Talk by Heloisa N. Bordallo – Niels Bohr Institute - University of Copenhagen

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Talk by Heloisa N. Bordallo

Understanding structure-properties relation is a central problem in materials science. It is especially important for pharmaceuticals, which are prone to be polymorphic - i.e. the same molecule can crystallize in different 3D-structures.

One of the most powerful ways of getting insight on the strength of atomic interactions is to measure the dynamic properties of the system, and neutrons with a 1 Å wavelength and energy close to 1 kcal/mol are a valuable technique to characterize thermal molecular motions and conformational changes in hydrogen bond systems. Normally dynamical properties are studied at simpler model systems - molecular crystals with selected functional groups - that can mimic important functional groups, such as the acetamide group. For instance, structure and vibrational studies of N-methylacetamide (CH3CONHCH3), a single amide containing methyl groups at both extremities, has been the subject of a numerous investigations.

Here I take the approach that relating the dynamics of molecular fragments in the acetamide group to molecular packing and to the properties of the hydrogen bond network in crystalline prescription drugs is a motivating question. During this talk I will present recent results on Paracetamol, Methacetine and Phenacetine, widely used medicaments, obtained using inelastic neutron scattering (INS) carried out using the time-of-flight spectrometers NEAT (BERII, Berlin), IN6 (ILL, Grenoble) and the backscattering instruments IN10 and IN16 (ILL, Grenoble). As I shall discuss, the experimental findings allowed to relate the intermolecular hydrogen bonding response to the dynamical behaviour of various molecular fragments, which justify the ability of the structure to different interactions. Such results are important to control polymorphism, shelf-life, processing properties and bioavailability.

Talk by Heloisa N. Bordallo