Structure and Dynamics in Disordered Solids

College Of William And Mary, Williamsburg VA

Investigators

Abstract

Professors Gina Hoatson and Robert Vold of the College of William and Mary are funded by the Experimental Physical Chemistry program to perform experimental Nuclear Magnetic Resonance studies on disordered solids. One project involves study of the structure, disorder and dynamics of amino acids and cyclic dipeptides in the solid crystalline form and as complexes in the hydrophobic cavities of cyclodextrin. The latter environment is intended as a model for biological systems. The issue of disorder in peptides and proteins is important since a number of systems such as amyloidiogenic proteins and membrane proteins all show significant disorder and are to date difficult to study. The other project involves the investigation of inorganic ferroelectrics. Some of these materials display exceptional piezoelectric and electronic properties, and the origin of these affects is not understood. Studies of mixed perovskites will test the hypothesis that ion disorder and motion are responsible for the unusual dielectric effects. The PIs propose to measure dynamic line shape and relaxation 2H NMR and 13C-15N REDOR distance measurements on the organic complexes. They also propose to use 93Nb/45Sc high resolution MQMAS studies on the inorganic relaxors. This work will allow understanding of the macroscopic behaviors of two classes of disordered solids, based on measurements that give microscopic details. The host-guest chemistry will be of interest to protein structure chemists, as they attempt to understand the structures of the many proteins still not solved. The perovskite work has potential impact on the development of new ceramic electronics materials. There is a considerable component in this work dedicated to developing new nuclear magnetic resonance methods that ultimately could be of benefit in the health and materials fields.