Oligoenes

A special field of application of CD to oligoenes is that of some antibiotics, like filipin51 and amphotericin B52. These molecules are characterized by a strong tendency to autoaggregation, which causes the CD spectra to be strongly solvent, temperature and concentration dependent. In fact, in the presence of dimers, the CD is dominated by the appearance of a strong exciton couplet between the polyenic chains of neighbouring molecules. 

TABLE 3. Radiolytic yields of the final products of the radiolysis of cyclic oligoenes I. Liquid phase... 

Scheme 13 Ti-Catalyzed acyclic-cyclic carbometallation tandem reactions of dienes and higher oligoenes.

SCHEME 50. Synthesis of conjugated oligoenes via an iterative hydrozirconation-cross-coupling tandem process149... 

For example the SQMF was found very efficient in predicting the vibrational spectra of rotational isomers (e. g. cis and trans) of several molecules, provided the scale factors for the ground-state isomer are known [6,7,20-22], The transferability of the scale factors has been proven also for a large variety of molecules containing equivalent structural units like piridizine and dichloropy-ridazine [23], different polyenes and the corresponding oligoenes [24], naphthalene and anthracene [25] as well as many other systems. 

Figure 6. Dinuclear complexes containing oligoenes as bridging ligands.

The radiation chemistry of cyclic oligoenes was studied, and the radiolytic yields of the final products are summarized in Table 3, which shows that l, 4-cyclohexadiene differs from all others in its high yield of hydrogen, both in the gas phase and in the liquid phase. Cserep and Foldiak attributed it to the presence of two doubly allylic CH2 groups. In addition, the geometric orientation of the allylic hydrogens is favourable for hydrogen... 

Reference should also be paid to Launay s pivoting series of oligoene-bridged diferrocenes Fc—(CH = CH) —Fc, where n ranges from 1 to Careful redox... 

S. Hirata, H. Torii M. Tasumi (1995). J. Chem. Phys., 103, 8963-8979. Vibrational analyses of tra 5-polyacetylene based on ab initio second-order Moller-Plesset perturbation calculations of tranj-oligoenes. 

The shorter oligoenes have mainly been studied by gas electron diffraction, c.g, frans-hexatriene [159], Such studies provide molecular data, but no crystallographic information. 

Crystallographic data from substituted oligoenes, in combination with model calculations have also been presented by Enkelmann el al. [161]. Calculated energy differences between various packing arrangements in the cell are generally slight and therefore not conclusive. 

Sundahl et al. extended the scope of the isomerization of this type of molecule to the photoisomerization of oligoenes with three stilbene-like chromophores [100]. Although there are six isomers, the photostationary state consists of > 99% 24f, indicating that the photoisomerization of 24 always gives trans isomers in a one-way manner (Scheme 10). Furthermore, the conversions 24a - 24d, 24b 24e, and 24c - 24f take place adiabati-... 

Uan, T., and Yanagida, S. (2004) Phenyl-conjugated oligoene sensitizers for Ti02 solar cells. Chem. Mater., 16, 1806-1812. 

Figure 9. Gap between HOMO and LUMO orbital energy for various conjugated systems oligoynes, oligoenes, and fullerenes. The upper scale is for the oligoynes and oligoenes and the lower scale for fullerenes.

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