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 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.
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→
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→
Some of our last research work will be presented 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.
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. Continue reading HOBS experiments to measure T1/T2 relaxation times in overlapped regions→
Location: SeRMN, Facultats de Ciències i Biociències, C2/-135
Speaker: Laura Castañar, SeRMN PhD Student & Teaching Assistant, Dept. of Chemistry.
Several NMR applications using HOmodecouped Band-Selective NMR experiments  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  and long-range  heteronuclear coupling constants. Also the use of HOBS experiments to enantiodiscrimination studies are presented .