The Effect Of Metal Ions/UV-Irradiation On The Third-order Nonlinear Optical Properties Of Pyrene And Bendiophene Derivatives

In recent years,organic materials with large π conjugate system have brought lots of concerns due to the advantages of easily control and cut. At present, lots of third order nonlinear researches focuseed on the phthalocyanine, porphyrin and their derivatives have been reported, while the compounds with big conjugate system such as pyrene and thiophene groups, people have paid less attention for their third order nonlinear research. In this paper, by using 1 - Pyrenecarboxaldehyde and 2,2’ -bithiophene - 5- carboxaldehyde as π conjugate group, react with different acceptors,we obtained two kinds of different compounds. Then the 1H NMR, 13C NMR, and high resolution mass spectrum proved that the synthesized compounds are consistent with the target products. In the following, the effects of the UV absorption spectra,UV light and the addition of metal ions on the third-order nonlinearity of the compounds were studied.In the study of third-order nonlinear of pyrene-based derivatives (1、2、3、4 and 5) using Z-scan method, it was found that the change of the acceptor fraction had a great effect on the third-order nonlinearity of the compound. Under the femtosecond Z-Scan, the third-order nonlinear absorption coefficient of pyrene-based hydrazone compounds(4 and 5) is higher than pyrene-based chalcone compounds(1, 2 and 3).The Z-scan under picosecond showed that the third-order nonlinear absorption coefficients of compounds 2 and 3 were higher than those of compound 4, and compound 1 and 5 did not observe the nonlinear absorption phenomenon in picosecond; When the pyrene-based derivatives were irradiated with ultraviolet light,the cis-trans isomerization was changed, and the UV spectra and third-order nonlinearity of the compounds changed; The addition of metal ions had a greater effect on the third-order nonlinearity of compounds 1, 2 and 3. some transition metal ions such as Ag+, Cd2+ and the addition of the main group metal Na+, Al3+ can reduce the third-order nonlinear absorption coefficients of compound 2. The addition of Cd2+、Fe3+ ions can respectively greatly improve the third-order nonlinear response of compounds 1 and 3, and modulate the third-order nonlinearity of the compounds.The picosecond Z-scan experiments of 2,2’-bithiophene derivatives(6、7、8、9、10、11、12、13 and 14) were also carried out, it was found that the third-order nonlinear absorption coefficient of the chalcone compound (6、7 and 8) was gradually increased with the increase of the number of nitrogen atoms in the acceptor. The third-order nonlinear response of the thiophene-based hydrazones compounds(9、10、11、12、13 and 14) are more complicated due to the influence of electron withdrawing groups: The hydrazone compounds (9 and 10) containing carboxyl groups have little effect on the carboxyl group position, and the compounds have no third-order nonlinear absorption phenomena. A fluorine atom-containing hydrazone compounds(11、12、13 and 14),with the increase of the number of fluorine atoms,the third-order nonlinear absorption phenomenon of the compound appeared from none (11) to yes,from the anti-saturated absorption (12) to the saturated absorption (13), and then to the anti-saturating absorption (14); In addition, both the dithiophene chalcone compounds and the dithiophene hydrazone compounds, due to the UV-irradiation,compounds occured cis-trans isomerization, which had different effects on the third-order nonlinearity: the third-order nonlinear absorption coefficient of the compounds 7, 8,12 and 14 after illumination were increased,the nonlinear absorption coefficient of compound 13 was decreased, after the UV-irradiation, and the compounds 6, 9 and 10 were not found before and after the light. The addition of metal ions can greatly influence the third-order nonlinear response of the bithiophene chalcone compounds;The addition of Cd2+ results in a third-order nonlinear absorption of compound 6, the addition of Ag+ can increase the third-order nonlinear absorption coefficient of compounds 7 and 8, and can be used as a good third-order nonlinear response ion.