. Carotenoids. Carotenoids; Carotenoids. CHAPTER VII Relationships between the colour and constitution of carotenoids It has already been stressed that the yellow to violet colour of carotenoids is one of their most important characteristics. It is thus not surprising that repeated attempts have been made to elucidate the relationships between the colour and constitution of carotenoids and to employ absorption spectra for the characterisation and identification of polyene pigments. Many advances in this field have been made during the last 20 years and it is possible to-day to draw definite co
. Carotenoids. Carotenoids; Carotenoids. CHAPTER VII Relationships between the colour and constitution of carotenoids It has already been stressed that the yellow to violet colour of carotenoids is one of their most important characteristics. It is thus not surprising that repeated attempts have been made to elucidate the relationships between the colour and constitution of carotenoids and to employ absorption spectra for the characterisation and identification of polyene pigments. Many advances in this field have been made during the last 20 years and it is possible to-day to draw definite conclusions regarding the constitution of a carotenoid from its absorption spectrum. Conversely, certain changes in the spectrum can be predicted from a given change in structure^. Although carotenoids possess a relatively complex structure, the absorption spectra of these pigments are comparatively simple in character. In the visible region the spectrum usually consists of three, or occasionally four, absorption maxima and the position of the maxima is related in a relatively simple manner to the constitution of the pigments. In the ultra-violet region, the relationships between constitution and spectral properties are more complicated and it is. 2W0 2500 3000 3500 UOOO 4500 Fig. 3. Light absorption of xanthophyll in hexane solution 5000 XinS References p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Karrer, Paul, 1889-1971; Jucker, Ernst, 1918-. New York, Elsevier Pub. Co.
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