NMR investigation of guest–host complex between chloroform and cryptophane C

Takács, Zoltán; Šoltésová, Mária; Kotsyubynskyy, Dmytro; Kowalewski, Józef; Lang, Jan; Dutasta, Jean‐Pierre

doi:10.1002/mrc.2637

Cited by 7 publications

(14 citation statements)

References 40 publications

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“…For interstitial chloroform, we observe an essentially fully averaged dipolar interaction. These observations accord overall with earlier reports on chloroform encaged in a larger host, cryptophane‐E (with three linkers with n = 3), | b C‐H | = 19.0 kHz, as well as with relaxation measurements in solution . For the ‘interstitial’ (here perhaps adsorbed) site, the earlier study displayed a sizable splitting not observed here.…”

Section: Resultssupporting

confidence: 92%

“…linkers with n = 3), |b C-H | = 19.0 kHz, [14] as well as with relaxation measurements in solution. [31][32][33][34] For the 'interstitial' (here perhaps adsorbed) site, the earlier study [14] displayed a sizable splitting not observed here. Indeed, the presence of the butoxy chains in the cryptophane makes the system to crystallize differently, thereby affecting the motions of the chloroform molecules.…”

Section: Dipolar Interactions (Right Panel)contrasting

confidence: 50%

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Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction

Steiner

Mathew

Zimmermann

et al. 2015

Magnetic Reson in Chemistry

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Host‐guest complexes between cryptophane‐A analogue with butoxy groups (cryptophane‐But) and chloromethanes (chloroform, dichloromethane) were investigated in the solid state by means of magic‐angle spinning 13C NMR spectroscopy. The separated local fields method with 13C‐1H dipolar recoupling was used to determine the residual dipolar coupling for the guest molecules encaged in the host cavity. In the case of chloroform guest, the residual dipolar interaction was estimated to be about 19 kHz, consistent with a strongly restricted mobility of the guest in the cavity, while no residual interaction was observed for encaged dichloromethane. In order to rationalize this unexpected result, we performed single crystal X‐ray diffraction studies, which confirmed that both guest molecules indeed were present inside the cryptophane cavity, with a certain level of disorder. To improve the insight in the dynamics, we performed a 13C NMR spin‐lattice relaxation study for the dichloromethane guest in solution. The system was characterized by chemical exchange, which was slow on the chemical shift time scale but fast with respect to the relaxation rates. Despite these disadvantageous conditions, we demonstrated that the data could be analyzed and that the results were consistent with an isotropic reorientation of dichloromethane within the cryptophane cavity. Copyright © 2015 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.

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Section: Resultssupporting

confidence: 92%

Section: Dipolar Interactions (Right Panel)contrasting

confidence: 50%

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction

Steiner

Mathew

Zimmermann

et al. 2015

Magnetic Reson in Chemistry

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“…in the 1980s. We have reported over the last decade a series of nuclear magnetic resonance (NMR) studies of cryptophane complexes with chloroform and dichloromethane . Among other physicochemical studies of cryptophane complexes of relevance for the present work, we wish to mention the vibrational dichroism studies combined with quantum chemical calculations of the DFT type .…”

Section: Introductionmentioning

confidence: 99%

“…Both of these systems were recently studied by our laboratories. For cryptophane‐C, we reported a 1 H NMR study of the complex with chloroform, including measurements of cross relaxation between bound chloroform and host protons, where the most important finding was that one of the orientations of the guest molecule inside the host cavity was somewhat more probable than the other one . Cryptophane‐D was studied in complexes with both chloroform and dichloromethane, using both the 1 H and 13 C NMR spectroscopy, along with quantum chemical (DFT) calculations .…”

Section: Introductionmentioning

confidence: 99%

Host–guest complexes between cryptophane‐C and chloromethanes revisited

Takács

Šoltésová

Kowalewski

et al. 2012

Magnetic Reson in Chemistry

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Cryptophane-C is composed of two nonequivalent cyclotribenzylene caps, one of which contains methoxy group substituents on the phenyl rings. The two caps are connected by three OCH2CH2O linkers in an anti arrangement. Host–guest complexes of cryptophane-C with dichloromethane and chloroform in solution were investigated in detail by nuclear magnetic resonance techniques and density functional theory (DFT) calculations. Variable temperature proton and carbon-13 spectra show a variety of dynamic processes, such as guest exchange and host conformational transitions. The guest exchange was studied quantitatively by exchange spectroscopy measurements or by line-shape analysis. The conformational preferences of the guest-containing host were interpreted through cross-relaxation measurements, providing evidence of the gauche+2 and gauche−2 conformations of the linkers. In addition, the mobility of the chloroform guest inside the cavity was studied by carbon-13 relaxation experiments. Combining different types of evidence led to a detailed picture of molecular recognition, interpreted in terms of conformational selection. Copyright © 2012 John Wiley & Sons, Ltd.

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“…We also implemented the DFT B3PW91/6‐31G** method, first described by Forsyth & Sebag . This method has been used in relatively complex organic molecules with great success …”

Section: Resultsmentioning

confidence: 81%

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

Torres

Ishikawa

Prieto

2012

J of Physical Organic Chem

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The organoaluminum mediated epoxide ring opening of epoxy alcohols is a key step in the oxirane-based approach for polypropionate synthesis. However, this reaction has shown unanticipated regioselectivities when applied to 2-methyl-3,4-epoxy alcohols. In order to gain mechanistic insight into the factors controlling the epoxide ring opening process, diastereomeric 2-methyl-3,4-epoxy alcohols were reacted with triethylaluminum in order to identify the aluminum complexes formed by these systems. Different epoxide-aluminum complexes were calculated using ab initio HF/[13s7p/11s5p] and B3PW91/6-31G** gauge-including atomic orbital (GIAO) methods and compared to the experimental NMR data. The calculated and experimental data correlates with the aluminum dimer complex (TIPSOCH 2 CH(OAlEt 2 )CH(CH) 3 CHCH(O)(AlEt 3 )) 2 (VIII) for the systems favoring the nucleophilic attack at the external C4 epoxide carbon, while an unusual trialuminum species TIPSOCH 2 CH(OAlEt 2 )CH(CH) 3 CHCH(O)(AlEt 3 ) 2 (X) is consistent with the systems favoring the internal C3 attack. The 27 Al NMR data established the tetracoordinated nature of the aluminum metal in all alkoxy aluminum intermediates, while the 13 C NMR data provided insight into the aluminum-oxygen coordination. The formation of the complexes was dictated by the stereochemical disposition of the substituents. These complexes are different from the generally accepted bidentate intermediates proposed for 2,3-epoxy alcohols and simpler 3,4-epoxy alcohols.

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NMR investigation of guest–host complex between chloroform and cryptophane C

Cited by 7 publications

References 40 publications

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction

Host–guest complexes between cryptophane‐C and chloromethanes revisited

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

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NMR investigation of guest–host complex between chloroform and cryptophane C

Cited by 7 publications

References 40 publications

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using 13C NMR in the solid state and solution along with single crystal X‐ray diffraction

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using 13C NMR in the solid state and solution along with single crystal X‐ray diffraction

Host–guest complexes between cryptophane‐C and chloromethanes revisited

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

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Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction

Investigation of chloromethane complexes of cryptophane‐A analogue with butoxy groups using ¹³C NMR in the solid state and solution along with single crystal X‐ray diffraction