Physical Poster Presentations

Solution & Solid State NMR Spectroscopy: Applications in Radiopharmaceutical Chemistry

Shank, Roxanne

• Roxanne A. Shank, Erik van Oosten, Neil Vasdez*, Michael Gerken*, Paul Hazendonk*
• Organization: University of Lethbridge
• Funding: UofL, CAMH, CFI, NSERC, ANPI

Abstract:

Solution state nuclear magnetic resonance (NMR) spectroscopy is a powerful structural tool. However, as new techniques emerge, solid state NMR is rapidly bridging the gap in structural studies. NMR has also proven to be a valuable method for probing the dynamics of molecules.

Dynamic information is particularly important when considering pharmacoactive compounds. For instance, beta-blockers are drugs which interact with beta-adrenergic receptors and are typically used in the treatment of maladies of the heart, liver, kidneys and brain. With the recent crystallographic characterisation of this receptor, structural studies have become increasingly important for this drug class.

In vivo imaging studies of these compounds in the body can be performed by Positron Emission Tomography (PET), which employs the use of [₁₈F]-labelled beta-blockers. Due to the short half-life of ¹⁸F, t_1/2 = 109.7 min, rapid yet highly stereo- and site-specific chemistry must take place. It was previously demonstrated that aziridine precursors offer a novel method for introducing the radio-isotope. The aziridine precursors were studied in order to determine if the internal dynamics of the molecule influence ring opening. The structure and dynamics of the ¹⁹F-labelled FIPA, Bz-2-FPA and 2 fluorinated derivatives of Toliprolol and Bisoprolol were also studied.

Multiple Quantum Filter NMR Spectroscopy of Hydrate Nafion Membranes

Vanderveen, Jesse

• Jesse Vanderveen, Mark Blackburn, Kristopher J. Ooms*
• Organization: The King's University College
• Funding: The King's University College, NSERC

Abstract: Proton exchange membranes (PEMs) are important components in hydrogen fuel cells and research on membranes will help to understand and improve their performance. To understand the structure of water in PEMs, ²H double quantum filtered(DQF) NMR spectroscopy was used as a tool for observing the structural changes that take place in hydrated Nafion PEM. Experiments were carried out on Nafion hydrated with D₂O using ²H DQF and zero quantum filtered(ZQF) NMR spectroscopy. The residual quadrupolar couplings, CQ values, which are related to signal build up, and T₂ relaxation times, which are related to signal decay, were calculated from the DQF spectra. Along with T1 relaxation times, these parameters provide structural and kinetic information about water in hydrated Nafion. Experiments were performed using Nafion at different hydration levels and the DQF and ZQF spectra were compared. The signal build-up and decay rates decreased with increasing hydration resulting in a decrease in maximum DQF signal intensity. This change corresponds to a structural change in the membrane which gives Nafion its conductive properties. ²H DQF NMR was found to be an effective tool for observing the structural changes in Nafion and describing the kinetics of protons in the membrane.