Session WOF. There are 3 abstracts in this session.

Session: TUTORIAL SESSION, time: 4:00 - 4:40 pm

Magnetic Relaxaxation Dispersion: Why, How, What?

Robert G. Bryant
University of Virginia, Charlottesville, VA

The magnetic field or Larmor frequency dependence of nuclear spin-lattice-relaxation rates, 1/T1, maps the spectral power-density function and thus provides a fundamental characterization of the molecular dynamics in the system that modulate the magnetic interactions driving relaxation.  The MRD profile provides a direct experimental test of relaxation theory. Magnetic relaxation-dispersion measurements permit characterization of intra- and inter-molecular dynamics including molecular structural fluctuations, rotational and translational mobility, as well as the character of the dynamical restrictions.  After a brief review of experimental methods, a selection of applications from proteins, polymers, paramagnetic systems, and microporous materials will show that magnetic relaxation dispersion measurements provide information from the millisecond to picosecond range.  

Session: TUTORIAL SESSION, time: 4:40 - 5:20 pm

Ultra-Wideline Solid-State NMR Spectroscopy: Exploring the Periodic Table

Robert W. Schurko1, 2
1Florida State University, Tallahassee, FL; 2National High Field Magnetic Laboratory, Tallahassee, FL

Many NMR-active nuclei from elements across the periodic table have broad solid-state NMR patterns ranging from hundreds of kHz to several MHz in breadth. The broadening in these so-called ultra-wideline (UW) NMR patterns can arise from large anisotropic NMR interactions, including chemical shift anisotropy, quadrupolar interactions, paramagnetic interactions, and Knight shift anisotropy. In this tutorial, I will review techniques that are used to acquire ultra-wideline solid-state NMR patterns, including (i) field sweeps, (ii) frequency-stepping, (iii) Carr-Purcell Meiboom-Gill (CPMG) sequences, (iv) frequency-swept pulses, (v) broadband cross polarization, (vi) MAS techniques, (vii) indirect detection, (viii) probes with automated tuning, and (ix) combinations of these methods.

Session: TUTORIAL SESSION, time: 5:20 - 6:00 pm

NMR of Molecules and Biomolecules in the Presence of Paramagnetic Metals

Giacomo Parigi
University of Florence, Sesto Fiorentino, Italy

Paramagnetic ions introduce a contribution to the NMR shifts (called hyperfine shifts), to the J-splittings (called paramagnetic residual dipolar couplings - RDCs), and to the nuclear relaxation rates (called paramagnetic relaxation enhancements - PREs), which can be translated into long-range structural restraints. For nuclei far away from the paramagnetic center, the hyperfine shifts correspond to the pseudocontact shifts (PCSs). PCSs depend on the nuclear positions in a unique axis frame centered onto the paramagnetic ion, RDCs depend on the relative positions of coupled nuclei in the same frame, and PREs on the metal-nuclear distances. These paramagnetic restraints can be used to calculate and/or refine molecular structures and to recover information on the conformational freedom of the molecule.