Electroabsorption measurements of polysquaraine

We report an electroabsorption signal for the main IR-Vis absorption peak in thin films of polysquaraine. Spectra from 1.0 to 2.0 eV at a temperature of 10 K show a positive peak at 1.29 eV, followed by a negative peak at 1.35 eV with vibronic structure on the high energy wing. The results are discussed in terms of a Stark effect on molecular states. Using the results a Stark shift of about 1 meV is calculated, consistent with values for other pi-conjugated polymer systems

An investigation into the synthesis of polycarbazole squaraine derivatives

The polycondensation of squaric acid with 1,2-(9-Ethylcarbazol-3-yl)ethene and N-ethyliminostilbene in polyphosphoric acid yielded insoluble polymers which included substituted phosphate groups on the phenyl rings. The presence of phosphorus in these polymers was identified using solid-state P-31 NMR and EDAX techniques. Furthermore the phosphate groups were not ionic, hence no charge-balancing anions were present; Both polymers did not electrically conduct but exhibited dielectric breakdown values of 0.1 and 0.06 MV cm(-1) respectively

Second-harmonic generation in centrosymmetric crystals of chiral molecules

For centrosym. structures of chiral mols., the interaction with circularly polarized light gives nonzero 2nd-order susceptibilities. It is ascribed to transitions that are both magnetic and elec. dipole allowed. Exptl. demonstration is given of 2nd-harmonic generation from centrosym. crystals of R,S-N-acetylvaline (P21/c) using a fundamental wave having elliptic polarization in most parts of the trajectory through the crystal. These results demonstrate the existence of optical activity in the hyperpolarizability term b, similarly to the well-known optical-rotation phenomena in the linear polarizability. [on SciFinder (R)

SELF-DOPED WATER-SOLUBLE CONDUCTING POLYMERS

a-Terthienyl and pyrrole, substituted with alkylsulfonate side chains, can be polymd. electrochem. without the addn. of a conduction salt. This gives rise to self-doped conducting polymers and are sol. in water in the doped state. [on SciFinder (R)

POLY-1,4-DIKETONES OBTAINED BY THE STETTER REACTION - A NEW ROUTE TO CONDUCTING HETEROCYCLIC POLYMERS

Polymers with p-phenylene-2,5-pyrrole or p-phenylene-2,5-thiophene repeat units were prepd. by reaction of terephthalaldehyde and the bis-Mannich base of 1,4-diacetylbenzene (Stetter reaction), followed by heterocyclic ring closure with ammonia or Lawesson's reagent, resp. The polymers exhibited elec. cond. ?0.1 S.cm-1 upon doping with I or AsF5. [on SciFinder (R)