SeRMN presentations at the 2014 Ibero-American NMR & GERMN Bienal & Iberian NMR meeting

Imagen1Some of our last research works will be presented the next week at the VI Ibero-American NMR – VII GERMN Bienal – IV Iberian NMR joint meeting that will take place in Alcalá de Henares, Madrid (Spain) from 22nd to 25th September. Find below a summary of our contributions.

Laura Castañar presents an oral communication and a poster entitled “Enantiodifferentiation throgh frequency-selective pure shift 1H NMR”.  NMR-aided discrimination of enantiomers using chiral solvating agents (CSAs) is a well established method to carry out enantiodifferentiation studies. The analysis is traditionally performed by observing chemical shift differences (ΔΔδ) in 1H signals by conventional 1D 1H NMR spectra. However signals overlapping caused by low ΔΔδ values and homonuclear scalar couplings (JHH) lead to the lack of spectral signal dispersion that preclude a straightforward analysis. Recently, pure shift NMR spectroscopy has emerged as a promising tool to simplify the typical JHH multiplicity pattern of 1H signals to singlets.This affords a general improvement on signal dispersion that allows an improved analysis of complex and overcrowded resonances. Based on the full-sensitive 1H-HOBS experiment, frequency-selective technique for the fast and simple discrimination of ΔΔδ in overlapped signals and for the determination of the R/S molar ratio in the presence of CSAs is here proposed.

SeRMN presentations at the SMASH NMR 2014 Conference

SMASH logo. Click to go to home page.

Some of our last research works will be presented at the annual meeting of the Small Molecule NMR Conference (SMASH) that will take place in Atlanta (USA) from 7th to 10th September 2014.

 Poster presentations:

  • Pure In-Phase Heteronuclear Correlation NMR Experiments; Laura Castañar, Josep Saurí, R. Thomas Williamson, Albert Virgili and Teodor Parella.
    A general pulse scheme to provide pure in-phase (PIP) multiplets in heteronuclear correlation NMR experiments is presented. The implementation of a zero-quantum filter efficiently suppresses any unwanted anti-phase contributions that usually distort the multiplet pattern of cross-peaks and can hamper their analysis. The clean in-phase pattern obtained in PIP-HSQC and PIP-HSQMBC experiments is suitable for a direct extraction of coupling constants in resolved signals, for a peak-fitting process from a reference signal, or for the application of the IPAP technique in non-resolved multiplets.
  • Fast and efficient enantiodifferentiation through pure shift NMR; Laura Castañar, Míriam Pérez-Trujillo, Eva Monteagudo, Lars T. Kuhn, Pau Nolis, Albert Virgili, R. Thomas Williamson and Teodor Parella.
    Several NMR enantiodifferentiation studies by using new pure shift (PS) NMR methods will be discussed. First, a frequency-selective 1D HOmodecoupled Band-Selective (HOBS) experiment is proposed for the fast 1H chemical shift discrimination of overlapped signals.  On the other hand, the concepts of spectral aliasing (SA) and PS NMR are combined into a novel and robust 2D SAPS-HSQC experiment which provides simultaneous 1H and 13C enantiodifferentiated data with high digital resolution and excellent signal dispersion for both broadband-decoupled 1H and 13C nuclei.
  • Perfect-HSQC: Suppression of phase and amplitude JHH modulation; Laura Castañar, Eduard Sistaré, Albert Virgili, R. Thomas Williamson and Teodor Parella.
    The amplitude and the phase of cross-peaks in conventional 2D HSQC experiments are modulated by both proton-proton, JHH, and proton-carbon, 1JCH, coupling constants. In this work we shown by spectral simulation and experimentally that JHH interferences can be efficiently suppressed in a novel perfect-HSQC pulse scheme that incorporates JHH-compensated INEPT periods. The improved 2D spectra afford pure in-phase cross-peaks with respect to 1JCH and JCH, irrespective to the experiment delay optimization. In addition, peak volumes are not attenuated by the influence of JHH, rendering practical issues such as phase correction, signal integration and multiplet analysis more accurate.
  • Simultaneous measurement of the magnitude and the sign of multiple heteronuclear coupling constants in 19F- or 31P-containing molecules; Josep SauríPau Nolis and Teodor Parella.
    A suite of selHSQMBC experiments are presented for the simultaneous measurement of multiple homo- and/or heteronuclear coupling constants from a single 2D cross-peak. A time-shared version allows such determinations for 13C and 15N at the same time and the incorporation of a TOCSY transfer extents its applicability for an entire spin system. The use of non-uniform linear sampling (NUS) and/or the signal detection under homodecoupling conditions will be also evaluated and illustrated with examples.

Simultaneous 1H and 13C NMR enantiodifferentiation from highly-resolved pure shift HSQC spectra

CoverIssue“Simultaneous 1H and 13C NMR enantiodifferentiation from highly-resolved pure shift HSQC spectra” by Miriam Perez-Trujillo, Laura Castañar, Eva Monteagudo, Lars T. Kuhn, Pau Nolis, Albert Virgili, R. Thomas Williamson and Teodor Parella. Chemical Communications (2014)

DOI: 10.1039/C4CC04077E

NMR-aided discrimination of enantiomers using chiral solvating agents (CSAs) is a well established method of enantiodifferentiation and measurement of enantiomeric ratios (er). The analysis is traditionally performed by observing chemical shift differences (ΔΔδ) in 1H signals by conventional 1D 1H NMR spectra. However, low ΔΔδ values and signal overlap caused by complex multiplets lead to the lack of spectral signal dispersion that preclude a straightforward analysis. The alternative of using 13C NMR spectroscopy can be more advantageous, because singlet signals are analyzed, but its routine use is limited by its low sensitivity.TOC_14ChemCommThe combination of spectral aliasing and pure shift HSQC in SAPS-HSQC experiments represents an excellent routine tool for NMR enantiodifferentiation studies, yielding simultaneous 1H and 13C enantiodifferentiated data in short times and with high digital resolution and signal dispersion for both nuclei. Its use increases significantly the probability to detect an enantiodifferentiated nucleus, overlapping problems of common 1D 1H experiments are overcome, and poor enantiodifferentiation in 1D experiments can now be detected. The method is compatible with other heteronuclei, with the use of other chiral auxiliaries, and it can be of special interest for enantiodifferentiation experiments of complex mixtures.

Pulse Program Code for Bruker:

SAPS-HSQC

SAPS-HSQCsi

Pure In-Phase Heteronuclear Correlation NMR Experiments

“Pure Incover-Phase Heteronuclear Correlation NMR Experiments ” by Laura Castañar, Josep Sauri, Robert Thomas Williamson, Albert Virgili and Teodor Parella. Angewandte Chemie International Edition (2014)

DOI: 10.1002/anie.201404136

 A general NMR approach to provide pure in-phase (PIP) multiplets in heteronuclear correlation experiments is described. The implementation of a z-filter efficiently suppresses any unwanted anti-phase contributions that usually distort the multiplet pattern of cross-peaks and can make their analysis difficult. The clean pattern obtained in PIP-HSQMBC experiments is suitable for a direct extraction of coupling constants in resolved signals, for a peak-fitting process from a reference signal, or the application of the IPAP technique in non-resolved multiplets.PIP1

Pulse Program Code for Bruker:

Data set Example:

Presentations at the EUROMAR 2014 Conference

EUROMAR 2014

In a few days several SeRMN members will present our research work at the annual meeting of the European magnetic resonance community EUROMAR 2014 Conference  that will take place in Zurich (Switzerland) from 29th June to 3th July. Find below a summary of our contributions.

  • Teodor Parella presents a Lecture entitled “Improvements in Heteronuclear Correlation NMR experiments”. A presentation of some new simple solutions to improve the performance of heteronuclear correlation experiments will be provided. A discussion on the effects of JHH coupling constants in direct and long-range heteronuclear correlation experiments will be made and examples to obtain pure in-phase HSQC and HSQMBC experiments will be given. Experimental aspects such as phase properties of cross-peaks, their signal intensity dependences, the extraction of coupling constant values, and solutions to achieve resolution enhancements will be presented. A particular emphasis will be made on the measurement of one-bond and long-range heteronuclear coupling constants from non distorted cross-peaks and the measurement of 1JCH/2JHH for diastereotopic CH2 spin systems in both isotropic and anisotropic media. Finally, it will be shown how the combination of pure-shift NMR and spectral aliasing afford a significant resolution enhancement in both dimensions of 2D HSQC spectra, and its successful application in enantiodifferentiation studies will be illustrated.
  • Laura Castañar presents a Poster entitled “Band-Selective pure shift 1H NMR experiments with full sensitivity“. The poster is focused on the HOmodecoupled Band-Selective (HOBS) 1H NMR experiment and its applications. The HOBS method is a band/frequency-selective experiment for the fast acquisition of full-sensitive homodecoupled spectra.  It affords pure shift spectra in particular areas of the 1H spectrum where do not appear mutually J-coupled protons. We show that the implementation of the HOBS approach becomes easy and reliable for a large number of NMR experiments and guarantees the rapid data acquisition of region-selective NMR experiments even for samples at low concentrations. We also illustrate several practical applications to differentiate signals with small chemical shift differences, such as found in enantiodifferentiation studies by using chiral solvating agents, the analysis of individual signal intensity decays for measuring T1/T2 relaxation times in overlapped signals or the measurement of heteronuclear coupling constants from simplified multiplet patterns.

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Related Posts

  1. Presentations to the EUROMAR 2013 Conference
  2. Pure in-phase heteronuclear correlation NMR experiments
  3. Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments
  4. Implementing homo- and heterodecoupling in region-selective HSQMBC experiments
  5. Rapid and efficient enantiodifferentiation through frequency-selective pure-shift 1H NMR spectroscopy
  6. HOBS experiments to measure T1/T2 relaxation times in averlapped regions
  7. Easy measurement of one-bond proton-carbon and geminal proton-proton coupling constants in distereotopic methylene groups

PhD Thesis: Modern NMR Methodologies for the Measurement of Homo- and Heteronuclear Coupling Constants in Small Molecules

Last 21st May 2014 I defended my PhD Thesis entitled: Modern NMR Methodologies for the Measurement of Homo- and Heteronuclear Coupling Constants in Small Molecules

 

PhD thesis JSauri - Graphical Abstract - Publications

 

The dissertation is focused on the development of modern NMR methodologies for the measurement of homo- and heteronuclear coupling constants in small molecules, and is presented as a compendium of eight (8) publications that have been published in several peer-reviewed journals as original research papers. The starting point was the previous experience and knowledge of our research group in that topic. Taking as a reference the selHSQMBC experiment, several features have been implemented in order to design a complete set of different methodologies that allow us to overcome some of the most typical drawbacks regarding such measurements, namely, a) the magnitude of small nJ(CH) (<2-3 Hz), b) the determination of the sign-sensitive information,  and c) measurement in both protonated and non-protonated carbons. In most of the cases the IPAP methodology has been used to achieve an accurate measurement. A spin-state selective technique like the E.COSY pattern, as well as the concept of J-resolved spectroscopy, have been implemented in conjunction with the IPAP methodology to obtain simultaneous measurement of several coupling constants from a single 2D cross-peak. Moreover, advances in the measurement of one-bond proton-carbon coupling constant and geminal proton-proton coupling constants in diastereotopic methylene groups are also presented. Each experiment has been discussed from a methodological point of view. An assessment on its application has been also performed.

Useful Links: Pulse Programs and Data Set Examples, here

HOBS experiments to measure T1/T2 relaxation times in overlapped regions

S10907807“Measurement of T1/T2 relaxation times in overlapped regions from homodecoupled 1H singlet signals” by Laura Castañar, Pau Nolis, Albert Virgili and Teodor Parella. Journal of Magnetic Resonance 244 (2014) 30-35

 DOI: 10.1016/j.jmr.2014.04.003 

 

The implementation of the HOmodecoupled Band-Selective (HOBS) technique in the conventional Inversion-Recovery and CPMG-based PROJECT experiments is described. The achievement of fully homodecoupled signals allows the distinction of overlapped 1H resonances with small chemical shift differences. It is shown that the corresponding T1 and T2 relaxation times can be individually measured from the resulting singlet lines using conventional exponential curve-fitting methods.

Figuras articulo_lau

 

Pulse Program Code for Bruker:

Data set Example:

Reference:

“Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments” by L. Castañar, P. Nolis,A. Virgili and T. Parella. Chem. Eur. J. 2013, 19, 17283-17286. DOI:10.1002/chem.201303235

Presentations at the Joint Annual Meeting ISMRM-ESMRMB 2014

Next week several SeRMN members will present our research work at the Joint Annual meeting ISMRM-ESMRMB 2014 that will take place in Milan (Italy) from 10th to 16th May. Find below a summary of our contributions.

Joint Annual Meeting ISMRM-ESMRMB

PhD Thesis by Josep Saurí: Pulse Programs and Data Set Examples

image cover

In the following links one can find Data Set Examples of each Publication presented in the Thesis Work, as well as the corresponding Pulse Program Code for Bruker. All spectra have been previously phased and 2ii, 2ir, and 2ri files removed, otherwise data sets would be too big.

Publication 1CLIP-HSQMBC: Easy measurement of small proton-carbon coupling constants in organic molecules. J. Saurí, T. Parella, J. F. Espinosa. Org. Biomol. Chem. 2013, 11, 4473-4478. DOI: 10.1039/C3OB40675J

Publication 2: A definitive NMR solution for a simple and accurate measurement of the magnitude and the sign of small heteronuclear coupling constants on protonated and non-protonated carbons. J. Saurí, J. F. Espinosa, T. Parella. Angew. Chem. Int. Ed., 2012, 51, 3919 –3922. DOI: 10.1002/anie.201108959

Publication 3Efficient measurement of the sign and the magnitude of long-range proton-carbon coupling constants from a spin-state-selective HSQMBC-COSY experiment. J. Saurí, T. Parella. Magn. Reson. Chem. 2012, 50, 717–721. DOI: 10.1002/mrc.3867

Publication 4Efficient and fast sign-sensitive determination of heteronuclear coupling constants. J. Saurí, P. Nolis, T. Parella. J. Magn. Reson. 2013, 236, 66–69. DOI: 10.1016/j.jmr.2013.08.013

Publication 5On the interference of J(HH) modulation in HSQMBC-IPAP and HMBC-IPAP experiments. J. Saurí, T. Parella. Magn. Reson. Chem. 2013, 51, 509–516. DOI: 10.1002/mrc.3977

Publication 6P.E.HSQMBC: Simultaneous measurement of proton-proton and proton-carbon coupling constants. J. Saurí, P. Nolis, L. Castañar, A. Virgili, T. Parella. J. Magn. Reson. 2012, 224, 101–106. DOI: 10.1016/j.jmr.2012.09.007

Publication 7Simultaneous measurement of J(HH) and two different nJ(CH) coupling constants from a single multiply-edited 2D cross-peak. J. Saurí, T. Parella. Magn. Reson. Chem. 2013, 51, 397–402. DOI: 10.1002/mrc.3960

Publication 8Straightforward measurement of individual 1J(CH) and 2J(HH) in diastereotopic CH2 groups. J. Saurí, L. Castañar, P. Nolis, A. Virgili, T. Parella. J. Magn. Reson. 2014, 242, 33–40. DOI: 10.1016/j.jmr.2014.02.003

On the other hand, this link contains a png file with 1H NMR and 13C NMR assignments for Strychnine and 2-Fluoropyridine compounds.

HOBS Applications

SeRMN seminar

  • Date:  Friday 28th March, 2014
  • Hour: 12 am
  • Location:  SeRMN,  Facultats de Ciències i Biociències, C2/-135
  • Speaker:  Laura Castañar, SeRMN PhD Student & Teaching Assistant, Dept. of Chemistry.

HOBS Applications (27-03-2014)

Several NMR applications using HOmodecouped Band-Selective NMR experiments [1] are proposed. The easy implementation of this HOBS scheme as a general building block into a great variety of multidimensional NMR experiments leads to pure-shift spectra with enhanced resolution and with the maximum attainable sensitivity. In this talk is presented the application of HOBS for measuring direct [1] and long-range [2] heteronuclear coupling constants. Also the use of HOBS experiments to enantiodiscrimination studies are presented [3].

Reference:

[1] “Full sensitivity and enhanced resolution in homodecoupled band-selective NMR experiments” by L. Castañar, P. Nolis, A. Virgili and T. ParellaChem. Eur. J. 2013, 19, 17283-17286. DOI: 10.1002/chem.201303235

[2]Implementing homo- and heterodecoupling in region-selective HSQMBC experiments” by Laura CastañarJosep Sauri, Pau Nolis,Albert Virgili and Teodor ParellaJournal of Magnetic Resonance,2014, 238, 63-69.  DOI:10.1016/j.jmr.2013.10.022
 
[3] “Enantiodifferentiation through Frequency-Selective Pure-Shift 1H Nuclear Magnetic Resonance Spectroscopy” by Laura CastañarMíriam Pérez-Trujillo, Pau Nolis, Eva MonteagudoAlbert Virgili and Teodor ParellaChemPhysChem, 2014. DOI: 10.1002/cphc.201301130