Tag Archives: Pure shift

SeRMN at the SMASH NMR 2016 Conference

Some of our last research works has been presented at the annual meeting of the SmallMolecule NMR Conference (SMASH) that has been taken place in La Jolla (USA) from 11thto 14thSeptember 2016.

Teodor Parella presented two posters.
“In situ determination of 1DCH and 2DHH RDCs from a single 1JCH/2JHH -resolved NMR measurement” of Núria Marcó García, Roberto R. Gil and Teodor Parella.

Abstract: A fast RDC-assisted strategy involving the simultaneous determination of isotropic (scalar) and anisotropic (total) interactions is reported. The concerted use of individual 1DCH for all CHn multiplicities and 2DHH obtained from a single 1JCH/2JHH-resolved NMR spectrum offers an unambiguous assignment of diastereotopic protons and an efficient discrimination between all eight possible diastereoisomeric structures of strychnine which contains six stereocenters.

Figure: 500.13MHz JCH/JHH-Resolved spectra of 1 in A) isotropic CDCl3 and B) anisotropic PMMA-CDCl3 (2H nQ(CDCl3)=26 Hz) conditions. The projections along the F2 dimension are the conventional 1H spectrum in isotropic conditions and the 1H-CPMG spectrum in anisotropic conditions, respectively.

“Pure shift NMR covariance” of André Fredi, Pau Nolis, Carlos Cobas, Gary E. Martin, Teodor Parella.

Abstract: The development of novel experimental strategies to significantly enhance signal resolution by broadband homodecoupling is a current topic of high interest in 1H NMR spectroscopy . A number of different building blocks have been implemented into 1D and 2D homo- and heteronuclear experiments in order to provide resolution-enhanced pure chemical shift 1H NMR spectra, where signals appear collapsed to singlets. On the other hand, Covariance processing methods have been used to generate challenging NMR spectral representations . We present here the first attempts towards a general solution to generate Pure Shift NMR spectra by using Generalized Indirect Covariance (psGIC) co-processing3,4 . The current strategy is based on the calculation of a new 2D psGIC spectrum from the combination of a parent homo- or heteronuclear spectrum and a reference 2D F1-homodecoupled 1H- 1H correlation spectrum only showing diagonal cross-peaks (DIAG), which share a common 1H frequency dimension. Using psGIC, the F1 dimension in the DIAG spectrum is transferred to the F2 dimension of the parent spectrum, thus generating a new pure shift 2D spectrum

Figure: Generation of Pure Shift NMR spectra by using Generalized Indirect Covariance (psGIC)

André Fredi’s oral presentation at 8th GERMN / 5th Iberian NMR Meeting

André Fredi made an oral presentation at the 8th GERMN / 5th Iberian NMR Meeting (GERMN 2016) held in Valencia, Spain from 27th to 29th June 2016.

In his presentation, that was titled  Exploring the use of Generalized Indirect Covariance to reconstruct Pure Shift NMR spectra: Current Pros and Cons”, André explained how to make pure spectra shift from Generalized Indirect IMG-20160628-WA0028Covariance processing (psGIC). This new method is basically a new way to get “synthetic” pure shift spectra without the need to purchase a pure shift spectrum in the spectrometer and without the penalties that pure-shift experiments cause.

André has been working as a Ph.D. candidate at the Department of Chemistry and SeRMN under the direction of Dr. Teodor Parella and Dr. Pau Nolis since November 2014, when he enrolled in the Department of Chemistry doctoral program at Universitat Autònoma de Barcelona with a fellowship from CNPq-Brazil. He is currently in his second year and expects to defend the doctoral thesis on 2017/2018.

 

Exploring the use of Generalized Indirect Covariance to Reconstruct Pure shift NMR Spectra: Current Pros and Cons.

JMR

Title: Exploring the use of Generalized Indirect Covariance to Reconstruct Pure shift NMR Spectra: Current Pros and Cons.
Authors: André Fredi, Pau Nolis, Carlos Cobas, Gary E. Martin and Teodor Parella.
DOI: 10.1016/j.jmr.2016.03.003

ABSTRACT: The current pros and cons of a processing protocol to generate pure chemical shift NMR spectra using Generalized Indirect Covariance are presented and discussed. The transformation of any standard 2D homonuclear and heteronuclear spectrum to its pure shift counterpart by using a reference DIAG spectrum is described. Continue reading Exploring the use of Generalized Indirect Covariance to Reconstruct Pure shift NMR Spectra: Current Pros and Cons.

Ultra-high-resolved NMR: Analysis of complex mixtures of compounds with near-identical 1H and 13C NMR spectra

Title: cover7Disentangling complex mixtures of compounds with near-identical 1H and 13C NMR spectra using pure shift NMR.
Authors: L. Castañar, R. Roldán, P. Clapés, A. Virgili and T. Parella.
Reference: Chem. Eur. J., 2015, 21, 7682-7685.
DOI: 10.1002/chem.201500521

 

Abstract: The thorough analysis of highly complex NMR spectra using pure shift NMR experiments is  described. The enhanced spectral resolution obtained from modern 2D HOBS experiments incorporating spectral aliasing in the 13C indirect dimension enables the distinction of similar compounds exhibiting near-identical 1H and 13C NMR spectra. It is shown that a complete set of extremely small Δδ(1H) and Δδ(13C) values, even below the natural line width (1 and 5 ppb, respectively), can be simultaneously determined and assigned.

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References:

 

Pulse Programs Code for Bruker:

Data set Example:

 

PhD Thesis by Laura Castañar: Pulse Programs and Data Set Examples

Development and application of modern pure shift NMR techniques and improved HSQC/HSQMBC experiments

Presentación1

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 2D spectra have been previously phased and 2ii, 2ir, and 2ri files removed, otherwise data sets would be too big. Continue reading PhD Thesis by Laura Castañar: Pulse Programs and Data Set Examples

Review – Pure shift NMR experiments: recent developments, methods and applications

MRC_teo copy“Broadband 1H homodecoupled NMR experiments: recent developments, methods and applications” by Laura Castañar and Teodor Parella. Magnetic Resonance in Chemistry, 2015. DOI: 10.1002/mrc.4238

In recent years, a great interest in the development of new broadband 1H homonuclear decoupled techniques providing simplified JHH multiplet patterns has emerged again in the field of small molecule NMR. The resulting highly resolved 1H NMR spectra display resonances as collapsed singlets, therefore minimizing signal overlap and expediting spectral analysis. This review aims at presenting the most recent advances in pure shift NMR spectroscopy, with a particular emphasis to the Zangger–Sterk experiment. Continue reading Review – Pure shift NMR experiments: recent developments, methods and applications

SeRMN presentation at the 56th ENC 2015 Conference

Imagen1

During these days takes place the 56th Experimental Nuclear Magnetic Resonance Conference (ENC) in Asilomar Conference Grounds (Pacific Grove, California, USA) where Laura Castañar presents an Oral Communication entitled “HOBS: Broadband Homonuclear Decoupled Band-Selective NMR Experiments with Full Sensitivity” Continue reading SeRMN presentation at the 56th ENC 2015 Conference