No abstract

We report two-photon absorption properties of newly synthesized compounds consisting of styrylpyridines or their triflates linked by a diacetylene p-bridge in a symmetric way as well as the compounds containing the same substituent groups linked by a phenylenevinylene-type p-bridge. Femtosecond open aperture Z-scan measurements revealed that the two-photon absorption cross-sections s (2) of the diacetylene compounds in DMSO were in the order of 10 248 cm 4 s molecule 21 photon 21 in the wavelength range of 650-800 nm. The largest value was found to be 8.50 6 10 248 cm 4 s molecule 21 photon 21 at 764 nm for the methoxy-substituted triflate of the diacetylene compound. This value is one of the largest values obtained for molecules of a similar size by use of femtosecond pulses, indicating that the incorporation of the diacetylene moiety as the p-bridge would be useful for two-photon dyes.

Two-photon absorption (TPA) properties of a series of cationic, linear π-conjugated systems with donor(D)/ acceptor(A) substitution have been examined systematically in terms of the type and length of the π-conjugation core and symmetric and asymmetric D/A-arrangement. The TPA spectra of the chromophores measured by the femtosecond open-aperture Z-scan method reveal that the double-bond core results in much more intense TPA than the triple-bond one, with a significant red shift of the TPA peak while the TPA becomes more intense as the chain is extended for the triple-bond core compounds with a little red shift. It is also found that the difference in the D/A-arrangement gives a small difference in the amplitude of the TPA spectrum although the spectral shapes differ considerably.

1,4‐Bis(4‐alkylpyridinium)butadiyne triflate (2a and 2b) that was prepared by the reaction of 1,4‐bis(4‐pyridyl)butadiyne (1) with alkyl trifluoro‐methanesulfonate, was found to grow into a large crystal as a result of the quaternized structure. The thermal treatment of 2a and 2b gave rise to 1,4‐addition polymerization to yield the polydiacetylene. The third‐order nonlinear optical susceptibility [χ(3)] of the polymer was determined by the femto‐second Z‐scan method to exhibit the remarkable high value of 1.1 × 10−11 esu at 650 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3686–3691, 2001