Conjugation chain, regularity

C. P. de Melo and R. Silbey, Non-linear polarizabilities of conjugated chains regular polyenes, solitons and polarons, Chem. Phys. Lett. 140 531 (1987). 

In recent years, significant improvement in the synthesis of electroactive polymers has been observed leading to the preparation of soluble conjugated polymers with high chain regularity. These two features... 

Attempts to establish a relationship between a c the length of the conjugated chains were made for K-doped PPP and polyphenylene oligomers. Oligomers from biphenyl to / -sexiphenylene were doped with K in THF, and it appeared that the conductivity was highly dependent on the chain length and increased with the number of monomer units, but not regularly. Furthermore, differences of structures in the case of p-... 

In a perfectly ordered solid or a perfectly ordered macromolecule excitons move according to quantum-mechanical kinetics, i.e., like wave packets. Because this requires strict phase relationships in space and time, this mode of motion, addressed in the literature as coherent motion of excitons, is perturbed by all deviations from regularity. Chains of conjugated polymers always include various defects such as kinks and torsions. These break the conjugation. Typically, regular sequences extend only over five to ten repeat units. The results of measurements for a series of oligomers like the ones displayed in Fig. 7.4 can be used for the estimate. The red shift of the exciton frequency to with increasing monomer number, n, can be described by the equation... 

The special properties of aromatic compounds and conjugated systems are related to the regular alternation of single and second-order C-C bonds along molecular chains. Each second order bond is associated with a balanced charge circulation and a couple of odd electrons with paired spins. The... 

---