Application of HRMAS <sup>1</sup>H NMR Spectroscopy To Investigate Interactions between Ligands and Synthetic Receptors

Händel, Heidi; Gesele, Elke; Gottschall, Klaus; Albert, Klaus

doi:10.1002/anie.200390133

Cited by 40 publications

(36 citation statements)

References 23 publications

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“…Hence, the small molecule will show a negative NOE-crosspeak in the spectra [17 -19]. It has been shown earlier that it is possible to detect trNOE-crosspeaks by recording a suspended state magic angle spinning (MAS) trNOESY experiment when an analyte is equilibrated with a HPLC stationary phase [20]. It was observed that the magnitude of the negative trNOE could be correlated to the strength of the interaction between a stationary phase and an analyte.…”

Section: Introductionmentioning

confidence: 97%

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Skogsberg

Händel

Gesele

et al. 2003

J of Separation Science

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Investigation of the retention behaviour of steroids with calixarene-based stationary phases by modern NMR spectroscopy A separation of four structurally similar steroids was performed on two calix[8]arene based stationary phases. It was observed that two of the steroids had a reversed retention order when the columns were changed. This implies that two different retention mechanisms are taking place when the analytes are separated. In order to evaluate the mechanism responsible for the reversal of the retention order an extensive study of the interactions between the stationary phases and the analytes was undertaken. By performing a series of transferred NOESY measurements in the suspended state valuable information was obtained about the strengths of the interactions between the analytes and the stationary phases. The magnitudes of the integrals from the trNOESY measurements showed a good correlation with the k9 values obtained from the chromatographic evaluation. The retention mechanism is based mainly on hydrophobic interactions. However, the reversal of the elution order was mainly due to an additional p-p interaction between one of the analytes and the stationary phase.

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Section: Introductionmentioning

confidence: 97%

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Skogsberg

Händel

Gesele

et al. 2003

J of Separation Science

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“…2 Através da HR-MAS, têm sido estudados materiais intactos de vegetais, como folhas, frutos e flores, 3 e de animais, como fígado, cérebro, pulmão, rim, entre outros. 4 A aplicação dessa técnica tem apresentado ainda excelentes resultados na caracterização de géis, 5 moléculas adsorvidas em zeólitas 6 e ligadas a resinas, 7 proteínas nanocristalinas, 8 micro-organismos intactos 9 e, recentemente, aplicada a nanopartículas de óxido de ferro -contendo ferro paramagnético, onde demonstrou ser possível a obtenção de espectros com sinais finos e bem resolvidos. 10 Na quimiotaxonomia de liquens, essa técnica demonstrou ser uma relevante ferramenta na discriminação entre famílias, gêneros e espécies, onde a identificação, baseada somente na análise morfológica, é comumente complexa e pouco conclusiva.…”

Section: Introductionunclassified

Perfil químico de cultivares de feijão (phaseolus vulgaris) pela técnica de high resolution magic angle spinning (HR-MAS)

Lião¹,

Choze²,

Cavalcante³

et al. 2010

Quím. Nova

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“…The spatial variation of the magnetic susceptibility caused by the heterogeneous structure of the liquid͞solid mix results in broad signals and a large loss of resolution, because of variation of the susceptibility and residual solid-state effects. Highresolution magic angle spinning (HRMAS) NMR has been designed to recover well-resolved spectra for similar cases (18)(19)(20)(21), and very recently it was applied to the study of chromatographic phases (22). In this study, HRMAS coupled with diffusion-based NMR techniques (23-26) on a mixture in the presence of a silica gel was used to achieve well-separated and high-resolution spectra for the single components.…”

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Enhanced diffusion-edited NMR spectroscopy of mixtures using chromatographic stationary phases

Viel

Ziarelli

Caldarelli

2003

Proc. Natl. Acad. Sci. U.S.A.

104

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We introduce an analytical method that combines in one pot the advantages of column chromatography separation and NMR structural analysis. The separation of the NMR spectra of the components of a mixture can be achieved according to their apparent diffusion rates [James, T. L. and McDonald, G. G. (1973) J. Magn. Reson. 58, 58 -61]. We show that the separation of the spectral components, corresponding to single molecular species, can be enhanced by order of magnitudes upon addition of a typical stationary phase used in HPLC. The solid phase imbibed by the mixture for analysis is an heterogeneous ensemble, so that solidstate NMR methods (high-resolution magic angle spinning) are necessary to recover high-resolution spectra. We demonstrate applications of this combination of high-resolution magic angle spinning and NMR diffusometry on test mixtures for direct (silica gel) and inverse (C18) columns. However, many common chromatographic supports available for HPLC should be readily adaptable for use with this technique.T he challenge in the analysis of complex mixtures is 2-fold: to achieve an effective separation of the components and provide a proper structural characterization for each of them. The common solution is hyphenation, which is a sequential combination of chromatography and spectroscopic analysis such as mass or UV spectrometry. Because NMR is often the tool of choice for precise structural characterizations of organic molecules, an effort has been done to introduce NMR as a detector in hyphenated techniques (1). An alternative solution for the NMR characterization of mixture components exploits the behavior of the NMR signal of a molecule diffusing in an inhomogeneous magnetic field. In this case, the frequency of the observed target becomes time dependent, with consequent broadening of the resonance line (2). The apparent diffusion rate associated to a molecular resonance can be estimated by performing a series of experiments varying the amplitude of the inhomogeneous field and inverting the corresponding decay curve of the signal amplitude. Diffusion-ordered spectroscopy (DOSY) (3) is a particularly convenient means of displaying this information, organized in a bidimensional array with the NMR spectrum on one dimension and the apparent diffusion rate on the other one. As a collateral aspect, the DOSY display decomposes the overall NMR spectrum of a mixture into those of its components if these latter possess different molecular mobility, without previous collection of separate fractions (4-7). In optimal conditions, the diffusion experiment is capable of resolving contributions from molecules whose diffusion coefficients differ only by a few percent (8). In cases of serious signal overlapping, other methods for processing diffusion data achieve better spectral separation (9-11). We present here an analytical procedure that capitalizes on this idea, but in which the separation properties of the NMR method are enhanced by addition of a solid phase, a typical stationary phase material used for chromato...

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Application of HRMAS ¹H NMR Spectroscopy To Investigate Interactions between Ligands and Synthetic Receptors

Cited by 40 publications

References 23 publications

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Perfil químico de cultivares de feijão (phaseolus vulgaris) pela técnica de high resolution magic angle spinning (HR-MAS)

Enhanced diffusion-edited NMR spectroscopy of mixtures using chromatographic stationary phases

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Application of HRMAS 1H NMR Spectroscopy To Investigate Interactions between Ligands and Synthetic Receptors

Cited by 40 publications

References 23 publications

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Investigation of the retention behaviour of steroids with calixarene‐based stationary phases by modern NMR spectroscopy

Perfil químico de cultivares de feijão (phaseolus vulgaris) pela técnica de high resolution magic angle spinning (HR-MAS)

Enhanced diffusion-edited NMR spectroscopy of mixtures using chromatographic stationary phases

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Application of HRMAS ¹H NMR Spectroscopy To Investigate Interactions between Ligands and Synthetic Receptors