Phenyl-vinyl torsions

The role of the central bond torsion and of the double bond and phenyl-vinyl torsions in nonvertical triplet excitation transfer to stilbenes was stressed [83]. The... 

Results of calculation of potential energy curves for twisting about the central bond in So and Ti of stilbene were reported (Figure 4.5) [22]. The origin of nonvertical triplet excitation transfer and the relative role of double-bond and phenyl-vinyl torsions in stilbenes were described. 

Stationary point geometries on Bi So and Tj surfaces are presented in Figure 4.14. The crystal structure of t-Bi shows it to be strictly planar, eliminating phenyl-vinyl torsion toward planarity as a crucial NVET reaction coordinate. The authors emphasized that while experiment and theory support the initial proposition that double-bond torsion is the key reaction coordinate enabling NVET to stilbenes, as multidimensional surfaces are involved, other vibrations, including bond stretching, will also contribute. 

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