Category Archives: Quadrupole Nuclei

[NMR] Postdoc position at Univ. Lille, France, on high-field solid-state NMR of low-gamma quadrupolar nuclei in materials

From the Ampere Magnetic Resonance List

Postdoc position at Univ. Lille, France, on high-field solid-state NMR of low-gamma quadrupolar nuclei in materials

Project PIs: Laurent Delevoye, Olivier Lafon

Project objectives: Quadrupolar nuclei with gyromagnetic ratio lower than that of 15N nucleus represent about 40% of NMR active nuclei. Many important chemical elements, such as Mo, Zn, Zr, Ti or Mg, are only observable through these low-gamma quadrupolar nuclei. This project aims at developing methods for the observation of these isotopes and applying them for the structural study of hybrid materials. This project will take advantage of the use of Lille high-field solid-state NMR spectrometers (800 and 900 MHz), which are equipped with specific probes for the detection of low-gamma nuclei.

Hosts and research infrastructure: Lille is vibrant city, imbued with a rich history. It is located in the middle of northwestern Europe (only 30 min by high-speed trains from Brussels, 1h from Paris and 1h30 from London). Lille is a leading center for magnetic resonance. Lille magnetic resonance facility includes 800 and 900 MHz NMR spectrometers for the study of solids. It has also been selected to host the first 1.2 GHz NMR spectrometer to be installed in France.

The applicant: You hold a PhD degree in physics, chemistry or material sciences and you have first-author publications in peer-reviewed journals. Other requirements are good skills in written and spoken English. The successful applicant will be given the opportunity to work in an exciting environment with national and international collaborations. 

Interested candidates should send his/her CV with a covering letter (one single PDF) before Feb. 3, 2017 to Laurent Delevoye, laurent.delevoye@ensc-lille.fr and Olivier Lafon, olivier.lafon@univ-lille1.fr

====================================

This is the AMPERE MAGNETIC RESONANCE mailing list:

http://www.drorlist.com/nmrlist.html

NMR web database:

http://www.drorlist.com/nmr.html

35Cl dynamic nuclear polarization solid-state NMR of active pharmaceutical ingredients #DNPNMR

Hirsh, D.A., et al., 35Cl dynamic nuclear polarization solid-state NMR of active pharmaceutical ingredients. Phys Chem Chem Phys, 2016. 18(37): p. 25893-25904.

https://www.ncbi.nlm.nih.gov/pubmed/27711465

In this work, we show how to obtain efficient dynamic nuclear polarization (DNP) enhanced 35Cl solid-state NMR (SSNMR) spectra at 9.4 T and demonstrate how they can be used to characterize the molecular-level structure of hydrochloride salts of active pharmaceutical ingredients (APIs) in both bulk and low wt% API dosage forms. 35Cl SSNMR central-transition powder patterns of chloride ions are typically tens to hundreds of kHz in breadth, and most cannot be excited uniformly with high-power rectangular pulses or acquired under conditions of magic-angle spinning (MAS). Herein, we demonstrate the combination of DNP and 1H-35Cl broadband adiabatic inversion cross polarization (BRAIN-CP) experiments for the acquisition of high quality wideline spectra of APIs under static sample conditions, and obtain signals up to 50 times greater than in spectra acquired without the use of DNP at 100 K. We report a new protocol, called spinning-on spinning-off (SOSO) acquisition, where MAS is applied during part of the polarization delay to increase the DNP enhancements and then the MAS rotation is stopped so that a wideline 35Cl NMR powder pattern free from the effects of spinning sidebands can be acquired under static conditions. This method provides an additional two-fold signal enhancement compared to DNP-enhanced SSNMR spectra acquired under purely static conditions. DNP-enhanced 35Cl experiments are used to characterize APIs in bulk and dosage forms with Cl contents as low as 0.45 wt%. These results are compared to DNP-enhanced 1H-13C CP/MAS spectra of APIs in dosage forms, which are often hindered by interfering signals arising from the binders, fillers and other excipient materials.

Have a question?

If you have questions about our instrumentation or how we can help you, please contact us.