Tag Archives: HSQC

PhD Thesis: New Applications of Covariance NMR and Experimental Development for Measurements of Homonuclear Coupling Constants in Overlapping Signals

2018-04-03Methods & Applications, News from the SeRMN, Our Researchcoupling-constants, covariance NMR, enhanced resolution, full sensitivity, Generalized Indirect Covariance, homonuclear decoupling, HSQC, HSQMBC, J-resolved, perfect HSQC, PhD Thesis, PIP experiments, pure in-phase signals, pure-shift NMRAndre

On 21st March 2018 I sucessfully defended my PhD Thesis entitled: “New Applications of Covariance NMR and Experimental Development for Measurements of Homonuclear Coupling Constants in Overlapping Signals” (ISBN: 9788449079252), supervised by Dr. Teodor Parella and Dr. Pau Nolis, and obtained the degree of Ph.D. in Chemistry at the Department of Chemistry, Universitat Autònoma de Barcelona.

The thesis can be downloaded in PDF format from the TDX repository and from the TESEO repository.

Accurate measurement of proton homonuclear coupling constants in overlapped signals by using a doubly-selective TOCSY G-SERF experiment.

Abstract

The experimental results obtained in this thesis are presented in the form of three papers published in NMR specialised scientific peer-reviewed journals.

Exploring the use of Generalized Indirect Covariance to Reconstruct Pure shift NMR Spectra: Current Pros and Cons. André Fredi, Pau Nolis, Carlos Cobas, Gary E. Martin and Teodor Parella. Journal of Magnetic Resonance, Volume 266, May 2016, Pages 16-22. DOI: 10.1016/j.jmr.2016.03.003
Access to experimentally infeasible spectra by pure-shift NMR covariance. André Fredi, Pau Nolis, Carlos Cobas and Teodor Parella. Journal of Magnetic Resonance, Volume 270, September 2016, Pages 161-168. DOI: 10.1016/j.jmr.2016.07.010
Accurate measurement of JHH in overlapped signals by a TOCSY‐edited SERF Experiment. André Fredi, Pau Nolis and Teodor Parella. Magnetic Resonance in Chemistry, Volume 55, Issue 6, June 2017, Pages 525-529. DOI: 10.1002/mrc.4572

The first two articles deal with the use of covariance NMR as a general method to generate novel psNMR spectra. The last work describes a new selTOCSY G-SERF experiment, for accurately measuring JHH in overlapped regions.

The first publication describes a novel general protocol to generate psNMR spectra by Covariance NMR. This new approach is unique in NMR spectroscopy; giving a cheap, fast an easy way to reconstruct psNMR spectra without spending time in the spectrometer. This new strategy has been referenced to as psNMR Covariance.

The concept of psNMR Covariance has been extended in the second publication by inserting Multiplicity-Edited (ME) information into 2D experiments that are difficult or even impossible to achieve experimentally. It is shown how the ME information can be efficiently transferred to a set of homonuclear and heteronuclear 2D NMR spectra by Covariance processing, reconstructing new psME spectra in a fast way. Finally, G-SERF and related methods only work for isolated 1H signals on which selective excitation can be successfully applied.

Unfortunately, as it happens in other frequency-selective experiments, this approach fails for overlapped signals. A doubly-selective TOCSY G-SERF scheme is presented in the third publication to circumvent this limitation, by measuring JHH efficiently even for protons resonating in crowded regions.

Access to experimentally infeasible spectra by pure-shift NMR covariance

2016-10-04Methods & Applications, Our Publications, Our Research2D DIAG, coavriance, enhanced resolution, Generalized Indirect Covariance, homodecoupling, homonuclear decoupling, HSQC, HSQMBC, HSQMBC-TOCSY, indirect covariance, NOESY, NUS, psGIC, Pure shift, pure-shift NMRAndre

Access to experimentally infeasible spectra by pure-shift NMR covariance. André Fredi, Pau Nolis, Carlos Cobas and Teodor Parella. Journal of Magnetic Resonance, Volume 270, September 2016, Pages 161-168. DOI: 10.1016/j.jmr.2016.07.010

Abstract: Covariance processing is a versatile processing tool to generate synthetic NMR spectral representations without the need to acquire time-consuming experimental datasets. Here we show that even experimentally prohibited NMR spectra can be reconstructed by introducing key features of a reference 1D CHn-edited spectrum into standard 2D spectra. This general procedure is illustrated with the calculation of experimentally infeasible multiplicity-edited pure-shift NMR spectra of some very popular homonuclear (ME-psCOSY and ME-psTOCSY) and heteronuclear (ME-psHSQC-TOCSY and ME-psHMBC) experiments.

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SeRMN at the SMASH NMR 2016 Conference

2016-09-18NMR Events & Courses, Our ResearchAnisotropic, covariance, HSQC, Jres, PMMA, Pure shiftNúria

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 11^thto 14^thSeptember 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 ¹D_CH for all CH_n multiplicities and ²D_HH obtained from a single ¹J_CH/²J_HH-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)

Presentations at the EUROMAR 2016 Conference

2016-07-20Methods & Applications, News from the SeRMN, NMR Events & Courses, Our Researchcovariance NMR, Generalized Indirect Covariance, homodecoupling, HSQC, HSQMBC, psGIC, pure-shift NMRAndre

André Fredi (PhD student) and Teodor Parella presented our last research works at the annual meeting of the European magnetic resonance community EUROMAR 2016 Conference that was celebrated on days 3th to 7th July in Aarhus, Denmark. Find below a summary of our contributions. Continue reading Presentations at the EUROMAR 2016 Conference →

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

2016-03-14Methods & Applications, News from the SeRMN, Our Publications, Our Research2D DIAG, coavriance, enhanced resolution, Generalized Indirect Covariance, homodecoupling, homonuclear decoupling, HSQC, HSQMBC, HSQMBC-TOCSY, indirect covariance, NOESY, NUS, psGIC, Pure shift, pure-shift NMRAndre

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. Reconstructed pure shift NMR spectra of NOESY, HSQC, HSQC-TOCSY and HSQMBC experiments are reported for the target molecule strychnine.

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PhD Thesis: Development and application of modern pure shift NMR techniques and improved HSQC and HSQMBC experiments

2015-07-27Methods & Applications, News from the SeRMN, Our Researchcoupling-constants, enhanced resolution, full sensitivity, HOBS, homonuclear decoupling, HSQC, HSQMBC, perfect HSQC, PhD Thesis, PIP experiments, pure in-phase signals, pure-shift NMR, residual dipolar couplings, SAPS-HSQC, sensitivity enhancementLaura

Last 16^st July 2015 I defended my PhD Thesis entitled: Development and application of modern pure shift NMR techniques and improved HSQC/HSQMBC experiments.

The present doctoral thesis is framed within the Nuclear Magnetic Resonance (NMR) spectroscopy field, more specifically in the design of modern NMR methodologies. The research work carried out is focused on the design and application of new and modern NMR methodologies (i) to perform efficient broadband ¹H homodecoupling in 1D/2D NMR experiments and (ii) to accurately determine homo- and heteronuclear coupling constants in isotropic and anisotropic conditions through improved HSQC and HSQMBC-type experiments. The thesis is presented as a compendium ten (10) publications that have been published in several peer-reviewed international scientific journals as original research papers. Continue reading PhD Thesis: Development and application of modern pure shift NMR techniques and improved HSQC and HSQMBC experiments →

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

2015-05-31Methods & Applications, News from the SeRMN, NMR Events & Courses, Our Publications, Our Researchaligned-media, coupling-constants, enantiodifferentiation, enhanced resolution, full sensitivity, heteronulear coupling constants, HOBS, HOBS-HSQC, HOBS-HSQC-TOCSY, HOBS-HSQMBC, HOBS-TOCSY, homodecoupling, homonuclear decoupling, HSQC, HSQMBC, J-resolved, multi-slice selection, multiple frequency pulses, NUS, one-bond proton-carbon coupling constants, perfect HSQC, PhD Thesis, PIP experiments, proton-carbon coupling constants, proton-proton coupling constants, pure in-phase signals, Pure shift, quantitative nmr, RDCs, Relaxation times, residual dipolar couplings, resolution enhancement, SAPS-HSQC, sensitivity enhancement, sign of coupling constants, spectral aliasing, T1-relaxation, T2-relaxation, two-bonds proton-proton coupling constantsLaura

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

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 →

Ultra high-resolution HSQC

2015-04-29Our Research, Seminarsheteronulear coupling constants, HSQC, spectral aliasingNúria

SeRMN seminar

Date: Thursday 7th May, 2015
Hour: 15:30
Location: SeRMN, Facultats de Ciències i Biociències, C2/-135
Speaker: Núria Marcó, SeRMN PhD Student

The content of our recently published article entitled “Ultra high-resolution HSQC: Application to the efficient and accurate measurement of heteronuclear coupling constants” will be explained and discussed briefly. A rapid NMR data acquisition strategy in terms of enhanced resolution per time unit for the simple and efficient determination of multiple coupling constants is described. The use of 13C spectral aliasing combined with broadband 1H homodecoupling allows accurate measurements from ultra high resolved 2D HSQC cross-peaks.

Review: Recent Advances in Small Molecule NMR: Improved HSQC and HSQMBC Experiments

2015-03-02Methods & Applications, NMR Bibliography, Our Publications, Our ResearchHOBS-HSQC, HOBS-HSQMBC, HSQC, HSQMBC, IPAP, nmr, one-bond proton-carbon coupling constants, perfect HSQC, PIP experiments, proton-carbon coupling constants, pure-shift NMR, quantitative nmr, SAPS-HSQCLaura

“Recent Advances in Small Molecule NMR: Improved HSQC and HSQMBC Experiments” by Laura Castañar and Teodor Parella. Annual Reports on NMR Spectroscopy, 2015, 84:163–232. DOI: 10.1016/bs.arnmr.2014.10.004

A general description of the latest developments in heteronuclear single-quantum correlation and heteronuclear single-quantum multiple bond correlation experiments designed for small molecules at the natural isotopic abundance is reported. Continue reading Review: Recent Advances in Small Molecule NMR: Improved HSQC and HSQMBC Experiments →

Ultra high-resolution HSQC: Application to the efficient and accurate measurement of heteronuclear coupling constants

2015-01-16Our Publicationsheteronulear coupling constants, HSQC, spectral aliasingNúria

“Ultra high-resolution HSQC: Application to the efficient and accurate measurement of heteronuclear coupling constants” by Núria Marcó, Andre Fredi and Teodor Parella. Chemical Communications 2015, 51:3262-3265. DOI: 10.1039/C4CC10279G

A rapid NMR data acquisition strategy in terms of enhanced resolution per time unit for the simple and efficient determination of multiple coupling constants is described. The use of 13C spectral aliasing combined with broadband 1H homodecoupling allows accurate measurements from ultra high resolved 2D HSQC cross-peaks.

Pulse Program Code for Bruker:

SAPS-HSQC (see post “Simultaneous 1H and 13C NMR enantiodifferentation from highly-resolved pure shift HSQC spectra” for details).

Data set Example:

Fluoropyridine

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