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Sapienza Università di Roma
Dipartimento di Chimica
e Tecnologie del Farmaco
Sapienza Università di Roma
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Dipartimento di Chimicae Tecnologie del Farmaco

Seminars by prof. Stéphane Viel

On 7 and 9 July, from 10 to 12 a.m., prof Stéphane Viel (Aix-Marseille Université & CNRS), visiting professor at the Department,  will hold 2 seminars for Phd students, open to everyone.

 
Seminar 1  (7 July)
Principles and selected applications of Diffusion Ordered NMR Spectroscopy		 


Seminar 2  (9 July)
Structural investigation of organic materials by solid-state dynamic nuclear polarisation (DNP) nuclear magnetic resonance (NMR) spectroscopy

 


Diffusion nuclear magnetic resonance (NMR) spectroscopy is nowadays a well-established technique for characterizing the structure and dynamics of many kinds of physicochemical systems. Typically, this technique relies on pulsed field gradients to label the spatial position of the nuclear spins and infer the molecular diffusion coefficient from their translational displacement over a given time period. As such, pulsed gradient spin echo (PGSE) and, more recently, diffusion ordered NMR spectroscopy (DOSY), have become invaluable tools for: (i) investigating intermolecular interactions; (ii) estimating molecular weight; (iii) analyzing complex mixtures. Combined with High-Resolution Magic Angle Spinning (HR-MAS), which is known to reduce significantly magnetic susceptibility broadenings in heterogeneous samples, diffusion NMR can be readily applied to both liquid and semi-solid samples. In this communication, several applications of diffusion NMR along the three above-mentioned axes will be reported.

 
Solid-state nuclear magnetic resonance (SSNMR) is a versatile and purely non-destructive technique that can provide high-resolution molecular structural information on a large variety of materials, either directly by acquiring the NMR experiments at high magnetic fields or indirectly by taking advantage of multidimensional correlation schemes (or both). Contrary to scattering techniques, SSNMR is perfectly suited for the analysis of powdered samples (i.e. single crystals are not required), and it can access supramolecular structural information without the need of long-range translational order. The Achilles’ heel of NMR, however, remains its low sensitivity that usually precludes analysis of structural details, which are intrinsically associated with NMR signals of low intensity. One of the most promising methods for boosting the SSNMR sensitivity is dynamic nuclear polarisation (DNP), which enhances nuclear magnetisation through the microwave-driven transfer (usually at cryogenic temperatures) of electron spin polarisation to nuclei via exogenous paramagnetic centres. DNP is nowadays attracting renewed attention owing to recent spectacular technological and theoretical developments. This communication will describe recent advances in the field of DNP SSNMR for the characterisation of materials in the solid-state by focusing on organic materials, including organic polymers and pharmaceutical compounds.