th  - 1988 - 51st ENC Conference

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176 I
Michael A. Kennedy and Paul D. Ellis
Department of Chemistry
University of South Carolina
Columbia, South Carolina 29208
SING~.CRYSTAL NMR STUDIES OF II3cD COMPLEXES
AND --SCD NMR OF CADMIUM PROTOPORPHYRIN IX AND
CADMIUM MYOGLOBIN.
For the past ~eral years, we have been involved in establishing a
understanding of ~Cd NMR chemical-shift-structure correlations throug
single crystal oriented NMR experiments. A major impetus for thes
studies has be~ 3 the desire to interpret chemical shift tenso
information for Cd substituted proteins. In the absence of adequat
single crystals, one must rely on trends established through singl
crystal experiments for interpretation. In the case of oxocadmiu
complexes, the following has been established; i) the least shieldeq
element is aligned most nearly perpendicular to the plane containin,
water oxygens, ii)two tensor elements having similar values must havq
similar orthogonal environments, iii) in the absence of water oxygen
the deshielded element is oriented to maximize the short-bond oxygel
shielding contribution, and iv) the most shielded element is most nearl'
perpendicular to the longest cadmium-oxygen bond. The results o
investigation of some mixed cadmium-oxo-nitrogen complexes and cadmium
oxo-halogen ~plexes will be presented here.
Also, Cd solid and solution state NMR for i) cadmium
protoporphyrin IX dimethyl esterl13a model complex for cadmium-myoglobil
and cadmium-hemoglobin, and ii) Cd-myoglobin will be presented an,
discussed. This work was supported by the National Science Foundation
grant #CHE86-11306, and the National Institues of Health, grant #GM26295
- - 177
I
Beth Crockett and Paul D. Ellis
Department of Chemistry
University of South Carolina
Columbia, South Carolina 29208
~E ADSORptiON OF Rb + AND Cs + TO TRANSITION ALUMINAS BY
"Rb AND ---Cs SOLID STATE NMR SPECTROSCOPY
8~ecently, in this lab, Cheng and Ellis have shown the effects on
the Rb I solid state nmr of varying coverages of RbCl adsorbed on 7-
iAlumina. Through this work, the following conclusions have been made:
IFirst, there are at least four different species present on the surface
fat sub-monolayer coverages of RbCl. Secondly, going from lower to higer
Icoverages corresponds to a relative decrease in the rate of growth of
the surface species compared to th~ salt specles. And thirdly, the
Rb ion motion in the interstitial sites
~ resence of water facilitates
f the surface, giving credence to the idea of adsorbate islanding.
In work to be presented here, we intend to show the effects of RbCl
and CsCI adsorbed onto aluminas with varying surface areas. These
transition aluminas are prepared by heating boehmite in a tube furnace
under N~, and their surfa~g area de~mined with a Quantachrome surface
area analyzer. Through U'Rb and - =Cs solid state nmr, the following
questions: how will going from higher to lower surface areas affect the
relative formations of the salt and surface species, and how will the
varying forms of the alumina affect the motion of the cations on the
surface, will be addressed. This work was partially supported by the
National Science Foundation, grant #CHE86-I1306.
i. Cheng, J. T. and Ellis P. D., submitted to J. Amer. Chem. Soc.