Porphyrins line width

The NMR spectra, which diflFer markedly from spectra for low- and high-spin iron (III) and low-spin iron (II) porphyrins in chemical shifts and in line widths, and infrared bands between 800 and 900 cm" have been particularly useful in estabhshing that FeOFe compounds can in fact be prepared from hemin A derivatives. For example, the diethyl ester, monoethyl ether derivative of heme A (Figure 15) when reduced... 

S — 5/2) reconstituted with 3,7-DF was characterized in order to evaluate relaxation mechanism in the protein with a variety of magnetic properties (Fig. 40). Since the fluorine atoms introduced to 3,7-DF are dynamically fixed to the porphyrin ring, analysis of the field strength dependence of the line width of the F signals provides the correlation time (tr) of the haem accommodated in the active site of Mb. 

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