledge our colleagues, Prof. Jean-Pierre Dutasta and Dr. Thierry Brotin (ENS Lyon), for their assistance, and for generously providing samples of cryptophane-A and bis -cryptophane. We thank Prof. Jukka Jokisaari (U. Oulu) for helpful correspondence concerning the use of the gradient method, and Prof. Cynthia Jameson (UIC) for helpful discussions. B.M.G. is a Cottrell Scholar of Research Corporation. Work at SIUC is supported by the National Science Foundation (CAREER Award, Grant No. CHE-03492550), the ACS Petroleum Research Fund, Research Corporation, the Oak Ridge Associated Universities (ORAU), and SIUC's Materials Technology Center and Office of Research Development and Administration (ORDA). ",

year = "2006",

month = feb,

doi = "10.1016/j.ssnmr.2005.08.012",

language = "English (US)",

volume = "29",

pages = "104--112",

journal = "Solid State Nuclear Magnetic Resonance",

issn = "0926-2040",

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T1 - NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals

AU - Chaffee, Kathleen E.

AU - Marjanska, Malgorzata

AU - Goodson, Boyd M.

N1 - Funding Information: It is a pleasure to acknowledge our colleagues, Prof. Jean-Pierre Dutasta and Dr. Thierry Brotin (ENS Lyon), for their assistance, and for generously providing samples of cryptophane-A and bis -cryptophane. We thank Prof. Jukka Jokisaari (U. Oulu) for helpful correspondence concerning the use of the gradient method, and Prof. Cynthia Jameson (UIC) for helpful discussions. B.M.G. is a Cottrell Scholar of Research Corporation. Work at SIUC is supported by the National Science Foundation (CAREER Award, Grant No. CHE-03492550), the ACS Petroleum Research Fund, Research Corporation, the Oak Ridge Associated Universities (ORAU), and SIUC's Materials Technology Center and Office of Research Development and Administration (ORDA).

PY - 2006/2

Y1 - 2006/2

N2 - 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 13C NMR of the labeled guests. Large 1H-13C dipolar splittings for 13CHCl3 guests indicated significantly enhanced (∼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 13C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored 1H-13C 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.

AB - 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 13C NMR of the labeled guests. Large 1H-13C dipolar splittings for 13CHCl3 guests indicated significantly enhanced (∼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 13C chemical shift anisotropy (CSA) shifts (via the gradient method) and the restored 1H-13C 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.

KW - Chloroform

KW - Cryptophane-A

KW - Dipolar couplings

KW - Dynamic coupling

KW - Gradient method

KW - Inclusion complexes

KW - Liquid crystals

KW - NMR

KW - ZLI 1132

KW - bis-cryptophane

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U2 - 10.1016/j.ssnmr.2005.08.012

DO - 10.1016/j.ssnmr.2005.08.012

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C2 - 16213691

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VL - 29

SP - 104

EP - 112

JO - Solid State Nuclear Magnetic Resonance

JF - Solid State Nuclear Magnetic Resonance

SN - 0926-2040

IS - 1-3

ER -

NMR studies of chloroform@cryptophane-A and chloroform@bis-cryptophane inclusion complexes oriented in thermotropic liquid crystals

Abstract

Bibliographical note

Keywords

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