All-trans-Spheroidene in Solution

The Triplet-Excited Region of All-trans-Spheroidene in Solution and the Triplet-State Structure of 15-cis-Spheroidene Bound to the Bacterial Reaction Center Determined by Raman Spectroscopy and Normal Coordinate Analysis [18] 

36 I 3 Mechanisms of Cis-Trans Isomerization around the Carbon-Carbon Double Bonds via the Triplet State 

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The triplet-excited region has been spectroscopically identified in terms of carbon-carbon stretching force constants in all-trans-spheroidene in solution and in 15-ris-spheroidene bound to the bacterial reaction center (Fig. 3.16). Large changes in bond order are actually seen in the central part of the conjugated chain in both cases. The conformation of the reaction center-bound 15-cis-spheroidene in the T, state was determined to be (+45°, -30°, +30°) around the cis C15=C15, trans 03=04 and 01=02 bonds. 

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