Conjugated polyene

Reductive elimination from 2-en-l,4-diol derivatives has been used to generate 1,3-dienes. Low-valent titanium generated from TiCl3-LiAlH4 can be used directly with the diols. This reaction has been used successfully to create extended polyene conjugation.305... 

Since 1987 numerous metallocenes, in particular ferrocenes, have been found to possess NLO properties, many of which have substituents containing polyene conjugate groups,72 Scheme 14. 

The table below shows the approximate wavelengths of light absorbed by a polyene conjugated system containing various numbers n of double bonds. Note that the colour absorbed is complementary to the colour transmitted—a red compound must absorb blue and green light to appear red. 

Streptomyces rosecflavus. which has the polyene conjugated to the lactone... 

Ultraviolet and visible light spectroscopy makes use of the quantized nature of the electronic structure of molecules. One example that is commonly observed by eye is the yellow color of polymeric materials that have been slightly degraded by heat or oxidation. Frequently this is due to the appearance of conjugated double bonds (5). For example, the 10-polyene conjugated structure absorbs light at 473 nm in the blue region. 

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